Heathkit VF-1 Installation instructions

ASSEMBLY AND OPERATION OF THE
HEATHKIT VARIABLE FREQUENCY
OSCILLATOR
MODEL VF-1
SPECIFICATIONS
Output Frequencies, ..........00eeeeuee eee 1750-2000, 7000-7425, 6740-6808
Calibrated Bands............... eceaeeeeeese 160-80-40-20-15-11-10
RF Output............. acc str padie aa yeu ee ...... Approximately 10 volts
Tube Complement............--..00. 20 eeeue 6AU6 -Oscillator
OA2Z - Voltage Regulator
Power Requirements.......... seeeveesecess 6.3 VAC at.45.A, 250-350 DC at 15-20 MA
Cabinet Size... 0.05... eee eee ... 7 high x 6 1/2" wide x 7" deep
Net Weight....... 0.04... c cece cece eens cee 4 Ibs,

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Page 2

INTRODUCTION
The Heathkit model VF-1 Variable Frequency Oscillator was designed to provide the Ham Fra-
ternity
with
an
economical,
yet
very
stable,
VFO
which
is
so
necessary
for
operation
in
today's
crowded bands. It has sufficient output to drive any multi-stage transmitter of modern design
on all bands from 160 through 10 metexs. If operation of the 6 or 2 meter bands is desired, the
11 meter padder condenser may be adjusted to give fundamental frequencies down to 6 mc from
the VFO. With suitable doubling, the 6 and 2 meter bands may be operated with the 8th or 24th
harmonic of the VFO.
The VF-1 is wired to operate with the Heathkit AT-1 Transmitter by merely plugging into the
proper receptacles on the AT-1. With any other transmitter, simple adapters can be used to
obtain the necessary connections.
CIRCUIT DESCRIPTION
The
primary
consideration
in
the
designof
any
device
which
determines
the
operating
frequency
of
a
transmitter
is
stability.
Stability
in
turn
is
dependent
upon
both
the
electrical
and
mechan-
ical
characteristics
of
the
unit.
Mechanical
stability
may
be
defined
as
freedom
from
vibration
or
any
movement
of
the
frequency
determining
components.
Electrical
stability
means
that
the
electrical
characteristic
of
the
components
must
not
change
during
circuit
operation.
Neither
of
these
conditions
can
be
completely
obtained
but
certain
precautions
can
be
taken
to
minimize
mechanical
instability
and
most
forms
of
electrical
instability
can
bé
compensated
for.
The quartz crystal "rock" has excellent frequency stability because its small size and rigid
mounting practically preclude mechanical instability and if operated at the moderate grid cur-
rents characteristic to small tetrode or pentode tubes, the heating effect of RF currents is small
and has little effect upon frequency. However, the crystaloscillator gives no freedom of move-
ment, consequently the self-excited oscillator has returned to the fold in new dress.
Mechanical stability in the Heathkit VFO has been achieved in the following manner. The coils
are wound on heavy ceramic forms using litz or double cellulose wire then coated with Q-Max
and baked. Double bearing construction is used on the tuning capacitor and both coils and capac-
itor mounted on a sub-assembly to make them independent of the panel. The frequency deter-
mining components are enclosed in a separate compartment to maintain rigidity, shielding and
isolation from the hotter elements of the circuit. The padding and temperature compensating
capacitors
are
also
mounted
on
or
in
this
compartment,
thus
maintaining
all
the
frequency
deter-
mining components at the same temperature.
One of the primary electrical causes of frequency shift in, self-excited oscillators is due to
changes in tube capacitance with applied filament and plate voltage. There are two basic meth-
ods used to lessen this effect. (1) Swamp the tuned circuit with a large amount of capacity so
that any change in tube capacitance will be small by comparison (high C VFO). (2) Present a
very low impedance tuned circuit for the tube grid to look into (series tuned Colpitts or Clapp
oscillator).
The Heathkit VF-1 uses the series tuned Colpitts circuit which besides having the low impedance
tuned circuit, also contains a considerable amount of swamping capacity in the form of a capac-
itive voltage divider. This voltage divider, consisting of two 510 wuf capacitors, is necessary
in a Colpitts circuit to supply in-phase voltage from the grid to cathode to maintain oscillation.
The seriestuned circuit of the VF-1 consists of two separate coils and two separate stator sec-
tions of a differential capacitor to develop the basic output frequencies. By using two tuned
circuits, a better LC ratio and bandspread is obtained over a wide range. Padder capacitors
are placed in parallel with the sections of the differential tuning capacitor for adjustment and
an additional padder capacitor is switched in to cover the 11 meter range. Rigidly mounted iron
core slugs compensate for small variations of coil inductance and ceramic temperature com-
pensating capacitors correct the frequency deviation due to coil heating.
Page 3

The
6AU6
tube
operating
in
a
Clapp
oscillator
circuit
is
also
operating
as
an
electron
coupled
oscillator.
In
this
circuit
the
tube's
screen
grid
acts
as
the
plate
of
the
oscillator
circuit
with
its
voltage
stabilized
at
150
volts
by
the
OA2
voltage
regulator
tube...
The
tube
plate
is
coupled
to
the
oscillator
section
only
by
the
electron
stream
and
further
isolated
by
grounding
the
sup-
pressor
grid.
Thus
the
plate
circuit
operates
substantially
independent
in
relation
to
the
oscil-
lator
section
of
the
tube.
This
increases
the
isolation
between
the
oscillator
and
the
following
load
and
minimizes
the
effect
of
loading
upon
frequency.
The
use
of
slug-tuned
coils
in
the
plate
circuit
of
the
6AU6
provides
relatively
broad
banding
yet
maintains
a
fairly
high
output.
Two
coils
are
operated
in
series
for
the
lower
frequency
bands.
The
higher
inductance
coil
is
shorted
out
when
operating
on
higher
bands.
The
VFO
output
is
capacitively
coupled through
a
50
coaxialcable
to
the
transmitter.
A
plas-
tic
plug
which
will
fit
1/2"
spaced
crystal
sockets
is
furnished
with
the
kit.
If
so
desired,
the
builder
can
substitute
a
coaxial
plug
without
any
ill
effects
to
VFO
operation.
Power
for the
VF-1
is
obtained
from
the
transmitter
or
an
auxiliary
source
by.
means
of
a
3-wire
shielded
cable
and
an
octal
plug.
The
octal
plug
wiring
shown
in
the
manual
is
designed
to
fit
the
Heath-
kit
AT-1
Transmitter.
It
may
be
changed
to
fit
any
other
transmitter
that
the
builder
may
have.
NOTES ON ASSEMBLY AND WIRING
The
Heathkit
model
VF-1
Variable
Frequency
Oscillator
when
constructed
by
carefully following
the
instructions
set
forth
in
this
manual,
will
result
in
a
highly
stable
and
reliable
VFO
capable
of
years
of
trouble-free
service.
All
of
the
components
furnished
with
the
VF-1
are
of.the
high-
est
quality
and
should
last
indefinitely
under
normal
service.
Tubes
may
have
to
be
replaced
after
their
normal
lifetime
but
due
to
the
type
of
circuit
used,
this
will
have
very
little
effect
upon
calibration.
The
VF-1
is
easily
constructed
and
can
be
completed
in
a
fairly
short
time.
However,
the
very
nature
of
the
instrument
is
such
that
the
highest
quality
of
workmanship
should
be
exercised
in
its
construction.
We
therefore
urge
you
to
take
the
necessary
time
to
assemble
and
wire
the
kit
carefully.
Do
not
hurry
the
workand
you
will
be
rewarded
with
a
VFO
that
can
be
entrusted
with
the
frequency
control
of
your
transmitter.
This
manual
is
supplied
to
assist
you
in
every
way
to
complete
the
VFO
with
the
least
possible
chance
for
error.
We
suggest
that
you
take
a
few
minutes
now
and
read
the
entire
manual
through
before
any
work
is
started.
This
will
enable
you
to
proceed
with
the
work
much
faster
when
construction
is
started.
‘The
large
fold-in
pictorials
are
handy
to
attach
to
the
wall
above
your
work
space.
Their
use
will
greatly
simplify
the
completion
of
the
kit.
These
diagrams
are
repeated
insmaller
form
within
the
manual.
We
suggest
that
you
retain
the
manual
in.
your
files
for
future
reference,
both
in
the
use
of
the
VFO
and
for
its
maintenance.
UNPACK THE KIT CAREFULLY AND CHECK EACH PART AGAINST THE PARTS LIST. In
so doing you will become acquainted with each part. Refer to the charts and other information
shown
on
the
inside
cover
of
the
manual
to
help
you
to
identify
any
parts
about
which
there
may
be a question. If some shortage is found in checking the parts, please notify us promptly and
return the inspection slip with your letter to us. Hardware items are counted by weight and if a
few are missing, please obtain them locally if at all possible.
Read the note on soldering on the inside of the back cover. Crimp all leads tightly to the ter-
minal before soldering. Be sure both the lead and terminal are free of wax, corrosion or other
foreign substances. Use only the best rosin core solder, preferably a type containing the new
activated fluxes such as Kester "Resin-Five," Ersin "Multicore" or similar types.
NOTE: ALL GUARANTEES ARE VOIDED AND WE WILL NOT REPAIR OR SERVICE
INSTRUMENTS IN WHICH ACID CORE SOLDER OR PASTE FLUXES HAVE BEEN
USED. , WHEN IN DOUBT ABOUT SOLDER, IT IS RECOMMENDED THAT A NEW
ROLL PLAINLY MARKED "ROSIN CORE RADIO SOLDER" BE PURCHASED.
Page 4

Resistors
andcondensers
usually
have
a
tolerance
rating
of
+20%
unless
otherwise
stated
inthe
parts
list.
Therefore,
a
100
KQ
resistor
may
test
anywhere
from
80
KQ
to
120
K&.
The
letter
K
is
commonly
used
to
designate
a
multiplier
of
1000.
Tolerances
on
condensers
are
generally
even
greater,
limits
of
+100%
and
-50%
are
common
for
electrolytic
condensers.
The
parts
furnished
with
your
Heathkit
have
been
specified
so
as
to
not
adversely
affect
the
operation
of
the
finished
VFO.
In
order
to
expedite
delivery
to
you,
we
are
occasionally
forced
to
make
minor
substitutions
of
parts.
Such
substitutions
are
carefully
checked
before
they
are
approvedand
the
parts
supplied
will
work
satisfactorily.
By
checking
the
parts
list
for
resistors
for
example,
you
may
find
that
a
2.2
megohm
resistor
has
been
supplied
in
place
of
a
2
megohm
as
shown
in
the
parts
list.
These
changes
are
self-evident
andare
mentioned
here
only
to
prevent
confusion
in
checking
the
contents
of
your
kit.
We
strongly
urge
that
you
follow
the
wiring
and
parts
layout
shown
in
this
manual.
The
position
of
wires
and
parts
is
extremely
critical
in
a
stable,
calibrated
VFO
and
changes
may
seriously
affect
the
characteristics
of
the
circuit.
STEP-BY-STEP ASSEMBLY INSTRUCTIONS ©
The
following
instructions
are
presented
in
a
simple,
logical,
step-by-step
sequence
to
enable
you
to
complete
your
kit
with
the
least
possible
confusion.
Be
sure
to
read
each
step
all
the
way
through
before
starting.
When
a
step
is
completed,
check
it
off
in
the
space
provided.
This
makes
it
easy
to
resume
construction
after
your
work
has
been
interrupted.
NOTE:
We
suggest
that
you
do
the
following
before
any
work
is
started.
1,
Select
from
the
large
fold-in
pictorials
included
with
the
manual,
the
diagram
showing
the
phase
of
construction
you
are
engaged
in
at
the
time.
Attach
this
diagram
tothe
wall
above
your
work
space.
2.
After
identifying
the
parts
from
the
parts
list,
place
them
in
a
large
shallow
box
so
that
they
are
readily
accessible.
This
will
save
considerable
time
in
construction.
3.
Read
thoroughly
the
assembly
and
wiring
instructions
on
the
inside
rear
cover
of
the
manual
and
refer
tothe
general
information
on
both
inside
covers
of
the
manual
to
identify
the
parts.
4.
In
assembling
the
kit,
use
lockwashers
under
all
nuts
unless
a
solder
lug
is
used.
Tube
sockets
are
mounted
with
the
metal
flange
on
top
of
the
chassis.
All
screws
have
their
heads
on
top
or
outside
of
the
chassis.
This
construction
may
be
noted
by
referring
to
Figure
4.
Unless
otherwise
stated,
6-32
screws,
lockwashers
and
nuts
are
used
in
mounting
of
parts.
ASSEMBLY AND WIRING
(S) means solder. (NS) means do not solder yet.
x
i,
Mount
the
differential
tuning
capacitor
to
the
front
plate
of
the
sub-chassis
as
shown
in
Fig-
ure
1
and
Pictorial
1.
Use
a
3/8"
lockwasher
on
the
rear
of
the
sub-chassis
and
a
flat:
washer
and
3/8
nut
on
the
front.
Position
the
capacitor
so
that
the
stator
sections
appear
as
shown
in
Figure
1
and
the
capacitor
terminal
lugs
appear
as
shown
in
Pictorial
1.
X
(
Mount
the
40
meter
ceramic
coil
(one
having
the
least
number
of
turns)
on
the
sub-chassis
onthe
side
of
the
capacitor
having
only
two
stator
plates,
as
shown
in
Figure
1.
Use
assem-
bly
method
shown
in
Figure
2.
The
coil
terminals
should
be
toward
the
capacitor.
The
position
of
this coil
will
hereafter
be
referred
to
as
the
right
side
as
viewed
from
the
rear.
Use
care
in
mounting
the
coils
to
prevent
damage
to
the
ceramic
form.
Page 5

PICTORIAL 1
Page 6

Figure 2
1 Figure 1
X iY) Mount the 160 meter coil on the left side of the sub-chassis in the same manner, also with
its terminals toward the capacitor.
(vf Connect a 22 uuf silver mica capacitor (black-red-red-black-gold-red) from the ground lug
fp under the top 40 meter coil mounting lug (NS) to terminal 2 on the tuning capacitor (NS).
The capacitor should be mounted flat against the chassis with the leads no longer than nec-
essary to make the connections.
(7 Connect a 4.7 uf negative 750 temperature compensating ceramic capacitor to the same
points. Lay the ceramic capacitor tight against the mica capacitor (NS) as shown in Pic-
torial 1.
KX! Connect a short bare wire from the solder lug (S) to tuning capacitor terminal 5 (S).
X(W Connect a 2" length of bare wire to terminal 2 on the tuning capacitor (S). Leave the other
end free.
\ Connect a 47 pf silver mica capacitor (black-yellow-purple-black-gold-yellow) from the
ground lug under the top160 meter coil mounting lug (NS) to terminal 1 of the tuning capac-
itor (NS). Use the same procedure described above. .
Ki Connect a 10 ywuf negative 750 ceramic capacitor to the same points in the same manner.
Solder the ground connection only.
(W) Connect a 2" length of bare wire to terminal 1 of the tuning capacitor (S). Leave the other
end free.
Temporarily set this section aside.
Ji On the L-shaped section of the sub-chassis, mount the pilot light socket K using a 6-32
screw through the socket and chassis with a lockwasher and nut on the under side. Position
as shown in Pictorial 2 and tighten.
h ny Insert the two irorl core slugs in the bushings on the back of the L section as shown in Pic-
torial 2. Add 6-32 nuts to slug shafts but do not tighten yet.
Page 7

PICTORIAL 2
Page 8 ,

K re With a pair of long-nosed pliers, bend one terminal of all three 4.5-25 wuf zero temperature
coefficient ceramic trimmer capacitors, as. shown in Figure 3. Use extreme care in bending
to prevent damage to the capacitor and be sure to bend the correct terminal, as shown in
the figure.
(1 Using 4-40 screws and nuts, mount two of the capacitors on either side of
the pilot light socket and position as shown in Pictorial 2. Tighten care-
fully and not too tightly or the ceramic will break.
AK (W With a hot iron, solder the bent terminals to the chassis as shown in Pictorial 2. Figure 3
Set this section aside temporarily.
{won the under side of the main chassis, mount the remaining 4.5-25 wuf ceramic trimmer
capacitor
using
4-40
screws
and
nuts
and
taking
the
same
precautions
outlined
above.
Po-
sition as shown in Figure 4 and solder the bent terminal to the chassis.
Figure 4
x ane 3/8" rubber grommets in holes El, E2 and E3.
4 ae a 5/16" rubber grommet in hole E4.
XK (V} Mount the two shielded ceramic sockets in holes A and B, using 3-48 round head screws
: and nuts (do not use the four semi-flathead screws here). Position the sockets so that the
erminals appear as shown in Figure 4.
X (V) Mount the cable clamp bracket D to the rear apron of the chassis by means of the phone
jack G, as shown in Figure 4. Position both as shown. Do not use a lockwasher here, but
place a flat washer under the nut.
Page 9

Y
(I
Examine
the
slug-tuned
output
coil.
You
will
notice
that
the
four
terminals
are
numbered.
Mount
the
coil
as
shown
in
Figure
4
with
the
#1
and
#2
terminals
toward
the
front
of
the
\
chassis.
Use
4-40
nuts
on
the
spade
lugs
to
secure
the
coil.
WA
visant
the
front
sub-chassis
to
the
main
chassis
with
the
40
meter
coil
or
right
side
over
the
grommet
E3,
using
6-32
screws.
On
the
under
side
of
the
chassis,
place
solder
lugs
over
each
screw
and
position
as
shown
in
Figure
4.
Lightly
tighten
the
two
nuts.
I
(WF
Assemble
the
tuning
dial
as
shown
in
Figure
5,
using
the
four
semi-flathead
3-48
screws.
f
(i
Mount
the
dial
to
the
tuning
condenser
shaft
using
a
1/4"
8-32
set
screw.
Before
tight-
PROSTED
SIDE
ening
the
set
screw,
adjust the
dial
so
that
the plastic rim is clear of and about 1/32"
from
the
front
skirt
of
the
chassis.
As
it
Q=>---—
will be further adjusted later, donot tighten
the set screw more than sufficient to hold the
dial
in
place.
O=>--Qz>---}
X
(~%)
If
necessary,
loosen
the
screws
holding
the
Q=m---~-
i
sub-chassis
front
plate
and
adjust
it
to
allow
the dial to rotate freely and parallel to the
front apron of the chassis. It may be nec-
essary to bend the plate slightly toward the
back or front also to achieve perfectly par-
allel rotation of the dial on both the vertical
and horizontal axes in respect to the chassis.
After the dial has been properly adjusted,
tighten the two nuts holding the sub-chassis
securely.
Figure 5
NOTE:
The
following
wiring
to
the
range
switch
can
be
more
easily
accomplished
before
the
switchis
mounted.
In
all
the
following
instructions
where
a
specific
lengthof
wire
is
mentioned,
it
should
be
stripped
1/4"
at
each
end
before
installing.
: (Wf Connect a 2 1/2" length of,wire to S6 (S). Leave the other end free.
K
(vw)
Connect
a
5
1/2"
length
of
wire
to
S5
(NS).
Leave
the
other
end
free.
fof
cut
one
lead
of
a
22
KQ
resistor
(red-red-orange)
to
1/2"
length
and
connect
it
to
$5
(S).
Leave
the
other
end
free.
} iH Gaekeet a3 3/8" length of wire to S4 (NS). Leave the other end free.
SS aa a short bare wire from $4 (S) to $3 (NS).
t( Cut one lead of a 2.2 KQ resistor (red-red-red) to 5/8" length. Connect it to S$3(S). Leave
the other end free.
fF Connect a 2" length of wire to S8 (S)._ Leave the other end free.
y! Connect a 3" length of wire to S9 (S). Leave the other end free.
y( ) Afterthe switch is mounted, the wires coming from S4, S5 and S9 will gothrough the grom-
met E3.
Page 10

PICTORIAL 3
Page 11

PANEL MOUNTING
Ais
Mount
the
drive
bushing
through
the
center
panel
hole
from
the
rear.
Place
a
flat
washer
and
a
3/8"
nut
on
the
front
and
screw
up
to
finger
tightness.
A
Insert
friction
drive
shaft
through
this
bushing
from
the
rear.
Do
not
put
the
knob
on
yet.
(
Place
thetwo
switches
through
the
chassis
holes
as
illustrated
in
Figure
4
and
Pictorial
3.
A
PANEL.
Yl
Assemble
the
parts
onthe
switchshaft
in
prop-
CHASSIS
7
er sequence as illustrated in Figure 6.
x
hfe
On
the
range
switch,
slide
wires
coming
from
terminals
$4,
S5
and
S9
through
grommet
E3.
x
-y
By
tilting
panel
slightly
forward
after
it
is
slid
over
the
two
switch
shafts,
and
at
the
same
AEG
time
holding
the
friction
drive
shaft
toward
the
;
e\
2/g
LOCKWASHER
rear,
it
will
be
possible
to
make
the
split
wash-
ers
of
the
friction
drive
wheels
engage
the
plas-
tic
dial
disk.
See
Figure
5.
If
the
dial
was
placed
too
far
from
the
chassis
originally,
it
may
be
necessary
to
move
it
back
slightly.
K
(
UY
There
is
a
slight
amount
of
clearance
in
the
drive
bushing
panel
hole.
If
the
drive
turns
the
dial
without
slipping,
tighten
the
bushing
nut
securely.
If
not,
make
use
of
the
hole
clear-
ance
by
pushing
down
onthe
shaft
before
tightening
the
nut.
This
will
engage
the
drive
more
firmly.
If
too
tight,
reverse
the
above
procedure.
}
(7
After
the
dial
has
been
adjusted
to
rotate
freely
and
the
friction
drive
mechanism
has
been
satisfactorily
engaged,
the
dia]
must
be
matched
with
the
tuning
capacitor.
To
the
left
of
the
7000
calibration,
you
will
note
a
small
line
near
the
dial
edge.
Rotate
tuning
capacitor
until
rotor
plates
are
completely
meshed
with
the
larger
stator
section,
then
loosen
the
dial
set
screw
and
turnthe
dial
until
this
mark
is
centered
in
the
panel
opening.
Retighten
set
screw.
X
(ws
Using
1/4
x
8-32
set
screws,
mount
the
large
round
knob
on
the
dial
drive
shaft
and
the
two
skirted
knobs
on
the
switch
shafts.
Align
the
skirted
knobs
to
conform
with
panel
markings.
x
(vf
Connect
a
short
bare
wire
from
tuning
capacitor
terminal
4
(NS)
to
coil
terminal
4(S).
See
Pictorial
1.
4
(Connect
the
wire
coming
from
S9
to
tuning
capacitor
terminal
4
(S).
(vf
Connect
the
wire
coming
from
S4
to
coil
terminal
3
(S).
X
(wy
Connect
the
wire
coming
from
$5
to
coil
terminal
i
(S).
So
Connect
a
short
bare
wire
from
coil
terminal
2
(S)
to
tuning
capacitor
terminal
3
(S).
\
(Mount
the
L-shaped
sub-chassis
plate
to
the
main
chassis
using
two
6-32
screws
inserted
with
their
heads
above
the
chassis.
Below
the
chassis,
mount
the
two
terminal
strips
H
and
J
onthese
screws.
Position
as
shown
in Figure 4 and secure using lockwashers and nuts.
¥
(Wj
On
the
slotted
green
plastic
strip,
mount
two
small
L-brackets
as
shown
"
in
Figure
7.
Page 12
ae fh, FLAT
te --CONTROL
@) "NUT
WASHER
~~ 9" THICK
WASHER

NOTE:
‘In
the
next
step,
if
any
forcing
is
necessary
tc
obtain
hole
alignment,
do
the
bending
on
the
L-plate
only
so
as
not
to
disturb
the
dial
alignment.
i VV insert 6-32 screws through the small L-brackets then through the L-shaped sub-chassis
;
plate
and
through
the
front
sub-chassis
plate
as
shown
in
Pictorial
2.
Make
sure
the
plastic
strip
just
clears
the
dial
when
the
latter
is
rotated
and
that
the
slot
is
centered
in
the
panel
opening.
This
canbe
checked
by
placing
a
light
behind
the
unit
and
viewing
it
from
the
front.
Secure
the
assembly
with
lockwashers
and
nuts.
FINAL WIRING
x
(
The
two
free
bare
wires
coming
from
the
tuning
capacitor
should
be
brought
through
the
adjacent
holes
in
the
L-shaped
sub-chassis
and
connected
to
the
ceramic
trimmer
conden-
sers.
See
Pictorial
2.
Arrange
the
wires
neatly
and
centered
in
the
holes.
Cut
off
excess
lead
wire
and
solder
both
connections.
(WI
Strip
both
ends
of
a
wire
7"
long
and
connect
one
end
to
K1
(S).
Pf
(V¥
Strip
both
ends
of
a
wire
il
1/8"
long
and
connect
one
end
to
K2
(S).
Ky
Twist
the
two
wires
for
a
length
of
4
1/2"
and
run
through
grommet
E4.
For
the
following
wiring
refer
to
Pictorial
3:
x
(“¥
Connect
the
short
wire
to
J1
(NS).
K
7
Connect
the
long
wire
to
L2
(NS).
K
A
conser
a
bare
wire
from
L3
(S)
to
the
adjacent
solder
lug
(S).
AWS
connect
one
end
of
a
wire
8
1/2"
long
to
A4
(Ss).
K
A
Connwel
the
other
end
to
L2
(S).
X(A%
connect
one
end
of
a
wire
5"
long
to
L1
(S).
X eee the other end to J4 (NS).
( Connect a wire 7 1/2" long to J4 (NS). Connect the other end to G2 (S).
Xvyon
the
range
switch,
connect
the
two
loose
ends
of
the
22
KQ
and
2.2
K
resistors
to
the
adjacent
solder
lug.
Arrange
resistors
neatly,
cut
off
excess
leads
and
solder.
XK
Vi
Connect
the
wire
coming
from
$8
to
the
ceramic
trimmer
capacitor
(S).
See
Pictorial
3.
x
Sa
the
wire
coming
from
S6
to
H3
(NS).
K
cs Connect a wire 4 1/8" long from $1 (S) to C1 (NS).
Connect a wire 4" long from $12 (S) to C2 (8).
Xo connect a wire 2 1/2" long from C1 (S) to J2 (NS).
rh Connect a wire 2 1/2" long from C3 (S) to A5 (NS).
X(Vh
connect
a
short
bare
wire
from
H3
(NS)
to
Al
(S).
Arrange
to
clear
chassis.
tit
cone
a
bare
wire
to
H2
(NS).
Run
flat
against
chassis
and
through
A2
to
the
center
tube
socket
shield
(NS).
See
Pictorial
3.
-
Page 13

} (I Connect a short bare wire from H1 (NS) to A7 (NS). Arrange to clear chassis.
k (Connect a 510 uyf silver mica capacitor (black-greén-brown-brown-gold-yellow) from H3
(S) to Hi (NS).
x (vec Connect a 510 uwuf silver mica capacitor from HI (S) to H2 (S).
K Pott Connect a .005 disc ceramic dapacitos from A2 (S) to A3 (NS).
i (vf Connect a 4 1/8" length of wire from A3 (S) to J1 (NS).
ah Connect a .005 disc ceramic capacitor from the center tube shield (S) to A6 (NS).
XK Vf Connect a 6 1/2" length of wire from A6 (S) to B5 (NS).
xX WS Connect a 15 KQ 5 watt resistor from B5 (S) to J2 (NS).
Kw Connect a bare wire from B7 (S) to J3 (NS).
K(f Connect a .005 disc ceramic capacitor from J3 (S) to J2 (NS).
Xa Connect one end of a 1.1 mh RF choke to AT (S). Leave the other end free.
Kt
Wout
both
leads
of
a
100
wuf
mica
capacitor
(white-brown-black-brown-silver-brown)
to1/4"
length.
Connect
one
lead
to
A5
(S).
Leave
the
other
end
free.
PREPARATION OF CABLES
W
strip
1"
of
the
outer
coating
from
both
ends
of
the
coaxial
cable,
comb
out
and
twist
the
shield
braid
as
shown
in
Figure
8.
¥ (of strip 1/4" from the inner insulation.
Figure 8:
} MN Place a 3/16" cable clamp over the outer covering and insert cable through
! grommet Et as shown in Pictorial 3.
f (1 Mount the cable clamp to the clamp bracket and include a soldering lug in
the mounting as shown in Figure 9.
} (Ww Connect a .005 disc ceramic capacitor from the solder lug (NS) to Gl (NS).
F
)
+4 (M% Connect the inter coax conductor to the 100 wuf capacitor coming from
A5 (NS). See Pictorial 3.
f (yf Twist the shield braid together and connect to the solder lug (NS).
Figure 9
Page 14

(Uf Connect a 47 KQ resistor (yellow-purple-orange) from this point (S) to the solder lug (NS).
(WIC Connect a bare wire to the same solder lug (8). Run the wire along the back of the chassis
through G3 (S). Leave 1" extended free past G3.
(»7% Connect free end of the 1.1 mh RF choke to Gt (S).
"ee Strip off the outer covering for 3"' on the 3-wire shielded cable.
CT ‘Place a 1/4" cable clamp over the outer covering as shown in Figure 9.
WW Unwind the shield braid up to the cable pain .
(WT Insert the cable through grommet E2 and secure the cable clamp and a solder lug to the
bracket in the same manner used with the coaxial cable. See Figure 9 and Pictorial 3.
(7 Twist the shield braid together and connect to the adjacent solder lug (NS). Cut off excess
braid.
Connect the wire coming from G3 to the solder lug (S).
(J Connect the red wire to J2 (S).
we Connect the green wire to J4 (S).
(WF Connect the yellow wire to Ji (S).
(#4) Refer to Figure 8 and prepare the remaining end of the coaxial cable as shown.
( WFTin both the inner conductor and the shield braid and connect to the rystal plug by tight-
ening the plug screws on the wire and braid.
vA Strip 1 1/2" of the outer covering from the 3-wire silat unwind the braid and re-
twist it tightly. \
\
( Slide the octal socket cap over the wire as shown in Figure 8 with the large end toward the
wire end.
mi The twisted braid is connected to pin 1 of the octal plug. uo
Ca
ae red wire is connected to pin 4 of the octal plug. =
WY) T
A The yellow wire is connected to pin 2 of the octal plug.
(
he green wire is connected to pin 8 of the octal plug. WA
.
Connect a jumper wire between pins 6 and 7 of the octal plug if the VF-1 is to be used with
a Heathkit AT-1 Transmitter.
NOTE: For use with the VF-1, the Heathkit AT-1 Transmitter miist have a wire connected from
socket connections A5 to D6. This will bring the 6AG7 oscillator cathode to ground when the
VFO power plug is inserted. In the event that both stages of the AT-1 are to be keyed, connect
the jumper wire from pin 5 to pin 6 in the VF-1 power plug, and an additional wire from D5 to
TB3 inthe AT-1. If it is desired to key the VF-1 with the transmitter, connect an additional
jumper from D5 to-D8 in the AT-1 and leave the VF-1 panel switch in.the STANDBY position.
NOT & » Page 15

TESTING AND FINAL ASSEMBLY
NOTE:
The
instructions
given
here
for
testing
will
be
based
on
use
with
the
Heathkit
AT-1
Transmitter.
In
the
event
another
transmitter
is
used,
follow
the
general
procedure,
remem-
,
bering
that
the
VF-1
power
requirements
must
be
provided
for;
6.3
VAC
at
.45
amp
and
250
to
\
350
VDC
at
20
to
25
MA.
IMPORTANT
WARNING:
MINIATURE
TUBES
CAN
BE
EASILY
DAMAGED
WHEN
PLUGGING
THEM
INTO
THEIR
SOCKETS.
THEREFORE,
USE
EXTREME
CARE
WHEN
INSTALLING
THEM.
WE
DO
NOT
GUARANTEE
OR
REPLACE
MINIATURE
TUBES
BROKEN
DURING
INSTALLATION.
xX
(A
Install
the
6AU6
tube
in
socket
A
and
cover
with
the
tube
shield.
KC
wt
Install
the
OA2
tube
in
socket
B,
no
shield
is
required.
4 (V7 Install the pilot lamp.
}
(J
Plug
the
VF-1
power
plug
into
the
AT-1
VFO
power
socket
and
switch
both
VF-1
and
AT-1
;
to
STANDBY
position.
Turn
on
the
AT-1
power
switch.
:
Ȥ
(WS
The
pilot
light
on
the
VF-1
should
light.
If
it
doesn't,
check
to
see
if
the
VF-1
is
plugged
into
the
AT-1
modulator
connection.
A
(
4
Plug
the
VF-1
output
connector
into
the
AT-1
crystal
socket
with
shield
braid
at
the
bottom.
CAUTION:
Before
proceeding,
be
sure
the
AT-1
is
connected
to
a
dummy
load,
not
to
the
an-
tenna.
As
the
VF-1
has
not
yet
been
calibrated,
it
might
be
operating
far
outside
the
band.
1
(vy
On
the
VF-1,
set
all
three
ceramic
trimmer
capacitors
to
mid
position
(screw
slot
in
line
with
terminals)
and
screw
both
slugs
in
the
output
coil
in
until
about
1
/2"
of
screw
thread
is
exposed.
t
(7
Switch
the
VF-1
range
switch
to
the
160-80-40
position
and
the
operation
switch
to
ON
pos-
ition.
x
WA
Switch
the
AT-1linto
80
meter
position,
grid
plate
switch
to
plate
position
and
standby
switch
to
ON.
X
(
Ly
Bet
VF-1
dial
to
about
3700
ke
and
tune
the
AT-1
output
control
for
dip.
Meanwhile
moni-
tor
with
your
receiver.
If
a
dip
cannot
be
obtained,
try
again
with
VF-1
dial
near
either
band
edge
3500-4000.
Be
sure
AT-1
Transmitter
has
been
modified
as
explained
above.
.
(a
After
completing
the
step
above,
switch
VF-1
to
40-20-15-10
position
and
the
AT-1
to
20
meter
position.
Set
the
VF-1
dial
for
about
7100
kc.
Tune
the
AT-1
driver
and
output
con-
trols
in
the
same
manner
used
with
crystal
operation.
Check
as
above.
If
difficulty
is
en-
countered
at
this
‘stage,
see
the
trouble-shooting
section
farther
on
in
this
manual.
»
X
(v)
At
this
stage,
the
slugs
of
the
output
coil
may
be
roughly
tuned
for
further
output.
The
top
slug
controls
the
low
frequency
output
and
the
bottom
slug
the
high
frequency
output.
x
(4
Install
rubber
feet
on
cabinet
as
shown
in
Figure
10.
}
(/
)
Mount
the
VF-1
in
the
cabinet
using
#6
sheet
metal
screws.
When
sliding
unit
into
the
cab-
-—~inet,
take
care
not
to
damage
the
range
switch
or
the
plastic
dial
light
shield
against
the
binet
flange.
The
VF-1
is
now
ready
for
final
calibration.
Page 1

CALIBRATION
If
the
kit
constructor
has
access
to
one
of
the
LM
or
BC
frequency
standards
they
are
excellent
for
calibration.
The
other
alternative
is
to
accumulate
as
many
crystals
in
the
bands
concerned
as
possible.
The
crystals
preferably
should
be
near
the
edge
of
the
bands.
A
separate
oscillator
circuit
for
the
crystals
will
be
necessary
so
that
both
crystal
oscillator
and
VFO
can
be
beat
against
each
other
in
the
receiver.
Before
beginning
calibration,
allow
the
VF-1,
crystal
os-
cillator,
frequency
meter
and
receiver
to
warm
up
for
one-half
hour
or
more.
If
a
BC
221
fre-
quency
meter
or
equivalent
is
used
(do
not
use
ordinary
radio
service
generators)
it
should
be
set
to
1750
kc.
If
a
crystal
oscillator
is
used,
have
the
frequency
as
near
as
possible
to
1750
or
3500
ke.
Set
VF~-1
dial
to
1750
or
to
the
crystal
frequency
used
with
the
VF-1
bandswitch
in
the
160-80-
40
meter
position.
Insert
an
insulated
screwdriver
type
tuning
wand
through
the
right-hand
hole
on
top
of
the
cabinet
as
viewed
from
the
front
and
engage
the
trimmer
capacitor
under
the
hole.
Using
the
trimmer
capacitor,
tune
the
VF-1
for
zero
beat
with
the
standard
as
heard
in
the
re-
ceiver
with
the
BFO
off.
The
trimmer
capacitors
are
very
critical
in
tuning
and
tend
to
drift
for
a
second
after
being
moved
sotune
with
extreme
care
and
withdraw
the
wand
for
final
checking.
Using
the
frequency
meter
or
another
crystal,
check
the
dial
at
the
high
frequency
end
of
the
band.
If
the
dial
reading
is
higher
than
the
actual
frequency,
screw
in
the
slugon
the
same
side
as
the
trimmer
capacitor.
The
slugs
are
accessible
through
the
holes
in
the
rear
of
the
cab-
inet.
Readjust
the
trimmer
to
read
correctly
at
the
high
end
of
the
dial
and
check
frequency
at
the
low
end.
If
dial
reads
lower
than
actual
frequency,
screw
slug
in
further
and
recheck.
It
may
be
necessary
to
repeat
the
steps
several
times
before
both
ends
of
the
dial
read
correctly.
However,
when
they
dothe
in-betweencalibration
will
have
a
high
degree
of
accuracy.
Inserting
the
slug
further
into
the
coil
decreases
the
dial
spread
for
a
given
frequency
range.
After aligning the frequency to the dial in the step above, tune the VF-1 to about the mid-scale
point
and
peak
its
output
by
adjusting
the
low
frequency
output
coil.
This
adjustment
is
made
by
‘uning
the
slug
which
is
accessible
af
the
rear
top
cabinet
hole.
i
grid
meter
reading
on
the
itter will indicate ut. é coil is very far off resonance, it will probably be
necessary
to
slightly
retune
the
trimmer
capacitor.
It
should
be
rechecked
at
any
rate.
When the low frequency range is calibrated to your satisfaction, switch to the 40-20-10 position
and repeat the above steps using a 7 to 7.3 mc standard or appropriate crystals. The left-hand
top cabinet hole will give access to the high frequency trimmer, the rear cabinet hole access to
the slug, and the rear bottom cabinet hole access to the output coil. The last turn on the high
frequency coil may have to be moved in extreme cases where the slug does. not cover enough
range. Moving turn closer tothe winding duplicates screwing the slug in further and vice versa.
For 11 meter calibration, the frequency standard or crystals must operate at 6740 to 6808 kc.
The trimmer is accessible through the front bottom cabinet hole. The switch must be in the 11
meter position.
After the VF-1 has been completely calibrated, remove from cabinet and tighten the nuts on the
slug shaft against the bushings and replace in cabinet.
The VF-1 will holdcalibration over a long time if properlycared for. However, any VFO should
be
checked
for
calibration
from
time
to
time.
Remember,
a
VFO
is
by
no
means
a
frequency
standard
and
if
operation
very
close
to
a
band
edge
is
desired,
a
constant
check
must
be
kept
upon its frequency.
VFO OPERATION
By
means
of
the
OFF-STANDBY-ON
switch,
the
VF-1
may
be
controlled
independently
of
the
transmitter
or
controlled
by
the
transmitter.
Thus
with
the
key
up
on
the
transmitter,
the
VF-1
can
be
operated
alone
for
tuning
purposes,
and
incidentally,
should
be.
It
is
definitely
bad
oper
-
ating
procedure
to
swish
a
VFO
across
the
band
with
the
entire
transmitter
following
it.
This
causes
needless
interference
to
other
stations.
The
VFO
alone
should
be
set
tothe
desired
fre-
quency,
THEN
quickly
tune
the
transmitter
to
resonance
at
the
new
frequency.
This
procedure
produces
far
less
interference
and
will
not
classify
you
as
a
"lid"
among
your
fellow
hams.
Page 17

As was mentioned previously, crowding the band edges is not recommended unless a positive
and constant check upon frequency is maintained. Particularly with a phone transmitter where
the
sidebands
may
run
three
or
more
kc
over
and
under
the
base
frequency.
Even
a
single
side-
band
transmitter
can
put
some
hash
on
the
undesired
sideband
and
create
signals
outside
of
the
amateur
band.
When plugging the VFO output into a crystal socket, be sure that the "hot" lead or center wire
of the VFO plug is connected tothe grid side of the crystal socket. If the VF-1 tends to overdrive
the
crystal
stage,
swamping
resistance
can
be
connected
across
the
crystal
socket.
The
transmitter
used
in
conjunction
with
the
VF-1
must
be
free
of
parasitics
or
any
tendency
toward
self-oscillation
and
must
have
the
equivalent
input
power
sensitivity
of
the
average
crystal
oscillator
stage.
IN CASE OF DIFFICULTY
’
Mistakes
in
wiring
are
the
most
common
cause
of
difficulty.
Consequently,
the
first
step
is
to
recheck all wiring against the pictorials and the schematic diagrams. Often having a friend
check the wiring will locate an error consistently overlooked.
Also, with miniature sockets there is a possibility of shorts between adjacent socket terminals
due tothe close spacing. This should be checked and if any doubt exists, the terminal should be
pried apart until obvious spacing can be seen between them.
Sometimes apparently good solder connections will have an insulating coating of rosin between the
wire, terminalandsolder. This is oftenthe case when insufficient heat was applied in soldering.
An
ohmmeter
check
of
connections,
WITH
ALL
VOLTAGES
OFF,
will
test
this
condition.
A voltage check at tube socket terminals will often indicate the reason for faulty operation. A
table
of
voltages
is
shown
below.
These
voltages
were
measured
with
a
20,000
chm
per
volt
multimeter, during VF-1 operation with the Heathkit AT-1 Transmitter.
Range Switch
40-20-15-10
NOTE: A VTVM should not be used to measure voltage asthe presence of RF will invalidate the
reading obtained. If a different source of power supplies the VF-1, the voltages in columns 1,
5 and 7 of socket A (6AU6) will change accordingly.
In
the
event
that
the
voltages
test
approximately
as
shown
and
the
VF-1
still
will
not
oscillate,
look
for
a
possible
short
from
tuning
capacitor
stator
to
ground
or
grounds
at
pins
1
or
7
of
socket
A.
Also
be
sure
that
the
2.2
KQ
and
22
KQ
resistors
are
not
reversed
and
that
the
1.1
mh RF
choke
or
the
key
jack
does
not
present
an
open
circuit
to
the
tube
cathode.
Page 18

REPLACEMENTS
Material supplied with Heathkits has been carefully selected to meet design requirements and
ordinarily will fulfill its function without difficulty. Occasionally improper instrument opera-
tion can be traced to a faulty tube or component. Should inspection reveal the necessity for re-
placement, write to the Heath Company and supply all of the following information:
A. Thoroughly identify the part in question by using the part number and description found in
the manual parts list.
B. Identify the type and model number of kit in which it is used.
C. Mention the order number and date of purchase.
D. Describe the nature of defect or reason for requesting replacement.
The Heath Company will promptly supply the necessary replacement. Please do not return the
original component until specifically requested to do so. Do not dismantle the component in
question as this will void the guarantee. If tubes are to be returned, pack them carefully to
prevent breakage in shipment as broken tubes are not eligible for replacement. This replace-
ment policy does not cover the free replacement of parts that may have been broken or damaged
through carelessness on the part of the kit builder.
SERVICE
In event continued operational difficulties of the completed instrument are experienced, the fa-
' cilities of the Heath Company Service Department are at your disposal. Your instrument may
be returned for inspection and repair for a service charge of $3.00 plus the cost of any addi-
tional material that may be required. THIS SERVICE POLICY APPLIES ONLY TO COM-
PLETED INSTRUMENTS CONSTRUCTED IN ACCORDANCE WITH THE INSTRUCTIONS AS
STATED IN THE MANUAL. Instruments that are not entirely completed or instruments that
are modified in design will not be accepted for repair. Instruments showing evidence of acid
core solder or paste fluxes will be returned not repaired.
The Heath Company is willing to offer its full cooperation to assist you in obtaining the proper
operation of your instrument and therefore this factory repair service is available for a period
of-one year from the date of purchase.
SHIPPING INSTRUCTIONS:
Before returning a unit for service, be sure that all parts are securely mounted. Attach a tag
to the instrument giving name, address and trouble experienced. Pack in a rugged container ,
preferably wood, using at least three inches of shredded newspaper or excelsior on all sides.
DO NOT SHIP IN THE ORIGINAL KIT CARTON AS THIS CARTON IS NOT CONSIDERED
ADEQUATE FOR SAFE SHIPMENT OF THE COMPLETED INSTRUMENT. Ship by prepaid
express if possible. Réturn shipment will be made by express collect. Note that a carrier
cannot be held liable for damage in transit if packing, in HIS OPINION, is insufficient.
SPECIFICATIONS
All prices are subject to change without notice. The Heath Company reserves the right to dis-
continue instruments and to change specifications at any time without incurring any SbUBston
to incorporate new features in instruments previously sold.
WARRANTY
The Heath Company limits its warranty of parts supplied with any kit (except tubes, meters and
rectifiers, where the original manufacturer's guarantee only applies) to a period of three (3)
months from the date of purchase. Replacement will be made only when said part is returned
postpaid, with prior permission and in the judgment of the Heath Company was defective at the
time of sale. This warranty does not extend to any Heathkits which have been subjected to mis-
use, neglect, accident and improper installation or applications. Material supplied with a kit
shall not be considered as defective, even though not in exact accordance with specifications, if
it substantially fulfills performance requirements. This warranty is not transferable and ap-
plies only to the original purchaser. This warranty is in lieu of all other warranties and the
Page 19

Heath
Company
neither
assumes
nor
authorizes
any
other
person
to
assume
for
them
any
other
liability
in
connection
with
the
sale
of
Heathkits.
The
assembler
is
urged
to
follow
the
instructions
exactly
as
provided.
The
Heath
Company
as-
sumes
no
responsibility
or
liability
for
any
damages
or
injuries
sustained
in
the
assembly
of
the
device
or
in
the
operation
of
the
completed
instrument.
HEATH COMPANY
Benton Harbor, Michigan
PARTS LIST
PART PARTS DESCRIPTION PART PARTS
No. Per Kit No. Per Kit
Resistors Hardware
1-22 1 22 KQ 73-1 3
1-25 1 47 KQ 73-4 1
1-44 1 2.2 KQ 204-M67 1
3-6E 1 15 KQ 5 watt 204-M68 2
206-25 1
Capacitors 207-4 1
20-1 1 47 wy silver mica 207-5 1
20-11 1 100 wuf mica 250-2 4
20-41 1 22 uuf silver mica 250-8 8
20-42 2 510 wut silver mica 250-9 15
21-27 4 005 ufd ceramic 250-34 6
21-28 1 10 puf N 750 ceramic 250-43 4
21-29 1 4.7 wut N 750 ceramic 250-49 4
26-20 1 11-35 yf dual variable 252-1 8
31-10 3 4.5-25 uuf NPO trimmer 252-3 17
252-7 5
292-15 8
Switches-Tubes
953-10
5
63-77 1 1 pole 3 pos. switch 253-22 2
63-78 1 3 pole 3 pos. ceramic switch 253-23 4
411-11 1 6AU6 tube 954-1 13
411-59 1 OA2 tube 254-4 3
412-1 1 - #47 pilot light 259-1 6
261-1 4
Coils-Chokes 455-6 1
40-54 1 160 M coil 475-3 2
40-55 1 40 M coil
40-56
1
Dual
plate
coil
Miscellaneous
45-4
1
1.1
mh
RF
choke
90-30
1
100-M43 1
Sockets-Terminal
Strips-Knobs
200-M65
1
431-10
1
3-lug
terminal
strip
200-M66
1
431-12 1 4-lug terminal strip 200-M67 1
434-35
2
7-pin
ceramic
socket
203-M60F80
1
434-44
1
Pilot
light
socket
206-M26
1
436-4 1 Phone jack 340-2 1
438-6
1
Octal
plug
343-2
1
438-10
1
Crystal
plug
344-1
1
440-1
1
Octal
plug
cover
347-4
1
462-19
2
Skirted
knob
464-M3
1
462-26 1 Round knob 100-M44 1
, 595-91 1
Page 20
‘DESCRIPTION
3/8" rubber grommet
5/16" rubber grommet
Cable bracket
Light shield bracket
1 3/4" tube shield -
1/4" cable clamp
3/16" cable clamp
3-48 round head screw
#6 sheet metal screw
6-32 x 3/8 screw ©
4-40 x 1/2 screw
8-32 x 1/4 set screw
3-48 binder head screw
3-48 nut
6-32 nut
Control nut
4-40 nut
Control flat washer
1/8 steel spacing washer
1/16 fiber spacing washer
#6 lockwasher
Control lockwasher
#6 solder lug
Rubber feet
1/4 shaft bushing
Iron core slug
Cabinet
Dial drive plate
Chassis
Sub-chassis front
Sub-chassis cover
Panel
Light shield
length #20 bare wire
length Coaxial cable
roll Hookup wire
length 3-wire cable
Dial
Friction drive
Manual