Before you fix a receive problem be sure there is a problem. I have used ARR GasFet preamps for some time with excellent results. Be sure you have a filter or cavity ahead of the preamp, and that you do not have so much out of band energy getting to the preamp that it goes into overload and becomes a non-linear mixer. I have used GasFets in tower top systems (one at 600 ft for over 15 years) with PolyPhaser's ahead of the amp.
I also built a relay tree to bypass the preamp when power was removed. The relays (GE Pro antenna relays) caused more trouble than they solved because there was no wiping action in the contacts. Aside from the obvious gain of the preamp, the very low noise figure ahead of a not so good front end amp can make a substantial improvement. Be the 3rd order intercept point is as high as possible for intermodulation mixture products. Also test for receiver desentization with an isolated tee incase there is not enough receiver protection from the transmitter. What worked before preamp now needs to be at least 15 db better with the preamp. That is, if you had a little desensitization before adding the preamp, it will probably get worse - double shielded cable and ground is a must. 73, steve nu5d Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
