Radio Alpha Products Inc. ® Alpha 99
36
Amplifier transmits but red GRID LED often lights.
1) Amplifier overdriven or underloaded; reduce transceiver output and /or
increase amplifier loading.
2) Load VSWR (reflected power) exceeds 200W.
3) Exciter output poorly controlled. External ALC may help.
Amplifier operates but green GRID LED will not light and plate current is low;
transceiver does not seem to be able to drive amplifier to its rated RF output
power level.
1) External ALC control voltage to transceiver excessive (see Section 5,
Automatic Level Control).
2) Input rf load resistor or bias circuitry damaged.
3) Possible damaged or defective tube(s).
Receive signals disappear or are severely attenuated when switching from STBY
to OPR.
1) RELAY (T/R) control cable from transceiver is shorted.
2) Transceiver locked in transmit
Plate current indicated when amplifier is in STBY or receive.
1) 4CX800A/GU74b tube heater-to-cathode leakage or short.
2) Tube bias supply or T/R bias switch faulty.
Distorted SSB signal; possible severe television interference.
1) Excessive RF drive from transceiver and/or insufficient amplifier loading.
2) Coaxial connector, coax feedline, antenna feedpoint balun, tuner, or antenna
trap arcing on voice peaks.
3) RF feedback from antenna into transceiver via the transceiver power cord,
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