Adding the capacitance forces the the network to become a PI when the
L-network matches the
combined input impedance.
73
Bill wa4lav
At 11:11 AM 4/19/02 -0400, carl seyersdahl wrote:
>Gary and all: I have built a couple amps and repaired a few and modified the
>inputs on some and had good luck with the pi-net input ckts. my homebrew is
>4-811a's, and I've reworked some sb200's with no trouble, HOWEVER, I'm now
>working on a gla1000 and it's a nightmare. I haven't been able to get a. pi
>type ckt. to work but I discovered that a tee network will do it fairly
>well. Accidents do happen now and then. With EL509's the input capacity is
>ungodly High.along with the stray capacity it's in the the 110 pf area. I'm
>not the expert here I know , but I'll wait and see who else gets into this
>discussion!!!have a good day!!
> carl / kz5ca
>----- Original Message -----
>From: "wlfuqu00@uky.edu" <Wlfuqu00@uky.edu>
>To: "Gary Smith" <mandolinist@interlync.com>; <amps@contesting.com>
>Sent: Friday, April 19, 2002 10:19 AM
>Subject: Re: [Amps] Thinking about building an amp.
>
>
> >
> >
> > At 09:29 PM 4/18/02 -0500, Gary Smith wrote:
> > >I was thinking it might be nice to use one of the
> > >automatic tuners like the AT-11MP instead of making a fixed tuned
> > >input. Seems like the AT-11MP would find a nice match regardless
> > >of where I tuned.
> >
> > If you had a capacitor between cathode and ground who's capacitive
> > reactance is say 1/5 of the cathode resistance and if the AT-11MP
> > would match it then you should have your fly-wheel effect and a Q of at
> > least 5. However, this may require switching in a different capacitor for
> > each band.
> >
> > 73
> > Bill wa4lav
> >
> > _______________________________________________
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> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
>
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