OK, question... If you put a cable which is 1/4-wavelength at VHF between the T and the UHF cavity, it's 3/4-wavelength at UHF. Since any odd multiple of a quarter wavelength will invert the impedance, what will this really accomplish on the UHF cavity side?
The dual-band diplexers are usually high-pass/low-pass arrangements, and lose something like 0.2 dB while providing 40 dB or more isolation. Assuming you get a real one, and not something made with PIM-prne materials, would this not be a safer bet? Or, am I missing something? (It's happened before...) 73, Paul, AE4KR ----- Original Message ----- From: Gary Schafer To: Repeater-Builder@yahoogroups.com Sent: Tuesday, March 09, 2010 4:53 PM Subject: RE: [Repeater-Builder] Dual receivers on one antenna for RX only site The UHF cavity loop provides a short circuit at the VHF frequency but the quarter wave cable from it transforms the short to an open (high impedance) at the T connection so you get no attenuation of the VHF signal there. The VHF signal then passes to the VHF cavity as if the UHF cavity was not there. The same thing happens to the UHF signal going to the other cavity...
