User's Manual

Operator Adjustments
(Continued)
P1 This is a basic power adjustment for the unit. It is a 10 turn potentiometer which sets the
RF output power level. Changing its setting may require resetting all other adjustments. To
make this adjustment it is necessary to monitor the output with a calibrated RF power meter. As
a reference, set the adjustment to produce nominal RF output.
P5 Lower the RF input drive (from its nominal level) until the RF output drops to its lowest
acceptable value. Adjust P5 until the front panel LED begins to flash. Restore normal
drive power. The LED should then extinguish.
P4 Set the RF input drive to a level 6dB below the nominal drivel level. Adjust P4 to activate
the amplifier and its fans at this threshold.
P8 Adjust this potentiometer to a nominal 20 units at nominal input drive.
SW1 Return the switch to the down (ALC ON) position.
P6 Toggle the front panel switch until the top line of the display reads FWD PWR. With the
proper RF termination still in place, monitor the RF forward power output on a calibrated power
meter. Set P1 to provide nominal power output. Adjust P6 so that the front panel Meter is in
agreement with the calibrated power meter. Note this power reading.
Note: The recommended output power range is from the specified maximum output level to one
half that value. Consult the
manufacturer if a lower power level is required. In all cases, a spectrum analyzer should be
used to assure that no spurious signals are generated when the power level is changed.
P7 Attach a 3:1 VSWR load to the output and, with an external calibrated power meter,
measure the reflected power. Toggle the front panel switch until the top line of the display reads
RFL PWR and adjust P7 so that the front panel meter is in agreement with calibration power
meter.
P3 The optimum setting for this VSWR threshold adjustment is to have the trigger with a 3:1
VSWR. It may, however, be set anywhere at the users discretion. With the 3:1 VSWR used in
the previous step still terminating the amplifier, apply normal RF drive and adjust the
potentiometer until the front panel SWR LED begins to flash. The LED should extinguish when
the VSWR is reduced or the normal load is connected.
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