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.
