TN160 Base Station or Link Confi guration Settings
MT-3/4 Radio Systems
TECHNICAL NOTES
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TN160, REV 5-0-0, © Nov 2018
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Control Card Simplex Operation
When a control card with LVDS Serial Data interconnect is used for the radio confi guration, the simplex muting
jumpers in the control card should be used in place of the jumpers on the motherboard. The jumpers on the control
cards activate faster than the jumpers on the motherboard
The CI-RC-4M-G2 Multiple Link Controller can be set for simplex link operation in the software under the System
Settings tab, but requires the MUTE line to be connected from the subrack to the controller.
The CI-RC-4L Repeater Control Card can be set for simplex link operation via the jumpers in the control card.
Simplex Operation Improvement
On some simplex base or link systems, the Rx MUTE line may be released too quickly after the Tx PTT is deactivated.
The RF signal has not had enough time to decay before the receiver is un-muted and this can produce an audible
noise burst or blip at the end of each transmission.
MT-3 Systems require that two resistors within the receivers be replaced with 47K ohm resistors (1150-4B1002FP).
R95 and R96 require replacement in FM receivers. AM receivers require that R35 and R83 are replaced.
MT-4E Systems have a software selectable Simplex Unmute Delay jumper setting that can be enabled in the RSS
software Service section.
MT-4D Systems require that JU33 is installed in the Y position in the receivers.
MT-4R Systems require a 4.7 uF capacitor (1055-5B475K16) to be added to the PTT OUT signal line. This
modifi cation was part of ECO 758. Any transmitters that were sold before, and have not been returned to the factory
since March 2003, will require this modifi cation for simplex operation.
MT-4R or MT-4D Base Station with Telex (Vega) DSP-223 Control
If an MT-4R or MT-4D base station is operated by a console other than a Telex product, through a Telex DSP-223
tone remote adapter, there is a possibility the transmitter may not change channels properly (only changing channels
every second time the PTT is activated at the console).
If the MT-4R or MT-4D system is being controlled by a CI-BC-4E Base Controller, JU125 is required to be installed
in the controller.
If the MT-4R or MT-4D system is being controlled by an AC-3E Audio Control Card (not recommended), a 22 uF
capacitor (1054-6G226M20) is required to be added by soldering the positive lead to J23 and the negative lead to
ground.
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