Re: RE : [Amps] .82 ohm

[R.Measures <r@somis.org>]

On Dec 7, 2004, at 7:24 AM, kwasny wrote:

> ----- Original Message -----
> From: "R.Measures" <r@somis.org>
> To: "hermans" <on4kj@skynet.be>
> Cc: <amps@contesting.com>; "'kwasny'" <kwasny@netzero.net>
> Sent: Monday, December 06, 2004 3:30 PM
> Subject: Re: RE : [Amps] .82 ohm
>
> How would one determine if the grid current is being exceded?

 --  There is no max. grid-I rating on 3-500Zs or 3-400Zs.  The max. 
grid dissipation for a pair is 40w, however, provided that it isn't 
being driven beyond the max anode-I rating of 0.8A, if a g-g amplifier 
is tuned for max P-out, grid dissipation will always be reasonable.  
The reason for this is that diverting more electron flow to the grid 
requires detuning so that less than optimal power out results.  Thus, 
when P-out is max, one can relax.
-  The type of amplifier that requires a grid-I meter is: Class AB1 
grid-driven, not Class AB2 cathode-driven.

> I have no
> doubt that is was caused the problem with my SB-220 in the first 
> place. I
> inadvertently drove it at full output from my exciter (110 to 120 
> watts).
> That is when the trouble started.

Whenever I tune my SB-220 or TL-922,, I fully drive it to 0.8A because 
I know that if I drive it to less anode current,  RL will decrease and 
I will have a mistune when I drive it to full PEP.
> Darryl - K5WAS
>
>
> The safest thing to put in place of a kaput grid-current meter shunt
> (R3) is a jumper wire since the meter can not could not be damaged by
> another anomaly, and grid-current metering is of no value - either
> during tune-up or operation.
>
> On Dec 6, 2004, at 12:03 PM, hermans wrote:
>
> > What about putting 4 x 330E (0.6 W) in //?
> >
> > Jos on4kj
> >
> > -----Message d'origine-----
> > De : amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
> > De
> > la part de kwasny
> > Envoyé : lundi 6 décembre 2004 16:03
> > À : amps@contesting.com
> > Objet : [Amps] .82 ohm
> >
> > I have been working on my SB-220 which had a parasitic oscillation. I
> > have installed the parasitic oscillation kit but stilll have not been
> > able to find a 2 watt .82 ohm resister which blew. Where can I get 
> > that
> > resister? I live in the Ft Myers area and we have absolutely NO
> > electronic part stores here. The closeist one is in Sarasota which is
> > 60
> > miles away. I would like to get a few of thest resisters by mail if
> > possible.
> >
> > Thanks, Darryl - K5WAS
>
> Richard L. Measures, AG6K, 805.386.3734.  www.somis.org
>
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Richard L. Measures, AG6K, 805.386.3734.  www.somis.org

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