Yeah, of course you'd want to order any filter optimized for your application. Yes, DCI markets products for the Amateur market but they also have a lot of products for commercial markets. I have indeed used some of their products (HAM & commercial) and have had very good results. Hi-Q bandpass cavities is absolutely the best thing for frequency specific filtering between the TX & RX ports of a duplexer and the transmitter & receiver but a "window" filer is going to be more appropriate for the antenna side of the duplexer. DCI is not the only one out there that makes window filters either. If you're going to use split antennas a window filter would not be needed.
As I think a couple of others have already mentioned a spectrum analyzer is a necessary tool in today's RF environment to make sure you're being a good "RF neighbor" as well as finding external sources of IMD too. Richard "Nate Duehr" wrote: Careful. I've looked over their product line and their stock filters have published SWR numbers that don't look good for high 147 and low 145 repeaters... they tend to be made for the center of the band for the end-users, not for repeaters. The skirts on even their 4 MHz wide filters start to roll off if your machines are at either end of the spectrum. Check carefully if you choose to use their filters, or call them and ask them if they'd tune them lower/higher (probably for a charge). Better yet, buy big, real, high-Q bandpass cavities and don't mess around with these little things made for hams at home. Nate WY0X
