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TEST EQUIPMENT.
The following text presents the test equipment required for alignment of STL–10A Transmitters. A sample test re-
port is also provided in the following text.
1. Bird, Model #43, Wattmeter, 50 ohm impedance.
2. Bird, 25–Watt Element, 400–1000 MHz.
3. Microwave Associates, 50–Watt RF Load, Model 44003.
4. Kron–Hite, Distortion Analyzer, Model 6900B.
5. Kron–Hite, Oscillator, Model 4500.
6. Hewlett Packard, Attenuator Set, Model 350D.
7. Signoteck Frequency Counter.
8. Hewlett Packard, Spectrum Analyzer, Model 8558B.
9. Wavetek, Automatic Modulation Meter, Model 4101.
10. Wavetek, Digital Multimeter, Model 27XT.
12. Kay, RF Attenuator, Adjustable 0–110 dB, Model 437A.
13. Marconi, RF Signal Generator, Model 2022C.
TOOLS FOR ALIGNMENT OF STL–10A SERIES TRANSMITTERS.
1.
GC, 9300, Tuning Tool.
2.
GC, 9440, Tuning Tool.
3.
Spectrol, 8T000, Tuning Tool.
4.
Sprague–Goodman, Tuning Tool.
TUNE–UP PROCEDURE FOR STL–10A.
MODULATOR CIRCUIT BOARD 800–195 ADJUSTMENTS.
Connect a dummy load with a sampling attenuator to the ANTENNA connector J6 of the transmitter. Connect an
accurate standard FM deviation meter and frequency counter to the sampling attenuator or J5 the FREQUENCY
TEST JACK. Operate the CONTROL switch to TRANSMIT.
1. Measure the bias voltage at TP (test point) of modulator circuit board 800–195 using digital dc voltmeter.
This voltage should be recorded on STL–10A TRANSMITTER TEST REPORT. To ensure low distortion
modulation, do not change this voltage setting.
2. Operate the transmitter on frequency by adjusting L2 (fine) coil slug using correct insulated tool. If
necessary, L1 (coarse adjustment) can be made using the insulated tool specified.
3. Monitor the PEAK MODULATION LED bar and feed a 400 Hz, +8 dBm signal from an audio signal
generator into TB–1. The PEAK MODULATION meter should read 100%. If not, adjust R24 (modulation
meter calibrate) on audio circuit board 800–194 for 100% on PEAK MODULATION meter. The FM
deviation meter should read the deviation specified under 100% modulation on STL–10A TRANSMITTER
TEST REPORT. If not, adjust R6 on modulator circuit board 800–195.
4. Remove the 400 Hz tone. Feed the audio signal generator set for 67 KHz at one (1) volt into J1 Sub In.
Operate the TEST METER switch to SUB LEVEL and adjust audio signal generator level for a meter reading
of 0 VU. Adjust R11 for a 20% sub–carrier injection as indicated on the linear vertical display on a spectrum
analyzer.
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