ZETRON 4000 Series, Руководство по установке

Страница: 184 / 418

Audio Level Adjustments
184 025-9533Y
4. On a four-wire channel, use the “4W-RX” adjustment. On a two-wire channel, use
the “2W-RX” adjustment. Start with the adjustment fully counter-clockwise (10
turns) on both potentiometers and then turn the adjustment clockwise while
observing the AC voltage measurement. Only adjust the potentiometer that is
required to configure the desired channel.
5. Adjust for the knee of compression by stopping when the measurement begins to
stop increasing, which will be at about 0.82 Vrms (2.3 Vpp or +0.5 dBm). Once
the adjustment has been made the Rx test point should be reading about -30 dBm
(25 mV rms or 70 mVpp) when the input sine wave level is at the knee of
compression.
Setting Tx Levels for Dual Channel Cards
Prior to making the transmit adjustment, program a 1000 Hz alert tone to a button on the
console. Confirm the console interface card MIC LVL and console alert tone level has
been correctly setup by observing the console LCD meter while transmitting the alert tone.
If the alert tone is programmed and adjusted correctly, the console LCD meter should be
reading "0 dB" while transmitting. If this is not true, recheck the console alert tone level
adjustment at the console and the MIC LVL adjustment at the console interface card. The
CIC card transmit MIC test point level should be at -10 dBm during an alert tone transmit.

To adjust transmit audio levels for conventional radios
1. Ensure that gain settings throughout the Series 4000 system are configured for
their default settings. See Before Adjusting Levels on page 182.
2. Using a communications service monitor to monitor the channel deviation, key up
the channel being adjusted with the 1000 Hz alert tone programmed to a console
button.
3. While transmitting the alert tone, observe the communications service monitor
received signal level and adjust the dual channel card Tx adjustment on the front of
the dual channel card so that the service monitor shows a channel deviation of
67%. A clockwise adjustment rotation should increase the channel deviation (10-
turn range).
The alert tone is measurable on the channel's
TX- / TX+
pair of pins at the punch
down block. The signal level at the punch down block should be close to 0dBm,
which is equivalent to an oscilloscope reading of 2.2V(Peak to Peak).
Note
This procedure sets the audio levels to the factory adjusted setting,
which places the card in the general area that should work for most
end-user's applications. Each end-user should also make their
personal adjustments with their specific equipment needs and their
personal preferences.