Test Procedures; Power Output; Tone Deviation; Voice Deviation - GE Mastr II Maintenance Manual

LBI-4732
TEST PROCEDURES
These Test Procedures are designed
to assist you in servicing a transmitter
that is operating--but not properly.
Problems encountered could be low power
output, tone and voice deviation, defec-
tive audio sensitivity, and modulator
adJust control set too high. Once a de-
feet is pin-pointed, refer to the "Service
Check" and the additional corrective meas-
ures included in the Transmitter Trouble-
shooting Procedure. Before starting with
the Transmitter Test Procedures, be sure
the transmitter is tuned and aligned to
the proper operating frequency.
1. Wattmeter similar to:
Bird # 43
Jones # 711N
4. Deviation Meter (with a
,75kHz scale) similar
to: Measurements # 720
TEST PROCEDURE
TEST EQUIPMENT REQUIRED
for test hookup as shown:
2. VTVM similar to: 3. Audio Generator similar to:
Triplett # 850
Heath # IM-21
5. Multimeter similar to:
GE Model 4EX6Al0
GE TEST SET MODEL 4EX3All,
MODEL 4EX8Kl2 or
20,000 ohms-per-Volt voltmeter
POWER MEASUREMENT
1. Connect transmitter output from the antenna jack to the wattmeter through a 50-ohm
coaxial cable. Make sure the wattmeter is terminated into a 50-ohm load.
2. Key the transmitter and check the wattmeter for the desired power output.
SERVICE CHECK
Check the setting of the Power Adjust Control (R216).
Refer to the QUICK CHECKS on the Transmitter Troubleshooting Procedure.
10
- - · - · · - - - -
VOICE DEVIATION AND SYMMETRY
TEST PROCEDURE
1. Connect the test equipmlent to the transmitter as shown.
2. In radios with Channel Guard, set Channel Guard Mod Adjust Rl28 for zero tone
deviation.
3. Set the audio generator frequency to 1kHz.
A. In all station combinations except Local Control Intermittent Duty combina-
tions, set the audio generator output to 30 millivolts RMS.
B. In Local Control Intermittent Duty station combinations, set the audio
generator output to .1.0 volt RMS.
4. Key the transmitter and adjust Deviation Meter to carrier frequency.
5. Deviation reading should be ±4.5 kHz in radios without Channel Guard, and ±3.75
kHz in radios with Channel Guard.
6, If necessary, adjust MOD ADJUST control Rl27 for the proper deviation on plus
(+) or minus (-) deviation, whichever is greater.
NOTES:
MASTR II station transmitters are adjusted for 4.5 kHz deviation at the
factory. The ifactory adjustment will prevent the transmitter from de-
viating more than 5.0 kHz under the worst conditions of frequency, volt-
age and temperature.
7. If the deviation reading plus (+) or minus (-) differs by more than 0.5 kHz,
recheck Steps 1 and 2 as shown in the Transmitter Alignment Chart.
TONE DEVIATION WITH CHANNEL GUARD
TEST PROCEDURE
l. Set up the Deviation Meter and monitor the output of the transmitter.
2.
Remove the 1000 Hz signal from the audio generator.
3. Key the transmitter and check for 0,75 kHz deviation. If the reading is low or
high, adjust Channel Guard MOD ADJUST Rl28 for a reading of 0.75 kHz.
NOTES:--
l . On units supplied with Channel Guard, the Phase
justed carefully to insure proper performance.
mitter Alignment Chart).
Modulator Tuning should be ad-
(Refer to Step l in the Trans-
2. The Tone Deviation Test Procedures should be repeated every time the Tone
Frequency is changed.
EXCITER
ASSEMBLY
AN'TENNA
DEVIATION METER
PAASSEMBLV
'
'
'
'
'
AC VTVM
CONTINUOUS DUTY PA
---·-----·· .. ------·----------·
- - - - - - - - - - - -
................
-·-·-·-
AUDIO LO TO J11
AUOIO OSCILLATOR AUDIO HI TO J10
GE TEST SET 4EX3A 11
4EX6A 10
INTERMITTENT AND CONTINUOUS DUTY
ALL EXCEPT LOCAL CONTROL
SYSTEM BOARD
INTERMITTENT DUTY
LOCAL CONTROL
SYSTEM BOARD
I
I
I
I
I
I
I
I
I
I
I