12
OPERATING PROCEDURE
After reading this manual and completing the Installation/Preparation Instructions, position
the Commander II front panel controls as follows:
•
ON/OFF — OFF
•
OPERATE/SSTANDBY — STANDBY
•
MULTIMETER SWITCH — Vp (PLATE VOLTAGE)
•
INPUT — CENTER ON SCALE
•
LOAD — MINIMUM (COUNTER-CLOCKWISE)
•
TUNE — LEAVE AT FACTORY SETTING (NOTE: the TUNE control is a multi-turn
piston capacitor and was factory preset for operation at 144.200 MHz. See page 13 for more
information.)
After presetting these controls, switch the ON/OFF switch to the ON position. The meter
lamps will illuminate, the blower will be running and plate voltage will be approximately 2700
VDC.
The 3CPX800A7 used in this amplifier requires a warm up period before RF drive may be
applied, to prevent damage to the tube. A 2 minute warm up is provided by a solid state timer
circuit. At the end of the warm up period, the green POWER LED on the front panel illuminates
and the unit is ready for operation.
Switch the meter switch to the Ip (plate current) position.
Switch the OPERATE/STANDBY switch to the OPERATE position and key the exciter with
ZERO
RF drive applied. The Red Transmit light should illuminate, the tube will be biased
“on”, and plate idling current should approximately 80 ma. as displayed on the Ip meter.
Apply a very low RF drive (less that 5 watts) and adjust the INPUT control for a peak in the
plate current (Ip) on the meter. Next adjust the TUNE control for maximum output as indicated
on an external Wattmeter. DO NOT adjust the LOAD control at this time.
COMPLETE
THESE ADJUSTMENTS AS QUICKLY AS POSSIBLE TO AVOID STRESSING THE
TUBE.
Place the meter switch in the Ig (grid) position. Key the exciter, and while increasing the RF
drive, adjust the LOAD control clockwise in order to keep the grid current below 40ma. and to
obtain a peak in output power on an external wattmeter (see chart: Typical Operating Condi-
tions chart on the next page).
Re-peak the TUNE control for maximum output.
Return the meter switch to the Ip position and the Commander II is ready for SSB or CW on
the air operation. Normal SSB operation is indicated by plate current readings on voice peaks of
approximately 1/3 to 1/2 of the CW key down value.
For FM or other high duty cycle modes, limit drive to 15 watts maximum.
