[Amps] More parasitic choke questions

[Carl]

----- Original Message ----- 
From: "Bill, W6WRT" <dezrat1242 at yahoo.com>
To: <amps at contesting.com>
Sent: Friday, July 30, 2010 11:27 PM
Subject: Re: [Amps] More parasitic choke questions


> ORIGINAL MESSAGE:
>
> On Fri, 30 Jul 2010 19:36:35 -0400, "Carl" <km1h at jeremy.mv.com> wrote:
>
>>
>>The coil must be self resonant at/near the parasitic frequency.
>
> REPLY:
>
> In all my years as a ham, this is the first time I have heard anyone
> say that a VHF parasitic suppressor coil MUST be self-resonant. Where
> did you get that from? Did you think of it yourself?
>
> Don't get me wrong - I'm not saying a self-resonant coil won't work,
> only that it isn't necessary. Just to be sure I hadn't missed
> something, I pulled out my 2010 ARRL handbook and re-read the section
> on VHF suppressors. Nowhere is self-resonance mentioned.
>
> Here is what the handbook has to say about the coil:  "Lz [the
> suppressor coil] should be just large enough to constitute a
> significant part of the total parasitic tank inductance (originally
> represented by LP), and located right at the tube plate terminal(s)."
>
> Note they say "...just large enough". No requirement for
> self-resonance or any particular inductance value.
>
> So I ask again, where did the idea that it MUST be self-resonant come
> from?
>
> 73, Bill W6WRT

So I ask again Bill, why dont you research the articles I mentioned 
yesterday? I would not take the current ARRL staff or their HB contributors 
as the final word on very much as they seem to just repeat the same stuff 
over and over. I prefer the research done by past generations when the 
competence level was much higher in the amplifier department.

Carl
KM1H