User Manual

47
NOTE
THE HIGH VSWR LED MAY BLINK FROM TIME TO TIME, BUT SIMPLY IGNORE IT DURING
THIS CALIBRATION PROCEDURE.
23. The front panel TRANSMIT LED should be off. On the SYNTHESIZER, tweak the MAX PWR pot (R74)
clockwise until the TRANSMIT LED just comes on. The output “reverse” power should increase as indicated by
the WATT METER.
24. Referring to Table (2) - Forward and Reverse Power Calibration, find the row that lists your model. Follow this
row to the first number listed under the REV PWR LEVELS (W) column (@ Decimal 5 = 0). This number is the
maximum reverse calibrated power.
25. On the TWO-STAGE POWER AMFLIFIER board, tweak the RP CAL pot (R17) counter-clockwise (slowly) until
the output power (as indicated by the WATT METER) reaches this maximum reverse calibrated power.
WARNING
THE RP CAL POT (R17) IS NOW CALIBRATED.
DO NOT ADJUST IT ANYMORE!
STEPS 26 THROUGH 31 ARE REQUIRED FOR RE-PROGRAMMING THE INTERNAL FORWARD
POWER CALIBRATION TABLE. THIS WILL YIELD THE MOST ACCURATE CALIBRATION.
HOWEVER, IN MOST CASES THESE STEPS CAN BE SKIPPED WHILE STILL MAINTAINING A VERY
ACCURATE CALIBRATION. IF DECIDE TO SKIP, PLEASE CONTINUE AT STEP 32.
26. Set the front panel FREQUENCY SELECT pushwheel switches as follows:
DECIMAL 7 (far left digit) = “2”
DECIMAL 6 = “any number”
DECIMAL 5 = “0”
DECIMAL 4 = “any number”
DECIMAL 3 = “any number”
DECIMAL 2 = “any number”
DECIMAL 1 (far right digit) = “any number”
27. Depress and release the front panel EXECUTE pushbutton switch. This command will store the raw power into the
internal calibration table.
28. Referring again to Table (2) – Forward and Reverse Power Calibration, find the row that lists your model
number. Follow the row to the column REV PWR LEVELS (W). The corresponding number under DECIMAL 5
= 1 is the next reverse calibrated power. On the SYNTHESIZER, tweak the MAX PWR pot (R74) such that the
output power equals this reverse calibrated power.
29. On the front panel FREQUENCY SELECT pushwheel switches, change only DECIMAL 5 = “1”.
30. Depress and release the front panel EXECUTE pushbutton switch. This command will store the reverse calibrated
power into a software calibration table.
31. Repeat steps (28) thru (30) for the remaining decimals, DECIMAL 5 = “2” thru DECIMAL 5 = “8” using the
corresponding reverse calibrated power numbers under DECIMAL 5 = “#”.
NOTE
THE INTERNAL REVERSE POWER CALIBRATION TABLE IS NOW COMPLETE.
AT THIS POINT WE WILL NOW CALIBRATE THE FRONT PANEL METER – REVERSE POWER.