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The last step is to set the Radio 1 Microphone Transmit Gain. Micro-
phone Transmit Gain (labeled MIC XMIT GAIN) adjustment for the
radio (or both radios for UT-4D, UT-6D) is also provided on the back
of the UltraSound unit. The adjustment(s) sets the microphone audio
level going to the radio(s) during transmit. The Microphone Transmit
Gain adjustment(s) will need to be initially set to your particular
radio(s). The gain(s) once set, should never need adjustment again
unless the type of radio(s) used is changed. The following simple
procedures take you through the adjustment of the Microphone
Transmit Gain(s).
Radio Microphone Transmit Gain Adjustment can be made with
a small, flat blade screwdriver. Referring to Figure 6 above, the gain
adjustment is set by two controls - a “HI/LO” RANGE switch and a
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 Passenger’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 on UT-4D
/ UT-6D units) for this adjustment. On dual radio units (UT-4D
/ UT-6D), set RADIO 1/ RADIO 2 switch to “RADIO 1” and the
AUTO / BOTH switch to “AUTO”.
2. Put on the Passenger’s headset and position the headset micro-
phone 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 Passenger’s 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
UltraSound unit are fine, for UT-4S / UT-6S units this completes
the installation. Skip to the “System Operation” section. If every-
thing is OK for UT-4D / UT-6D units, skip to the “Radio 2 Hook Up”
section. If something does not work correctly, check the following
troubleshooting guide:
Radio Troubleshooting Guide:
NOTE: For dual radio units (UT-4D / UT-6D) it is far easier to trouble-
shoot 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.
d) For UT-4D or UT-6D 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 adjustment.
c) For UT-4D or UT-6D 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 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. . .
