Hy-Gain 644 Installation instructions

ORDER NO.
644
FOOTWARMER AMATEUR RADIO AMPLIFIER
The Hy-Gain Footwarmer Ampl ifier is a p[ecision built
amplifier of advanced design. It utilizes two tubes, two
transistors in a tuned grid tuned plate circuit for ampl ifi-
cation of AM, FM, CW and SSB signals.
The Footwarmer is designed for 117v AC 60 cycle base
installation. It has a built-in automatic antenna change
over relay, which operates without special external con-
nections, making it perfect for operation with low power
transceivers having nO external ampl ifier control circuits.
The Footwarmer has been designed and constructed to
suppress radi ation that may cause tel evi si on interference.
TVI problem has been given full consideration in the
design and the layout of the chassis. There are, however,
some types of TVI that cannot be prevented within the
amplifier. This is particularly true in weak signal areas.
In such cases, a good commercial low pass filter is recom-
mended.
INSTALLATION
OPERATION INSTRUCTIONS
Height (including feet) '" " 59/16
Width , , 14"
Depth 11 1/2
Construction Lightweight aluminum chassis with
rugged steel cover
Frequency Range Amateur 10 meter band
Types of Emission AM, FM, CW, SSB, DSB
Power Output 200 watts AM with fu II upwa rd
modul ation
Dri ve Requi red to Trigger Antenna Reiay 1 watt
Max Drive (unmodulated carrier and FMi 5 watts
(amplitude modulated carrier) 3.5 watts
(ampl itude modulated peak) , 14 watts PEP
Input Impedance (unbalanced) , 50 ohms nominal
Qutput Impedance (unbalanced) 50 ohms fixed
Antenna Switching Automatic provided by
RF sensing circuit
Power Requi rements 117v AC
Cable Connector Data Input & Output requires PL-259
SECTION II
UNPACKI NG
Carefully remove the Footwarmer Amplifier from the carton.
Examine it closely for signs of shipping damage. If in-
spection shows damage the del iveri ng carrier must be
contacted immediately and a claim filed.
The responsibility for safe delivery rests with the carrier.
The responsibility of obtaining reimbursement rests with
you. Proillpt action wi II speed adj ustmeht. Our warranty
does not cover malfunction or damage which is a result of
improper handling by a carrier.

SECTION III
INSTALLATION
The location of the mounting is not critical, but considera-
tion must be given to provide adequate ventilation. The
amplifier has a built-in fan that blows air out of the top.
Therefore, care should be taken not to place papers, books,
or other objects on top of the amplifier.
When the amplifier has been suitably mounted in a con-
venient position, connect a length of RG 58/U coaxial
cable between the transceiver and the XCVR socket.
Connect a 50 ohm antenna to the ANT socket (on the left,
viewed from the back).
The antenna system should be checked for VSWR of less
than 2: 1 before the Footwarmer is used. For best perfor-
mance of your communication system, the VSWR should be
as low as possible.
ON-OFF Switch Controls power to amplifier
AM-FM & SSBSwitch Adjusts delay constant of
automatic antenna reiay
XMT-Standby Switch Controls the automatic antenna
cirr.uit
Output Meter Visual indication of relative
RFpower output
Tune-Operate Switch (Rear Panel) , .. Provides for
low power tune-up duri ng
initial tuning
Drive Control (Rear Panel) Controls power output
for optimum operation
The side control in the cover is used for tuning the ampli-
fier. The amplifier is pretuned at 27.575 MHz and the tune
control wi II allow tuning the amplifier to some other
frequency.
NOTE
THE LOAD CONTROL IS NOT ACCESSIBLE FROM THE OUT-
SIDE. IT IS PRESET TO PROVIDE A CORRECT MATCH TO
50 OHM ANTENNA SYSTEM. THIS CONTROL SHOULD NOT
BE ADJUSTED. IT IS FACTORY PRESET.
CAUTION
THIS SECTION SHOULD BE READ THOROUGHLY BEFORE
OPERATING THE AMPLIFIER.
Place the function switch in the AM-FM position. Push
the ON-OFF switch to ON. The red pilot light will come
on. After allowing approximately 60 seconds for warm-
up, push the XMT Standby switch to XMT. This will ener-
gi ze the automatic antenna rei ay control ci rcuitry.
Set the Slide switch on the rear panel to the Tune position.
Adjust the drive control for midway position. Apply 3.5
watts drive power by keying the exciter (transceiver)
microphone and quickly adjust the tune control for maxi-
mum reading on the output meter. Removethe drive power
after adjustment.
Do not apply drive power for more than five seconds with
out adjusting the tune control or damage to the tubes can
result.
Reapply drive power and adjust the drive control (on the
rear panel) so that the amplifier produces approximatel y
100 watts output.
The input tuning coil is preset for the 26-35 MHz range.
If operated outside this range it should be reset. To reset
the input tuning coil (accessible from bottom), first place
a VSWRbridge between the Iinear and the exciter. Appl y
drive power and reset the coil slug with a hex shaped non-
metallic alignment tool for lowest SWRand maximum output
in the "tune" position of the switch.
Set the Tune-Operate sIide switch to the Operate position,
reapply drive power and adjust the drive control for 150
watts output on the wattmeter. A readjustment of the input
tuning coil may be necessary to produce minimum input
VSWR.
Always use a good peak reading watt meter such as the
Hy-Gain 421A when trying to read Modulation peaks.
Readjust the tune control for maximum output and reset
the drive control for 150 watts carrier output.
The amplifier is now adjusted to provide 150 watts carrier
and 300 watts with full upward modulation. If the average
output power decreases with modulation then either the
transmitter (exciter) is incapable of upward modulation or
the Amplifier has not been tuned up correctly and the
above procedure should be re-checked. If this do.es not
correct the situation, the drive control (on the rear panel)
should be adjusted for a sl ightly lower power level neces-
sary to produce upward modulation. It is far better to have
reduced carrier power with upward modulation than a
carrier power of a higher level with downward modulation.
This will increase your communication range and provide
a clearer signal with much less distortion.
The automatic antenna change-over operati on in the ampli-
fier is provided by a special transistorized input sensing
circuit. Should you desire to hold the amplifier in a ready
position, but not use it until needed, simply place the
XMT-Standby switch in the Standby position. The sensing
circuit wi II be di sabled and the antenna connected to the
exciter (transceiver) at all times.

3.5 TUNING FOR AM WITHOUT WATTMETER
(26- 35 MHz)
After proper installation and attachment of a nominal 50
ohm antenna, place the function switch in the AM,FM
position and push the ON-OFF switch to ON.
The red pilot light will come on. After allowing approxi-
mately 60 seconds for warm-up, push the XMT Standby
switch to XMT. This will energize the automatic antenna
relay control circuitry.
Set the Slide switch on the rear panel to the Tune position.
Adjust the drive control for midway position, Apply 3.5
watts drive power by keying the exciter (transceiver)
microphone and quickly adjust the tune control for maxi,
mum reading on the output meter. Remove the drive power
after adjustment.
Do not apply drive puwer for more wan five seconds with
out adjusting the tune control or damage to the tubes can
result.
Reapply drive power and adjust the drive control for a
meter reading of "6". Remove drive power,
Set the Tune-Operate switch to the Operate position, re-
apply drive power and adjust the drive control for a meter
reading of 1 . Readjust the Tune Control for maximum
reading on the meter. Reset the drive control for a meter
reading of 1 , if necessary.
The amplifier is now adjusted to provide approximately
150 watts carrier output with full upward modulation to
300 watts. If the meter reading decreases with modulation,
either the exc iter is incapable of upward modulati on or the
amplifier has not been tuned correctly and the procedure
should be rechecked. If this does not correct the situation
the drive control (on the rear panel) should be adjusted
fa a slightly lower power level necessary to produce
upward modul ation,
Always use a good peak reading watt meter such as the
Hy-Gain 421A when trying to read modulation peaks.
For best AM operation the linear must be tuned according
to above procedures. Many misconceptions regarding
linear operation exist among linear users. Reviewing a
few points regarding proper linear operation will help to
provide better tune,up and communications for the user,
1. The linear amplifies the Radio Frequency (RF) signal.
2. If the output signal reproduced is identical to the input
except stronger, the amplifier is said to be linear. If not,
the amplifier is non,linear.
3. Non, Iinear operation produces spurious outputs and
distortion of the signal.
5. All power used to produce distortion and spurious sig-
nals is power not being used for communication.
6. The Amplifier provides a 300 watt RF envelope maximum
power output.
7. Any attempt to operate AM·at the :rlO watt carri er level
wi II produce downward modulation with distortion, and
spurious signals.
8. Distortion and spurious signals (lost power) will occur
in all linear amps if operation at maximum carrier power
is attempted.
9. All linear amplifiers should be operated at about one
half the maximum carrier output to allow for modulation
expansion of the carrier.
10. Operation without Ieaving room for moduIation expan-
sion wi II not provide good communication. The carrier
'contributes nothing toward intelligibility, only good modu'
lation can carry intelligence. Running higher carrier power
and lower modulation is a detriment rather than an asset.

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SECTION IV
SERVICE INFORM TION
DO NOT ship equipment to the Manufacturer without prior
authorization. We prefer to send special shipping labels
which will avoid the delay of unexpected shipment.
If time is extremely important, wire or call for approval
and we will rush labels to you. When a shipment is ex-
pected, even the time of sending the labels is less than
that lost when an unexpected shipment is received.
It is VERY IMPORTANT that the shipment be well packed
and fully insured. Damage claims must be settled between
you and the carrier and wi II greatly delay any returns.
Proper packing normally avoids this trouble.
ALL SHIPMENTS MUST BE SENT TO US PREPAID. We do not
accept collect shipments. All returns should be made in
our standard cartons only - so save your carton when un-
packing the unit. When a shipment is returned it will be
handled in one of three ways ...
1- Where all service is in warranty the shipment will be
returned prepaid by a carrier of our choice.
2 - If there are any charges not covered by warranty we
wi I hold the shipment and advi se you of costs, wh ich you
can then send.
3 - Or, upon your written authorization, we will ship COD
for any charges not covered by warranty, then the carrier
will collect these charges and the transportation costs on
arrival. Unclaimed or refused COD shipments will not be
reshipped until payment of service and transportation
charges is received. Shipment wi II then be made collect
for reshipment transportation charges. Unclaimed equip-
ment automatically becomes the property of the Manufac-
turer 60 days after date of refusal or return and wi II be
disposed of for payment of charge due.
We WILL NOT ship by means of a carrier that will not fully
insure the shipment. Some carriers have a $200. 00 limit.
The exception to this is when there is no other means
(APO-FPO-etc.) of shipment than parcel post, and then we
will ship by this means with your written agreement that
you assume any loss over that which the carrier will
insure. COD shipments cannot be made to APO-FPO ad-
dresses.
Replacement part price quotes wi II be furni shed on request
for those who desi re prepa id shipment or cannot accept
COD shipments.
All requests, inquiries, warranty claims or equipment
returns should be made to:
Hy-Gain Electronics Corporation
8601 N.E. Highway 6
Lincoln, Nebraska 68507
Attn: Customer Service Manager

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SECTION V
W RR NTY
Hy-Gai n Electronics Corporation warrants each new product
manufactured to be free from defects in material and work-
manship and agrees to remedy any such defect, or to fur-
nish a new part, in exchange for any part of any unit which
under normal installation, use, and service discloses such
defect within ninety days from the date of purchase by
origi nal owner. The unit serial number must be registered
by the original owner at the time of purchase to val idate
the warranty.
This warranty does not extend to any of our products which
have been subjected to mis-use, neglect, accident, in-
correct wiring not our own, improper installation or to use
in violation of instructions furnished by us. Nor does it
extend to units which have been repaired or altered out-
side of our factory nor to accessori es used therewi th not
of our own manufacture, nor to any cases where the serial
number has been removed, defaced, or changed.
Hy-Gain Electronics Corporation reserves the right to make
any changes deemed necessary or desi rable without ad-
vance notice or incurring any obligation to make like
changes in units previously manufactured or sold.
This warranty does not cover transportation or instal-
lation costs that may be incurred. Hy-Gain Electronics
Corporation"s sole liability is the remedy of any defect for
ninety days. Hy-Gain Electronics Corporation is not respon-
sible for personal injury or property damage resulting from
improper or careless installation not intended by the manu-
facturer.
No person is authori zed to assume for us any other Iia-
bility in connection with the sale of our products.
All warranties are void and terminated one year after the
last unit of its type and design has been manufactured by
us.

PARTS LIST
Symbol Description Part No. Symbol Description Part No.
C101 2.2 pf Disc Cap 721609 D101 1N270 Diooe 765722
C102 20 pf Capacitor 725717 D102 1N270 Diode 765722
C103 .1 mfd 721574 D103 1N5054 Diode 765713
C104 Load Capacitor 720015 D104
""
765713
C105 Tune Capacitor 721157 D105
" "
765713
C106 .001 mfd 2.5 KV 721660 D106
"
765713
C107 10 pf 3 KV 721613 D107
fl
765713
C108 390 pf DSM 721700 D108
""
765713
C109 .001 mfd 721158 D109
"
765713
C110 .001 mfd 721158 D110
"
765713
C111 .0033 3 KV 721159 DIll
"
765713
C112 .0022 mfd 721161 D112 1N645 Diode 761113
C113 .0068 mfd 721160
C114 10 Ele Cap 721121 M101 0-1 MA Meter 795680
C115 500 Ele Cap 721120
C116 500 Ele Cap 721120 M0101 110V Motor 740005
C117 100 mfd 400 VDC 721806
C118 }OOmfd 400 VDC 721806 K101 4 PDT Relay 12VDC 730006
C119
10' ·j mfd 400 VDC 721806
C120 30-30 150VDC Dual Cap 721796 J101 S0239 to Ant 657570
C121 .001 mfd 721158 J102 S0239 toXcvr 657570
C122 .001 mfd 721158 T101 Input XFMR 720018
R101 18 K 1/2w 10% 721339 T102 Power XFMR 730211
R102 270..J'\..lW 720016
R103 18..J'\..2W 720017 L101 Pi-Network Coil 270014
R104 270- ,-1 W 720016
R105 7.5 K 1/2 W Lin Tap 721451 RFC101 800 uh 2-P1 721902
R106 4.7 K 1W 721367 RFC102 2-28 Choke 721124
R107 100- ,-1/2 W 720005 RFCI03 2-28 Choke 721124
R108 22 K 1W 721373 RFC104 2-144 Choke 728025
R109 100- ,-1/2 W 720005
R110 15 K 1/2W 721340 S101 DPDT Slide Switch 700206
RIll 330- ,-1/2W 721167 8102 SPST Rocker Switch 701147
R112 270..J'\..1/4W 721112 S103 DPDT Rocker Switch 700010
R113 33 -,,-1/4 W 721103 S104 DPDT Rocker Switch 700010
R114 33 -,,-1/4 W 721103
R115 3.5KI0W 721515 VIOl Vacuum Tube 760004
R116 2 K lOW 721527 V102 Vacuum Tube 760004
R117 2.2 K 1/4 W 721116
R118 1-,,-1/2 W 720020 Q101 MPS6516 761115
R119 22 -,,-1/2 W 725639 Q102 2N 696 761114
R120 22 K 1W 721373
R121 330 - -1/2 W 721167 N101 12V Lamp 710007
R122 150 K 2W 721404
R123 150 K 2W 721404 FI0l 5A MDX 3AG 710003
R124 150 K 2W 721404
P1U1 Parasitic Choke 721950
P102 Parasitic Choke 721950