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@gmail.com> wrote:
>
> ---------- Forwarded message ---------
> From: Jim Brown <jim@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@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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