Service manual

ALIGNMENT AND TEST PROCEDURES
7-16
Month 2000
Part No. 001-2004-601
Transmitter Hum and Noise Ratio (Optional)
NOTE: An HP8901A modulation analyzer is required
for this test.
1. On the modulation analyzer press:
300 Hz HPF
3000 Hz LPF
FM
Pre-Display
750 µS
Avg RMS Cal
.44 (25 kHz channels)
.22 (12.5 kHz channels)
dB
2. Use the "Turn on carrier" button to key the transmit-
ter and measure the Hum and Noise Ratio. The
reading should be less than -50 dB (12.5 kHz) or
-55 dB (25 kHz).
3. Use the "Turn on carrier" button to unkey the trans-
mitter.
Transmit Audio Distortion
1. On the modulation analyzer press:
FM
50 Hz
15 kHz
2. On the MAC, apply -11.7 dBm at 1 kHz to P100,
pin 32.
3. Use the "Turn on carrier" button to key the
transmitter.
4. Adjust audio level to produce ±1 kHz deviation
(25 kHz) or ±0.5 kHz (12.5 kHz deviation).
5. On the modulation analyzer select:
300 Hz
3 kHz
750 µs de-emphasis
6. Distortion is < 2%.
LTR Modem Repeat Audio Level Adjust
NOTE: Valid only with LTR modem option.
1. Adjust the RF generator for 100 µV into the
receiver with a 1 kHz tone at ±1.5 kHz deviation
(25 kHz channels) ±800 Hz (12.5 kHz channels).
Be sure the Modulation Analyzer LPF switch is set
to 3 kHz.
2. Use the "Turn on carrier" button to key the
transmitter.
3. Adjust R305 for ±1.5 kHz ±100 Hz deviation
(25 kHz channels) or 800 Hz (12.5 kHz channels)
out of the Transmitter.
4. Use the "Turn on carrier" button to unkey the
transmitter.
7.4.7 AUDIO/DATA LEVEL ADJUSTMENTS
NOTE: Section 7.4.6 must be completed before any of
the following adjustments can be made.
NOTE: All audio generators and audio voltmeters are
unbalanced unless specifically stated otherwise.
Voice Audio From Repeater
1. On the MAC, set S100 and S101, all Sections OFF.
2. Adjust the RF generator for 100 µV modulated with
a 1 kHz tone at ±1.5 kHz deviation.
3. Connect a balanced AC voltmeter with a 600 ohm
input impedance between balanced lines RXA+ and
RXA- on J2, located on the back of the Repeater.
4. On the MAC, adjust R239 for the type of line used.
Leased Line/Direct Connect (default)
-12 dBm (194 mV RMS)
Microwave/T1 (optional)
-28 dBm (31 mV RMS)