[Lowfer] Common Mode Chokes (was Active Whips)

[Douglas D. Williams]

Regarding the Clifton Labs common mode choke plans, once I told Jack at
Clifton Labs that I was mainly interested in 8 kHz to 500 kHz reception and
was planning on building one of his common mode chokes he told me, and I
paraphrase, to glue five 40T1417-10H (Digi-Key part # 240-2537-ND) together
and to wrap as many turns of RG-174 through them as I could fit. This I did.

https://dl.dropbox.com/u/33457409/common%20mode%20choke.jpg

73, Doug KB4OER

On Thu, Jan 24, 2013 at 5:22 PM, pbunn <pbunn at matrixei.com> wrote:

> The website has the complete plans for the choke. He does not sell them.
> Google Clifton Labs .
>
> Pat
> N4LTA
>
> Laurence KL1 X <hellozerohellozero at hotmail.com> wrote:
>
>
> Wonder what type he uses- J's or maybe a lower mu (77's) a wide-band non
> res compromise?
>
> Sent and miss typed
> from my iPhone - waiting for a plane....
>
> On Jan 24, 2013, at 7:43 AM, "pbunn" <pbunn at matrixei.com> wrote:
>
> > Jack Smith has some very effective chokes on the Clifton Website that he
> recommend for use with active probes. They involve about 28 feet of RG174
> wound  on four cores in series. The cores are not cheap, if I remember
> correctly about $25 per set. The chokes are effective down to VLF
> frequencies. With them hooked to a probe that expects to see a feed line as
> an element (the PA0 design), they probably had a bad effect on performance.
> >
> > Pat
> >
> > -----Original Message-----
> > From: lowfer-bounces at mailman.qth.net [mailto:
> lowfer-bounces at mailman.qth.net] On Behalf Of Dexter McIntyre W4DEX
> > Sent: Thursday, January 24, 2013 10:29 AM
> > To: Discussion of the Lowfer (US, European, &amp; UK) and MedFer bands
> > Subject: Re: [Lowfer] Active Whips
> >
> > pbunn wrote:
> >> I built that antenna last year making a nice PCB board for it and using
> the PC Board as the antenna element and installed chokes. The antenna was a
> very poor performer and it biased me against active probes. The chokes
> probably made it a bad performer. My Clifton Labs probe antenna is mounted
> on a 8 foot mast in the water at the edge of a small pond 300 feet from any
> house or power line. The whip is extended about 6 feet. Maybe I should
> elevate it more?
> > Interesting comments about the RDT design.  I wish I had done more
> meaningful active antenna comparisons last fall while I was out in the open
> operating portable in the van.  It's way to cold for me to try that now but
> my interest has been renewed.  Many years ago when the only active antenna
> I had, a simple MPF-102 design, was that it performed much better mounted
> on top of the van than on a mast beside the van.
> > Even with the antenna elevated twenty feet the antenna gave much more
> signal on a mag mount right on top of the van.  This antenna was built in
> the coil base of an NMO VHF 5/8th wave mobile antenna and used the original
> approximate 36" whip.
> >
> > Dex
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