Service manual

Service Manual SD170E Series
Page 21 of 44
Adjust the RF output level of the RF signal generator to –47dBm and connect to the radio.
Monitor the output on the audio output pin and adjust RV401 for the specific audio output
level.
LEVEL SHIFTER for Modem option Board (ACC-513E, ACC-514E)
Prepare a suitable GMSK or FFSK test signal and apply to the test set (or use a tested radio
and transmit via an antenna with the same frequency and channel spacing).
Connect the radio to the test set and adjust the deviation level in accordance with the channel
spacing of the radio as follows:
12.5 kHz channel spacing = 1.5 kHz dev.
20 kHz channel spacing = 2.4 kHz dev.
25 kHz channel spacing = 3 kHz dev.
Adjust RV403 until the centre voltage of demodulated signal (1 KHz sine wave) of TP401 is 2.5
Volts.
Squelch Adjustment
Before squelch adjustment is made the squelch type should be selected via software. Squelch
level to open or close (un-mute or mute) is set up by not only software control but also hardware
control and programmed by the system option of the ACC-916E programming software.
Squelch Adjustment (Noise SQ only)
Select a receiver channel which is programmed for narrow band (12.5 kHz) operation. Set the
RF signal generator to the receiver frequency and set the AF modulation signal to 1 kHz at
1.5kH deviation.
Adjust the RF output level of the RF signal generator until the 1 kHz signal is heard. Adjust
the RF signal to the desired level for squelch sensitivity as you monitor SINAD, usually 8 to 12
dB. On the RF board, adjust RV5 until the squelch is just un-muted (open).
Switch off the RF generator (squelch should be closed).
Switch on the RF generator, Squelch should be opened at the SINAD point where RV5 was
adjusted.
Select a receiver channel that is programmed for wide band operation (25kHz). Set the RF
signal generator to the receiver frequency and the AF modulation signal to 1 kHz at 3kH
deviation.
Adjust the RF output level of the RF signal generator until the 1kHz signal is heard, then
adjust the RF signal to the desired level for squelch sensitivity as you monitor SINAD, usually
8 to 12 dB. On the RF board, adjust RV6 until the squelch is just un-muted (open).
Switch off the RF generator (squelch should be closed).
Switch on the RF generator, Squelch should be opened at the SINAD point where RV6 was
adjusted.
Disconnect the test equipment.
Squelch Adjustment (RSSI SQ only) using ACC-2016E & ACC-916E
Default setting of squelch level for all radios is approximately set at:
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