Topband: Updated K9YC common-mode choke PDF now available

[Guy Olinger K2AV]

I would not repeatedly bend any coax with a solid center conductor. Which
leaves RG142 for permanent routing. Jumpers to and from back of TXR and
amps etc are always RG400. Windings on cores are always RG400. RG400 shield
weave and center conductor made of very fine strands of silver coated
copper.

On K9YC’s latest cookbook he only specifies RG400. Do it right, do it once,
happily keep it.

RG400 can usually be had in useful lengths off EBay for half retail or
better.  The stuff almost never goes bad. So these are safe buys.

There are a lot of jumpers listed. I can sometimes get the stuff with a
needed connector already installed.

73, Guy K2AV

On Wed, Jan 23, 2019 at 8:07 AM MU 4CX250B <4cx250b at miamioh.edu> wrote:

> Very interesting, Jim. I wasn't familiar with RG-400, but I've used
> RG-142B for years. I compared the specs and found they're virtually
> identical, the only significant difference being that RG-400 has a
> stranded center conductor, while RG-142B has a solid steel
> (silver-plated) center conductor. They both have a 1 inch minimum
> bending radius (for repeated bending), but I imagine the RG-400 Is
> slightly more flexible and the RG142B is slightly stronger. At GHz
> frequencies, the RG142B has slightly lower loss. They both have
> excellent high temperature properties. If you buy it new from a
> distributor, either will cost about $5 a foot.
> 73,
> Jim w8zr
>
> Sent from my iPad
>
> > On Jan 22, 2019, at 6:42 PM, Mike Waters <mikewate at gmail.com> wrote:
> >
> > ---------- Forwarded message ---------
> > From: Jim Brown <jim at audiosystemsgroup.com>
> > Date: Mon, Jan 21, 2019, 11:36 PM
> > Subject: Re: Topband: Inverted L improvements - Part 3 (now with data)
> > To: Mike Waters <mikewate at gmail.com>
> >
> > After nearly a year of work, I published a new "cookbook" last month.
> > For reasons that are detailed in the accompanying text, I no longer
> > recommend coax wound through multiple cores.
> >
> > The short answer for "why not?" is that it's simply not practical to wind
> > chokes that way and get anything close to the same result every time --
> > turns must go through the core in the same order, a scrambled turn
> cancels
> > a turn, turn diameter matters a lot, and so on.
> >
> > The new cookbook uses RG400, 12-2 Teflon/silver pairs, or 12/2 THHN or NM
> > pairs, all tightly wound around a single core.  There are recommendations
> > for chokes in series to increase power handling. There is also data for
> the
> > new 4-in o.d. supersized toroids, which are great for 160M.
> > k9yc.com/2018Cookbook.pdf
> >
> > 73, Jim K9YC
> > _________________
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