[Amps] Why always one parasitic suppressor per tube?

[Mike Waters]

>From the off-list responses, I get the impression that the common practice
of using one parasitic suppressor per tube is just "habit", that is, "But,
we've ALWAYS done it that way!".  This is regardless of how well the
components are laid out for minimum lead inductance, etc.

I suppose commercial amplifier manufacturers do it because there would be
no end of negative press if they left even one parasitic suppressor out.

Earlier handbooks, etc, show plenty of amps with different tubes with no
parasitic suppressor at all, and that's what I'm going to try. The pi-net
tuning cap is very close the the anode connections (there's almost no room
for parasitic chokes) and all the leads are 1/2" wide copper strap. If we
get a VHF parasitic oscillation, then I'll start with just one for both
tubes.

73, Mike
www.w0btu.com

From: "Carl" <km1h at jeremy.mv.com>

> To: "Mike Waters" <mikewate at gmail.com>, <amps at contesting.com>
> Date: Tue, 19 Feb 2013 21:58:07 -0500
> Subject: Re: [Amps] Why always one parasitic suppressor per tube?
>
> Ive done it a few times using 2 suppressors in a 4 tube amp where each
> tube was contributing 100-300W and it seemed fine even on 10M. The tubes
> were GG 1625's and 813's.
>
> OTOH a L-Pi had to be used for 10M and I dont know if it was just due to
> the tubes output C or the presence of the configuration creating its own
> problems plus the tubes C.
>
> Carl
> KM1H
> ----- Original Message ----- From: "Mike Waters" <mikewate at gmail.com>
> To: <amps at contesting.com>
> Sent: Friday, February 15, 2013 7:28 PM
> Subject: [Amps] Why always one parasitic suppressor per tube?
>
>
>  I'm layout out a 160m legal limit AB1 amplifier design using two parallel
>> 833-C tubes, and a thought occurred to me: Why are two parasitic
>> suppressors always needed (one for each tube)?
>>
>> Of course, it's not like the cost for an extra suppressor is going to
>> matter. It would just be easier in this application to use just one. (long
>> story).
>>
>> 73, Mike
>> www.w0btu.com
>>
>