The balun is an unusual design. It's a combo 22 to 50 ohm unun plus a
common mode choke. Most people say that won't work. However if you
look at what they did it almost makes sense. The unun part is tri-filar
wound which produces very little core flux. They only used about half
the core for this. So if it produces little core flux then it shouldn't
affect the other part of the core. So they took the the coax that hooks
to the unun and used the other part of the core to wind a choke. That
is the part that is questionable in my mind. The choke will produce
core flux. So shouldn't that couple back the the unun? Apparently this
arrangement works or so they claim. I just don't know how well it
works. I was hoping you had measured it.
Jerry, K4SAV
Richard (Rick) Karlquist wrote:
> K4SAV wrote:
>
>> N6RK wrote: "I spent a lot of time analyzing the balun in my MonstIR and
>> characterizing it on a network analyzer."
>>
>> I have always wondered how well that thing worked. They use half of the
>> core for a voltage balun and they use the other half for a choke by
>> winding a few turns of the coax thru it. What does your measurements
>> tell you about how well the common mode choke works?
>>
>> Jerry, K4SAV
>>
>
> I didn't measure it as a common mode choke because I thought it was
> a voltage balun. The fact that the coax is one of the windings
> does not necessarily indicate that it is a common mode choke.
>
> Rick N6RK
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