I believe he said he was troubleshooting a duplex noise issue; which
doesn't necessarily mean desense. I have a repeater on a commercial
tower in which AC power (for the light on top) goes up a rusty metal
conduit. When the wind blows, the conduit makes duplex noise *if* I'm
using a common antenna. If I separate the repeater on two antennas, the
problem disappears, or, if the tower ices over, it disappears. Now
trying to figure out how to keep the tower iced over cheaply during the
summer months.... <grin>
Kevin
Q wrote:
>You would gain much more isolation by separating them vertically. Side
>by side would also mess up the pattern. Not familiar with that
>duplexer,but if it has a Tee at the antenna port,simply remove it and
>connect the two antennas where the Tee was. This >may< throw the tuning
>off some but is worth a try. Why do you feel the need to split the
>antennas? Having desense problems? 73,Lee,N3APP
>
>k3phl wrote:
>
>
>
>>Hello all,
>>
>> I am considering running split antennas at my 220 MHz site in
>>Philadelphia as a test to increase sensitivity and troubleshoot a
>>duplex noise issue. The machine is currently a modifed Motorola
>>Micor using a TX/RX 4 can duplexer, DCI bandpass filter in the RX
>>leg, and a Comet Super 22 (220) base antenna.
>>
>> I am considering running separate Super 22 antennas 12 feet apart
>>horizontally. One feedline run will go from the transmitter direct
>>to the TX antenna. The other feedline run will run from the receiver
>>to RX port of duplexer, common port of duplexer to 220 bandpass
>>filter and then to the RX antenna. The TX port of the duplexer will
>>remain unconnected.
>>
>> I expect the duplexer to act as a 2 can deep notch, eliminating the
>>transmitter from the receiver with the TX port open. I assume the TX
>>rejection in the receiver line should improve and the resulting RX
>>sensitivity should improve since the transmitter has been reduced to
>>a strong near field instead of RF on the same line. Is this the
>>correct theory of using a duplexer in a split antenna site and if so,
>>should the TX port be left unconnected or capped with a 50 ohm load?
>>
>>Thanks in advance,
>>
>>Steve
>>K3PHL
>>
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/Repeater-Builder/
<*> To unsubscribe from this group, send an email to:
[EMAIL PROTECTED]
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
