DANIELS
DANIELS
ELECTRONICS LTD.
ELECTRONICS LTD.
TM
TM
TN100 System Installation and Troubleshooting
MT-3 Radio Systems
4
. Operate the receiver and ensure the sensitivity, squelch and squelch hysteresis are set to the desired
levels. The point at which the squelch breaks is not necessarily the 12 dB SINAD sensitivity measure-
ment for the receiver. The receiver has an internally adjustable squelch hysteresis control. This control
allows a spread between the opening and closing of the squelch (i.e., the sensitivity of the receiver may
be -117 dBm for 12 dB SINAD, but the squelch control could be set to unsquelch at -114 dBm and
squelch at -120 dBm).
The hysteresis control, typically factory set to 6 dB, is located on the main receiver board. The purpose
of this control is to allow a mobile or hand held radio to access the repeater with a "good" RF signal. The
receiver will then hold the signal over the 6 dB range while the signal from the mobile or hand held radio
is varying over this 6 dB range. This prevents the mobile or hand held radio from intermittently access-
ing the repeater in a marginal coverage area. To measure for 12 dBm SINAD sensitivity, press and hold
the front panel squelch disable button while making the measurement. This opens the receiver for max-
imum sensitivity.
Daniels Power Amplifier Set-Up and Installation
1.
Check the frequency label to confirm that the power amplifier is set up to operate at the desired fre-
quency.
2.
Install the power amplifier in the transmitter and receiver A or transmitter and receiver B slots as
required. If the power amplifier is upgrading the power output of the radio system, ensure that the guide
rails for the power amplifier are installed properly.
3.
Connect the RF cables and ensure they are firmly screwed on.
4.
Apply power to the subrack while measuring the RF power output. The RF output should be approx-
imately 30 watts with a 13.8 Vdc supply voltage. If the power level must be changed adjust the exciter
level (internal potentiometer) for the desired RF output (20 to 30 watts).
5.
The VHF power amplifier has an 8 amp internal fuse. The fuse rating may be exceeded if the power
amplifier is driven to levels of 40 to 50 watts output. Ensure the exciter output is set to the correct drive
level and the VHF power amplifier is correctly tuned.
6.
If the power amplifier is upgrading the power output of the radio system, check that the power feed
to the subrack is able to handle the increased current.
7.
Check that the exciter power output does not exceed the maximum power input to the amplifier. In
some case the exciter may need to be replaced with a lower power version. VHF amplifier maximum
power input is 4 Watts, and UHF maximum power input is 2 Watts.
Installation and Set-Up
Page 4 of 9
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Phone:
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TECHNICAL NOTES
TN100 Rev 3-0-0 Sep 08
© Copyright 2008 Daniels Electronics Ltd. All rights reserved.
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