Instruction manual

10
7. ADJUSTMENTS
There are relatively few adjustments within the Audio Control Unit; however, the following
adjustments are possible if at some time they are felt needed. Appendix 2 shows the location of
the adjustments on the circuit boards.
7.1 Speaker Output Level. The speaker output level is set by R22 on the Amp & P.S. Board.
This adjustment is set to maximum and may be reduced if desired. With the input set as
described in section 5 and the front panel volume control set to maximum the audio amplifier is
just beginning to clip. Any higher level will cause distortion.
7.2 Headphone Level. The headphone volume relative to the speaker volume level is
adjustable. During initial set-up, the headphone level is set to approximately 1/6 that of the
speaker output. R18 on the Audio Amp & P.S. board may be adjusted as desired.
7.3 Supervisor Audio Output level. The supervisor output level is set to 100 mV with a receive
input of 100 mV and the volume control on the front panel is set to the 9 O’clock position with
R15 on the Amp & P.S. board
7.4 Microphone Gain (individual). Two microphone amplifiers are used in the event that two
different types of microphone are to be used. The amplifiers are adjusted for the Heil HC-5
elements for both boom and headset microphones. If a different microphone type is to be used
by either input, R16 and R17 on the Transmit Audio board may be adjusted to accommodate
them.
7.5 Microphone Gain (overall). Initial microphone gain was set for 100 mV to the adapter
cables to give 3 kHz deviation out of the transceiver being controlled. If all radios seem to be
either too high or too low in deviation, R18 on the Transmit Audio board may be adjusted to
compensate.
7.6 ICS / PA Audio Output Level. The ICS / PA output level is set to 100 mV with a
microphone input level of 5 mV at 1 kHz using R13 on the ICS circuit board.
7.7 ICS Alert Tone Level. The alert tone level is set to maximum and may be reduced using
R10 on the ICS circuit board.