LEVEL SETTING AND INTERFACE ADJUSTMENTS - continued
(4) The ratio of high to low tones may be modified by changing the value of C9 (470 pf):
Increase the value to reduce the DTMF twist ratio
Decrease the value to increase the DTMF twist ratio
Table of Single-Tone Encoding - Service Mode
Keypad
Location
Reference
Tone (Hz)
Actual
Tone Output (Hz)
Percent
Deviation
Row Tone 1 697
699.1 +0.30
Row Tone 2 770
766.2 -0.49
Row Tone 3 852
847.4 -0.54
Row Tone 4 941
948.0 +0.74
Column Tone 1 1209
1331.7 +0.57
Column Tone 2 1336
1331.7 -0.32
Column Tone 3 1477
1471.9 -0.35
(5) Reinstall JP6 with a wire jumper, returning the microphone to normal operation.
Isolating Analog, Logic, and Power Grounds
If your application requires that the microphone audio, push-to-talk logic, and -12 VDC
grounds be separate: Cut the jumper JP2 on the printed circuit board as shown in
Figure "A".
PTT Logic associated with Microphone Audio
If your application requires that the push-to-talk logical low signal be on the microphone
audio line: Then install a wire jumper or resistor, as required by the application, at JP3.
CTCSS Monitor (Standard Communications GX series)
For the Standard Communications GX series mobile radios: Install a 10K ohm 1/8 watt
resistor at R6. If you ordered the 600L microphone for this application, this (GXC)
option has already been installed.
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