User's Manual

ALIGNMENT PROCEDURE SST-442
22
MODULATION BALANCE
Transmitter modulation balance has been set at the
factory and should not require adjustment.
1) Select “Mod Bal” from the PC Programmer
“Alignment” screen.
2) Set the RF communications test set to the
Alignment Frequency on the Alignment screen.
3) Press the “Tune” button on the Alignment screen
to activate the transmitter.
4) Check the de-modulated waveform for a 20 Hz
square wave.
5) If adjustment of the modulation balance is
required, press the left arrow on the tuning bar to
flatten the top of the waveform or the right arrow
to reduce overshoot.
6) Press the “Save” button to store the new
alignment setting or “Cancel” to leave setting
unchanged.
TRANSMITTER TONE DEVIATION
Transmitter tone deviation has been set at the factory
and should not require adjustment.
1) Select “Tone” from the PC Programmer
“Alignment” screen.
2) Set the RF communications test set to the
transmit frequency on the screen.
3) Select either “Wide Band” or “Narrow Band” by
pressing the desired option button.
4) Press the “Tune” button on the Alignment screen
to activate the transmitter.
5) If adjustment of the tone deviation is required,
press the left arrow on the tuning bar to lower
deviation or the right arrow to raise deviation.
6) Press the “Save” button to store the new
alignment setting or “Cancel” to leave setting
unchanged.
TRANSMITTER VOICE DEVIATION
Transmitter voice deviation has been set at the
factory and should not require adjustment.
1) Select “Voice” from the PC Programmer
“Alignment” screen.
2) Set the RF communications test set to the
transmit frequency on the screen.
3) Select “Voice Only - Wide Band“, “Voice Only -
Narrow Band”, “Voice & Tone – Wide Band”, or
“Voice & Tone – Narrow Band” by pressing the
desired option button.
4) Press the “Tune” button on the Alignment screen
to activate the transmitter.
5) If adjustment of the voice deviation is required,
press the left arrow on the tuning bar to lower
deviation or the right arrow to raise deviation.
6) Press the “Save” button to store the new
alignment setting or “Cancel” to leave setting
unchanged.
RECEIVER SENSITIVITY AND SQUELCH
The SST-442 receiver is factory tuned for a frequency
range of 460 - 470 MHz. The SST-442 receiver is
configured from the factory for Wide Band operation,
with a Narrow Band Model available as an option.
The SST-442 receiver bandwidth is configured on a
per radio basis, it cannot be switched on a per
channel basis.
The receiver may be tuned to any 10 MHz frequency
band between 450-470 MHz.
1) Program the radio to a receive frequency in the
middle of the desired 10 MHz band.
2) Set the RF communications test set generator to
a frequency exactly 87.3 MHz below the
programmed receive frequency at a RF level of
approximately –40 dB. Modulate the RF signal
with a 1 KHz tone at 3 KHz deviation for wide
band, 1.5 KHz deviation for low band.
3) Connect an 8-Ohm speaker to the 3.5mm audio
jack on the SST-SRVBD test assembly.
4) Adjust L101 for the minimum received signal at
this image frequency.
5) Set the RF Communications Test Set’s generator
to the programmed receive frequency at a RF
level of –120 dB. Modulate the RF signal with a 1
KHz tone at 3 KHz deviation for wide band, 1.5
KHz deviation for low band.
6) Adjust L103 and L104 for the best receiver
SINAD as measured across the 8-Ohm speaker.
7) Check receiver sensitivity at the lowest and
highest operating frequencies and make slight
adjustment to L103 and L104 to balance
between the two, if necessary.