351804-1 Rev. 100
COM5000-8 TECHNICAL MANUAL
Setting System Controller potentiometers, output power (ALC level) adjustment:
a. With a CW power output of 5000W, adjust the System Controller PCB potentiometer VR2 clockwise
until the power drops to 4750W.
Un-key the system.
b. Change the T-4180 mode to ISB. Select “TONE” as modulation source with a modulation frequency
of 500 Hz.
c. Key the system. While observing the PEP output power, readjust VR2 to obtain 5000W of PEP
output power.
Un-key the system.
Setting System Controller potentiometers, Reflected Power
a. Connect the T-4180 – through a variable attenuator – to the COM5000-8. The variable attenuator is
set for maximum attenuation. The T-4180 is set to operate in CW mode of operation at 100% power
at a frequency of 15 MHz.
Key the transmitter system and observe the output power. Change the attenuation on the Variable
Attenuator in small increments until the output power reaches 2000W.
b. Un-key the system. To prevent the microprocessor from reducing the power during this alignment,
apply a short from the junction of R118 and C93 to ground using a “clip lead”.
c. Replace the 50 Ohm Load with two 50 Ohm loads connected in parallel to produce a VSWR of 2:1.
Connect the two loads as shown below. The "T" connector must be connected directly to the Watt-
Meter. The coaxial cable length from the “T” to the 50 Ohm loads is not critical. Note the placement
of the Watt-Meter directly at the output of the LC connector.
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General