Hammarlund HX50 Manual

THE
HX-500
TRAN MITTE
..
2 DESCRIPTION
- AND
-
The Hammarlund Manufacturing Co., Inc.
460 W •• t 34th Street, New York 1, N Y.
Interna lonal Dlvl.lon: 13 East 40th Street. New Vork 16, • Y.
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THE HX-500
TRANSMlTTER
INSTRUCTION AND SERVICE INFORMATION
ESTABLISHED 1910
ISSUE NO.1
In order to receive the full unconditional 90·day warranty
against defective material and workmanship in this receiver,
the warranty card must be filled out and mailed within two
weeks of purchase.
Please refer to serial number of equipment in correspond-
ence, and refer to ins ide bock COver for terms of warronty.
THE HAMMARLUND MANUFACTURING COMPANY~ INC.
460 West 34th Street~ New York l~ New York~ U.S.A.
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m
INTRODUCTION
The HX-500 Exciter-Transmitter is a self con-
tained unit designed with your present and future
requirements in mind. The transmitter is completely
self contained; employing 21 tubes (plus four semi-
conductor diodes), and requires only the addition of
a
suitable mike, key, or bug and suitable antenna
system for immediate" on the air" operation.
This Transmitter-Exciter covers, 80, 40, 20, 15
and 10 meter amateur bands by means of an eight
position rotary bandswitch. Four bandswitch posi-
tions are provided for complete coverage of the 10
meter band and the built-in VFO covers a range of
500 KC's. The eight crystals needed for complete
band coverage are supplied. The rotating drum, il-
luminated slide rule dial is calibrated to indicate
better than 10 KC's and the tuning knob skirt can be
read to better th an 200 cycles. One rotation of the
frequency knob covers two divisions or 20 KCS on
the illuminated dial drum.
The unit is capabie of transmitting the following
types of signals: LSB, USB, DSB, CW, FM, and
FSK.
The power output on SSB is 70-100 watts; 70-100
watts on CW, FSK, FM and 17-25 watts on DSB (AM).
The carrier suppression on both USB and LSB is
greater than -50 db and the unwanted sideband is
rej ected by more than -50 db. Spurious frequencies
generated within the unit are suppressed to a level
of -50 db or more. The intermodulation distortion
products have been suppressed beyond the -30 db
level.
The transmitter output pi-network has been care-
fully designed to match a 52 ohm transmission
cable impedance and suppress harmonic TVI.
A logarithmic type of carrier level indicator pro-
vides a very simple yet adequate means of tuning
up and continuously monitoring the transmitter. The
VOX circuit adjustments (Sensi tivity, Delay and
Anti-Trip) are located on the front panel.
The single sideband signal is generated III the
HX-500 Transmitter-Exciter by means of a highly
stable 60 KC oscillator whose signal is fed into a
carefully balan ced diode modul ator and subse-
quently applied to a series of cascaded overcoupled
and under coupled tuned circuits (with carrier re-
jection trap) which provides the necessary unwanted
sideband rejection. The choice of LSB, USB, or
DSB transmission is determined by the position of
the function switch which shifts the resonant fre-
quencies of the 60 KC tuned circuits to provide the
proper bandwidth for the desired mode of operation.
All of the controls that are required for proper
tune up and operation of the Transmitter-Exciter are
provided on it's front panel and these controls are
logically grouped for maximum operating ease.
The HX-500 was designed with you in mind. You
will find many hours of pleasure in operating this
truly fine communications instrument.
Page 2
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flll'l'l.fjlOllfi
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2
6 17 18 7 19 20 8 9 10
II
12
Figure J. The HX 500 Transmitter
1l0CATION OF CONTROLS
I. R.F. Output Level Meter
II. Tuning Dial Drag or lock
2. Calibrate Level Control 12.
Frequency Control
3. Meter
Sensitivity Control 13.
VOX Delay Adjustment
4.
R.F. Level Control 14. FSK
-FM N Adjustment
5. Final Amplifier Tuning Control 15. Anti-Trip Sensitivity Adjustment
6.
Function Switch Selector (Type of Transmission)
16. VOX Sensitivity Adjustment
7.
Operations Switch Selector
17. Key
Jack (CW -FSK 40 cycle Identification)
8. Audio
Level Control 18. Monitor Jack
9. Driver
Tuning Control 19.
Patch Jack
10. Band
Selector 20.
Microphone Connector
Page 3
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.. ----------- ----- ------~_ ..
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_---_.-
INSTALLATION
UNPACKING
After unpa~king the transmitter carefully, make
sure that all tubes, associated tube shields, and
pilot lamps are properly seated in their respective
!!lockets. Inspect the unit for any signs of damage
during shipment and carefully read all tags and labels
for any special instructions before discarding them.
MONI'TOR JACK
The microphone and key connections to the trans-
mitter are located along the bottom edge of the trans-
mitter panel. A standard microphone connector such
as the Amphenol type 75-MCIF or equivalent is
required to connect the microphone to the transmitter.
Any high impedance microphone, either crystal or
dynamic, will give satisfactory results when used
with this transmitter. The key or "bug" is con-
nected to the front panel receptacle by means of a
standard two contact phone plug. The key or "bug"
may be connected to the remote control plug, lo-
cated at the rear of the chassis, instead of the front
panel if desired. See Fig. 2 for remote key connec-
tions on the 14 prong plug located at the rear apron
of chassis.
MICROPHONE & KEY CONNECTIONS
The monitor jack provides a means of listening to
the received signals. Any headset fitted with a
standard two conductor phone plug can be used.
When the phones are plugged into the receptacle, the
communications receiver speaker will be disabled,
provided that the receiver output and speaker are
wired as shown in Fig. 2.
PHONE PATCH
The phone patch jack requires a standard two
conductor phone plug. This input receptacle is con-
nected directly across the high impedance audio
level control. Any of the phone patches available
should be useable when the output is fed into this
jack (on the assumption that sufficient gain has been
provided in the patch).
Page 4
117 VOLT POWER CONNECTION
Before inserting the line cord plug into the power
outlet, make certain that the power source is of the
proper voltage and frequency. The Model HX-500
Transmitter-Exciter is designed to operate on
105-125 volts, 50-60 cycles A.C. Do not under any
circumstances, connect this unit to a source of direct
current as doing so will blow the fuse.
ANTENINA CONNECTION
The output impedance of the HX-500 is '50 Ohms.
A suitable RF cable and cable connector is RG-8/u
coaxial cable with an Amphenol type 83-1SP or
equivalent coaxial cable connector.
The selection of the type of antenna and coupler
will depend upon the band of operation and the ob-
jectives of the user. The ARRL publications are an
excellent source for information on the design and
construction of various types of antenna systems.
ANTENNA RELAY
The HX-500 is equipped with an internal antenna
changeover relay. The typical Send-Receive connec-
tions are illustrated in Fig. 2.A stanaard phonograph
plug is required for the receiver connections to the
changeover relay contacts.
RECEIVER AUDIO CONNECTIONS
In order to have the VOX relay control the signals
from the station receiver's loud speaker, the HX-500
Transmitter must be connected to the station receiver
as shown in Fig. 2. In many cases the blocking bias
connections will be needed to put the receiver in
standby in place of the "make and break" contacts
as shown in the Figure.
BLOCKIING BIAS CONINECTIIONIS
A high impedance bias source (-lOOV.) is provided
to silence the station receiver during periods of
transmission. Pin 6 of the rear receptacle supplies
this voltage when the VOX relay is energized,
(transmit position) and grounded in the normally
open position. Pin 7 is a suitable groun? connection
for running a shielded lead to the receiver if it be-
comes necessary to minimize RF pick up in the lead.
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HX-500 TRANSMITTER HQ-170 RECEIVER
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0-300 MA DC
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METER READINGS
IDUNG CURRENT -60 MA.
FULLY LOADED -200 TO 230 MA.
(WITH MATCHED LOAD AN 0 IN
OSB-MOX POSITION)
EXTERNAL
~
1,7,13
2
3
4
5
6
8
9
10
II
12
14
WIRING CONNECTIONS
FUNCTION
GROUND
NORMALLY OPEN CONTACT}
CENTER CONTACT R:~:Y
NORMALLY CLOSED CONTACT
-100 V.
-IOOV. FOR RECEIVER BLOCKING
REMOTE
CW - 40 CYCLE FS K KEY
RECEIVER OUTPUT TRANSFORMER SECONDARY
STATION RECEIVER SPEAKER
FSK RELAY CONNECTION
FSK RELAY CONNECTION
CATHODE CURRENT OF VI5 S. VI6 (6146'S)
Figure 2. Typical Amateur Station Wiring
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FUNCTION OF OPERATING CONTROLS
FUNCTION SWITCH
The Function Switch determines the type of
emitted signal selected by the station operator. The
HX-500 is capable of transmitting the following
types of signals as indicated on the knob: LSB, USB,
DSB (AM),
CW, FSK, and FM.
OPERATION SWITCH
The five position Operations Switch turns the AC
power ON (Standby) and OFF, and inel udes the MOX,
VOX, and Calibrate positions.
When manual control of the transmitter is desired,
the MOX position is used. In the MOX position, the
antenna and VOX relays are always energized and
are completely independent of control by the VOX
circuit knobs (VOX sensitivity, VOX delay and
anti-trip).
In the VOX position, the transmitted output is
controlled by the voice energy from the microphone.
In this position, the antenna and VOX Relays are
controlled by the adjustment of the VOX circuit
controls. The proper setting of the VOX knobs is
outlined in the Tuning Procedure.
In the calibrate position, the Antenna and VOX
Relays are always in the de-energized position
(receive). This position is used to monitor the trans-
mitted signal in the communications receiver and is
also used for zero beating the HX-500 signal fre-
quency to an incoming signal or desired frequency.
CALI BRATE LEVEL
A calibrate level control is included in the trans-
mitter to adjust the amount of signal fed into the
receiver from the transmitter in the Cal position.
The Calibrate Level knob is adjusted so that the
desired level of the transmitter output as observed
on "s" meter of Receiver or the loudspeaker, (or
headset connected to Monitor Jack) is sufficient for
monitoring. A very limited amount of RF power is
"leaked" from the final amplifier tank circuit to the
receiver input via the Antenna Relay wiring.
R.F. LEVEL
The RF Level control adjusts the gain of the 5.55
to 6.05 Mcs broadband amplifier. Optimum RF output
on all bands is achieved with the adjustment of this
control. This is usually set at 4 to 5.
Page 6
AUDIO LEVEL
The audio level control adjusts the amount of
audio gain required to fully voice modulate the
transmitter. This is usually set at 5.
DRIVER TUNE
The Driver Tune knob adjusts both the 3rd mixer
plate and driver plate tuned circuits to resonance at
the frequency desired.
FINAL TUNE ,
The Final Tune knob adjusts the output tank
capacitor for maximum RF output. The knob skirt is
marked to indicate the designated area on each band
w here maximum output can be obtained as observed
on RF Level indicator.
BAND SELECTOR
The eight position Band Selector control selects
the proper combination of tuned circuits and the
proper heterodyne crystal on each band. The Band
Selector shaft also indexes the direct reading dial
drum which indicates the band in use.
METER SENSITIVITY
The meter sensitivity knob controls the amount of
deflection of the output level meter. Clockwise
rotation increases the sensitivity of the meter circuit.
The Output Level Meter is used to tune up the
transmitter to any frequency within its range. The
meter indication is logarithmically proportional to
the RF voltage across the 50 Ohm output. This fea-
ture gives the meter wider dynamic range of indi-
cation.
DIAL DRAG & LOCK
The small knob adjacent to the Frequency tuning
knob has been included in the HX-500 for the pur-
pose locking the dial drive to a selected frequency
and adjusting the tuning knob calibration. Clockwise
rotation of this knob restrains the frequency knob
from
turning. It also enables the adjustment of dial
action or torque required for personal preference of
the operator.
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IIi
TUNING
GENERAL
The HX-500 Transmitter has been designed to
give the utmost in quick and easy operation for the
radio amateur operator. All operating controls are
clearly identified.
The slide-rule type of dial is marked off to indi-
cate every 10 kilocycle change in frequency on each
of the eight direct reading bands. In addition to the
10 kcs markings, every band contains two heavy dot
markings and two heavy diamond shaped markings.
The dot markings indicate the outer limits of each
amateur band in which authorized amateur communi-
cation is permitted. The diamond shaped markings
have been included to show at a glance the outer
limits of each amateur phone band. Since the 10
meter band extends over foUF band change positions,
the markings are included only on the first and last
of the four segments.
The frequency tuning knob and dial lock knob are
connected to the variable capacitor located on the
VFO sub-chassis by means of a spring loaded gear
drive mechanism. Twenty five revolutions of the
tuning knob covers a SOO Kcs band segment. The
major markings on the frequency tuning knob are
calibrated to indicate 1 Kcs changes in frequency
and are sub-divided to indicate frequency changes
of two hundred cycles between each small division.
To accurately set the transmitter to a specific
frequency; for example 3962.4 Kcs., turn the tuning
knob until the dial pointer indicates the nearest 10
Kcs point below the desired frequency e.g., 3960
Kcs and add two major divisions (2 Kcs) plus two
sub-divisions (400 cycles) as indicated on the
skirt of the tuning knob.
The HX-SOO dial drive mechani~m has been
machined to extremely close tolerances in manu-
facturing; however, there will exist (as with all gear
driv~s)· a very small error between dial pointer
indication and the tuning knob skirt calibration when
knob markings are compared with the pointer indica-
tion at various points across the band. There are
several other frequency determining elements which
also contribute to the dial inaccuracies such as:
VFO tuning capacitor and crystal tolerances.
As shipped from the factory the "0" marking on
the knob skirt has been mechanically aligned to the
high frequency end of all bands. Since most amateurs
operate within a limited portion of a particular band,
the knob markings should be indexed for the highest
a ccuracy possible in the area of operation.
To correct for this knob runout, the knob may be
PROCE
URE
turned when the pointer remains stationary with the
aid of the dial lock. The most accurate frequency
calibration means readily available to the amateur
is the crystal calibrator located in the communica-
tions receiver. Zero beat the transmitter as outlined
below to the nearest 100 Kcs check point, lock the
dial by turning the lock knob clockwise, then turn
tuning knob until "0" on the knob coincides with
the fiducial. This will require more force or torque
than when di al is free running.
CAUTION
The HX-SOO Transmitter has been very
conservatively designed to give reason-
ably long vacuum tube life. However, the
life expectancy of vacuum tubes greatly
depends upon how much use and abuse
they get. All tuning adjustments should
be made with the RF output level meter
indicating less than -10 db for conserva-
tive operation (with the meter sensitivity
set at its proper operating level). The
final setting of the RF level control
should be the last tune-up adjustment to
be made.
INITIA TUNE-UP ADJUSTMENT
The Operating controls should be set as follows:
FUNCTION:
DSB
OPERATION:
OFF
AUDIO LEVEL:
o
DRIVER TUNE: Set to "5"
BAND SELECTOR: Set to desired band
FREQUENCY: Set to desired frequency
CAUBRATE LEVEL:
Set to "s"
METER SENSITIVITY:
Set to "5"
R.F. LEVEL:
Set to "3"
FINAL TUNE:
Set to middle of desired
band segment
VOX DELAY: C ounterc1ockwise posi-
tion
FSK-FM-~F:
Set to middle of range
ANTI-TRIP SENSITIVITY: C ounterc1ockwise posi-
tion
VOX SENSITIVITY: Counterclockwise posi-
tion
ALC (REAR APRON): Clockwise position (OFF)
Page 7
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m
Turn the "Operations" switch to Standby and
allow at least a one minute vacuum tube warm-up.
Turn the "Operations" switch to MaX and adjust
"Driver Tune" for maximum meter deflection. Then
adjust "Final Tune" for the highest reading. Repeat
adjustment of both Driver and Final Tune until Meter
deflection cannot be improved.
CW OPERATION
Turn the "RF Level" control until the "Level
Indicator" reaches a maximum (saturates). Use the
lowest setting of the control consistent with obtain-
ing maximum output (knee of curve). Adjust "Meter
Sensitivity" control to read "0" db.
Turn the "Function" switch to CW and key the
transmitter via the "Key" jack.
SIDEBAND OPERATION
After the transmitter ha s been tuned up to a de-
sired frequency on CW, adjust the "ALC" control
(on the rear of the chassis) so that the "Level Indi-
cator" drops to -1 db or one half a division. Turn
the "Function" switch to USB or LSB and the
"Audio Level" control knob until the "Level In-
dicator." meter fluctuates or averages around the -10
db marking when talking into the microphone at con-
versational level. This setting will usually be 4 to
5 depending on the mike, speaking level and distance.
VOX SENSITIVITY - VOX DElAY -
ANTI-TRIP OPERATION
After the transmitter has been tuned up to the
desired frequency with all of the larger sized knobs
adjusted, the VOX Relay control knobs are brought
into adjustment.
Turn the "Operations" switch to indicate VOX
and turn the "VOX Sensitivity" knob clockwise until
the VOX relay readily closes when talking into the
,microphone. It is desirable to keep the "VOX Sensi-
tivity" as low as possible since any undesired
background noise in the Ham Shack will trigger the
VOX relay and you will be on-the-air. Usually the
"VOX Sensitivity" knob will be near the center of
its range or pointer vertical.
The de-energizing time for the VOX Relay is
controlled by the "VOX Delay" control. This control
is used to keep the VOX Relay closed during the
quiet periods between words. Turn the "VOX Delay"
control clockwise until the relay flutter between
words is eliminated during the course of conversa-
tional speech. Excessive "VOX Delay" should be
avoided. Leave at CCW position to start.
The "Anti-Trip" Control is used when the "Oper-
ations" switch indicates VOX operation. When the
Page 8
Station receiver and speaker are connected for VOX
operation (see Figure 2) the speaker "Anti-Trip"
control is adjusted to a setting where the audio
'signa~ picked up by the microphone from the re-
ceiver's speaker will not energize the VOX Relay.
This feature prevents the retransmitting of the in-.
coming audio signals from your station receiver.
Excessive speaker volume is capable of disabling
the VOX Relay completely, therefore, minimum re-
quired gain should be used. Always adjust the
receiver audio gain to the desired level before ad-
justing the "Anti-Trip" control.
AM OPERATI,ON
Turn the "Frequency" and "Band Selector"
knobs to indicate anyone of the authorized amateur
phone bands. Tune the transmitter for maximum out-
put as outlined in the general and CW sections with
switches on DSB and MaX. Reduce the RF Output
level to indicate -6 db on the "Level Indicator".
Increase the audio level until there is a small fluc-
tuation or kick upward in the output level meter
pointer when talking into the microphone.
The carrier reference level can be established
more precisely if an oscilloscope and audio oscil-
lator are used to set up and monitor the output
signal. If the carrier level is set too high, peak
amplitudes are flattened before 100% modulation
occurs. If the carrier level is set too low the maxi-
mum power output capabilities are not attained at
100% modulation.
FSK OPERATION
FSK Operation is accomplished with the aid of V4
(l2BY7) Reactance Tube Modulator which shifts the
frequency of the 60 Kcs Carrier Oscillator by means
of a change in modulator screen voltage (see Figure
3). Lowering the screen voltage lowers the frequency
of the 60 Kcs Oscillator and raises the RF Output
Frequency; conversely, raising the screen voltage
raises the 60 Kcs Oscillator frequency and lowers
the RF Output Frequency. The change in screen
voltage is controlled by the Polar Relay keying
employed for RTTY.
The amount of Frequency Shift is adjusted by the
FSK Deviation control R140. When the Polar Relay
is closed the screen voltage on the Reactance Modu-
lator may be raised, lowered, or remain unchanged
depending on the position of the arm of FSK Devia-
tion Potentiometer. The zero position is located at
(approximately) the center of its range. Clockwise
rotation from the center position will decrease the
s cre en voltage and lower the frequenc y of the 60
Kcs Oscillator. Counterclo~kwise rotation from the
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+150V.
FSK
TO SF-ID REAR
(FOR CW OPERATION)
PIN 12 ON
J2 AND P2
PIN 9 ON
J2 AND P2
R22
I MEG.
R25
200
R 24
330
middle position will increase the screen voltage and
raise the frequency of the 60 Kcs Oscillator. The 40
cycle keyed identification frequency shift is accom-
plished by closing the key jack contacts.
Note that the 40 cycle keyed identification shift
is not adjustable and when the CW key Jack contacts
are closed the screen voltage is lowered thereby
lowering the 60 Kcs Carrier Oscillator by 40 cycles
and raising the RF Output Frequency by 40 cycles.
Tune up the transmitter as outlined on the preced-
ing general and CW sections. Turn the Operation
switch to Calibrate. Zero beat the transmitted signal
in the communications receiver. Rotate the Function
switch to indicate FSK and adjust the small "FM-
FSK~F" knob for zero beat if necessary. This ad-
justment is made with both Polar Relay Contacts
arid key Contacts Open.
Close Polar Relay Contacts and vary the FSK
Deviation Control for zero beat, then adjust in
either direction from this position for the desired
850 cycle shift.
FM OPERATtONI
FM Operation is accomplished by Reactance Tube
V4 (l2BY7) modulating the 60 Kcs Carrier Oscil-
lator. In the FM position, the audio amplifier output
is fed to the screen grid of the Reactance tube there-
by translating audio variations to frequency devia-
tions of the Carrier Oscillator.
Tune up the transmitter as outlined in the preced-
ing general and CW sections. Turn Operation Switch
to Calibrate. Zero beat the transmitted signal in the
communications receiver. Rotate the Function Switch
to indicate FM and adj ust the small "FM-FSK~F"
knob for zero beat if necessary. Turn Operations
Switch to MOX and raise Audio Level until a small
fluctuation of the Output Level is observed on the
meter.
BIAS CONTROL ADJUSTMENT
The output of the bias supply in the transmitter
DEV.
~
FOR REMOTE
KEY-40
CYCLE FSK
CONNECTION
(OPTIONAL) L-
has been set at the factory to -50 volts d.c. with 117
volts a.c. power line input. If the line voltage is
subject to variations, it is advisable to monitor the
plate current of the 6146 vacuum tubes and make
periodic adjustments in the bias voltage to keep the
plate current at its optimum value. Adjustments of
the bias supply will result in extending the life of
the vacuum tubes and will provide maximum output
power.
Provision has been made via the "External Con-
nection" plug to connect a 0-300 milliampere d.c. or
a 0-3
volt d.c. voltmeter to read cathode current on
the Final Amplifier tubes. The 0-3 volts d.c. meter
will read 0-300 milliamperes when connected. Con-
nect the positive meter terminal to pin 14 of the
plug and the other side of the meter to pin 13 of the
plug.
Rotate the "Bias Adj,." to read 60 milliamperes of
plate current when the equipment is in the standby,
LSB or USB positions.
MODEL HX-500 USED AS AN
EXCITER-DRIVER WITH
A LINEAR AMPLIFIER
The model HX-500 output power is more than ade-
quate for driving a high powered linear amplifier. It
may be necessary to insert a resistive pad to absorb
some of the power output and for the pQrpose of
maintaining a 50 Ohm load to the HX-500 Transmit-
ter. The amount of padding needed will depend upon
the circuitry in the linear amplifier and the tubes
used. Always use the least padding necessary so
that the HX-500 is working at well below its maxi-
mum output. This will result in more linear operation
overall and extend the 6146 tube life.
When the HX-500 is used as an Exciter-Driver, the
RF Level Control is adjusted for optimum drive on
the grid of the high powered linear amplifier instead
of the 6146's.
Figure 3.
CI63
l,005uF
Simplified Schematic Diagram
showing RTTY Operation
EXTERNAL
CONNECTION
PLUG
REG
R139
82K
5%
R 140
50K
R 141
22K
5%
-}TO POLAR
CoRJr'A~\S
Page 9
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