Telex C-2002 technical manual Level Adjustments, Transmit Side Adjustments, Transmit Monitor Setup

Remote Control Console 9

4.3 Level Adjustments

4.3.1Transmit 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.

4.3.2Transmit 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.

4.3.3RX 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