Plain 1/4 wave pass cavities usually work just fine at their 3/4 wavelength, i.e. 2 meter pass cans will work @ 440 MHz. I've heard from several sources that this works with BpBr duplexers as well, though I've never tried myself - I saw at least one 72 MHz duplexer being sold at Dayton as a 220 3/4 wavelength duplexer.
Mobile duplexers are a different story, as the VHF units are electrically short (& maybe the UHF ones too), so there would be quite a bit of modification needed to move one. Given how cheap & plentiful both are on the used market, it's probably easier to just buy the mobile duplexer you need. Bob NO6B At 5/29/2008 06:43, you wrote: >Wayne, you may have a point on the third harmonic cavity tuning. I have >several cans that are marked for 440 and look just like a standard 2 Meter >can. I have looked at the coupling loops and they are smaller than the >ones for 2 Meters. > >Also, I had two cavities that were marked for 300 mHz and I disassembled >them and found a large washer brazed to the bottom of the movable center >section. I removed the washers and the cavities now tune up through 450 mHz. > >Don't throw those out-of-band cavities away just yet. You might be able >to recover them for something useful. > >73 - Jim W5ZIT > >Wayne <[EMAIL PROTECTED]> wrote: >> >>Third, I had read, somewhere, that some cavities made for the VHF high >>band could be tuned as bandpass on the 440 band. After all, the 3rd >>harmonic of 147.00 MHz is 441.00 Mhz. Same would, more or less, hold true >>for reject filters. >>And I said "might"... >>I just might do a test with a 3 can high band filter I have that is NG >>for normal 2 meter repeater splits. >> >>Wayne WA2YNE > >
