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Old 08-03-2012, 9:58 AM
fdcaptjd fdcaptjd is offline
Join Date: Aug 2009
Location: NE OK
Posts: 20

As a test, try turning down the power on the transmitting radio to it’s lowest setting.
If the repeater’s coverage improves you have a de-sense problem.

A high SWR reading on the antenna will cause de-sense too.

I will probably regret this but here goes:

As mentioned above a duplexer allows the separate receiver and transmitter of a repeater to share a single antenna and coax by providing isolation between the two.

Remember, even though the radios are tuned to different frequencies; the receiver still “hears” the RF energy of the transmitter. This RF power overwhelms the receiver, and it cannot “hear” the relatively low level of the remote radio trying to talk into the repeater.

As mentioned in post above, one way to overcome this problem is to use two separate antennas separated by a large amount of open space, like two levels on a tower. The problem with this approach is that the repeater will most likely suffer some form of degraded performance. Whichever component has the upper antenna will cover better. If the TX antenna is the top, the repeater will talk further than it hears or the other way around.

A duplexer solves this problem by electrically providing the same amount of isolation as the open space.

I would be glad to explain how, but that would make for a long post. PM if you want to hear it.


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