MDS 05-3438A01, Rev. F
MDS 4790/9790 Series I/O Guide
89
Invisible
place
holder
Figure 41. Front Panel Removal/Replacement
8.4 Operating Frequency Change Considerations
Changing the radio’s operating frequency through a terminal command
or using the front panel is an easy process. However, there are fre-
quency-sensitive components within the radio that could impact opera-
tion on the new frequency—the receiver front-end helical coils and an
internal duplexer, if one is present. These elements have resonant cir-
cuits that prevent the transmitter from damaging the radio’s receiver and
interfering with other radios operating on nearby channels. The circuits
also attenuate out-of-band signals that could interfere with receiver
operation.
Changes in transmit operating frequency of granter than 100 kHz from
the factory settings will require retuning of the duplexer. Likewise,
changes in receive operating frequency greater than 5 MHz will require
retuning of the duplexer and/or the receiver’s front-end helical circuits
(
see “MDS 4790/970—Front End Helical Coil Alignment” on Page 91
).
Retuning of these circuits provides operation with maximum receiver
sensitivity and protection from damage to the radio’s receiver from the
transmitter’s RF output.
The feasibility of large changes in frequency depend on the type of
duplexer installed in the radio, or if there is an antenna switch module
present.
A
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