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Re: [RFI] tips on building common mode chokes

To: K7WXW@qrpdx.org
Subject: Re: [RFI] tips on building common mode chokes
From: David Eckhardt <davearea51a@gmail.com>
Date: Wed, 31 Oct 2018 23:50:50 +0000
List-post: <mailto:rfi@contesting.com>
Yes, hold off a bit.  I have CM chokes on both the input and output of my
twin-T matching network which I use with open wire feeders for my 450-foot
long doublet.  I have HF VNA data on both of them.  I used 43 material for
both, #14 stranded super 'flex' from Davis RF, wound quadfilar and
ultimately connected bi-filar to reduce losses and personify a lower
equivalent Z of the transmission line section on the toroids.  Tomorrow,
I'll try and locate my measured data somewhere on the hard drive.

Dave - WØLEV

On Wed, Oct 31, 2018 at 7:01 PM bill K7WXW <K7WXW@qrpdx.org> wrote:

> I am building a set of feed line common mode chokes to test in my shack,
> using K9YC's published test data and charts (mahalo, Jim!).  Since the
> chokes will be inserted into existing feed lines, each choke, wound on a
> type 43 or 31 2.4 inch toroid, will be terminated with SO239 and PL259
> connectors.  I run 200W maximum though my normal operating power is less
> than twenty.
>
> The bifilar chokes use #14 or #12 THHN wire. I can install a PL259
> solder connector designed for LM400 pretty easily on either but the
> SO239 side of things is giving me fits. I just can't figure out how to
> nake a solid solder connection with wire this size and the standard
> SO239, whether in bulkhead or panel mount form.  Is there some version
> of the connector I just haven't managed to locate? Some trick to getting
> big wire in a small hole? I've been staring at photos of other people's
> chokes for a couple of days and haven't figured it out.
>
> I will also be making coax versions with both toroids and the clamp on
> ferrites though I am inclined to the bifilar versions based on Jim's
> data. The idea is to compare them all side by side in operation and see
> which work the best in my situation. I'd also test them on a vector
> analyzer if I had one, but alas I don't.
>
> Thanks in advance!  73 de bill K7WXW
>
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-- 

*Dave - WØLEV*
*Just Let Darwin Work*
*Just Think*
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