Transmitter Performance Tests; Power Output; Transmit Frequency; Transmit Modulation - E.F. Johnson LTR-Net 7243 Service Manual

7.5vdc 1 and 4 watts part no. 242-7243-xxx
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5.15 TRANSMITTER PERFORMANCE TESTS

5.15.1 POWER OUTPUT

Refer to Section 5.14.1 for information on test
channels. Proceed as follows:
1. Connect a wattmeter and dummy load to the antenna
jack as described in Section 5.4.1.
2. Key the transmitter and high power output should be
3.8 - 4.2 watts. Check channels on both ends of the
band and in the talk-around mode.
3. Select a low power channel and power output
should be 0.8-1.2 watt in the standard and talk-
around modes.

5.15.2 TRANSMIT FREQUENCY

Monitor the transmit frequency with a communi-
cation monitor set to the channel frequency. At room
temperature, the frequency should be within ± 400 Hz.
This also checks the receive frequency.

5.15.3 TRANSMIT MODULATION

1. Select a channel not programmed for Call Guard
(CTCSS/DCS) squelch and monitor the transmit
signal with a communication monitor. Speak into
the microphone with a normal voice and modulation
should be approximately 3.4 kHz (wideband) or 1.4
kHz (narrow band).
2. Select a channel programmed for Call Guard
squelch and with no voice or other microphone
input signal, data deviation should be 1.0 kHz
(wideband) or 0.8 kHz (narrow band) ± 200 Hz.
3. Speak into the microphone with a channel
programmed for Call Guard squelch selected.
Maximum total audio and Call Guard deviation
should be 4.7 kHz (wideband) or 2.3 kHz (narrow
band).

5.15.4 TRANSMITTER CURRENT DRAIN

Maximum current drain in the transmit mode
should be as follows:
High Power - 2.0 A
Low Power - 950 mA
5-9
ALIGNMENT PROCEDURE
November 2001
Part No. 001-7240-001

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