Intercom Adjustments - Firecom 3000C Installation & Operation Manual

IMPORTANT
FIGURE 16:
The 3000C Adjustments
Range Switch
Assembly
VR4:
Transmit Audio
Adjust
VR6:
Receive
Audio Adjust
Range Switch
Enlargement
o
n
1 2
3000C
Circuit
Board
(front-right corner)
IMPORTANT
TABLE 2
Range Switch Settings
14.
I N S T A L L A T I O N

INTERCOM ADJUSTMENTS

In order to match the Transmit and Receive Audio to the radio, it will be necessary to per-
form some adjustments. These items are adjusted by switches and variable resistors located
on the circuit board inside the intercom unit (Figure 16).
These adjustments MUST be performed by a qualified Radio Technician. Failure to
perform these adjustments may result in problems hearing and in transmitting
radio signals when using the Intercom System.
RECEIVE AUDIO ADJUSTMENT:
26. Turn the 2-way radio on, and adjust the radio volume to the normal volume level
for use WITHOUT THE INTERCOM INSTALLED.
27. Adjust VR6 to set the Receive Audio so that it is at the same level as the audio
heard when listening to someone speak over the intercom (turning the wheel to the
right increases the volume, turning the wheel to the left decreases the volume).
TRANSMIT AUDIO ADJUSTMENT:
The Transmit Audio is adjusted using the Range Switch Assembly, and variable resistor
VR4. The range switch assembly has 2 switches which select ranges for the Transmit
Audio adjustment (see Table 2 for the range switch settings), and VR4 adjusts the Transmit
Audio level within these ranges.
28. Using a service monitor, adjust the range switch assembly and VR4 for proper
transmitter deviation and no transmitted audio clipping (turning the wheel to the
right increases deviation, turning the wheel to the left decreases deviation).
For proper adjustment of the Transmit Audio, this adjustment MUST be per-
formed by a qualified Radio Technician, using a service monitor.
S1
On
Off
On
S2 Mic To Output Gain
On 19 dB to -1.5 dB
On -1 dB to -21.5 dB
Off -21.5 dB to -43 dB
(Maximum Signal At Mic Jack: 1.1v pk-pk)