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Maximum Power Adjust
THIS ADJUSTMENT IS ALSO MADE DURING THE FORWARD POWER CALIBRATION
IT IS NOT RECOMMENDED TO PERFORM THE FORWARD POWER CALIBRATION JUST TO
1.
Remove the cover from the SYNTHESIZER.
2.
On the SYNTHESIZER tweak the MAX PWR pot (R74) fully counter-clockwise.
3.
With the SRPT-30/40A powered on and transmitting, tweak the front panel POWER ADJUST pot fully clockwise.
4.
On the SYNTHESIZER tweak the MAX PWR pot (R74) clockwise to the desired maximum output power, but do
not exceed Maximum RF Output Power as specified under ORDERING INFORMATION for your model.
5.
Replace the SYNTHESIZER cover.
Encoder Adjustments
1.
Connect dummy load with sampling attenuator to ANTENNA connector of SRPT-30/40A.
2.
Connect an accurate standard FM deviation meter and frequency counter to sampling attenuator.
3.
Place TRANSMIT/STANDBY switch in "TRANSMIT" position.
4.
Place ENCODE switch in "ON" position and adjust encode level pot R33 on COMPRESSOR AUDIO board, 800-
166 for 600 Hz deviation.
5.
Connect a scope probe to the bottom leg of R32 of the 800-166 COMPRESSOR AUDIO board and connect the
BNC end of the scope probe to a low-frequency counter.
6.
Adjust R37 on the 800-166 COMPRESSOR AUDIO board so that the frequency counter reads 27.1 Hz.
7.
Remove scope probe and return ENCODE switch to "OFF" position.
Audio Adjustments
1.
With no audio input, switch METER to AUDIO COMPRESSION position and set ZERO VU ADJUST pot (R22)
on COMPRESSOR AUDIO board, 800-166A to read 0 VU on the meter.
2.
With ENCODE switch "OFF", connect a harmonic distortion analyzer to the audio output of the Marti receiver
being used with the SRPT-30/40A.
3.
Feed a 100 microvolt signal from the transmitter into the receiver RF input via the sampling attenuator.
NEVER FEED THE OUTPUT OF THE SRPT-30/40A DIRECTLY INTO A RECEIVER!
THE INPUT STAGE OF THE RECEIVER WILL BE DESTROYED INSTANTLY!
4.
Modulate the transmitter with a 2500 Hz tone at 3 dB compression.
5.
Turn LIMIT LEVEL pot (R26) on the COMPRESSOR AUDIO board, 800-166 to maximum counter-clockwise
position. Note distortion. It should be less than 2%. Slowly turn R26 clockwise until an additional 0.1% distortion is
indicated on the distortion meter.
6.
With ENCODE switch "ON" and using a Marti receiver having a subaudible decoder which has been set to 27 Hz
by an audio generator of at least 1% accuracy, adjust ENCODE FREQ pot (R37) for maximum indication on the
"DECODE SIGNAL LEVEL" meter of the receiver.
CAUTION
ADJUSTMENT.
ADJUST THE MAXIMUM POWER.
WARNING
8/7/2003
41
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