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rotary “ADJ” control. Set the RADIO 1 MIC XMIT GAIN RANGE switch
to the “LO” position (up for Radio 1). This is the default factory set-
ting. Adjust the “ADJ” control clockwise to increase the output gain
or level to the radio. Counter-clockwise rotation decreases it. The
basic adjustment concept is simple. You will be setting the level and
clarity of outgoing radio transmissions through the UltraSound unit
headsets, to match or exceed that of transmissions using the radio’s
standard hand microphone. To do this, you will need to transmit
and receive on the vehicle’s radio to a remote station. Arrange to
have someone nearby with a radio compatible to the radio you are
using with the UltraSound. Then . . .
1. Plug a headset into the Officer’s jack. Make sure that the volume
control on the headset is turned up to full. It is not necessary to
connect the other headsets or Radio 2 for this adjustment.
2. Put on the Officer’s headset and position the headset microphone
as normal. Turn the UltraSound VOLUME control all the way down
(counter-clockwise). You should not be able to hear yourself in
the headset.
3. With the radio’s hand mic, transmit as normal, to the remote
station. Transmit long enough so that the receiving station can
get “calibrated” to your transmission (voice) level.
4. Verify radio reception. If OK, use Officer’s Radio 1 PTT to transmit
to your receiving party. If receiving station reports weak transmis-
sion, use the screwdriver to turn the RADIO 1 MIC XMIT GAIN
ADJ clockwise a small amount. If they report garbled, broken,
or noisy transmissions, turn the RADIO 1 MIC XMIT GAIN ADJ
counter-clockwise a small amount. Repeat as necessary until the
receiving party reports that transmissions through the Ultra-
Sound sound as good or better than when using the radio hand
microphone.
5. If the receiving party reports that your transmissions are still
weak with the MIC XMIT GAIN ADJ at the full clockwise position,
then switch the RADIO 1 MIC XMIT GAIN RANGE switch to the
“HI” position (down for Radio 1) and repeat steps 3 and 4 above.
That’s all there is to it!
Once the gain is set, also check radio operation with the vehicles
engine running. If radio reception and transmission through the Ultra-
Sound unit is fine, skip to the “Radio 2 Hook Up” section. If something
does not work correctly, check the following troubleshooting guide:
Radio Troubleshooting Guide:
NOTE: It is far easier to troubleshoot with only one radio connected
to the Sigtronics UltraSound unit at a time.
First determine if the trouble occurs with the vehicle engine running.
VEHICLE ENGINE OFF:
1. Can’t hear radio in headset:
a) Turn up radio volume at the radio as normal. Make sure how-
ever, you are not picking up the radio through the headset
microphones by briefly turning down (counter-clockwise)
the intercom VOLUME control all the way.
b) Check violet wire (SPEAKER HI and LO) connections from the
UltraSound to the radio.
c) Set the appropriate RADIO VOLUME switch on the back of
the UltraSound unit to the “HI” position.
2. Can’t talk to dispatch (transmit) on radio through the headset:
a) Check the connections between UltraSound unit and the
radio. Both white wires (PTT HI and LO) and the Brown and
Black wires (MIC HI and LO).
b) Check the UltraSound Radio Mic Transmit Gain adjustment.
c) Make sure the RADIO PTT switch used is the one for the radio
you want to transmit on.
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.
a) 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:
b) Check all six radio interface wires between the UltraSound
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.
c) If the wiring is OK, then noise is coming from radio:
i) Possible bad radio wiring, (Check radio power and ground
connections for loose or corroded connections) or. . .
ii) 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 fre-
quency 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 connec-
tions; 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.
