Telex C-2002 - Manual (Page 15)

Remote Control Console
9
4.3 Level Adjustments
4.3.1 Transmit Side Adjustments
The transmit audio consists of multiple audio sources – microphone audio, AUX input, function tones, and DTMF
tones. Each audio sources is summed or generated in the DSP with the analog signal being generated on a single
DAC. The following is a list of the potentiometers that affect the transmit path.
Reference Description
R125 Line 1 TX Output Level Adjustment
R123 Line 1 TX Monitor Level Adjustment
R143 Line 2 TX Output Level Adjustment
R162 Line 2 TX Monitor Level Adjustment
R196 Desk Microphone Adjustment
MIC INPUT LEVEL ADJUST:
Care should be taken to avoid overdriving the input TX circuitry, as this will distort the audio. Make sure you have
enabled the desired Microphone connection in setup mode. Saying and holding the word “Four” is a good audio
level test vocalization. Use a strong tone of voice.
When adjusting the Desk Microphone audio input level, make sure that the Desk Microphone is at the normal
distance from the operator when setting the level. Connect a oscilloscope to Test point TP13 and adjust R196 to
approximately 3.5Vp-p.
TX OUTPUT LEVEL ADJUST:
The transmit level potentiometer is used to adjust the output level of the transmit audio so that it is calibrated with
the tone levels that were set in setup mode. Calibration of the TX line will vary depending on system variables as
well as the number of consoles found in parallel on the line. A easy way to align the console for the correct level is
to press and hold the PTT key. While the console is keyed up, the unit will, by default, generate a Hold tone at
–20dBm. A meter reading dbm can then be used and R125 (Line 1) or R143 (Line 2) adjusted to read the correct
value.
4.3.2 Transmit Monitor Setup
The transmit monitor provides a portion of the transmit audio of a four-wire circuit to the receive path. This allows
the console operator to listen to the transmissions of parallel console operators. To set this level have a parallel
console operator press the intercom button. Adjust R123 (Line 1) or R162 (Line 2) until the level is comfortable in
the handset/headset earpiece or the speaker. Make sure this feature is enabled or no audio will be passed.
See Setup Mode.
4.3.3 RX Level Adjustment
The RX level should be adjusted so that the maximum level coming into the console use the entire range of the
ADC, which is 0-4V. A test tone of +3dBm to -5dBm coming into the line interface is a good value to use. Adjust
R153 (Line 1) so that the signal seen on an oscilloscope at Test point TP11 is approximately 3.5Vp-p or R161
(Line2) so that the signal seen on an oscilloscope at Test point TP12 is approximately 3.5Vp-p