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5.14 RECEIVER PERFORMANCE TESTS
5.14.1 PRELIMINARY SETUP
With the standard LTR-Net operating code, the
transceiver does not have a special test mode that can
be selected to perform testing. Therefore, program
temporary conventional channels or use the functions
available with the test code to perform this function.
If programming test channels, program channels
near the low, middle, and high ends of the band (wide-
band, narrow band or both) and with and without Call
Guard (CTCSS/DCS) squelch as applicable. In addi-
tion, to check high and low power and talk-around
operation, program High/Low Power and Repeater
Talk-Around option switches.
When the temporary special test code is loaded as
described in 5.2, there are several test channels and
functions that can be selected. Refer to Section 5.16
for information on these test functions.
Proceed as follows to check receiver operation:
1. Select the channel near the center of the band
(around 450 MHz).
2. Connect the signal generator to the antenna jack (see
Section 5.4.1 for more information). Set the output
to the channel frequency, modulated with 1 kHz at 3
kHz (wideband channels) or 1.5 kHz deviation
(narrow band channels).
5.14.2 SINAD SENSITIVITY
NOTE: The audio output level of the accessory con-
nector is at a lower level than at the internal speaker.
In addition, the internal speaker automatically mutes
when a load of approximately 1k ohm or less is con-
nected to this output.
1. Connect a SINAD meter to the speaker output of the
RPI (see Section 5.4.1).
PERFORMANCE TESTS
2. Decrease the signal generator output to obtain a 12
dB reading on the SINAD meter. The signal gener-
ator output should be 0.35 µV maximum.
3. Check both wide and narrow band channels if appli-
cable, and also check the channels on each end of
the band.
5.14.3 SQUELCH SENSITIVITY
slowly increase the signal generator output until the
squelch just opens (audio is enabled). Then decrease
the signal generator output until it just closes. The
squelch should open after 12 dB SINAD and close
before 6 dB SINAD.
5.14.4 AUDIO POWER AND DISTORTION
across the speaker must be measured because full
output power is not available at the accessory
connector. If a load of approximately 1k ohm or less is
connected to the speaker output of the accessory
connector, it must be disconnected to enable the
internal speaker. Proceed as follows:
1. Open the transceiver as described in Section 5.13
and connect a 16-ohm load in place of the speaker.
Connect an AC voltmeter and distortion meter
across the load (both should have floating inputs).
2. Set the signal generator output for –60 dBm (220
µV). Minimum audio power should be 0.5 watt
across the 16-ohm load (2.8 V rms). Distortion
should be less than 5% at 0.5 watt.
5.14.5 RECEIVER CURRENT DRAIN
output is 275 mA. With the receiver squelched, it
should be 100 mA maximum.
5-8
ALIGNMENT PROCEDURE
With the test setup used for the preceding test,
To measure audio output power, the actual level
Maximum transceiver current with 0.5-watt audio
November 2001
Part No. 001-7240-001
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