Sigtronics US-12D - Manual (Page 10)

necessary to connect the other headsets (or Radio 2 on US-
12D units) for this adjustment. On dual radio units (US-12D),
set RADIO 1/ RADIO 2 switch to “RADIO 1” and the AUTO
/ BOTH switch to “AUTO”.
2. Put on the Officer’s headset and position the headset
microphone as normal. Turn the UltraSound VOLUME
con-trol 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 receiv-
ing station can get “calibrated” to your transmission (voice)
level.
4. Verify radio reception. If OK, use Officer’s PTT to transmit
to your receiving party. If receiving station reports weak
transmission, 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 UltraSound 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 UltraSound unit are fine, for US-12S units this
completes the installation. Skip to the “System Operation”
section on page 11. If everything is OK for US-12D units, skip
to the “Radio 2 Hook Up” section on page 11. If something
does not work correctly, check the following troubleshoot-
ing guide:
Radio Troubleshooting Guide:
NOTE: For dual radio units (US-12D) it is far easier to trou-
bleshoot 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
however, 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.
d) For US-12D units, make sure that RADIO 1/RADIO
2 switch is set to the radio you want to hear.
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 adjust-
ment.
c) For US-12D units, make sure the RADIO 1/RADIO
2 switch is set to the radio you want to transmit on.
VEHICLE ENGINE ON:
1. Electrical noise (alternator whine) in headsets when receiv-
ing on radio, or ...
Dispatch reports that they hear electrical noise (alternator
whine) when transmitting from vehicle through the head-
sets.
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 con-
nected) on page 7 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 physi-
cally 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 connec-
tions) 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 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 ser-
viced. The most common cause of this type of noise
is bad diodes in the vehicles alternator. Other pos-
sible 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 fil-
tered. 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.
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