Hi Peter,
QSL.
Your method requires much higher (2X plate V plus margin) voltage ratings on
the vacuum caps plus a larger than typical blocking cap. The concentric coil
trick employs caps with "normal" ratings.
I just looked at the coil(s) you mentioned on E-Bay. Looks like as though
there were two of the Harris coils up last week. Studying the photos, it
appears that one of them may have had the magic wire removed. Those are a bit
on the large side for for my tastes! :-)
It didn't seem feasible to incorporate the "extra" wire into rotary coils
with mere 2KW proportions, which is why I'm using fixed coils with a bandswitch
in my project.
73 & Good morning,
Marv WC6W
-- "DF3KV" <df3kv@aol.com> wrote:
>Hi Marv,
>
>It was clear to me that I have the low impedance at the EHT feedpoint
>and the high impedance at the tube like with any other choke,
>therefore I wondered if I missed something.
>When I talk about the impedance of a choke I always mean the hot end,
>not the one
>where I feed it or decouple it to ground.
>I saw also a high power rotary coil by Harris on Ebay lately using
>exactly that solution with an inbedded wire, it was taken from a 20KW
>broadcast transmitter.
>When I build my high power linears I use two vacuum caps anyway, so my
>blocking capacitor is always at the 50 Ohm site of the Pi-L network
>with a very simple rf choke
>
>73
>Peter
*
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