Sigtronics S-A-F-E Installation Instructions - Manual (Page 9)

a) Make sure the BOTH/OFF/AUTO switch is set to “AUTO”
position and that the XMIT SELECT switch is set to the
radio you want to hear. Turn up the RECeive VOLume
control to 12 o’clock position.
b) Turn up radio volume at the radio as normal. Make
sure however, you are not hearing the radio through
intercom mics by turning down (counter-clockwise)
both SAFE intercom VOLume controls all the way.
c) Check violet wire (SPEAKER HI and LO) connections
from the SAFE to the radio
2. Can’t transmit to dispatch on radio through the headset.
a) Make sure that the XMIT SELECT switch is set to the
radio you want to transmit on.
b) Check the connections between SAFE unit and the
radio. Both white wires (PTT HI and LO) and the Brown
and Black wires (MIC HI and LO).
c) Check the specific Radio Mic Gain Adjustment on the
SAFE unit.
Vehicle Engine On:
1. Electrical noise (alternator whine) in headsets when
receiving on radio, or…
Dispatch reports that they hear electrical noise (alternator
whine) when transmitting from vehicle through the
headsets.
First make sure that the problem is only related to the
radio hook up. Make sure that you did the “Electrical Noise
Test” for the intercom (without the radios connected) and
fixed any problems there before you go further. If OK then:
Check all six radio interface wires between the SAFE unit
and the radio - MIC HI, MIC LO, PTT HI, PTT LO, SPEAKER HI,
and LO. Make sure that you have the correct pin numbers
for the radio you are hooking to. Make sure that MIC LO
and SPEAKER LO are not physically tied to the same pin on
the radio; even if they are tied together inside the radio.
If the wiring is ok, then noise is coming from radio.
Possible bad radio wiring, (Check radio power and ground
connections for loose or corroded connections) or…
Excessive noise is generated directly by the vehicle’s
electrical/charging system - most commonly known as
alternator whine. This is only present when the vehicle’s
engine is running and recognized by the fact that the
pitch or frequency of the whine changes directly with the
change in engine rpm.
The preferred way to solve this type of problem is to have
the vehicle’s electrical/charging system serviced. The
most common cause of this type of noise is bad diodes
in the vehicles alternator. Other possible causes are:
Bad vehicle voltage regulator; Bad alternator or battery
cable connections; Missing or bad engine or alternator
grounding straps.
If servicing the vehicle’s charging system is impractical,
installing a good alternator whine power line filter in-
line with the radio power wire(s) will usually accomplish
the same thing. All radio power wires will have to be
filtered. Some radios have more than one wire that hooks
to vehicle power. Contact the radio manufacturer for a
recommendation on the best filter for the particular
radio. NOTE: This solution should not be considered a
permanent fix. Vehicle charging system problems of this
type will eventually cause other equipment failure as well
as shorten the life of the vehicle’s batteries.
2. Dispatch says too much background noise or unclear or
weak transmissions.
a) Check to see if a radio hand mic on the vehicle is also
active or “live” when transmitting through the SAFE
unit. Check this while not wearing a headset and by
talking directly into the radio hand mic and pressing
either SAFE intercom radio PTT switches. Do not press
the PTT button on the hand mic itself. If dispatch
can hear you loud and clear, then the background
noise pick up is coming from this active hand mic.
If you have this type of hand mic then it is best to
contact the radio manufacturer for instructions on a
possible microphone modification to fix the problem.
Some radio manufacturers can supply a compatible
microphone that does not have this problem.
b) Readjust the SAFE Radio Mic Gain Adjustment. If the
mic gain is set too low, you will get reports of weak
transmissions. If the mic gain is too high, you will get
reports of noisy or garbled transmissions. See “A/C
Radio Mic Gain Adjustment” or FM Radio Mic Gain
Adjustment.
FM (Radio 2) Radio Hook Up
Connect the FM radio to the six SAFE wires bundled by the
FM (Radio 2) label. Adjust mic gain as follows:
The FM Radio Mic Gain Adjustment is the right one of the
two located on the top of the SAFE unit. The adjustment
procedure is very similar to that of the A/C (Radio 1) radio
mic gain adjustment. Arrange to have someone nearby with
a radio compatible with the FM radio that is connected to the
SAFE unit. Then, proceed as follows:
1. Set the SAFE ON/OFF switch to the “ON” position. Again,
Plug in a headset into Officer 2’s jack. Make sure that the
volume control on the headset is turned up to full. (A/C
radio and the other headsets are not needed for this
adjustment.) On Officer 2’s side of the SAFE, set the XMIT
SELECT switch to the “FM” position, the BOTH/OFF/AUTO
switch to “AUTO”, and the AUX/OFF switch to “OFF”. Set
the RECeive VOLume control to the 12 o’clock position.
2. Set the headset aside for a moment. With the FM radio’s
hand mic, transmit as normal to the remote station.
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