E F Johnson Company 2422001-1 Benutzerhandbuch

7-5

August 2000

Part No. 001-2001-200

4. Measure the Power Output of the Exciter at J402.  

Reading should be > +18 dBm.

5. Press the space bar to unkey the Exciter.

For Transmitters operating within 6 MHz of the top of 
the transmit band (144-150 or 172-178 MHz).

1. Program the Synthesizer for the Highest transmit 

frequency (i.e. 150 or 178 MHz).

2. Press the space bar to key the Exciter.

3. Set the control line voltage for 7.5V at TP1.

Check 6 MHz below the programmed frequency 
(i.e. 144 or 172 MHz) to verify that the control volt-
age at TP1 is greater than 2V.  The repeater receiver 
can now be programmed for the desired operating 
frequency.

4. Press the space bar to unkey the Exciter.

For Transmitters operating within 6 MHz of the bottom 
of the transmit band (132-138 or 150-156 MHz).

1. Program the Synthesizer for the Lowest transmit 

frequency (i.e. 132 or 150 MHz).

2. Set the control line voltage for 2V at TP1.

Check 6 MHz above the programmed frequency 
(i.e. 138 or 156 MHz) to verify that the control volt-
age at TP1 is less than 7.5V.  The repeater receiver 
can now be programmed for the desired operating 
frequency.

7.2.4  VCO TEST

1. The software programs the synthesizer for 

3 MHz above the Tune-Up frequency.

2. Press the space bar to key the Exciter.

3. The voltage on U403, pin 6 should be < 7V.  

Power output should be > +18 dBm.

4. Press the space bar to unkey the Exciter.

5. The software programs the synthesizer for

3 MHz below the Tune-Up frequency.

6. Press the space bar to key the Exciter.

7. The voltage on TP1 (U403, pin 6) should be > 2.5V.  

Power output should be > +18 dBm.

8. Press the space bar to unkey the Exciter.

9. The software programs the synthesizer for the 

Transmit Channel.

7.2.5  TCXO FREQUENCY ADJUST

1. Connect a 10 dB pad and frequency counter to J402.

2. Press the space bar to key the Exciter.

3. Tune TCXO Y401 for the Transmit Channel Fre-

quency, 

±

 50 Hz.

4. Press the space bar to unkey the Exciter.

7.2.6  TRANSMIT MODULATION ADJUST

1. Connect a 10 dB pad and modulation analyzer to 

J402.

2. Press the "FM" and "3 kHz LPF" switches of the 

modulation analyzer.

3. Inject a 1 kHz sine wave at 400 mV RMS into J2, 

pin 5 on the back of the Station.

NOTE:  This test changes the Tx Audio Deviation 
Limit.  To correct the limit, perform adjustment per 
Section 7.4.5.

4. Adjust U207 with "Up/Dn" and "PgUp/PgDn" keys 

for 707 mV RMS on P100, pin 29.  This waveform 
should be a "clean" sine wave.

5. Press the space bar to key the Exciter.

6. Set RV401 for 

±

3 kHz deviation for 25 kHz chan-

nels ( ±1.5 kHz deviation for 12.5 kHz channels).

7. Press the space bar to unkey the Exciter.

8. Adjust R237 for a 2V P-P square wave on 

P100, pin 29 of the TPI.