ZETRON 4000 Series, Installation Manual

Page: 186 / 418

Audio Level Adjustments
186 025-9533Y
5. Adjust the DCC “TX” adjustment for 0.77 Vrms (0 dBm) at TX Line output (into
600 ohm load or real line).
6. Adjust the associated Termination Panel/Radio Base Station for proper decoding
and maximum modulation deviation according to manufacturer’s procedure. For
trunking radio interface, refer to the appropriate installation and operation manual.
7. Repeat steps 5 and 6 for each channel of every DCC.
8. Adjust each console microphone for optimum voice clarity and modulation
deviation as observed on the RF channel of one of the radio base stations.
Console Line Loss Compensation
The CIC has one adjustment, labeled “MIC-LVL”. This adjustment compensates for
losses in audio from a console. This is normally factory-adjusted, but if the microphone
level of the console is improper relative to other fixed audio levels (such as guard tone or
function tone), use this adjustment to compensate. The adjusted level may be monitored
on the card’s mic test point on its legend plate. Factory adjusted level is - 10 dBm (0.25
Vrms) when the associated console is generating a 1 kHz test tone.
Transmit Monitor Adjustment
On 4-wire simplex (half-duplex) channels, the audio level heard by other consoles in the
system may be adjusted using the “2W-RX” adjustment on the DCC. On 2-wire channels,
the monitor level is set by the receive audio adjustment. The 4-wire full duplex channels
use a different monitor audio path at a fixed level.

To adjust the 4-wire transmit monitor audio
1. Cause a console to generate a steady 1 kHz test tone on the channel.
2. Measure the voltage at the “AGC” test point of the channel. Turn the “2W-RX”
adjustment fully clockwise and then turn the adjustment counter-clockwise while
observing the voltage measurement.
3. Stop at the knee of compression where the level begins to decrease (about 0.70
Vrms).