AFAIK, the answer in this case (choke or xfmr) is:
none of the above.
Only an autotransformer (or a transformer connected
as an autotransformer) could possibly work, utilizing
the coax shield as a counterpoise. Unless there is a
separate counterpoise connection point, which is not
evident in the description.
BTW, I use #61 ferrite cores in my 50 ohm to 450 ohm
transformers. However, if I was going to go from 50
ohms to 1000's of ohms, #67 or even #68 would probably
be necessary at legal limit power. The EFHW of 35
years ago that I posted about did not use a transformer,
just an LC network.
Rick N6RK
On 9/30/2020 10:36 AM, Jim Brown wrote:
On 9/30/2020 9:00 AM, Jim Thomson wrote:
## Danny Horvat is beyond a smart cookie. How many CM chokes do
you see that cover 160-10m,
with 8-12 K of RS..and RS > XS ? No Z bumps either.
Ingenious staggered core design. And no,
you wont blow em up with 4 kw.
The obvious question is, "is the winding on the ferrite core a choke or
a transformer?" Their behavior is VERY different. That it's being used
at a hi-Z feedpoint suggests the latter. N6RK, also a very smart
engineer, has used Fair-Rite #67 for high power transformers.
NA6O, another very sharp engineer who has done some serious lab work of
chokes inside enclosures, emailed me directly questioning the
dissipation issues with practical windings on Fair-Rite #61 and #54.
73, Jim K9YC
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