20-01-2017, 03:33 PM
Hi Dave,
You can use 70cm cavities in 3/4 wave mode for 23cm, you will have to reduce the loop size and depending on your separation between sites maybe you can get away with notch cavities in the receive leg not much rf floating around on 23cm.
We where lucky to pickup up a Sinclair Labs 6 cavity bandpass/reject 3/4 wave cavity duplexer 10 years ago when no body wanted them for $200 Canadian for the Newcastle repeater. I noticed that most of the TX/RX (now owned by Bird) 23cm units are 3/4 wave.
Maybe single loop and Tee pieces on each three cavities will give you the rejection you need, food for thought.
Cheers Peter VK2ZTV
You can use 70cm cavities in 3/4 wave mode for 23cm, you will have to reduce the loop size and depending on your separation between sites maybe you can get away with notch cavities in the receive leg not much rf floating around on 23cm.
We where lucky to pickup up a Sinclair Labs 6 cavity bandpass/reject 3/4 wave cavity duplexer 10 years ago when no body wanted them for $200 Canadian for the Newcastle repeater. I noticed that most of the TX/RX (now owned by Bird) 23cm units are 3/4 wave.
Maybe single loop and Tee pieces on each three cavities will give you the rejection you need, food for thought.
Cheers Peter VK2ZTV