My feelings are that the "Not Exactly 9913" is your problem. See if you can
get some LMR-400 and sub for it.
Joe W4AAB
----- Original Message -----
From: <k8bb@comcast.net>
To: <vhfcontesting@contesting.com>
Sent: Monday, January 01, 2007 5:13 PM
Subject: [VHFcontesting] impedence of 8" long bulkhead @ VHF/UHF?
> Hello,
>
> I have searched the archives for this, but I do not see an answer.
>
> My Question:
> What is the reason that I show *very weird* SWR curves at VHF/UHF when
> feeding through UHF bulkhead connectors that are 8" ( and/or 4") long when
> measured into a known 50 Ohm load good through VHF.
>
> My Situation:
> My feedlines enter my house/shack through two bulkhead "panels" connected
> with 9913 equiv. between. You can see pictures and a "story" at this web
> page http://home.comcast.net/~k8bb/ant.htm which explains why I have this
> arrangement and how I went about installing it. Through process of
> elimination, I have determined that somewhere between the shack panel and
> the outside panel there is occurring what I think is some sort of
impedance
> mismatch that is causing high and very inconsistent SWR at VHF and above.
>
> My Suspicion:
> I think that the bulkhead connectors that are feeding through the panels
> (probably the 8" ones?) are not a consistent 50 Ohms throughout and are
> causing enough of a "bump" in the system impedance to cause bad SWR
readings
> on 2m and 70cm. The 4" (UG-363/4INCH) and 8" (UG-363/8INCH) bulkheads were
> purchased through The RF Connection: http://www.therfc.com/uhf.htm
>
> Maybe Not The Coax?:
> The coax that connects them is 9913 equivalent (JSC Wire and Cable Type
> #3500) from a local CB shop. It is not exactly Belden or Times, but I have
a
> lot of experience with coax and connectors and the stuff "looked and felt"
> quite good. (In high school, I worked in a local CB/HAM shop and installed
> HUNDREDS of PL-259 connectors on countless types of coaxial cable. I
> developed a pretty good sense of what good cable and good connectors were
> all about. The connectors are all Amphenol with Teflon.)
>
> Eh? Ideas? Suggestions?
>
> Thanks for reading ... Happy New Year
>
> Don Chisholm K8BB
> Pontiac, MI
>
>
>
>
>
>
> _______________________________________________
> VHFcontesting mailing list
> VHFcontesting@contesting.com
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>
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