Thoughts threaded in:
> They are definitely Sinclair, welded top, side loop BpBr cans.
> They date from the late 50s or early 60s (by 1964
> or so the top adjustable loop design had been adopted).
Sounds about right. I thought they were Sinclair.
> They could also be part of a hybrid ring design although the
> can is the same regardless of the type of filter.
I don't think these were a Hybrid ring. There are 6 of them. I have never
seen a hybrid ring where 6 cans were needed. usually 4 cans provides more
than enough isolation in a hybrid ring. The other thing that points me
toward a standard set of duplexers is that the partial harness that I got:
1. didn't have enough wire to be a hybrid ring -
besides, don't the hybrid rings usually use crimp tees
instead of threaded connectors?
2. almost had enough wire to make a standard duplexer configuration. I am
short one stub though. I only have 5.
> Try them on the tracking generator over a much wider range (like
> 130-160MHz) You should see two notches, one above and one below the
> pass. If you want a HPLR you will have to reduce the capacity of the
> coaxial capacitor stub considerably. That will move the low side notch
> up closer to the pass.
Yep, tried that. It seems I can't get rid of enough capacitance in the rods
to get to 600Khz. They come close, but won't quite make 600KHz. I think that
if I had a proper harness with the correct length cables, that things may
come and be right.
The rods came with varying lengths of inner conductor. I have tried these
varying lengths to no avail. I'm not sure why there would be different
length centers, but I guess that's part of the mystery of buying a used set
of duplexers!!
> Just a guess, but try adding a near-1/4 wavelength of coax between the T &
> can connector. I once turned a pass cavity into a pass-notch that
> way. Perhaps the 1/4 wavelength will transform the LPHR into HPLR?
I have also tried this. It definitely changed things, but the tuning all
went weird. Again, I was hoping to find some info so I knew how they were
supposed to be cabled.
> Also are you getting decent specs out of the current LPHR response (~40 dB
> notch, 0.7 dB pass loss)?
The can we were working with was great as a LPHR can. It had good notch and
good pass response.
>Looks like the stub was absonded from a set of Wacom cavities in an attempt
to make the cavity into a BpBr type.
I don't think that this is the case. The Wacom stubs have hose clamps at the
end of the stubs. These have a ring and a nut soldered to either side of a
slit with a screw in them to make tension.
I would like to thank John, VE3AMZ. He sent me a spec sheet on 1-150 series
of cans, but the cans shown in the pictures seem to be the older spun cans.
Also, The 150 series seems to only go to a 4 can set (3R7). According to the
diagrams, (no measurements) one side has 2 ports per can and the other only
has 1 port per can. The cans that I have all have only one port per can.
Kevin W3KKC and I spent the better part of an afternoon trying to get these
to do something that seemed right. Maybe he has some opinions to the above
that I don't remember. Kev??
Scott
Scott Zimmerman
Amateur Radio Call N3XCC
612 Barnett Rd
Boswell, PA 15531
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