2m cavity progress in the VK2ZIW shack

[VK2ZIW]

Hi all,
We're all 'Jack Of All Trades" right, and duplexers, particularly for 2m are a problem....
Here is a surplus UHF set from a VK5 site, yes 3/4 wave @ 70cm, perfect for 2m


Using commercial surplus gear is "our speciality".
Coupling loop progress:
Higher freq pass

[b]Lower freq pass[/b]
TNC connectors because two N connectors won't fit in the cavity access hole.
I can only get 32db notch depth with a single N and the series loop and cap design.
The above do 35db or so. (measured by my Wiltron 640)
See: http://www.repeater-builder.com/projects...earch.html
===== Now here's the tricky bit ==============
Notice my coupling loops have a Large Area and a two & half turn loop.

"Why is it so?"  -- Julius Sumner-Miller

It makes it so so much easier to adjust the pass-to-notch spacing.
[b]Where is this discussed anywhere else?[/b]
Yes, I'd like to know.
All this "trade secret" stuff was done th the 60s and held tightly in company libraries.
I had a Decibel Products UHF cavity set, I want to see the innards!!
Alan VK2ZIW