Dyna FM-3 User manual

.tJlYIVaCD
STEREOMATIC
MULTIPLEX
MODEL FM-3
This number must be men-
tioned
in all communications
concerning this equipment.
INSTRUCTIO· S FOR
ASSEMEiLV
ALIGNMENT
OPERATION
\
Price $1.00
(/-
929116
tJlYI\IdCD il\lc_ 3060 JeffersDn St .• Philadelphia, Pa.19121 U.S.A•

CONTENTS
Operating Instruction!> 3
Technical Description
....•..............•..... 4
General Wiring Practice .......................
.. 6
Assembly Instructions 7
Alignment Instructions
................•........ 16
240 Volt Power Transformer 19
In
Case of Difficulty 20
Service and Warranty
21
How to Make aFolded Dipole Antenna 22
Parts
list 22
Voltage Check Points 23
SPECIFICATIONS
BASED ON IHf STANDARD T-l00
Useable Sensitivity: 4 microvolts for total noise and distortion
30 db below 100% modulation
Signal-to-Noise Ratio: 70 db @ 100% modulation
Harmonic Distortion: less than 0.25% @ 100% modulation
Drift: less than 0.03%
Frequency Response: ± 0.5 db 10 cps to 15 KC
Capture Ratio: 5 db
Selectivity: 54 db
Audio Hum: 73 db below 1 volt output
AM Suppression: greater than 63 db
ADDITIONAL SPECIFICATIONS
1M Distortion:
Audio Output:
Output Impedance:
Discriminator Peak to
Peak Separation:
Antenna Input:
Dial Calibration Accuracy:
Power Consumption:
less than 0.5% from 10 microvolts to
100,000 microvolts @ 100% modulation
2 volts @ 100% modulation
less than 5000 ohms
grea ter than 900 KC
300 n balanced
75 n unbalanced
0.2%
55 watts
STEREOPHONIC PERFORMANCE
Useable Sensitivity: 3 db less than mono mode
1M or Harmonic Distortion: less than 1% (including 19 KC and 38 KC
residual)
Separation: 30 db

THE FM·3 DYNATUNER
Your FM-3 Dynatuner is one of the most thoroughly
researched and field tested components in the h.igh fidelity
industry. More than four years of engineering effort have
been devoted to this one design with two specific goals in
mind: one, performance which cannot be improved at the
present state of the art; two, assurance that this perform-
ance level can be achieved and maintained by the user in
the home.
Side-by-side
listening comparisons of the Dynatuner
with tuners several times its cost demonstrate the great
extent to which these goals have been aChieved. Published
specifications cannot define the clear superiority of the
Dynatuner in low distortion reception of both very weak
and exceedingly powerful signals, its remarkable freedom
from the problems of cross-modulation and severe multi-
path effects, its high order of suppression of impulse-type
interference, its exceptional capacity to handle severely
overmodulated signals without distortion, and its unique
ability to maintain full stereo separation with the weakest
signals.
These comparisons can be demonstrated using Dyna-
tuners built and aligned by novice constructors, and it is
this that represents a fundamental difference from other
designs. The Dynatuner is a fresh engineering concept, not
an adaptation of an existing production unit. Every portion
of the circuit has been carefully investigated in terms both
of performance maxima and of the overall stability of
operation and simplicity of adjustment required of a kit
design. The net result significantly surpasses on all counts
units which require that certain sections be pre-built and
aligned, and which are therefore incapable of complete
home alignment.
The Dynatuner provides the same top performance in
your home as in the laboratory, as it can always be
properly aligned using the unique procedure detailed later
in this manual. This ability to be aligned without test
equipment, with an alignment as accurate as can be per-
formed in the laboratory, means that aiter shipping, after
aging, after tube replacement, or after any other cause for
change in alignment, the unit can be restored to peak
performance.
In addition to the adjustment requirements, the basic
engineering objective was to produce a tuner with sufficient
sensitivity for fringe area reception, with distortion levels
of the recovered audio signal comparable to that measured
on the best of audio amplifiers. The concentration of effort
to
reduce distortion of all types has produced a tuner
which is unquestionably one of the very lowest distortion
tuners available at any price.
The significant advantages of etched circuit construction
in terms of reliability, reproducibility and durability are
amply demonstrated in the Dynatuner. Their use has
further accomplished the ultimate goal of improved per-
formance. In no other tuner-kit or factory wired-bas
exact component placement and lead layout been so ac-
curately defined. Tbe excellent specifications of the Dyna-
tuners are possible, and guaranteeable, unit to unit, lab
model to production kit, because of tbe extraordinary uni-
formity which etched circuits provide, and the inherent
stability of the circuit configuration.
There has been no intent to enter the s2nsitivity speci-
fication
race (claims often engineered by the advertising
department). However, using the sensitivity standards pro-
posed by the Institute of High Fidelity, this tuner belongs
in the highly sensitive class and, in fact, will provide
listenable reception of more stations than tuners of osten-
sibly higher sensitivity rating.
There are many parameters in addition to sensitivity
and distortion which are part of a completely satisfactory
tuner design. Some are measurable; some are intangible.
The design requirements for a premium quality kit lead
automatically to a distinctly superior factory assembled
tuner as well. Extensive field testing under adverse and
marginal conditions has proven the Dynatuner to be as
fine a tuner as can be obtained today regardless of price
or specification claims.
Operation of 'he Controls
Operation of your FM-3 is remarkably simple. Its highly
refined engineering combines the performance of far more
costly and complex FM tuners with the operating ease
which has become a Dyna hallmark. The elimination of
front panel adjustments and controls is possible only
through exhaustive engineering research to accomplish
their objectives by automation, freeing the listener to enjoy
exceptional FM reception.
The function of the power switch is obvious. This switcb
also controls the AC outlet on the rear of the tuner so that
it is possible, if desired, to turn both tuner and amplifier,
for
example. on and off simultaneously if no preamplifier
is used. It is also possible when using the Dynatuner with
equipment which has additional switching facility, such as
the Dyna PAS preamplifiers or SCA-35 amplifier, to leave
the Dynatuner power switch "ON", and use the amplifier
for all switching,
The tuning knob is used to select stations. When the
station is correctly tuned, the lower tuning eye will close
to its
maximum. Always tune astation while watching the
tuning eye, rather than trying to set to aprecise frequency
on the tuning dial. The eye is designed so that it will never
overlap, but at any signal strength, there will be asingle
point of correct tuning. At this point you will receive the
station with lowest distortion, maximum noise rejection
and maximum separation of a stcreo signal.
The tuning eye will indicate maximum closure with a
signal strength below 20 fLv, yet higher signal strengths
will not overlap it. The precise center of channel is always
apparent-there is no "flat spot". It will indicate signals
as weak as 1 fLv, but these signals are likely to fluctuate
widcly. Normal center channel indication may be anywhere
between lit division and 3divisions gap on the reference
grid, depending on the particular tuner, and signal strength.
Once a station is tuned, the upper beam, or STEREOCATOR,
will indicate immediately whether or not the broadcast is
in stereo. Betwecn stations the STEREOCATOH may light or
flicker. There can be no confusion as to whether or not you
are listening to a stereo broadcast if you tune for closure of
the lower tuning eye first, and then observe whether or not
STEREO is lighted above it.
The STEREOCATOR operates from the 19KC pilot signal
which is an integral part of all stereo broadcasts. Occa-
sionally there may be instances where a station neglects
to tum off this 19KC pilot when it reverts to monophonic
programming, and this will give you an erroneous STEREO
indication. Noise on extremely weak signals (there is some
19KC in random noise) and also 19KC harmonics in tbe
program material may cause some flickering of the
3

STEREOCATOR during mono reception, but this is of no
consequence.
The volume control knob actuates a push-pull Stereo-
matic/Mono switch. When the knob is pushed "IN", the
Dynatuner will switch to full separation stereo operation
when tuned to a stereo signal, and will automatically revert
to mono operation (through both channels) on mono
broadcasts. The normal position of this control is "IN".
It may occasionally be desirable to disable the Stereo-
rnatic feature, and for this, the tuner can be locked in mono
operation by pulling the volume control "OUT". This will
enable you to make monophonic recordings of stereo pro-
grams, or to eliminate spurious interference on a mono
broadcast. Sometimes a very weak station can be received
with less background interference by operating the tuner
in the mono mode. The tuner will still indicate STEREO
when you are tuned to a stereo broadcast, but in other
respects reception will be identical to a purely monophonic
tuner. This switch does not change the tuner in any obvi-
ous way-the sound level, frequency response, and distor-
tion are the same.
The volume control is used primarily to set the level of
the Dynatuner to match that of other program sources, so
that when you switch your control amplifier's inputs, they
are heard at comparable levels. Normally in this usage,
the Dynatuner's volume control will be operated at %
clockwise rotation or higher. If the tuner is used with a
basic power amplifier only, such as the Dyna Stereo 70 or
Stereo 35, then this operates as a conventional volume con-
trol for the system.
Installation
There are two audio output sockets on the Dynatuner.
The socket marked "A" on the bottom plate (the one near-
est the line cord) is the left channel output. The "B"
(outer) socket is the right channel output. The two
shielded cables supplied (or similar type up to 25 feet in
length) should be connected between these sockets and
the "Radio" input (sometimes marked FM-MPX, or
FM-AM) of the control amplifier or preamplifier. The
Dynatuner can be connected to any audio input of 100,000
ohms or higher input impedance which can accept signal
levels between one and two volts.
The Dynatuner can also be connected directly to any
basic power amplifier which has an input sensitivity of
less than 2volts for full output. The amplifier may be
connected to the switched AC outlet on the Dynatuner,
and the volume level would be adjusted with the tuner's
volume control.
The Dynatuner's line cord should be plugged into an
AC receptacle furnishing 120 volts of 60 cycle current (120
or 240 volts at 50 or 60 cycles with the PB-012 optional
power transformer).
Antennas
Every FM tuner requires an antenna. For some metro-
politan area use, a twin lead folded dipole is adequate for
local station reception. Instructions for making one from
the flat wire included with the kit are given in a later sec-
tion of this manual. The television type known as "rabbit
ears" is also suitable if fully extended. Either of these
antennae should be rotated for best reception, and their
most favorable orientation may vary with different stations.
The normal antenna lead-in wire is 300 ohm twin lead,
similar to that supplied with the kit. The two leads should
be connected to the two outermost antenna screw terminals,
4
leaving the center terminal unconnected. In difficult recep-
tion areas, it is sometimes necessary to use coaxial cable
for the antenna lead-in. The Dynatuner has provision for
using 75 ohm coaxial cable by connecting the shield of the
cable to the center antenna screw terminal, and the center
conductor of the cable to either of the outer screw terminals
(but not both).
An outdoor FM antenna is always better than an indoor
one, particularly if reception is desired over long distances.
Stereo reception is also more critical of antennae than
comparable mono results. High gain antenna arrays are
available for fringe area reception. These are preferable to
the "omni-directional" or "non-directional" type, but
should preferably be used with arotator. Your dealer can
advise you on the use of these antennae, or you can write
to antenna manufacturers for detailed information.
You should realize that when difficult reception condi-
tions are encountered, improving the antenna will have far
more effective results than any other remedy, including
attempts to improve a tuner's sensitivity. The extreme
sensitivity of the Dynatuner, coupled with its exceptional
limiting action on very weak signals, may well enable you
to listen to stations you have not received before, when this
tuner is coupled with a properly designed antenna.
Mounting the Dynatuner
The Dynatuner, like all electronic devices, generates
some heat. Because the tuner has been designed with the
cover as an integral part, the unit in effect creates its own
thermal environment, and adequate allowance has been
made in the design for this normal temperature rise. Its
heat is equivalent to a60 watt light bulb and, therefore,
adequate ventilation is required. There should be amini-
mum of three inches of air above and behind the Dyna-
tuner. Never put anything on top of the case while the
tuner is operating. When stacked with the Dyna PAS pre-
amplifier, the tuner must be installed above the preampli-
fier. The preamplifier does not require ventilation. The
tuner cannot be stacked above the Dyna SCA-35 amplifier.
When mounting the Dynatuner in a panel or cabinet,
consideration must be given to adequate air flow, particu-
larly if other heat-producing devices, such as amplifiers,
are also in the same area. In restricted space, and particu-
larly
if the tuner must be mounted face up, it is essential
that a small circulating fan be used. The warranty on the
Dynatuner is void if it has been abused through inadequate
ventilation.
It is simple to install the Dynatuner in any panel up to
l" in thickness. A supporting shelf should be installed flush
with the bottom of a 13Y16" x 3l~G" cutout, and the rubber
feet are not used. A PBK bracket kit is available from
Dynaco for $2, which takes the place of the shelf. No
C.O.D.s please. If it is desired to mount the Dynatuner
and the Dyna PAS-3 in asingle cutout, the rubber feet are
used on the· tuner, which is mounted above the preamp,
and the cutout should be made 7J 0/16" high by 13YJl' wide.
TECHNICAL DESCRIPTION
The circuit features which distinguish the FM-3 can be
described only in somewhat technical terms. Those not
interested in the technology may ignore this section.
The FM-3 has the following basic tube and circuit se-
quence:
1. A cathode coupled tuned R.F. amplifier using a
6AQ8/ECC-85 dual high frequency triode.

2. An oscillator-mixer stage using a 6AT8A high con-
version
triode-pentode with screen injection.
3.
Four I.F. amplifier stages with progressive limiting
using two 6BA6 pentodes and two 6AU6 pentodes.
4. A symmetrical wide band discriminator with matched
semi-conductor diodes.
5. A
cathode follower providing discriminator isolation
and low impedance source to the multiplex and audio
channels using one-half of a 12AX7jECC-83.
6. Afeedback audio amplifier using one-half of a
12AX7jECC-83.
7. A 19KC amplifier and doubler using a pentode-triode
6BLBjECF-80.
8. A balanced bridge synchronous detector using four
matched semi-conductor diodes.
9. Stereo audio output stages consisting of feedback plate
followers using a 12AX7 jECC-83.
10. A dual indicator EMM-801 acts as a tuning eye and
as astereo indicator.
11.
The power supply, which uses a 6V4jEZ-80 full wave
rectifier.
The Antenna Circuit
Provision is made to match either a75 ohm unbalanced
or a300 ohm balanced transmission line, thus accommo-
dating any standard antenna array used for FM reception.
The R.f. Stage
The cathode coupled dual triode R.F. amplifier circuit
was chosen for the input stage. It combines the high gain
and low noise figures of the commonly used grounded grid
input with a tuneable input-a necessary feature to pre-
vent overloading from strong signals which might cause
cross-modulation and spurious responses.
The Oscillator-Mixer
The triode section of the 6AT8A is used in a "tickler
feedback" tuned grid oscillator circuit. Careful temperature
stabilization and choice of operating parameters result in
an oscillator circuit with sufficient stability to obviate any
need for automatic frequency control with its inherent
degradation of the audio signal.
The pentode section of the 6AT8A is used as the mixer.
The oscillator is injected into the screen circuit to provide
complete isolation of the oscillator tuning circuit from the
signal tuning circuit at the mixer grid. Oscillator drag
(change in oscillator frequency as the mixer tuning is ad-
justed) is virtually nonexistent, grea't1y simplifying the
adjustment and tracking of the fiont end. This isolation
also reduces re-radiation of the oscillator energy into the
antenna which might cause interference in other nearby
receivers and television sets.
Circuit constants of the oscillator and mixer circuits
have been adjusted to give uniform sensitivity over the
entire FM band.
The I.f. Amplifiers and Limiters
Phase shift in an FM signal corresponds to amplitude
non-linearity or distortion in an AM signal or in an audio
amplifier. Accordingly, the I.F. amplifier circuits were de-
signed for minimum phase shift across the pass band.
Since this occurs with undercoupled transformers, the
alignment of the I.F. section is greatly simplified. Simple
peak tuning (tuning for maximum signal) is the optimum
adjustment for the undercoupled I.F. transformers. This
minimum phase shift approach maintains low distortion of
the audio signal all the way down into the noise and per-
mits useful reception of weak signals even without full
limiting action.
A 6BA6 variable-mj.L pentode is used for the first and
second I.F. stages, and 6AU6 sharp-cutoff pentodes are
used for the succeeding two stages. Each I.F. stage acts as
a limiter when the signal input to that stage reaches apre-
determined point. Thus no automatic volume control cir-
cuit is needed and no additional recovery time constants
exist to introduce delay on fading signals. There is suffi-
cient gain in the receiver so that the last limiter is effective
on input noise.
The Discriminator
A symmetrical discriminator configuration is used in
place of the conventional unbalanced circuit. This circuit
balances out any noise and signal rectification occurring in
the plate circuit of the last limiter tube and is the key to
the phenomenally low distortion figures achieved by the
Dynatuner. Awide band discriminator transformer and
matched semi-conductor diodes are used to obtain the full
benefit of
this design.
The balancing action of this circuit reduces the inter-
channel noise (between stations) by a factor as great as
10 db in level over many conventional tuners which use
limiter-discriminator circuits.
The discriminator signal goes first through one-half of a
12AX7 functioning as a cathode follower and then through
the second half of this stage which is used as an audio
amplifier with plate to grid feedback. The output of the
cathode follower also is used as asource to a portion of
the multiplex circuitry.
The Multiplex Integrator
The first portion of the multiplex section is fed from the
cathode follower. This signal is Q-multiplied and amplified
at 19KC in the pentode half ot the 6BLB. Then it is
further amplified and doubled -to 38KC in the triode sec-
tion of this tube. This triode section also acts as alimiter,
holding a
constant 38KC level regardless of signal strength
and pilot amplitude. Such limiting greatly reduces noise
through the stereo "gates" and preserves equally good
separation at all level signals.
The audio signal from the plate circuit of the 12AX7 is
shaped in a 67KC band reject filter. Then it is mixed with
the reconstructed 38KC signal in a balanced transformer.
Afour-diode
bridge provides synchronous detection of left
and right channels which then are passed through acom-
bined
38KC rejection filter and audio de-emphasis network.
Asignal from the
19KC amplifier section is used to acti-
vate the upper beam of the EMM-801 tuning eye which
illuminates the word STEREO when there is a stereo trans-
mission.
The action of the multiplex section is automatic as the
38KC channel is quenched in the absence of a pilot signal
from the broadcast station. However, it can also be shifted
to locked mono reception by use of the push-pull Stereo-
rnatic-mono switch which can deactivate the automatic
stereo feature.
The Audio Section
A 12AX7 is used for audio output, with one half for each
stereo channel. This tube has plate-to-grid feedback and is
used as a plate follower. It has low impedance output, per-
mitting up to 25 feet of shielded cable. It has very low
distortion and minimum frequency discrimination.
5

nection almost immediately. Solder should then be applied
directly to the parts to be soldered, as shown in the middle
illustration above, and both iron and solder removed as
soon as the solder flows freely.
When soldering apart to the etched circuit board, the
solder
must completely surround the wire lead where it
comes through the board. Do not
apply excessive solder, but
do not hesitate to
apply sufficient heat to assure a smooth
(low of solder all around the lead and onto the board.
, i
WRONG
One of the best ways to make agood mechanical con-
nection is to bend asmall hook in the end of awire, and
then to crimp this hook onto the terminal to be connected.
The amount of bare wire exposed at the end need not be
exactly 11i-inch; however, if it is too long, there is danger of
the excess touching another terminal or the chassis. There
is no need to wrap the wire around the terminal more than
one time, as this makes a connection that is much more
difficult to remove if an error has been made.
To transfer heat from the iron to the wire and terminal,
the tip of the iron should be kept brightly tinned with
solder. If this is properly done the first time the iron is
used, the tinning may be maintained by wiping the tip with
acloth or sponge every few minutes while soldering. When
correctly tinned, the tip will heat both parts of the con-
The circuit boards are connected to other sections of the
Dynatuner by soldering wires to eyelets on the boards. To
solder awire to these numbered eyelets, first "tin" the
bared wire py heating it with the iron and flowing solder
over it. Insert the wire into the eyelet, and heat both the
eyelet and the wire while applying solder to the junction.
A correctly made connection looks like the illustration at
the right, above, which shows a smooth transition from the
eyelet to the wire and to the board.
GENERAL WIRING PRACTICE
When you unpack the kit, first check the components
against the parts list. You can identify unfamiliar compo-
nents by matching them to parts illustrated in the pictorial
diagrams supplied.
Have the proper tools at hand before beginning to build
your kit. You will need a pencil-type soldering iron of 30-
to 60-watt rating; long-nosed pliers; diagonal cutters; and
ascrewdriver. If you have asoldering gun, it should be used
with care, especially when working on the circuit board,
because of its higher than necessary heat output. Although
not essential, awire-cutting and stripping tool will help
considerably; these are available for less than adollar.
The only procedure involved in building a Dynakit
which requires a bit of technique is soldering, and this is
quite easy to master. There are four steps to making agood
solder cOTU1ection:
1. Make agood mechanical connection.
2. Heat both parts of the connection with the iron.
3. Apply solder to the connection until it melts and
runs.
4. Allow the connection to coo) undisturbed.
ALL SOLDERING MUST BE DONE WITH ROSIN
CORE SOLDER.
There is no warranty on any equipment in which acid
core solder has been used. Make Sure that the solder you
use is plainly marked "ROSIN CORE." Do not use cheap
solder or solder of doubtful origin. Recommended solder is
60/40 (60% tin, 40% lead) rosin core.
Whenever one (1) wire is to be soldered to aconnection,
the instructions will indicate this by the symbol (S). When
two (2) wires are to be soldered to aconnection, the sym-
bol (S-2) is shown; when three (3) wires are to be soldered,
the symbol (S-3) appears, etc. There may be as many as
five (5) wires to be soldered to aconnection. If no symbol
is shown, do not solder; further wiring will be made to that
cOTU1ection before soldering.
Components can be identified by comparison with the
pictorial diagrams. Capacitors are individually marked.
Resistors will be marked either with their values, or with
the color code specified in the instructions. The first color
is nearest the end of the resistor, and any fourth color band
may be ignored.
A number of steps in the instructions begin, "Connect
one end of awire ... ", with the length of the wire specified.
In each case, first cut apiece of wire to the correct length
from the roll supplied with the kit, and then remove about
114/1 of insulation from each end before making the connec-
tion. The leads on components should be trimmed as they
are used, the length chosen being that which permits acon-
nection to be made from point to point without strain on
terminals or components. The position of all wire leads
should follow that shown in the pictorial diagram as closely
as possible. Care must be exercised to see that uninsulated
wires do not touch each other, and cannot do so through
vibration or sagging, unless, of course, they are cOTU1ected
to the same point. It is especially important that uninsu-
lated wires and component leads or terminals do not touch
the chassis or bottom plate accidentally.
Check your work after each step, and, when you are sat-
isfied that it has been correctly done, mark the space pro-
vided and go on to the next step. Examine the pictorial
diagrams often; if you check your work methodically, your
Dynakit should work as soon as the wiring is complete.
6

ASSEMBLY INSTRUCTIONS
You will first assemble the three etched circuit boards
PC-7, PC-8 and PC-12, and then mount these and other
components on the chassis and complete the wiring. The
use of protectively coated circuit boards in the Dynatuner,
on which most of the components are mounted, greatly
simplifies assembly of the kit, and contributes consider-
ably to its outstanding performance. Close attention to the
suggestions made here will enable you to realize the fullest
capabilities of the Dynatuner.
On each etched circuit board all of the cOlll.ponent posi-
tions are diagrammed on the top of the board (the side
without the copper). The identification symbol for each
component is marked between the holes into which its leads
will be inserted. Resistors may be identified from the color
code on the parts list. The first color stripe is nearest the
end of the resistor. Any fourth color stripe may be ignored.
Each capacitor 'is marked with its value and any special
characteristics. Other special components will be identified
as they are called for in the assembly process. To speed
assembly, it is suggested that you first compare the com-
ponents with the parts list and sort them accordingly. The
edge of a corrugated box makes a handy storage rack for
resistors and small capacitors.
Before starting assembly of the etched circuit boards,
observe detail A. A GOOD SOLDERING JOB IS ESSEN-
TIAL TO THE SATISFACTORY PERFORMANCE OF
YOUR TUNER. Soldering to etched circuit boards is eas-
ier than conventional point-to-point wiring when it is done
correctly. The copper side of each Dynatuner board is
coated with a corrosion inhibitor which is also conducive
to soldering, but there is no substitute for good soldering
technique.
SNIP OFF EXCESS LEAD I
CORRECT SOLDER
CONNECTION
NOTE BODY OF RESISTOR IS PRESSED TIGHT
TO BOARD. MAKE SOLDER flOW SMOOTHLY
FROM LEAD TO COPPER. SNIP OfF EXCESS
LEAD CLOSE TO SOLDER.
DETAIL A
Be sure that enough heat reaches both the copper on the
board and the wire to be soldered to make a smooth solder
junction. When making connections to the eyelets, be sure
that the solder flows from the wire to the board, across the
eyelet, so that the eyelet is soldered to the wire and to the
board at the same time. Tlw insulating wax or enamel used
on the leads of some components (capacitors, chokes) may
prevent good contact when these leads are soldered, if all of
the insulation has not been removed from that part of the
lead which is to be soldered. Avoid getting solder on the
outer }S" edge of the boards. This area contacts the chassis
when the boards are installed and solder splashes here will
prevent ~miform contact, stressing the board.
ASSEMBLY OF THE R.F. CIRCUIT BOARD PC-7
l( J Position the PC-7 etched circuit board in front of
you as in the pictorial diagram. Support the board
over an open box or between two objects so that the
leads from the components may project through.
Insert all of the one-half watt resistors in their
places on the circuit board. To bend the leads of
each resistor to the correct shape, hold the resistor
between the thumb and forefinger of one hand and
bring the thumb and forefinger of the other hand
just across the ends of the body, bending the leads
as in detail B. It will help in rechecking your work
to orient the color codes of all resistors uniformly.
Spreading the leads slightly after installation will
hold the resistors flush to the board, so that they
will stay in place when the board is inverted for
soldering.
Solder each lead with a small amount of
solder. The solder should flow smoothly all around
the lead on to the copper. Cut off all excess leads.
Be careful not to allow the lead to form abridge to
another portion of the circuit.
DETAIL B
After soldering, there should be no space between
the bodies of the resistors and the top of the PC
board. If there is, the resistor should be gently
pressed to the board while the soldered leads are
reheated, until the resistor is flush with the board.
This also applies to other components mounted in
the following steps.
2(')) Insert the 3.9 microhenry choke L2 and the heater
choke L5. Insert aU the one watt resistors. Do not
confuse the larger 2 watt, 10,000 ohm resistors to
be used on PC-B with the one wall resistors used
here. Insert the 2.2 mmfd tubular capacitor Cll
(red-red-white-gray dots). Invert the board, solder
each lead of these components and trim off the
excess.
3
(;; Insprt the two 9pin sockets VI and V2. Note the
location of the flat side of each socket. Be certain
that each lab goes into its hole and dor:s not bend
over on top of the board. Seat each socket firmly
to
the board and then solder each pin and the cen-
ter ground pin.
7

TlGHTlN HNSION NUl fiRMLY
WITH LONG·NOHO PurRS
SOLO£R 3 CORNUS OF HN510H
NUl TO CIRCUIT aouo
MOUNTING CAPAC.lTOR C8
%" screw in the hardware bag. Be sure that the
points of the nut face away from the screw head, and
run the nut out on the screw so that it is at least 1;2"
from the head. Insert the tabs of the capacitor into the
matching cutout on the board. Note the location of the
wire lead. Hold the capacitor firmly against the board,
and turn the screw in from the bottom (see detail
"D") until the spring tension nut is firmly seated.
Now tighten the nut with long-nosed pliers, while
pressing the capacitor to the board. The points of
the nut must dig into the copper so that the capacitor
mounting is absolutely rigid. Solder the nut to the
board at three points. Insert the top lead of the
capacitor into the hole indicated in the pictorial,
keeping it as short as possible, and solder the lead.
7( j) Mount the special temperature compensating ca-
pacitor C7 (2.55 nunfd N2200, with six color
stripes) as shown in the pictorial. Make sure it is
seated
snugly against the board and against the
tube socket.
Solder both leads.
8( J) Mount the I.F. transformer Tl (one of the four
marked 432001) on the board. Note the indicator (a
slot or color marking) in one corner of the top of the
can. Be sure to mount the transformer with this indi-
cator oriented as shown in the pictorial. The trans-
former should snap into place and seat firmly against
the board. Solder the mounting tab next to C12 first,
but do not solder the other mounting tab. Solder
each of the four cormecting lugs. Avoid excessive
heat, but be sure agood connection is made. Do
not use too much solder, to prevent any excess from
running into the transformer and damaging it.
g( ,}) Observe the direction of the offset in the ground
straps as shown in the pictorial diagram. Insert the
ground straps into their slots in each of the tube
sockets. Solder both to the board ..
W() ) Insert a round toothpick or similar instrument into
eyelets #2 and #4 from the bottom of the board.
The purpose of this is to prevent solder from filling
these eyelets. Now solder the eyelets to the copper
on the board and remove the toothpick. (These
eyelets may already have been soldered when you
receive the board.) Be certain agood connection is
made all around each eyelet as this will be diffi-
cult to check later. Insert the two heavy leads of
the antenna coil L\ into eyelets #2 and #4. Note
that this coil is mounted on the bottom of the board,
and is oriented to align the center slug with the
hole in the board. Solder the two leads to the eye-
lets on the top of the board. It may be necessary to
scrape the coil leads, or to ream the eyelets slightly
if the inside of the eyelet is not perfectly free of
solder, as this is a very snug fit.
t
fJ
. '~
•
c:
,
4( J) Refer to the pictorial diagram, the parts list for
PC-7, and the values marked on the individual ca-
pacitors. Insert all the disc capacitors as shown in
detail C. Make certain that the body of each capac-
itor touches the board. Bend the leads slightly to
prevent them from falling out when the board is
inverted for soldering. Solder all leads.
NOTE CAPACITOR BODY
TOUCHES BOARD.
DETAIL D
6( J) The oscillator trimmer capacitor C8 is awhite tubu-
lar ceramic form with a #6 screw and special spring
tension nut. The nut is supplied threaded onto the
DETAIL C
5 (I ) Mount the oscillator coil lA (the one with four
leads at the bottom) in the group of four holes in-
dicated. The two heavier leads are inserted in eye-
lets #10 and #11. Mount the mixer coil 1.3 (the
one with only two leads at the bottom and none at the
top) in eyelets #7 and #8. Be sure it is oriented
as shown in the pictorial diagram. See that each
coil form is seated firmly to the board and solder
all six coil leads; the eyelets must be firmly sol-
dered to the coil leads and to the copper foil.
8

ASSEMBLY OF THE I.F. CIRCUIT BOARD PC-8
1( J) As before, support the board on an open box or
between two objects so that the leads may project
below the board as you insert components. Insert
all of the one-half watt resistors, after bending their
leads as before. Be sure all the resistors are seated
firmly against the board. Tum the board over and
solder all of the leads. Cut off the excess.
J
2(,j ) Insert the one watt resistor R22, the two watt resistors
Rll and R13, and the four heater chokes L6, L7,
L8 and L9. Solder these in place and trim off the
excess leads.
3( j) Mount the four seven pin sockets V3, V4, V5 and
V6. Note the orientation of the flat side of each
socket. Be sure each pin penetrates the board and
does not bend over on top of the board. Make sure
that each socket is seated firmly against the board
and then solder all seven pins and the center ground
pin of each socket.
4
(/; Mount the nine pin socket V7. Be sure each pin
penetrates the board
and does not bend over on top
of the board. Seat it firmly, and solder all nine pins
and the center ground pin.
5
(J) Install capacitors C29 and C31. Solder all four leads
and cut off the excess.
6
(J) Install all of the disc capacitors. As before, the leads
of these capacitors
may be bent slightly to hold them
in place, but be careful that no "bridges" are formed
to
adjacent parts of the circuit. Solder all leads and
cut off the excess.
7(
I) Install PEC 555004, making sure that it is correctly
oriented.
Solder all three leads and cut off the excess.
8( J)
Insert the remaining I.F. transformers T2, T3 and
T4 (all 432(01). Follow the location of the indi-
cator at the top of each transformer as shown in the
pictorial. Solder both tabs and all four lugs on each
transformer. Avoid excessive solder, which may
flow into the transformer and damage it. The dis-
criminator transformer
T5 will be mounted later.
9(
J) Note the orientation of the offset in the ground
straps and install them in each tube socket. Solder
these ground straps.
LO ( V) Install the pilot light socket. Observe that the con-
necting
tab from the socket center contact goes into
the hole adjoining eyelet #20. Do not install it
backwards! Solder both tabs.
ASSEMBLY OF THE MULTIPLEX BOARD PC-l 2
1( J) Insert the one-half watt resistors R71 through R93
in their places on the board after bending their leads
as before. Solder aU leads and cut off the excess.
2
(J) Insert capacitors C71 through C84 in their places
on
the board. Solder all leads and cut off the excess.
NOTE: It is necessary to spread the leads of C76 to fit their hole
spacing.
3 ( J) Insert the two 9-pin sockets V71 and V72. Note the
orientation of the flat side of each socket. Be sure
each
pin penetrates the board and does not bend
over
on top of the board. Seat each socket firmly to
the board and then solder all nine pins on each
socket. Do not solder the center ground
pin on
either socket at this time.
4 (rviInstali the small wooden wedge under the choke
L71,
and install L71 so that the thick part of the
wedge is adjacent to C81 when the choke leads are
inserted into the board. Solder both leads and cut
off the excess.
5(
v) Mount the transformers T71 and T72 (432003). Be
careful
to orient these correctly. Make certain that
the indicator
on top of the transformer coincides
with the heavy dash on the board and with the pic-
torial.
These transformers must be seated firmly
against the board, and the two mounting tabs
should
snap into place. Solder both mounting tabs
and all four lugs on each transforme:.:.
6
(J; Mount transformer T73 (432(04) . Note that this
transformer
can be mounted only one way. Seat it
firmly so that it snaps into position, and make cer-
tain that all 5connecting lugs, as well as the two
mounting tabs, penetrate the board. Do not solder
lugs
#2 and #3 as shown in the pictorial. Solder
both mounting tabs and the other three lugs.
7( h Mount PEC-l and PEC-2 (555001). Note that
these identical
units face in opposite directions.
Solder all 6leads and cut off the excess.
8
(J) Note the orientation of the offset in the ground
straps and install them in each tube socket. Solder
these ground straps.
9 (
J) Observing detail E, mount each of the four diodes
D71 through D74.
Those supplied may look like
either of those in the illustration, and will have
one end painted red, or marked with three stripes.
(Disregard single green dots or stripes.) DIODE
POLARITY IS IMPORTANT. The arrowheads on
the PC-12 board point to the marked ends of the di-
odes. Diodes should be soldered carefully using the
following technique:
The leads should
be bent up, and looped down in the
manner shown to provide a "heat
sink." When soldering them, grasp
the loop with a pair of pliers from
the top of
the board to absorb any
excess heat, and solder from the bot-
tom of
the board. This technique
prevents damage to
the relatively
delicate diodes from excessive heat.
DETAIL E
This completes the assembly of the etched circuit
boards. Your FM-3 is now almost half completed.
9

CHASSIS ASSEMBLY
1 () ) Install the on-off switch inside the front flange of
the chassis, noting the position of the lugs in the
pictorial diagram. Use two #4 (smallest nickel-
plated) screws. Lockwashers and nuts are not nec-
essary as the holes in the switch are threaded.
2( J) Install the three screw terminal strip with two sets
of #4 hardware. The screws go through the strip
first, which is mounted on the outside of the rear
flange of the chassis. Refer to the pictorial for
proper orientation of the lugs. Secure it with alock-
washer under each nut.
II d) Install the tuning capacitor shield, using three sets
of #4 hardware. Make sure that capacitors C6 and
C7 do not touch the shield. The tab of the shield
is fed through the hole in PC-7 for the mounting
tab of Tl. Solder both of these tabs to the board.
Be certain that no bare leads contact the shield.
12(
J) Install the LF. circuit board PC-8 on the top of the
chassis. Fasten with eight sets of #4 hardware.
13 (J) Install the multiplex circuit board PC-12 on top of
the chassis using four sets of #4 hardware. Follow
the orientation in the pictorial diagram.
3 ( J) Insert the fuse holder into the special D shaped
hole. Note the orientation of the lugs. The rubber
washer fits between the shoulder and the outside
of the chassis. Fasten in place securely with its
lockwasher and nut, but do not tighten excessively.
4( ) Install the AC outlet with two sets of #4 hardware.
5( j) Install the two audio output sockets on the inside
of the chassis using two sets of #4 hardware for
each.
Note the orientation of the ground (short)
lugs in the pictorial.
6( ) Install one of the two nine pin sockets which have
mounting flanges, in the center of the chassis. Note
the location of the blank space between the pins in
the pictorial. The socket is mounted on top of the
chassis with two sets of #4 hardware.
7 (J ) Install the 3 rubber grommets. The larger one is
inserted into the line cord hole at the rear of the
chassis, and the other two are fitted into the holes
in the dividing partition in the middle of the chassis.
H(
15(
) Feed all the power transformer (PA-509 or PB-012)
leads through the one-half inch hole as shown in
pictorial. Position the five lug terminal strip over
the power transformer mounting hole in the chassis
between the hole for the transformer leads and the
nine pin tube socket. Note the orientation of the
lugs in the pictorial. Fasten this corner of the
transformer and the terminal strip with #8 hard-
ware (the largest size). Use #8 hardware to fasten
the remaining three corners of the transformer to the
chassis. Be sure all transformer mounting bolts are
tight, and recheck all other hardware to make sure
that all components are securely in place.
~ Mount the filter capacitor C32 in the center of the
chassis. Note the identifying marks at each lug of
the capacitor (semi-circle, square, triangle, and
blank) and orient the capacitor according to the
pictorial diagram. Fasten it rigidly in position by
twisting the four mounting lugs 1;4 turn with a pair
of pliers.
WIRING THE FRONT PANEL SUB-ASSEMBLY
8( J) Hold the PC-7 board as shown in the pictorial, with
the I.F. transformer away from you, and carefully
pick up the tuning capacitor C1, holding it so that
the shaft points away from you. Be particularly
careful that you do not touch the semicircular cop-
per and aluminum colored plates of the capacitor.
If these are bent, even slightly, it will be difficult
to get the tuner to track accurately across the dial
when you come to the alignment procedure. Now
insert the small tabs which protrude from the bot-
tom of C1 into the corresponding five holes in the
top of PC-7. Be careful capacitor C7 is not dam-
aged. This fit is especially snug, but be sure that
the tuning capacitor is fully seated against the
board. Two of the threaded studs of the capacitor
will also engage the board. The shoulders of these
studs should seat against the board.
9d ) Mount the PC-7-C1 assembly on the top of the
chassis, locating it by the four threaded studs of
Cl. Install four sets of #6 (medium size) lock-
washers and nuts on these studs but do not tighten
them.
10(-.1 ) Fasten the PC-7 board in place with five sets of
#4 (smallest size nickel plated) hardware. Install
the screws from the top, and secure with alock-
washer under each nut. Tighten these, and also
tighten the nuts on the capacitor studs.
10
Unless otherwise specified, the insulation should be
stripped from each length of wire for a distance of 1;4" at
each end prior to installation.
1 () ) Mount the tuning eye socket V8 (with mounting
flange) on the front panel with two sets of #4
hardware. Note that it is installed with the blank
space between pins #1 and #9 at the top of the
panel. The mounting flange is flush with the bracket
if the socket is mounted correctly.
2 ( J ) Strip the insulation back 1J2" from one end of a 2%"
black wire. Remove the normal 114" of insulation
from the other end. Feed the 1;2" bare end through
pin #3 of socket V8 and connect it to pin #l.
Keep it clear of pin #2. Solder pins #1 and
#3. Position this wire under the right-angle mount-
ing bracket for V8 and close to the front panel.
3 ( ) Connect one end of an 81J2" red wire to pin #6 of
socket V8 (S).
4( ~ ) Connect one end of an gr' green wire to pin #7 of
V8 (S).
5( \.) Place the %" lockwasher on the shaft of the volume
control assembly and mount the assembly in the
front panel. Locate the lugs as shown in the pic-
torial diagram. Fasten with the %" nut.

6( \) Cut a41 12" black wire. Strip one end ¥.t" and feed
it through lug #1 of the volume control and con-
nect it to lug #4 of the control.
7 ( . )
Connect one end of an 81
/2"
black wire and one end
of a 51
/2"
black wire to lug #4 of the control (S-3).
8 ( '" ) Connect one end of an 81 12" green wire to lug #5of
the control (S).
9 (. ) Connect one end of a 21
/2"green
wire to lug #6 of
the control (S).
lO( ,h Twist together an 8" black and an 8" red wire.
Connect onc cnd of the black wire to lug #1 of
the control (S-2). Connect the corresponding end
of the red wire to lug #2 of the control (S).
11 ( , ) Connect one end of a 3" red wire to lug #3 of the
control (S).
12( V) Twist together the red wire from lug #3 and the
green wire from lug #6 of the control. Connect the
red wire to lug #1 of the switch. Connect the green
wire to lug #2 of the switch.
13 (i )
Connect one end of a5" red wire to lug # 1 of the
switch (8-2).
14 ( :' ) Connect one end of a4" green wire to lug #2 of
the switch (S-2).
15( .~ ) Position the shorter (5 ~ ") black wire from lug
#4 of the control across the switch bracket and
twist it together with the red wire from switch lug
#1 and the green wire from switch lug #2. These
wires will be soldered to eyelets on PC-12 later.
16 (.J) Cut two red wire--s each 6Y/, long and twist them
together. Connect one end of one wire to switch
lug #4 (S). Connect the corresponding end of the
other wire to switch lug #5 (S).
This completes the front panel sub-assembly. Set this
aside.
CHASSIS WIRING
1( J) Strip a 2%" piece of wire bare. Feed one end
through the rear tab of the tuning capacitor Cl
that projects through the steel chassis, and then
through the other tab, and over to the first tab that
projects through the PC-7 board. See pictorial.
Solder all three points and trim off the excess.
The wire should be soldered to the chassis at both
points. It is essential that agood bond be made to
the etched circuit board.
2 ( J)
Solder all four of the remaining connecting lugs of
the tuning capacitor which project through PC-7.
3 ( J) Twist together the two red and the red-yellow
power transformer leads. Connect one red lead to
pin # 1 of socket V9 (S). Connect the other red lead
to pin #7 of socket V9 (8). Connect the red-yellow
lead to ground lug A on filter capacitor C32.
4(
J) Connect one end of a 2%" black wire to lug # 3
of the five lug terminal strip. Connect the other end
to ground lug A on filter capacitor C32 (S-2).
[) (J) Connect the green power transformer lead to lug
#2 of the five lug terminal strip. Note that the
lead is inserted into the lower hole of the lug (S).
Solder to this lower hole of the lug only. The top
section of the lug will be soldered later.
6 (J ) Connect the green-white power transformer lead
to lug #3 of the five lug tenninal strip. This lead is
inserted into the lower hole of the lug (S). Solder
to this point on the lug only. The top section of
this lug will be soldered later.
7 (i) Twist together the two black power transformer
(PA-509) leads. Connect one lead to lug #2 of
the AC outlet. Connect the other lead to lug #2 of
the fuse holder (S).
NOTE: If you an~ u~in~ the optional l20J240 volt power t.ransformer
PB.OI2, replace this step with the steps specified on Page J9.
8 () COJU1ect one end of a 1%" green wire to lug #2 of
the five lug terminal strip. Connect the other end
to pin #4 of socket V9 (8).
9( J) Connect one end of a 11
/2"
black wire to lug #3 of
the five lug terminal strip. Connect the other end
to pin #5 of socket V9 (8).
10 C' ) Connect one end of a 500 ohm 5 watt resistor to
lug # 1 (semi-circle symbol) -of the filter capacitor
C32. COJU1ect the other end to lug #2 (square
symbol) of the capacitor.
11 ('. ) Connect one end of a 2" red wire to pin #3 of
socket V9 (S). Connect the other end to lug #1 of
the filter capacitor C32 (S-2).
12( ... ) Connect one end of the other 500 ohm 5 watt resis-
tor to lug # 2 of the filter capaci tor C32 (S-2).
Connect the other end to lug #3 (triangle symbol)
jof
the capacitor.
13 ( ) Connect one end of a470 olun (yellow-violet-
brown) one watt resistor to lug #3 of the filter
capacitor C32. Connect the other end to lug #4 (no
symbol) of the capacitor.
The following steps will refer to eyelets on the etched
circuit boards. Always he certain that you are connecting
to the correct point. The electrical requirements of the
layout of the circuit board, combined with the tight space
allowance, may lead to confusion unless the relationship
of numerals and eyelets is carefully observed.
Remember that when soldering to an eyelet, a smooth
well-soldered connection must be made from the wire to
the eyelet, and Irom the eyelet to the copper on the board.
Connecting to an eyelet is easier if the wire is "tinned"
first by heating it with the iron and applying a light coat-
ing of solder to the bared end.
14( I) Connect one end of a 3 Y2" green wire to eyelet # 1
on PC-7 (8). Connect the other end to eyelet # 5
(S). Position this wire as in the pictorial.
15 (~ ) Connect one end of a 6o/.t" green wire to eyelet #6
on PC- 7 (S). Connect the other end to eyelet
#13 on PC-8 (S).
16( J) Connect one end of a 3" green wire to eyelet
#14 on PC-8 (S). Connect the other end to eyelet
#17 (S).
11

PARTS LIST FOR SCHEMATIC DIAGRAM
All resistors are 1/2 watt 10%
unless otherwise noted.
R 1 68 ohms
R 2 10,000 ohms
1 watt 5%
R 3 10,000 ohms
1 watt 5%
R 4 390 ohms
R 5 10,000 ohms
R6' 47,000 ohms
1 watt
R 7 1,000 ohms
1 watt
R 8 1,000 ohms
1 watt
112068
116103
116103
112391
112103
115473
115102
115102
R 9 100,000 ohms
R 10 33 ohms
R 11 10,000 ohms
2 watt
R 12 100,000 ohms
R 13 10,000 ohms
2 watt
R 1. 100,000 ohms
R 15 330,000 ohms
R 16 220,000 ohms
R 17 62,000 ohms
R 18 100,000 ohms
R 19 3.3 megohms
PART #
112104
112033
118103
112104
118103
112104
112334
112224
112623
112104
112335
R 20
R 21
R22
R 23
R 24
R 25
R 26
R 27
R 28
R 29
R 30
R 31
R 32
R 33
R 34
R 36
100,000 ohms
100,000 ohms
47,000 ohms 1 w.
47,000 ohms
3,900 ohms
62,000 ohms 5%
62,000 ohms 5%
1.2 megohms
390 ohms
8,200 ohms
12,000 ohms
100,000 ohms
100,000 ohms
330,000 ohms
1,000 ohms
500 ohm
5 watt wirewound
112104
112104
115473
112473
112392
113623
113623
112125
112391
112822
112123
112104
112104
112334
112102
120501
R 37
R 38
R 71
R72
R 73
R 74
R 75
R 76
R77
R 78
R 79
R 80
R 81
R 82
R 83
500 ohm
5 watt wirewound
470 ohm 1 watt
18,000 ohms
240 ohms
22,000 ohms
47,000 ohms
150,000 ohms
1.2 megohms
3.3 megohms
2,200 ohms
220,000 ohms
150,000 ohms
47,000 ohms
47,000 ohms
47,000 ohms
120501
114472
112183
112241
112223
112473
112154
112125
112335
112222
112224
112154
112473
112473
112473
R 84
R 85
R 86
R 87
R 88
R 89
R 90
R 91
R 92
R 93
R 94
e
e2
e3
e4
47,000 ohms
100,000 ohms
100,000 ohms
1,000 ohms
1,000 ohms
100,000 ohms
100,000 ohms
470.000 ohms
470,000 ohms
470,000 ohms
1.2 megohms
ganged tuning
capacitor
180 mmfd
180 mmfd
47 mmfd NPO
112473
112104
112104
112102
112102
112104
112104
112474
112474
112474
112125
219450
225181
225181
244471
C 5 .OC
e6 10
C 7 2.5
C 8 eel
e9 .OC
C 10 .OC
C 11 2.,
e 12 47
C 13 18
C 14 .O(
e 15 47
C 16 .01
C 17 47
C 18 .01
C 19 .01
C 20 47
C 21 .0
PC-8
-
RIO ~ :~C14
R12 ~
RI4 ~
cn:;::~ :~R17
C19-;'
PC-7
5 5
I
:~
C32 -
...
R38
...
R37
. ....
:=
C32.
Ri;
....
~
A!'
.....
-
.....
~
555001
0
83pf
....
C28 C39
F.$=
L9
La
E~
17
:~
li
L5 =:
-
-/5
--,,5•
?
#47
~.
~ :~3~
C35
3 (j
~ =
C36 C31 C38
-I 2
3
=~
;:
3
=:=
3 =~
II
V7
V6 V5
V4 V3
V2
SCHEMATIC
~'U ~9, ~-. ~-
-/5 5 5
V72 V71 V9
PA509Jv V~l
BLK REDI
.,ll.L I3
.
!=:!1'~_'-I7 :~32"
RH
GR ..... --------- ...... ---- ..... ---- ..... -------------.,
Il 0 C~
10\
) SLO BLO
AC
l~1
~~
rl
3
l--
'-~
(~I\
RED

296127
227203
225472
225472
225472
225472
~7 mfd
nmld NPO
j mmld N2200
amic trimmer
~7 mfd
Umfd
mmld
mmfd
} mmfd
47 mfd
mmld NPO
47 mfd
mmfd NPO
47 mfd
~
• mid
fd NPO
d
t
225472
225100
240250
219010
225472
225472
240220
244471
225181
225472
244471
225472
244471
225472
225472
244471
244103
C 22
C 23
C 24
C 25
C 26
C 27
C 28
C 29
C 3D
C 31
C 32
C 33
C 34
C 35
C 36
C 37
.0047 mid 225472
.0047 mfd 225472
47 mmld NPO 244471
47 mmfd NPO 244471
.01 mfd 244103
.0047 mid 225472
.0047 mid 225472
.47 mid 244474
27 mmfd 244271
.22 mfd @ 200 V. 235224
40/40/20/20 mfd
@ 350 v.
.02 mfd
.0047 mfd
.0047 mid
.0047 mfd
.0047 mfd
C 38
C 39
C 71
C72
C 73
C 74
C 75
C 76
C77
C 78
C 79
C 80
C 81
C 82
C 83
C 84
180 mmfd
180 mmfd
500 mmld
220 mmfd
.012 mfd
.0068 mfd
500 mmfd
.001 mfd
.0033 mid
.0015 mfd
.01 mfd
500 mmfd
100 mmfd
.1 mfd
.1 mfd
18 mmld
225181
225181
245501
245221
245123
246682
245501
245102
246332
246152
245103
245501
245101
246104
246104
245180
D 71 1N541
D 72 IN541
D 73 1N541
D 74 1N541
l 1 antenna cOli
L 2 3.9 lJ.h choke
l 3 mixer coil
l 4 oscillator coil
L 5 heater choke
L 6 heater choke
L 7 heater choke
L 8 heater choke
L 9 heater choke
L 71 53 mh choke
luse-l ampere slo·blo
pilot lamp-#47
542541
542541
542541
542541
412001
423001
412003·
412004
423002
423002
423002
423002
423002
422530
T
T 2
T 3
T 4
T 5
T71
T72
T 73
IJ. transformer
432001
IJ. transformer
432001
IJ. transformer
432001
IJ. transformer
432001
Discriminator
transformer
432002
19 K.C. transformer
432003
19 K.C. transformer
432003
38 K.C. transformer
432004
V 1 6AQ8/ECC85
V 2 6Al8A
V 3 6BA6
V4 6BA6
V 5 6AU6/EF94
V 6 6AU6/EF94
V 7 12AX7/ECC83
V 8 EMM801
V 9 6V4/EZ80
V 71 6BL8/ECF80
V 72 12AX7/ECC83
volume control-dual,
250,000 ohms each
section with push·
pull switch - 180254
-----------6r------------------ ... ------------------------,
~
R33 ~
R32
-
--
r---1~-~7,..- --
• "R31
",_~C29 "'~
I-' -.C30
..
PEe
I
sss 004
I 2 3
R29
.
=~ =: "R23
C22 C23
-;..
r
TP
PC-12
V71A 6
R73
"R90
C.I.3 _,...
+---n--w>-~-U'>O )\ B
II T' :t RIGHT
~n . OUTPUT
--' ........
- V72B
--
r&_
lJI-H-D---€-----.J
cal ~C'O
~R79
C79.J. :~R80 lil~-I~l
L..- __ '~ T __ -, I' L=J Is
cee 1T73~8 1
TP ~:1----_---_--3~11--~ II!I.!H 11__..,:1
2
'-------.,
R8I 07.,! 1..----- ... ...J
012
~12
I
'~R89 '.... r .. • ....
Q""" W ••
A .J::' . .. R83" 073 DH itK"
LEFT ':"' R91 6
OUTPUT ,-\'N\~'----:<l'--' \ - - - --.
---, V72A .... 6~ \9 C?L..---1'"--1~------r---,
-- \
---_7-JV' .. WII' • ...--m--Ir4....;lrr:: .... >~'"' PEC·1 PEC
o2
tE.. .... """_. 2
Ri5 ';':'1l~; l I 555001 I II SHOOI I ~ ~:=r.;,;.. .....
\ . CP----t.3 2 14- I 2 ~~".. \ RIS
\ I \
\\
'- - - - - - - - - - - ~ OUAn~TROL ~ - -_\
5 DD4
22~
vvv
i ,51,OPI
'~2it
2~
1
--
":"
DIAGRAM

45 ( ) Connect the wire from each side of the antenna coil
L-l to the screw terminal nearest it. Follow the wire
arrangement in the pictorial diagram. Solder both
lugs # 1 and #3.
) Twist together the black and green wires from the
rear of the five lug terminal strip. Position the wires
as shown in the pictorial, under the green wire to
output socket A. Connect the black wire to the
center ground pin of socket V72 (8). Be sure it is
soldered to the board. Connect the green wire to
eyelet #83 (8).
40 ( J) Place the body of the .02 mfd disc capacitor under
the switch as shown in the pictorial diagram. Con-
nect one lead of the capacitor to lug # 1 of the
on-off switch. Connect the other lead of the capaci-
tor to lug #2 of the switch.
41 (
J) Twist together a 10" black wire and a 6%" black
wire so that one pair of ends is even. Feed the pair
through grommet #2 and connect one of the even
ends to lug #1 of the on-off switch (8-2). Connect
the corresponding end of the other wire to lug #2
of the on-off switch (8-2). Connect the other end
of the longer wire to lug #2 of the AC outlet (8-2).
Connect the other end of the shorter wire to lug # 5
of
the five lug terminal strip.
42( J) Connect one end of a 1%" black wire to lug #1
of the AC outlet (8). Connect the other end to lug
# 1 of the fuse holder.
43
(J ) 8trip a 1" piece of wire bare. Connect one end to
eyelet # 3 of PC-7 (S). Connect the other end to
lug #2 of the three-screw terminal strip.
44 (J ) Connect the twisted wire from the center of the
antenna coil L-l to lug #2 of the three-screw ter-
minal strip (8-2).
34( }) Twist together an 8" black wire and an 8" green
wire. Thread these wires through the small slot in
the front of the chassis, and through grommet #2.
Connect the black wire to lug #3 of the five lug
terminal strip. Connect the green wire to lug #4
of the five lug terminal strip.
35( J) Cut two 7" black wires. Connect one end of each
wire to lug # 3 of the five lug terminal strip. For
convenient wire placement, insert one wire from the
front, and one from the rear of the lug (8-5).
36CI) Connect one end of a 1%" green wire to lug #2 of
the five lug terminal strip (S-4). Connect the other
end to lug #4 of the terminal strip.
37( J) Cut two 7" green wires. Connect one end of each
wire to lug #4 of the five lug terminal strip. For
convenient wire placement, insert one wire from the
front, and one from the rear of the lug (8-5).
38(J) Twist together the black and the green wires from
the front side of the five lug terminal strip. Connect
the black wire to the center ground pin of socket
V71 (8). Be sure the center pin is soldered to the
copper on the board. Connect the green wire to eye-
let #74 (8). Position the wires as shown in the
pictorial.
39(J
17 (J ) Connect one end of a 6" green wire to lug # 2 of
the five lug terminal strip. Feed this wire through
grommet #1, and connect the other end to eyelet
#18 on PC-8 (S).
18(1) Connect one end of a 3" green wire to eyelet #19
on PC-8 (S). Connect the other end to eyelet
#24 (S).
19(J) Connect one end of a61 /2" green wire to eyelet #20
on PC-8 (S). Feed the wire through grommet #1
and connect the other end to lug #2 of the five lug
terminal strip.
20 (J ) Connect one end of a 6" green wire to eyelet #35
on PC-8 (S). Feed the wire through grommet #2
and connect the other end to lug #4 of the five lug
terminal strip.
21 ( ) Connect one end of a 9" red wire to eyelet #9 on
PC-7 (8). Connect the other end to eyelet #15 on
PC-8 (S).
22( J) Connect one end of a 4%" red wire to eyelet #16 on
PC-8 (8). Connect the other end to eyelet #21 (8).
23(J) Connect one end of a41 14" red wire to lug #3 of
the filter capacitor C32. Feed the wire through grom-
met # 1 and connect the other end to eyelet # 22
on PC-8 (8).
24( ) Connect one end of a 7" red wire to lug #3 of the
filter capacitor C32 (8-4). Feed the wire through
grommet # 1 and connect the other end to eyelet
#27 on PC-8 (8).
25 ( J> Connect one end of an 8" red wire to lug #4 of the
filter capacitor C32. Feed the wire through grommet
#2 and connect the other end to eyelet #34 on
PC-8 (8).
26( J) Connect one end of a 5%" red wire to lug #4 of
the filter capacitor C32. Connect the other end to
eyelet #12 of PC-7 (8).
27( ) Connect one end of a 7%" red wire to lug #4 of
filter
capacitor C32 (8-4). Thread this wire under
the transformer leads. Connect the other end to
eyelet #87 on PC-12 (8).
28 (J ) Connect one end of a11 12" red wire to eyelet #36
on the bottom of PC-8 (8). Connect the other end
to eyelet #38 (8).
29 (J ) Connect one end of a 6%" black wire to eyelet
#40 on PC-8 (8). Connect the other end of this
\wire to eyelet #73 on PC-12 (8).
30 (J ) Connect one end of a 6" green wire to eyelet #33
of PC-8 (8). Connect the other end to eyelet #72
on PC-12 (8).
31d) Connect one end of a 4" green wire to eyelet #39
on PC-8 (S). Connect the other end to eyelet
#71 on PC-12 (S).
32(~) Connect one end of a 2" green wire to eyelet #81
on PC-12 (8). Connect the other end to the center
(long) lug of output socket A (8).
33 (~ ) Connect one end of a 11;4" green wire to eyelet #85
on PC-12 (8). Connect the other end to the center
(long) lug of output socket B (8).
14

46(J) Connect a 1" bare wire from eyelet #23 on PC-8
(8) to eyelet B (S). This jumper should b<' k<,pt
close to tJw board, but it must not touch ;'ldjacent
circuitry.
47(~' ) Connect one end of a 3" red wire to eyelet #30 on
the top of PC-8 (S). "Tin" the wire with solder
first, and then insert the wire {rom above as the eye-
let is heal,ed (rom below,
48( J) Connect one end of a2V2" rcd wire to eyelet #2B
on the top of PC8 (S),
49 (,j) Connect one end of a3" gn'l'n wire to eyelet #2G
on the lop of PC-S (,S),
50( ,J) Slide the tuning dial indicator disc fully onto the
tuning capacitor shaft, The hub goes on the shaft
first, and its flat side engages the flat portion of the
shaft, Be sure the disc is pushed on to the full depth
of the flat.
51 (-,/) Te'lllporal'ily dl~mount the' volume' control assembly
from the front panel and set it to one sid(',
52 (, ) Position the front panel sub-assemhly adjacent to
the front of the chassis. Take the green and black
twisted pair of wire'S which protrude from the sm:lll
slot in the chassis, Connect th(' black wire to pin
#4 of V8 (8), Connect the green wire to pin #5
of VS (S).
53 ( ~ ) Thrcnd the red and gn'l~n wires from pins #6 and
#7 of VS through the small slot in the front of the
chassis and through grommet #2.
54 ( ~ Mount the front panel to the chassis usmg three
sets of #4 hardware.
55( >.5 Connect the black wire from pin #3 of socket V8
to
cyeld #25 on top of PC-8 (S).
56( !) Connect the red wire from eyelet #30 to pin #2
of socket VS (S), Access to pin #2 can be gained
through the front panel cutout. Position this wire
fiat
against the board, and over to the front panel.
57( 'I) Connect the red wire from l~yelet #2S to pin #8
of V8 (8).
58(, ') Position the gre~n wire from eyelet #26 under the
VS mounting bracket, and connect it to pin #9 of
VS
(S).
59(-,) Connect on~ end of a 1112" green wire to eyelet A
of
PC-S on the top of the board. 80lder it from the
bottom of the board.
60( J) Conneot the other end of the 11 12" green wire from
eyelet Aof PC-S to the top of eyelet A on PC-7 (S).
61 ( ) Slide the %" lockwasher on the volume control
shaft, and mount the assembly on the front panel,
positioning the lugs as in the pictorial, but do not
tighten the %" nut. Be careful of the disc capacitors
on PC-S,
62
(.A Connect the short black wire from lug #1of the
volume control to eyelet #37 on PC-S (S), Aquan-
tity of solder should be applied to ey<'!et #37 on
the copper side of the bO:lrd, and flowed over to the
chassis to make agood ground contact to thl'
chassis.
63(, ) Twist togeth<'f the remammg black wire from lug
#4 of the control and the green wire from lug #5
of the controL Connect the black wire to eycJd #S'l
on top of the PC-12 boa I'd (S). Connl'ct the greeIl
Iwire to cyt'let # SO (S).
64 ( " ) Take the red and black twisted pair of wires which
are connected to lugs #1 and #2 of the control.
Connect the black wire to eyelet #84 (8). Connect
the rpd wire to eyelet #86 (S). Position the rcd-
black and green-black pairs of leads from this and
from the prec~ding step exactly as shown in the
diagram, around V71, and away from 1'73. Keep
them clear of the board.
I
65 (I) Take the black, red and green twisted group of
wires from the switch on the volume control as-
sembly, and connect the black wire to eyelet #77
(S). Connect the green wire to eyelet #78 (S).
Connect the red wire to eyelet #76 (S),
66( v) Thread the twisted pair of red wires from the switch
through the slot in the chassis adjacent to PEC-I.
On the underside of the board, connect these wires
to lugs #2 and #3 of the transformer T73, as indi-
cated in the diagram. Wrap each wire around the
lug and solder it to the lug and to the copper on the
board. Note that this transformer has 5 connecting
lugs positioned around the access hole. Be sure that
the red wires are soldered to the proper points. Either
wire may connect to either lug. Be sure that bare
wire does not contact adjacent circuit points.
67( J) Observe the red and the green wires protruding
through grommet #2. Connect the red wire to eye-
let #79 on PC-12 (8). Connect th0. gr0.cn wire to
eyelet #75 (8). This gwen wire may appear long,
but the extra length is used in the alignment
procedure.
68( J) Mount the discriminator transformer T5 (432002).
This transfornH'r has five connecting lugs and two
mounting tabs, It can be mount(,d in only one po-
sition.
Press it firmly to the board and solder both
mounting tabs and the five connl:cting lugs. Do not
use excessivp heat on the five lugs. Avoid using too
much solder, which could flow into the transformer
and damage it.
69 ( t/) Insert the end of the line cord through grommet #3
in the rear of the chassis and pull through about 6
inches.
Tie aImot 4 inches from the end, and pull
the line cord back so that the knot seats against
the grommet. Split the two conductors of the line
cord down to the knot. Connect one of the two leads
to lug # 1 of the fuse holder (S-2). Connect the
other lead to lug #5 of the five lug terminal
strip (S-2). Now check to see that the black twisted
pair, of which one wire connects to lug #5, is
positioned away from PC-12.
15

II
This completes the assembly of your Dynatuner. You
should now make one final inspection of the unit to see
that all connections are soldered. One poor solder connec-
tion can upset the performance of your tuner, or prevent
proper aHgmnent. Be sure that there are no loose wire
clippings.or pieces of solder, and that there are no bridges
of solder across insulated areas of the circuit boards.
Check to be sure that the position of the wires in your
tuner agrees closely with the pictorial diagrams and with
the photographs. The diagrams must sometimes be exag-
gerated for clarity, but any discrepancies between them and
the photographs are of no consequence.
Insert the tubes into their sockets and install the dial
lamp and the fuse. Install the tube shields, making sure
that the ground strap of each socket slips between the tube
and the shield. The larger shields go on the 9 pin tubes, and
the smaller ones on the 7 pin tubes. V8 and V9 do not
use shields.
There are two small brass-plated self-tapping screws
which will be used to secure the aluminum front plate to
the front panel. To avoid scratching the front plate, it is
wise at this point to cut their threads into the holes above
and below the tuning capacitor shaft by inserting these
screws part of the way, and removing them. This will
enable much easier insertion when the front plate is
installed.
Remove the %" nut holding the volume control in posi-
tion. Insert the rectangular plastic insert into the front
plate cutout from the rear. The top edge is narrower than
the bottom. Place the front plate against the steel front
panel so that the plastic insert is held between the two
plates. Install the %" nut on the volume control shaft and
tighten it. Now install the two small brass self-tapping
screws above and below the tuning shaft. Rotate the volume
control shaft fully counter-clockwise and install the small
knob with the pointer at the 7o'clock position. Install the
large knob on the tuning shaft, and tighten the set screws
of both knobs.
Install the rubber feet in the comer holes of the bottom
plate by inserting a#6screw in the recess of each foot,
and secure each with a nut on the inside of the bottom
plate. Secure the bottom plate and cover with the four
sheet metal screws. The flange on the front of the cover
slides between the steel front panel and the aluminum front
plate. Care should be exercised when handling the unit,
for the gold anodized panel and knobs will not withstand
undue abuse.
Now plug the Dynatuner in (to AC current sources
only) and turn it on. Allow it to operate for an hour or
more to allow the tubes to age and for operating conditions
to stabilize before proceeding with alignment. During this
time you should be able to enjoy reception from local
stations.
ALIGNING YOUR DYNATUNER
The Dynatuner is unique in its simpHcity of alignment.
Every stage can be aligned using the dual beam tuning eye
as an indicating instrument, and this alignment is as pre-
cise as can be accomplished with the most complex labora-
tory equipment. The ability to achieve this measure of
accuracy without external test equipment is a Dynatuner
exclusive, and the indicating accuracy of the tuning eye
circuit surpasses that of any comparable meter system.
16
It is important to emphasize that when this procedure
has been carefully followed, it is not possible to "improve"
on this alignment, and the Dynatuner will meet the most
rigorous performance standards. It is essential that any
serviceman who works on this tuner be informed of this
procedure,
and that he is also advised that conventional
"sweep" alignment techniques are not considered either
satisfactory or desirable.
It should be understood that successful alignment is
dependent on a properly constructed tuner. Awiring error
or a poor solder connection could prevent satisfactory com-
pletion of some steps, or could cause erroneous settings to
the extent that additional test equipment might then be
required to reestablish the proper operating conditions for
realignment. Certain parts of the Dynatuner have been
preset close to the proper operating point. These include
the I.F. transformers, the discriminator transformer, the
multiplex transformers, and the slug-tuned coils on the
PC-7 board.
The cover and bottom plate must be removed for align-
ment. The complete stability of the Dynatuner allows pre-
cise alignment without special shielding. Before proceed-
ing with alignment, three approximate adjustments should
be made, which will permit reception of local stations dur-
ing the hour of operation while tube conditions stabilize.
A similar aging period should be allowed before realign-
ment following any tube replacement on PC-7 and PC-8.
On top of the tuning capacitor Cl there are two adjust-
ment screws (trimmer capacitors) accessible through the
two holes in the top of the shield. The center screw (C1-D)
adjusts the mixer, and the rear screw CI-B adjusts the R.F.
stage. The approximate settings given in steps # 1 and #2
below have already been made as the capacitor is supplied
to you.
1( ) Turn in the screw C1-D on the center (mixer) sec-
tion until it is in all the way. It should be snug,
but do not force it. Then back it off 14 turn counter-
clockwise.
2( ) Turn in the screw C1-B on the rear (R.F.) section
until it is in fully. but do not force it. Then back it
off % turn counter-clockwise.
3( ) The oscillator trimmer capacitor C8 screw (acces-
sible from below the chassis) should be turned until
the head of the screw is %(' from the triangular nut.
With an antenna attached, and with the tuner connected
to an amplifier and aspeaker, turn the tuner on. The dial
lamp should light, and there should be a slight glow visible
in each tube, and then the tuning eye should glow. All of
this should take only about 15 seconds. When turning the
tuning knob, some deflection of the lower beam of the tun-
ing eye should be apparent as the tuning passes the fre-
quencies of local stations. At higher settings of the volume
control, it should be possible to hear some hiss between
stations and sound from the stronger stations. If all of these
effects cannot be obtained, refer to the section "In Case of
Difficulty" before attempting to use the tuner further or to
align it.
Two tools are necessary for alignment: asmall tipped
screwdriver with an insulated handle, and a plastic tool
(supplied) which has ahexagonal end for adjustment of
the tuning slugs in the LF., discriminator and multiplex
transformers. Only the plastic tool should be used to adjust

these transformers. Any other type of instrument will dam-
age the tuning slugs, requiring replacement of the trans-
former. When using the plastic tool, all adjustments are to
be made using the end which has a shoulder to prevent
inserting the tool too far.
BE CAREFUL IN HANDLING THE CHASSIS DUR-
ING ALIGNMENT. THERE IS SOME SHOCK HAZ-
ARD BECAUSE OF THE EXPOSED WIRING.
It is suggested that you read these instructions com-
pletely before proceeding, to familiarize yourself with the
general procedure. The tuner is to be connected to an
amplifier and speaker, turned on, and the antenna attached
as for normal use.
The alignment of the FM-3 is carried out in two stages.
First, the main tuner portion (PC-7 and PC-8) is aligned,
and then the multiplex section. Pull the volume control
knob
"OUT" to disable the multiplex circuit and eliminate
its effects during alignment of the I.F. stages, discriminator,
and the front end. For these sections, the alignment instruc-
tions will refer to the lower (tuning eye) beam of V8,
where Dyna's exclusive reference grid will simplify locat-
ing the precise peaks.
Alignment of the I.f. Stages
These adjustments require the insertion of the plastic
alignment tool into the threaded slugs inside the aluminum
I.F. transformers, and the rotation of these slugs until they
are in aposition, easily determined, which represents cor-
rect alignment. If the tuner has been built correctly, it will
not be necessary to make more than a small adjustment to
reach the right point. IF A SLUG MUST BE TURNED MORE
THAN ONE FULL TURN, YOU WILL PROBABLY BE COMPENSAT-
ING FOR SOME FAULT IN WIRING OR COMPONENTS, AND YOU
SHOULD STOP TO CHECK BEFORE PROCEEDING FURTHER.
The end of the alignment tool with the shoulder should
always be used, with the tool inserted until the shoulder
stops it. IF THE CORE SLUG STOPS TURNING, DO NOT ATTEMPT
TO FORCE IT BEYOND THIS POINT. There are two slugs in
each I.F. transformer, and it is possible, particularly if the
slugs have been turned too much, for them to touch each
other. If an attempt is made to turn them further, the slugs
are likely to break, requiring replacement of the entire
transformer.
Two points require special attention. Never use any tool
or
instrument to turn the slugs except the alignment tool
supplied or one exactly like it. Aconventional metal tool
may break the slug. When working from the· underside of
the chassis with the tuner on, you must constantly bear in
mind the hazard of possible shock from exposed wiring. If
you wish, the bottom plate can be installed during align-
ment of the LF. stages.
4( \) Turn the tuning knob until you find a place where
no station can be heard (only hissing). Insert the
end of the plastic alignment tool into the top of
LF. transformer T4, and slowly rotate the slug until
the hissing is loudest.
As this and the following steps proceed, the hissing
will become louder, and the loudness peak will
become sharper and easier to locate. If the hiss
becomes annoyingly loud, adjust the level with the
volume control; the lower half of the eye tube V8
will usually begin to close as the noise increases
after the first step or two, and this should be used,
rather than the sound, for the remainder of the
adjustments.
If it is difficult to make the adjustment because of
lack of hiss, use a station to make this series of ad-
justments. Then repeat the procedure while tuned
between stations, using hiss as an audible signal
until there is sufficient deflection of the tuning eye
lowel' bar to use this as an indication. Always follow
t
the sequence described.
5( ) Adjust the bottom slug of T4.
6( ) Adjust the top slug of T3.
7 (J> Adjust the bottom slug of T3.
8( J) Adjust the top slug of T2.
9 ( 1> Adjust the bottom slug of T2.
10( V) Adjust the top slug of Tl.
11 ( \Jf Adjust the bottom slug of Tl.
Alignment of the Discriminator
The alignment of the discriminator determines the dis-
tortion and noise rejection of the tuner, and is therefore a
critical adjustment. The Dynatuner provides apositive
method of adjusting the discriminator to exactly the right
point.
12 <. J) Tune a station which gives agood clean mono
signal clearly indicated by adefinite tuning peak.
Ideally, it should not be a very weak or a very
powerful signal, and it should be separated from
adjacent channel stations by normal interstation hiss
as you tune through it. These precautions will in-
sure against imperfect alignment through using an
atypical signal. The accuracy of alignment depends
on the correctness of this tuning. Be sure that you
do not disturb the tuned setting during the following
steps. While
they are being performed the tuning
eye will be used to show other effects.
13(J) Unscrew (counter-clockwise) the top slug of the
discriminator transformer T5, using tl1e shoulder
end of the plastic alignment tool, until the top of
the slug is flush with the top of the transformer.
This detunes the secondary winding of the dis-
criminator transformer, essential in order to obtain
the optimum adjustment of the primary winding,
done in the next few steps. The tuning eye is used
as an indicator for this adjustment, by connecting
it to another part of the circuit than that to which
it is now connected.
If you are very careful, it is possible to do the neces-
sary unsoldering and resoldering of connections
without turning off the tuner. However, YOU
MUST BEAR IN MIND THE HAZARD OF POS-
SIBLE SHOCK FROM EXPOSED WIRING.
Care and deliberation can eliminate this hazard,
but, if you wish to avoid all risk of shock, turn the
tuner off before making the new connections, and
turn it on again to make the adjustments. If you
do this, it is essential that you allow the tuner to
warm up for afew minutes each time before making
an adjustment, even if it has been off for less than
aminute.
NOTE: It a VTVM Is available. discriminator alignment can be
considerably simplified by skipping Immediately 10 step 24 be-
low. The VTVM should be of a type which has at least a1
megohm resistor in the DC probe to Isolate the probe and lead
capacity from the measured circuit.
17

14 (> Unsolder and lift off the jumper wire which con-
nects from eyelet #23 on PC-8 to eyelet B.
15( v) Temporarily solder awire from eyelet #23 to eye-
let #32 on PC-8.
16( vi Adjust the bottom slug of T5 for maximum closing
of the eye.
17 (,v) Unsolder the end of the temporary wire from eyelet
#32 and temporarily connect it to eyelet #31.
18( /) Solder a2" piece of bare wire to the center ground
pin of socket V7,
19( v) Tum the top slug of T5 in (clockwise) 4to 5 turns,
which brings it close to the proper adjustment point,
20( V) Touch the free end of the wire from the center
ground pin of V7 to eyelet #31. You will observe
that there is adeflection of the eye (either inward
or outward), Rotate the top slug of the discriminator
transformer T5 back and forth slowly while alter-
nately touching and releasing the free end of the wire
from the center ground pin of V7 to eyelet #31. The
actual adjustment of the slug must be made while
the wire is not touching the eyelet. Check the eye's
deflection after each change. You are seeking the pre-
cise point where there is no shift in the tuning eye
as the wire is touched to, and removed from, eyelet
#31. There may be slight changes in the brightness
of the eye as this is done, but these are of no con-
sequence, Tum the slug in the direction which mini-
mizes the shift in deflection until there is no shift
when the wire makes or breaks contact with eyelet
#31.
21 (j Remove the temporary wire between eyelets #23
and #31.
22 ( !) Re-connect the jumper wire from eyelet #23 to
eyelet B. Keep it reasonably close to the board.
23 (J) Remove the wire from the center ground pin of
socket V7.
24 ( ) THIS STEP REPLACES STEPS 14 THROUGH 23 WHEN A
VTVM IS USED FOR DISCRIMINATOR ALIGNMENT. IF YOU
ARE NOT USING A VTVM AND HAVE COMPLETED STEPS
14 THROUGH 23, PASS TO STEP 25 NOW.
Switch the VTVM to -DC and set it for a range of
about 10 volts full scale. Connect the COMMON lead
to the tuner chassis, and the DC probe to eyelet #32.
Adjust the bottom slug of T5 for the maximum meter
reading (about -11 volts).
Switch the VTVM to its most sensitive scale. While
shorting its leads together, reset its zero adjustment
to bring the meter needle to aspecific point near
mid-scale which can serve as anew zero, or to a
center-scale zero if one has been printed on your
meter scale. Connect the COMMON lead to the chas-
sis again, but connect the DC probe to eyelet #31
this time. Tum the top slug of T5 in (clockwise)
4to 5 turns as afirst approximation, and then care-
fully adjust it until the meter reads exactly zero.
To do this conectly, it is essential that you go
through zero first, and then back up to locate it
precisely.
18
25( ,j Cut a one inch piece of wire and strip 114" of insu-
lation from one end. The other end need not be
stripped. Insert the stripped end into the bottom of
eyelet #29 (S). 'rhis wire should stand up straight
from the PC-8 board with the other end free, and
adjacent wires should be positioned away from it.
This wire should be cut off so that it stands up-
right to a height of IJAa" above the PC-8 board.
This wire may seem to be unusual, as it is con-
nected at one end only. However, it is what is known
in electronic parlance as a "gimmick" and it is actu-
ally asmall value capacitor which corrects for the
effects of interaction between the adjustments of
the two slugs in the discriminator transformer. At
such times as realignment is performed, this "gim-
mick" should be removed before aligning the dis-
criminator.
Alignment of the Front End
If you wish, the bottom plate can be installed during
alignment of the front end. In this section, dial tracking
will be simplified if another FM radio is available to enable
you to identify stations readily. Make sure capacitor C9
is vertical, for if it is tilted toward C8, dial tracking will
be affected.
26 (v5 Tum the tuning knob until you have located an FM
station of known frequency at the high end of the
band (close to 108 megacycles), the higher the
better.
27( ) Adjust the oscillator trimmer capacitor C8 using a
small screwdriver. At the same time readjust the
tuning knob until the station's frequency is indi-
cated in the plastic window by the tuning dial. In
other words, you set the dial to show the correct
frequency and adjust the trimmer capacitor until
J
the eye closes to a maximum.
28( ) Now find a station of known frequency at the low-
est end of the dial (close to 88 megacycles). Using
a s_mall screwdriver, and touching only the insulated
handle,
adjust the brass slug in the oscillator coil
LA while setting the tuning dial to the station's
broadcast frequency. This is the same type of ad-
justment as was made in the preceding step.
It may be necessary to repeat the adjustments at the two
extremes of the dial several times to have the tuner "track"
properly. If the adjustments are not made accurately, the
dial readings will not coincide with station frequencies
across the dial. Correctly following this procedure should
enable dial tracking which is accurate to within 7f; division
(±O.2 megacycles).
I
29 (J ) Tune accurately to a station near 108 megacycles
and adjust the two trimmer capacitors CI-B and
CI-D on the top of the tuning capacitor. The screw-
driver
should not touch the capacitor shield when
making these adjustments. The adjustment should
be made for maximum eye closing. If the eye is
closed to its normal maximum, the effects of these
adjustments will not be readily apparent, so it is
essential that aweak signal be used here (where the
eye is about %" open) or proper alignment will not
be realized.

Dynatuners supplied with optional power transformel'
PB-012 can be wired for use with either 120 or 240 volt,
50
or 60 cycle AC power sources, as follows:
BLACK
VIOLET
8 WHITE
t
BLACK
8 WHITE
.
VIOLET
~
240·yolt
VIOLET
:,
aWHITE
,
BLACK
i
aWHITE
~
VIOLET
-(
35( ) Unsolder the 1.2 megohm resistor from the V71
ground pin and eyelet #88. It can be saved for
future use when realignment is desired.
36( )
Unsolder the green wire from eyelet #88 and re-
connect it to eyelet #75 (8).
This completes the alignment of your Dynatuner. No
further alignment should be required unless there is a
change in tubes or components. When necessary, you have
the means of realigning it so that your Dynatuner will
always be at the very peak of its performance capabilities.
However, one word of caution is in order-do not make
these adjustments unnecessarily, as the various slugs will
eventually loosen and cause tuning shifts to the detriment
of performance. Alignment adjustments should be con-
sidered as a semi-permanent type of adjustment.
Reassemble the tuner, making sure the COVel' front flange
slips between the aluminum front plate and the steel panel.
Your STEREOMATIC Dynatuner is now ready for long pleas-
urable use.
120-yolt
For 120 Volt Operation
1( ) Twist together the black and black-white power
transformer leads. Connect both leads to lug #2
of the AC outlet.
2( ) Twist together the violet and violet-white power
transformer leads. Connect both leads to lug #2
of the fuse holder (8-2).
For 240 Volt Operation
1( ) Twist together the black and the violet power trans-
former leads. Connect the black lead to lug #2 of
SPECIAL INSTRUCTIONS FOR OPTIONAL
120-240 VOLT POWER TRANSFORMERS
BLACK
32(l ). Unsolder the end of the 1.2 megohm resistor sol-
dered to eyelet #75, and temporarily solder it to
\
eyelet #88. This is the other test point TP.
33( \j) Unsolder the green wire connected to eyelet #75
,and temporarily connect it to eyelet #88 (8).
34 ( ') Adjust the top slug of transformer T73 for maxi-
mum closing of the STEREOCATOR. Then adjust the
bottom slug of T73 for maximum closing of the
STEREOCATOR. Repeat these adjustments, first with
the top, and then the bottom slug, until the beam
closes no further.
To obtain asufficiently weak signal, it may be nec-
essary to remove the antenna and substitute a short
piece of wire. Shorting out half the antenna is
another alternative. With signals of this magnitude
(a very few microvolts) it will be noticed that the
eye is sensitive to flutter as a result of airplanes
passing overhead, or varying signal strength as a
result of atmospheric conditions. Care must be taken
not to allow this sensitivity to influence the actual
/ adjustment of C1-B and CloD.
30 (J) Tune carefully to a station near 88 megacycles and
adjust the two brass slugs in the mixer coil L3 and
the R.F. coil Ll for maximum eye closing.
The last two adjustments should be repeated, since there
is interaction between adjust~ent of the trimmer capac-
itors and the slugs of the coils. This adjustment of Ll and
L3 is not critical, and may be a broad peak, necessitating
an approximate center setting, but the accuracy of adjust-
ment of Cl-B and Cl-n has avery definite correlation with
the tuner's effective sensitivity, so that extra care here will
be well repaid in superior performance.
Alignment of the Multiplex Integrator
The basic Dynatuner alignment in the preceding sections
should be carried out before aligning the multiplex inte·
grator. In particular, the discriminator must be accurately
aligned if
maximum noise rejection is to be realized, and
this becomes doubly important in stereo operation, for the
effective sensitivity and noise rejection of any tuner is
lower
in stereo than in the mono mode.
The tuner must have an antenna connected, but it is not
necessary for an amplifier and speaker to be connected for
this part of the alignment. Tune precisely to a known
stereo broadcast, for this part of the aligrunent involves
tuning the multiplex transformers to the 19KC pilot signal
which is an integral part of every stereo broadcast. You
can enjoy normal monophonic reception prior to alignment
of the multiplex integrator, since its adjustments affect
only the separation of stereo' programs.
Push the volume control "IN" so that it is in the normal
STEREOMATIC operating position. The upper beam of V8 is
the STEREOCATOR. After alignment, it will be either fully
open or fully closed whenever you are tuned tCl a station,
and thus will illuminate or turn off the word STEREO
printed on the plastic insert in the front panel. Between
stations the ambient noise may cause it to flicker, but this
is of no consequence.
You will be able to see the STEREOCATOR quite well dur-
ing alignment if you look down on V8 from above, but if
you wish to observe its operation more easily, remove the
knobs, front plate and plastic insert.
31 ( v) Temporarily connect one end of the 1.2 megohm
(brown-red-green) resistor R94 to the center ground
pin of V71 (8). Temporarily connect the other end
to eyelet #75 (8). Eyelet #75 is one test point,
and is marked with the letters TP on the bottom of
the board. Using the shoulder end of the alignment
tool, adjust transforme.' T7l for maximum closing
of
the STEREOCATOR. Then adjust transformer T72
for maximum closing of the STEREOCATOR. Repeat
these adjustments, first with T71 and then with
T72, until the beam closes no further. Usually only
a small adjustment will be necessary.
19

the AC outlet. Connect the violet lead to lug #2
of the fuse holder (S).
2 ( ) Twist together the black-white and the violet-white
power
transformer leads. Connect both leads to lug
#1 of the five lug terminal strip (S-2).
When using the 240 volt connection, a one-half ampere
slo-blo fuse should be used instead of the one ampere fuse
recommended for 120 volt operation.
IN CASE OF DIFFICULTY
In the event that your first attempt at listening to your
Dynatuner is unsuccessful, a systematic approach to lo-
cating the difficulty will save you much time and trouble.
Because 90% of the difficulties which are encountered
can be attributed to either incorrect wiring or to a poor
solder connection, it is strongly recommended that you
first ask someone else to check the wiring against the
pictorial diagrams, as frequently one person will make the
same error twice.
In the course of trouble shooting, inspect very carefully
for "bridges" of solder from one point to another. Also
recheck for correctness of component positions on the
etched circuit boards. Many defects of this type, as weIJ
as faulty components, can be ascertained by voltage
measurements, and a complete voltage chart is provided.
Any deviation of 20% or more from this chart (except
for voltages marked ~) indicates a possible error or com-
ponent failure. Examination of components in the area of
incorrect voltage (with reference to the schematic dia-
gram) should help to uncover the difficulty.
For purposes of simplification, the initial trouble-shoot-
ing suggestions will be confined to the basic tuner circuit
for the Multiplex Integrator does not usually affect mon~
reception. The volume control knob should be pulled "QtJT"
for this part.
Normal radio servicing techniques of signal injection
and signal tracing are appropriate for localizing troubles.
For brst alignment, however, the procedure specified in
these instructions should be followed. If servicing is done
by aqualified technician, he can expedite alignment by
setting the J.F. transformers for peak eye deflection using
avery low level 10.7
me signal. The strength of this signal
should be just strong enough to actuate the tuning eye,
but not so strong that it closes it to its normal minimum
gap. As the alignment proceeds, it will be necessary to
reduce the level of this test signal so that the tuning eye
accurately indicates the alignment peaks. Discriminator
alignment must follow the technique described in these
instructions. Conventional "sweep" techniques should not
be used.
Drift, or shifting of the tuned signal frequency, should
be cause to suspect poor mounting or soldering of C7 or
C8, or a defective 6AT8A tube.
If the dial lamp and tubes do not light when the set
is plugged in and turned on, check to see if the fuse is all
right. Sometimes a fuse may appear to be intact, but the
circuit will be open at one end. A continuity test at the
prongs of the line cord with a meter will show if the fuse,
power switch, and the power transformer primary winding
are all properly connected and functioning.
If the one ampere fuse blows when the set is turned on,
remove
all the tubes, install another one ampere slo-blo
fuse
and try again. If the same size replacement fuse blows
20
when all of the tubes ar(' removed, the trouble lies either
in the line cord, the power transformer, or in heater con-
nections in the tuner. Check particularly those wires con-
nected to the 5 lug terminal strip.
If the tubes light, but not the dial lamp, the lamp may
be defective, or the wires which lead to it via the etched
circuit board may be open.
If the tubes light and the tuning eye tube shows a
lighted filament, but the pye does not have a blue-gwen
glow on the front screen (which is visible through the
plastic insert in the front panel) check the wiring around
the tuning eye socket. If this is all right, the fault may be
in the power supply, and the rectifier tube V9 and the
associated wiring should be chpcked. If the eye glows, the
power supply wiring can be assumed to be correct.
If the tuning eye does not defled when the tuning knob
is turned, the difficulty is probably on PC-7. Check the
6AT8A tube and also wiggle the antenna coil L1 to make
sure its solder connections are firm.
Frequently difficulties in the I.F. strip (PC-8) can be
localized by touching the #1 pin of each J.F. tube in the
sequence V6, V5, V4, V3. Anoise should be heard each
time the #1 pin is touched, and the tuning eye should
deflect. If you find a#1 pin which does not produce a
noise,
then look for the difficulty between that point and
the previously tested #1 pin.
If there is apparent distortion in the signal, make sure
that this is not a momentary effect because of poor trans-
mission. See if the same distortion is apparent on another
station. If it persists, compare the same system with phono-
graph or tape as a different program source to see if the
effect can be localized to the tuner. If it is definitely in
the tuner, it may be caused by improper discriminator
alignment, and this portion of the alignment procedure
should be repeated. Audio distortion is also an effect of
"multipath dispersion"- reflections of the signal by build-
ings,
hilly terrain, etc., which cause effects similar to tele-
vision
"ghosts", often accompanied by reduced separation
on stereo broadcasts. Multipath effects can be reduced only
by improving the antenna system-relocation, reorienta-
tion, or replacement with a more directional antenna.
If the tuner operates and can be aligned, but has hum
in the signal, there are several tests to be made. If the hum
is part of the signal and disappears when the volume is
turned down, try several stations, as it is possible that the
one used as a test signal is broadcasting some hum. If hum
occurs on all stations, the 6AT8A may he faulty and should
b.e checked (preferably by substitution). If the hum per-
SISts, even when the volume control is turned down, unplug
the tuner from the associated equipment and see if the hum
disappears. If it does not, the fault lies in the associated
equipment. If it does disappear, then the hum may be
caused by a defective ground contact in one of the audio
cables, or it may be associated with V7 or V72. Check the
12AX7s by substitution.
If the eye deflects as the tuning dial is turned this is an
~ndication that the R.F. stages and the I.F. stage~ are work-
mg, and the difficulty lies either in the discriminator trans-
former or the subsequent audio stages. Working backwards
from the audio outputs, touch the following points with a
screwdriver to see if you get a pop or hum through the
speaker when the tuner volume control is turned up: The
center conductor of each output socket, pin #2 and pin #7
of V72, eyelet 71, pin #2 and pin #7 of V7. If anoise is
not heard through the speaker when one of these points is