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Forward Power Calibration – SRPT-40A Only
Note: The SRPT-30 Forward Power Calibration can only be performed at the factory.
THIS ADJUSTMENT HAS BEEN SET AT THE FACTORY AND SHOULD NOT REQUIRE ANY
TO MAINTAIN CALIBRATION, NEVER ADJUST THE FP CAL (R20) POT ON THE TWO-STAGE RF
PA BOARD, OTHERWISE THE FORWARD POWER MUST BE RECALIBRATED.
IF IT BECOMES NECESSARY TO RECALIBRATE, READ AND STUDY THIS SECTION
1.
Power down the SRPT-40A (i.e., turn off AC LINE switch or turn off external supply).
2.
Make sure that the WATT METER is connected to the ANTENNA connector and that the WATT METER is
terminated with a 50-Ohm load rated at 100 Watts minimum.
3.
Remove cover from SYNTHESIZER.
4.
On the SYNTHESIZER make sure that the P2 jumper is in the FP position (FP is the normal position).
5.
On the TWO-STAGE POWER AMPLIFIER board, tweak the FP CAL pot (R20) fully clockwise (approximately
20 turns).
6.
On the SYNTHESIZER, tweak the MAX PWR pot (R74) fully counter-clockwise (approximately 20 turns).
7.
Power up SRPT-40A, but leave front panel TRANSMIT/STANDBY switch in the "STANDBY" position. Wait for
SRPT-40A to become locked on frequency.
8.
Referring to Table (2) – Forward and Reverse Power Calibration, find the row that lists your model. Follow this
row to the CAL FREQUENCY column. This number represents the frequency your model is to be calibrated at.
Change the SRPT-40A to this calibrated frequency.
9.
Measure the B+ voltage. Adjust the B+ if necessary by referring to Switching Power Supply Adjustment or B+
Adjustment When Using 15-30VDC External Supply. If using a 12-15 volt external supply, adjust its voltage to
12 to 15 volts. It is recommended that the VOLT METER is monitoring B+ throughout this procedure.
10. On the FRONT PANEL CONTROL & METER board, adjust S1 dip-switches with switch 1, 3, and 4 "OFF" and
switch 2 "ON".
11. Set the front panel FREQUENCY SELECT pushwheel switches as follows:
DECIMAL 7 (far left digit) = "1"
DECIMAL 6 = "4"
DECIMAL 5 = "0"
DECIMAL 4 = "0"
DECIMAL 3 = "0"
DECIMAL 2 = "0"
DECIMAL 1 (far right digit) = "0"
12. Depress and release the front panel EXECUTE pushbutton switch. This command will disable the front panel
POWER ADJUST pot.
13. Set the front panel FREQUENCY SELECT pushwheel switches as follows:
DECIMAL 7 (far left digit) = "1"
DECIMAL 6 = "2"
DECIMAL 5 = "0"
DECIMAL 4 = "0"
DECIMAL 3 = "0"
DECIMAL 2 = "0"
DECIMAL 1 (far right digit) = "0"
CAUTION
FURTHER ADJUSTMENTS.
WARNING
CAREFULLY BEFORE PROCEEDING.
8/7/2003
43
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