Palstar COMMANDER HF-2500 EXPORT Owner's Manual - page 11
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case it is inadvertently keyed when the switch is thrown). Key the exciter with no RF drive ap-
plied. The red transmit LED should illuminate, and the meter should indicate approximately
150 mA of plate current. Apply 5 to 10 watts of RF drive, the plate current should rise slightly.
If the plate current rises above 1800 mA, reduce drive. Adjust the TUNE control to peak the
grid current and achieve maximum output power as indicated on an external Wattmeter..
COM-
PLETE THESE ADJUSTMENTS AS QUICKLY AS POSSIBLE TO AVOID STRESSING
THE TUBES.
Adjust the LOAD control to reduce grid current while maintaining output power as indi-
cated on ther relative output meter or an external Wattmeter. Next, increase the drive in small
increments and adjust the LOAD control for maximum output while keeping the grid cur-
rent low. Under normal conditions the grid current should not exceed 60mA.
Readjust the TUNE control to again peak the reading on the grid meter. If the meter rises
above 150mA. quickly reduce drive and adjust the LOAD control counterclockwise to reduce
grid current. Repeat these adjustments as required to achieve the desired output up to 2800
Watts.
[NOTE: If the grid current is allowed to reach or exceed 180mA, the controller will imme-
diately un-key the amplifier and the “Status-Trip” LED will flash rapidly, indicating that a grid
current limit (a “Grid-Trip”) has occurred.
In order to reset the Grid-Trip circuitry, the exciter must be un-keyed and the “Standby-
Operate” switch must be switched to “Standby” and then back to “Operate.” Once the Grid-
Trip has been reset, the “Status-Trip” LED will stop flashing and remain illuminated.
Do NOT exceed 1800mA plate current.]
Note that when increasing output power the tune scale will always read higher and the load
will read lower. Also, the supplied inspection sheet has all of these settings and they should be
used as a guide for this procedure. If your settings vary widely from these you have something
wrong and should start over.
If your planned operation is on SSB, you should reduce the load control slightly counter-
clockwise, reducing the TOTAL output slightly about 30 to 50 Watts. This adjustment is neces-
sary to insure that the amplifier is sufficiently loaded to handle the plate current peaks caused
by the complex voice patterns during SSB operation. Nominal plate and grid current read-
ings during SSB operation will be about 30 to 40% of the key down CW readings.
CAUTION: THE TUNE AND LOAD AIR VARIABLE CAPACITORS MAY ARC IF
MAXIMUM DRIVE IS APPLIED BEFORE THE AMPLIFIER IS PROPERLY TUNED. AL-
WAYS FOLLOW THE DESCRIBED TUNE-UP PROCEDURE TO AVOID CAPACITOR
ARCING. ARCING MAY ALSO OCCUR IF YOU ATTEMPT TO TUNE INTO AN AN-
TENNA WITH A VSWR GREATER THAN 2:1.
Generally expect to tune by peaking grid current and
simultaneously dipping plate current.