Radio Alpha Products Inc. ® Alpha 99
26
other amplifiers.
ALC
The 99 grid current limiting circuits provide substantial tube protection against possible
damage. The ALC voltage generated by the 99 is for external feedback to transcievers.
It cannot control the amplifier itself and is not applied internally. If ALC control is
required, a connection must be made from the 99 to the transceiver ALC input.
Warm-up Procedure
NOTE: The forward and reflected power LED bargraphs and GRID LEDs are peak-
responding.
BEFORE INITIAL TUNE-UP, MAKE SURE A SUITABLE ANTENNA OR 50
OHM DUMMY LOAD IS CONNECTED TO THE 99. Leave the amplifier off or
in standby and apply exciter power to make a forward vs. reflected power check. If
reflected power is less than ten percent of forward power, the VSWR is lower than 2:1
and it is safe to proceed with tuneup.
Turning on the amplifier:
1. Place the OPR-STBY switch in STBY (standby).
2. Rotate the multimeter selector switch to HV.
3. Depress POWER/ON. If any of the following does NOT occur, depress
POWER/OFF switch immediately and investigate before proceeding:
a. The blower starts (note air exhausting above tubes).
b. The multimeter bargraph automatically displays HV; it should indicate
approximately 2.8 to 3.0 KV.
c. The WAIT LED is lighted
IMPORTANT: EXHAUST AIR MUST BE DETECTABLE FROM THE TOP
VENTS: If it is not, TURN OFF the amplifier immediately and verify that the exhaust
chimneys are properly positioned over the tubes. When the warm up delay is complete
(about 150 seconds), the WAIT LED will extinguish. The ALPHA 99 is now “ready”.
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