Noise
Suppression
2. Press the push-to-talk (PTT) button on the microphone and hold it down. Hold the
microphone four to six inches from your mouth and speak at a. normal level.
Announce the call letters of the station you are calling, followed by your call letters.
Repeat if necessary. To receive a reply, sign off and repeat the call letters of your
station.
PA Public Address)
1. Connect a external PA speaker to the PA jack on the rear panel.
3. Press the push-to-talk button on the microphone and talk into the mic. Your voice
will be heard from your external speaker.
NOTE:
The volume control on the transceiver does not control the speaker output
during PA speaker.
Tune-up
Before beginning any special noise suppression steps, be sure that the
vehicle is well-tuned. Clean and tighten all connections, including alternator,
battery, regulator, and coil connections. Perform the following maintenance
steps as necessary: Solder any cr(mped spark plug or distributor leads; if you
must use solid-wire leads, clean and regap or replace spark plugs and
ignition points; and check and clean alternator rings or generator brushes.
Retune the engine at the manufacturer's recommended intervals.
Corrective Steps
In order to find and eliminate the maximum number of noise sources that are
present in any vehicle, start the strong sources, then work back. To be sure
the noise comes from your vehicle and not outside it, drive to a location that is
free of man-made electrical interference (such as noisy power lines,
industrial noise, or other vehicles). Test for noise with a weak signal on the
channel and the engine off. Then start the engine. Ignition noise will probably
be present at all engine speeds. If it is severe, it will make a normally readable
signal unreadable.
To reduce ignition noise, install resistor-type spark plugs. If non-resistance
ignition wiring is used, install a 10 k-ohm suppressor resistor at each spark
plug tower of the distributor. Install a coaxial capacitor as close as possible to
the ignition coil primary.
A whining noise which varies with engine speed and continues with the
ignition turned off and the vehicle coasting in gear characterizes the
alternator. Check and clean it and install an alternator filter.
An irregular, clicking sound which disappears at a slow idle may be the
voltage regulator. Install a 4-ohm carbon resistor as close to the field terminal ••
of the regulator as possible, then a .002 uF capacitor in series with and as
close to the resistor as possible. Connect the capacitor to ground. See the
detail drawings on next page.
Irregular popping noises which vary with road surfaces indicate static
discharge at any of several locations in the vehicle. Tighten loose nuts and
bolts and bond large areas such as the fenders, exhaust pipe, firewall, etc. to
the frame with lengths of heavy wire braid. Contact a local electronics parts
or automotive electrical service company to purchase the necessary items.
Additional information is available in the
Radio Amateur s Handbook
published by the ARRL.
