Joe, I have two commercial UHF MTR2000 repeaters to each of which I have added a Telewave TWPC-4508-2 bandpass cavity filter comprising two 8" cavities. Both also have Angle Linear preamps followed by 6 dB attenuators to make up for the 1 dB or so loss in the filter and improve the sensitivity of the receiver. One repeater is about 150 feet away from an FAA ARSR-4 radar installation, and I wanted to be certain that so much power (at a much higher frequency, of course) would not desense the receiver. There are more than a dozen Government VHF and UHF radios at that site, but my repeater doesn't seem to be bothered at all. Telewave also makes 10" bandpass cavities, but a pair of them will not fit side-by-side in a standard 19" cabinet, so I chose two 8" cans.
You can see similar filters here, except that the TWPC-4508-2 is not shown: <www.telewave.com/pdf/TWDS-5018.pdf> Bear in mind that a bandpass filter may be tunable over the 430-450 MHz range, but once tuned to a specific frequency will pass only a very narrow band, just a few tens of kHz wide. If you really want to pass a 20 MHz wide band, then you should use a preselector rather than a bandpass filter. 73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Joe Landers Sent: Saturday, August 08, 2009 11:44 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] recommendations on a good bandpass filter Hello Folks, Would like to see what people are buying these days and see what is recommended as I am in need of the following. I need a band pass filter for uhf would like 430 to 450 but will consider 440 to 450. Would like to see what is out there I am missing Thanks Joe Landers Ke4eue
