SORRY, but the min static bending radius for RG-303 is 25 mm and RG-400 is 35
mm. For torroid wrap which is better?????
Mel, K6KBE
From: Chuck Catledge <ae...@att.net>
To: 'Guy Olinger K2AV' <k2av....@gmail.com>; 'Robert Nobis' <n7...@nobis.net>
Cc: elecraft@mailman.qth.net; 'Ron D'Eau Claire' <r...@cobi.biz>
Sent: Sunday, February 7, 2016 2:31 PM
Subject: Re: [Elecraft] Balun Questions
At hamfests around the Southeast, surplus RG400 is often found in terminated
cables (usually BNC or N) in lengths up to around 20 feet. The price I've paid
is always less than $1.00 per foot, sometimes much less. I've used it to make
dozens of RF chokes (1:1 baluns). The small size of RG400 allows the use of a
single medium to large clamp-on #31 ferrite that works effectively from
10-160M, conditioned by the number of turns. The large snap-on ferrite will
accommodate 10-12 turns; the medium snap-on will handle 5-6 turns. Jim, K9YC's
tutorials are excellent. Consult the Fair-Rite website for additional
technical data.
BTW, the Teflon dielectric allows easy soldering in PL-259s with RG-58 reducers
without any fear of melting the dielectric.
---
Chuck, AE4CW
-----Original Message-----
From: Guy Olinger K2AV [mailto:k2av....@gmail.com]
Sent: Sunday, February 07, 2016 01:08
To: Robert Nobis <n7...@nobis.net>
Cc: elecraft@mailman.qth.net; Ron D'Eau Claire <r...@cobi.biz>; Guy Olinger
K2AV <k2av....@gmail.com>
Subject: Re: [Elecraft] Balun Questions
RG303 is not rated for the tight bends. RG400 with its fine stranded center
conductor is rated for corner bends in aircraft wiring harnesses and will not
deform the dielectric within the bends. I would not wind any solid center
conductor coax on a toroid.
I would only buy cut lengths of RG400 after the lengths for a project are
known. Some number of such suppliers on eBay. One currently listed at 1.98 per
foot:
http://www.ebay.com/itm/RG400-Coaxial-Cable-Mil-spec-by-the-ft-US-supplier-/251260159394?hash=item3a8045c5a2:g:WpAAAOxy43FRafUe
True it ain't ham cheep. The good stuff that lasts and lasts almost never is.
Back in the early days of eBay I came by a 142' length of RG400 for $25. That's
$0.178 a foot I also came by bundles of miscellaneous 6 foot to 15 foot
jumpers with various connectors on end for similar ridiculous low prices per
foot.
The silvered copper strands stand up to migration of dampness in a way not
possible with same size copper strands minus the silvering. I have
*measured* the dry RF resistance at 1.83 MHz of a 67 foot length of corroded
#14 stranded plain copper at 62 ohms. When new this wire had resistance at RF
of less than an ohm. I have never found the silvered copper equivalent in
anything remotely approaching that degraded state.
RG400 wound on the proper core for the job will last a lifetime.
73, Guy K2AV
On Saturday, February 6, 2016, Robert Nobis <n7...@nobis.net> wrote:
> I have used RG303/U for chokes. A bit smaller diameter than RG400
> (0.170 versus 0.195 inches). RG303/U has a solid copper center
> conductor that is silver plated. The shield for RG303 is also silver
> plated copper. The jacket is Class 9 Teflon. Also the dielectric material is
> teflon.
>
> 73,
>
>
> Bob Nobis - N7RJN
> n7...@nobis.net
>
>
> > On Feb 6, 2016, at 17:49, Guy Olinger K2AV <k2av....@gmail.com> wrote:
> >
> > If one wants a small 50 ohm coax that will take QRO with a very
> > large margin and was *designed* for bending and use in aircraft
> > wiring
> harnesses
> > then use RG400 to wind around your core. RG400 uses a fine stranded
> > silvered copper center conductor that is more flexible than its
> > Teflon dielectric. It has a double shield made from silvered copper strands.
> >
>
>
>
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