I wonder if anyone using or recommending products like this have ever
measured them. They are not easy to measure. You can't measure them
accurately with a single-port antenna analyzer.
N6KT, a member of our contest club is building a station in the
Caribbean and asked me to measure a Balun Designs 1115T common mode
choke (often called a 1:1 current balun). It looks NOTHING like it's
data sheet, which shows an approximately flat high choking impedance
over the HF bands. It would be USELESS on 40, 80, and 160M! From what
I've seen them write about chokes, I don't believe that they understand
how common mode chokes work, and I certainly wouldn't suggest that
someone ask them for advice.
The Wireman 8232 is based on W2DU's excellent work from many years ago.
He built chokes with 50, 100, and 200 of the largest #73 Fair-Rite beads
that fit over RG142. This size bead of this material has the unique
property of relatively constant choking impedance in the HF spectrum,
but you have to a LOT of them. Only the 200-bead choke has sufficient
choking impedance to handle high power and kill receive noise, and
that's what he recommended, yet most products sold as a "W2DU balun"
have many fewer. The larger #31 cores are not useful at HF until you
wind multiple turns through them, but are often sold for use as a string
of beads on coax.
How many beads are in the 8232? Are they Fair-Rite #73?
73, Jim K9YC
On 12/9/2018 5:33 AM, Bob McGraw K4TAX wrote:
Balun Designs, both 1:1 and 4:1 for use with tuners. I have both because I
also have a folded dipole that I feed direct.
I suggest you give the folks at Balun Designs a call and discuss your exact
needs. Take their advice.
Also see the DJ0IP site for details on baluns. Just Google DJ0IP.
And I use the 8232 common mode choke from The Wireman.
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