Specifications

4-6. RECEIVER FRONT PANEL ADJUSTMENTS.
NOTE: Prior to setting levels be sure receiver is ON and set to proper frequency. See Section 3.
4-7. Squelch Adjustment.
A. Tune the receiver to an active channel. Presence of an Alarm indication and a CXR ALM
display may indicate one or more of the following conditions:
1) No carrier is being received.
2) Squelch adjusted improperly.
3) The carrier receiver is malfunctioning.
Whenever there is a CXR ALM (regardless of cause) there should be no audio output
from the receive channel with the alarm.
B. Squelch is factory set to operate if the incoming subcarrier amplitude drops below 25 mV p/p.
If you wish to adjust the squelch threshold for your unique receive site conditions, or if you
are using subcarrier levels of less than 50 mV p/p, proceed as follows:
1. If the CXR ALM is displayed, adjust SQUELCH counterclockwise until the Alarm
extinguishes.
2. With the Alarm off, adjust the SQUELCH clockwise until the Alarm just lights. This is
the receiver squelch threshold.
3. Tune the receiver to an unused channel (i.e. no RF carrier).
4. IMPORTANT - COUNT TURNS THIS STEP: Turn the SQUELCH
counterclockwise until the CXR ALM just extinguishes due to RF noise.
5. Turn the SQUELCH control clockwise one-half the number of turns counted in Step 4.
6. Return to an operating channel. The receiver is now adjusted to squelch at a level
halfway between the operating carrier and the RF noise floor.
450 Operation Manual Rev A Page 26 8/26/99