Don't forget that the length of the coupling loops inside the cans contributes
to the overall length of the coax. Ideally you would have a quarter wave from
the Tee coupling the two sides of the duplexer together back to each can,
including coupling loops. The idea is to have the pass side look into an open
circuit (the quarter wave line going to the other side of the duplexer) at the
Tee.
73 - Jim W5ZIT
--- On Tue, 11/10/09, Kris Kirby <k...@catonic.us> wrote:
From: Kris Kirby <k...@catonic.us>
Subject: [Repeater-Builder] Wacom WP-639 coax lengths
To: Repeater-Builder@yahoogroups.com
Date: Tuesday, November 10, 2009, 6:26 PM
I'm working on re-fitting a Wacom WP-639 for re-use. There are two
remaining jumpers on this four cavity filter set, located between the
cavities on each respective side; there is no coax between the High side
of the Low side, only coax between each of the two low side cans and the
two high side cans.
Due to the age of the jumpers, and with parts available on hand, I am
replacing the jumpers with RG-142. My questions are these:
Are the side pieces frequency specific or "middle of the road". (i.e.:
146.01 and 146.61 MHz for each side or 146.31MHz for both)?
How much length does a connector add to the length of the cable when
making a frequency-specific or critical jumper?
Is the distance between the high-side and the low-side of the duplexer
1/2 wavelength? I believe that from the "tee" in the middle of the set,
there should be 1/4 wavelength to the first high-side can, and 1/4
wavelength to the first low-side can. Is this correct?
I know that I have to factor for velocity factor, but I am at a loss as
to what to add or subtract for crimp N-type or PL-259 connectors.
Thoughts, comments, information are greatly appreciated.
--
Kris Kirby, KE4AHR
Disinformation Analyst
