On Jun 28, 2008, at 8:27 AM, Chuck Scott wrote: > Lee: > > I think most repeater operators would be appalled > to see what gets through their BP/BR duplexers. While they're called > that, most are not good bandpass filters. Also, at many sites the > repeater receiver is capable of dealing with the signals it sees, as > long as the owner hasn't put some 22 dB preamp on it. As always, > what you use depends on the application, and the notion of quality > is relative. > > Chuck - N8DNX > > [ED - A Wacom 678 UHF duplexer does a good job of passing VHF paging > signals right on thru - hence a band pass cavity - 2 loop job - > before any preamp, and a MONO band antenna] >
Amen, pass the Tylenol to all of the above, except that there's no need to have the "notion" of quality on analog systems... you can measure and see right where you're at. Digital, not so easy. [Yet. Of, course.] But we'll get there. A 900 MHz paging transmitter @ 300W from 3' away of your UHF antenna will also pass nicely through a standard BpBr nicely, and blow away the front end of the UHF receiver trying to listen to things, 2nd harmonics being what they are... even with some of it actually being "caught" by the BpBr. (GRIN). Bandpass cavities are almost always a requirement, not a luxury, at busy RF sites. -- Nate Duehr, WY0X [EMAIL PROTECTED]
