Specifications

Installing the Station Transponder Units on Site
122 025-9581M
Setting Station Transponder Unit Levels for a Radio-based System
It may turn out that the factory default settings on the Station Transponder Units in your
system are adequate and you do not need to do any adjustments in order to get adequate
audio levels from the radio receivers. If you do need to make level adjustments at the
individual stations, the procedure which follows will provide uniform levels compatible
with most PA systems.
Setting the Station Transponder Unit Levels for Radio
1. Attach the oscilloscope probe to R149 (near J4-pin3) on the transponder board of
the unit being adjusted. Attach the ground lead to R148.
2. Confirm that the receive audio level coming from the radio is nominally 0.4 Vp-p,
with the peak audio level no more than 1.0 Vp-p. If necessary, adjust the controls
in the radio receiver to get the audio within this range.
3. Attach the oscilloscope probe to R134 (near relay K2) on the transponder board of
the unit being adjusted. Attach the ground lead to R133.
4. From an FSA Console position, select the target Station Transponder Unit and
send it an Alert. While the alert tones are being played at the unit, use the TONE
control (R61) to adjust the peak tone level to 2.2 Vp-p (0 dBm). (The tone levels
can be readjusted later with R61, if necessary.)
5. Clear the Alert at the FSA Console position and set the VOICE control (R87) to
approximately the 1/4 CW (clockwise) position. (1/4 of its range from fully CCW)
6. At the console position, select Alert with PA for the target Station Transponder
Unit. When the alert ends and the operator starts speaking in a normal voice, adjust
the AUX RX control (R137) for the knee of compression at R134. (approximately
0.4 Vp-p) (The voice levels can be readjusted later with R137, if necessary.)
7. At the console position, select Alert with PA for the target IP station transponder.
When the alert ends and the dispatch operator starts speaking in a normal voice,
adjust the Voice Control R87 for a 2.2 Vp-p (0dBm) level at R134.
8. At the console position, have the operator clear the Alert with PA for the target
Station Transponder Unit.
9. (MIC Level - for handset option only) At the station unit, move the oscilloscope
probe to R139 on the transponder board (close to J4-pin 11). Lift the handset, press
Note The following procedure assumes two things: 1) the radio receiver
is the only source of voice audio supplied to the Station
Transponder Unit, and 2) that there is an external PA amplifier
between the Station Transponder Unit and the loud speakers in the
station.
Tip The following steps are only necessary if your Station Transponder
Unit has a handset. If you do not have a handset, the following 9
through 12 are unnecessary and you may skip to step 13 to finish
the procedure.