Communications Company IC-29, Manual

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Page 9
COMMUNICATIONS COMPANY • IC-29 Manual
POWER CALL ACTIVE LEVEL LIMITER THRESHOLD ANTIVOX VOX
INSIDE
MODEL IC29
DUAL CHANNEL
INTERCOM AMPLIFIER
ACTIVE LEVEL LIMITER THRESHOLD
OUTSIDE
ANTIVOX VOX
OUTSIDE INSIDE
FREQ 1 FREQ 2 FREQ 1 FREQ 2
Figure 4 • Optional Notch Filter Setup
OPTIONAL NOTCH FILTER SETUP
Turn both notch filters maximum clockwise (highest frequency).
Advance the inside level to maximum.
If there is feedback, reduce the level to the threshold of feedback, allowing feed-back to barely take place.
Adjust one notch filter until the feedback stops. Advance the level control clockwise until feedback returns (if
possible) and adjust the notch filter for minimum level.
Sometimes, when the level is advanced, the system will now feedback at a different frequency. Repeat the
procedure above with the second notch without affecting the adjustment of the first.
Sometimes there is no feedback. However, the sound has a poor quality. Again, the use of a radio or assistant
is useful. Even better is a noise source and a real-time analyzer.
Advance the inside level to maximum. Adjust one notch at a time to remove the peaky sound.
Since the notch filters have different ranges with some overlap, it is desirable to know at which frequency the
feedback occurs. This can be accomplished by connecting a frequency counter between common and one side
of the inside speaker.
120/240 VOLT SETUP
Be SURE to unplug the IC-29 from main power before changing the fuse or changing jumpers!
With the knobs facing you, the AC power jumpers are located in top left side of the unit, near the main power
fuse and power cable connector.
NOTE: These jumpers are soldered in place. Changing the power jumpers also requires a fuse change.
For 105-125 Volt operation: Install both "120 Volt" jumpers, if the "240 Volt jumper is installed remove it,
then replace the existing fuse with a 1/4 Amp, 250 Volt MDL fuse
For 210-250 Volt operation: Remove both "120 Volt" jumpers. Install the "240 Volt" jumper, and replace the
existing fuse with a 1/8 Amp 250 Volt MDL fuse.
We further recommend you note the change made on the voltage selection marking, which is located at the
right rear of the IC-29 so there is an external record of the current setting.