At 5/19/2010 15:29, you wrote:
>Hi > >In the attached picture you see the notch of the 70cm duplexer I built >according to W4NFR's description in QEX, those who can't receive >attachments find it here: > ><http://conturafm.mine.nu/_fh/438.95_notch.bmp>http://conturafm.mine.nu/_fh/438.95_notch.bmp > >The measurement has been made with both cavities of one branch connected >with a true quarter wavelength jumper of RG58 because I had no >double-shielded cable available. > >Can anybody tell me why the notch is this blurred and what can be done >about it? The isolation would be a bit better if the notch was a clear >sharp line, isn't it? I'd try a different length jumper between the cans & see what happens. As others have pointed out, you could use a little more signal in the vicinity of the notch. On my tracking gen. I narrow the sweep down to only the notch region so I can boost the generator power without overloading the spectrum analyzer. Bob NO6B
