Your pic shows the classic signs of an incorrect cable length. Did you include the effective length of the coupling loops in your calculations? Our rule of thumb is that they are 1/10th wavelength.
Otherwise, do what EMR does and try cable lengths until it meets specs. WalterH --- In [email protected], Atlantis <atlant...@...> 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 > > 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? > > Regards > Martin >
