> That's a hard question to answer. Some preselectors are based upon the > physical package used for mobile duplexers, and may work just fine- but > they are not flexible. I prefer to use an 8 inch bandpass cavity that I > can tune for almost any selectivity and insertion loss that I want. If > you have a good preamp with, say, 10 dB of gain, you can set up a > bandpass cavity to be extremely narrow but with 5 dB insertion loss, and > you will still be far better off (+5 dB) than without the preamp and you > will have reduced the vulnerability to overload and desense. At UHF, > with a 5 MHz split, the playing field is a lot different from that at > 2m, with a 600 kHz split. > > 73, Eric Lemmon WB6FLY >
This just does not seem to be a good way to go. If you put a 5 db loss before the preamp the noise figure can not be made up nomater how much gain the preamp has. To top it all off you have to add about 2 db to that for the losses in the duplexer. You let the bp/br duplexer take care of the in band problems and then use a band pass cavity that does not have to have very much loss to take care of the out of band problems if needed. de KU4PT Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
