You're welcome, Don.
One clarification....
The WACOM series of duplexers generally were provided with
variable capacitors with enough range to allow the filter to be
configured with the notch either above or below the pass
frequency.? In other words - each side of the duplexer can be
configured for LPHR or HPLR.
One comment....
1.35 dB insertion loss per cavity seems suspect.? I would have
expected it to be 0.5 dB, resulting in a total cabled loss of
around 1.4 dB or less.? You didn't mention what your total cabled
parameters ended up being - so you may want to let us know.
Kevin W3KKC
On 3/20/2025 11:02 PM, Don Roden wrote:
toggle quoted message
Show quoted text
Thanks Kevin,
This was a diplexer that was on my 443 repeater.? ?I bought
the repeater/diplexer as a package years ago.
It always had a 25% reflected out of the transmitter.? ? I
had been looking at some broadcast FM filters with notches, and
before I put the Nanovna up, I thought this would be a good time
to look at the WACOM.? The S11 looked horrible.. not at all as I
expected.? ?I purchased the repeater years before the Nanovna
was introduced.
?
I found that the capacitors? were on the wrong frequency side
of the notch? ( all these years ) .... After I saw the effects
of the capacitor, it took a few back and fourths to get the null
and the broad peak separated by 5Mhz .? ?By the way, the
Nanovna-F was calibrated nuts-on on both 443Mhz and 448Mhz.? ?
-1.35 and -21.25? were the single cavity readings.
Combined, there was some minor tweaking that had both notches
aligned and both rejects aligned.? ? I tightened everything up
and the notches stayed on frequency.
Back in-line and zero reflected on the transmitter. Great !!?
?I'm looking forward to seeing a much improved range on the
repeater.? ? Thanks Again Kevin
Don W4DNR? ? WA4NPL/R? 443Mhz
Kevin Custer