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Re: CP phasing harness: Coax Substitution?



Steve,

   Yes, you can substitute.  Just be sure to watch your velocity factor so
you get the right length.  I have made them with RG-11, RG-6 and RG-59 and
they all worked.  I have used RG-62 successfully for 100 Ohm needs as well.

73,
Joe


----- Original Message ----- 
From: "Steve Egert" <segert@adelphia.net>
To: "Amsat-bb" <amsat-bb@amsat.org>
Sent: Sunday, January 30, 2005 12:16 PM
Subject: [amsat-bb] CP phasing harness: Coax Substitution?


> I'm building a phasing harness for a 435 MHz cross-yagi antenna.  The
plans
> call out RG-11 for the odd quarter-wave sections that connect the antennas
> to "N-type" tees back at the coxial relay.
>
> RG-11 has proven a little tough to find.  Would RG-59 of the same
impedance,
> same velocity factor, and same capacitance per foot as the RG-11, be an
> acceptable substitute?
>
> I have the same issue with the RG-133 that connects the back sides of the
> tees together.  I've found some RG-62 that seems to be identical except
for
> the velocity factor and the capacitance per foot.  The length for this
part
> of the phasing section can easily be scaled given the velocity factor of
the
> coax, but the capacitance between RG-133 and RG-62 differs by 2.5 pF per
> foot.
>
> Are there some other characteristics that should be taken into account
when
> making substitutions like these?  I realize that there may be differences
in
> loss at that frequency, but the runs will be very short.  Your thoughts,
> please.
>
> Thanks,
> Steve -- K6UX
> ----
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