[AMPS] Blown TL922A... What to do?

Dave, AA6YQ dhb@mediaone.net
Sun, 10 Sep 2000 17:49:24 -0400


> From: owner-amps@contesting.com [mailto:owner-amps@contesting.com]On
> Behalf Of measures
> Sent: Sunday, September 10, 2000 4:00 PM
> To: AMPS
> Subject: RE: [AMPS] Blown TL922A... What to do?

> >Clearly there are limits to the fidelity of software models. But if a
model
> >oscillates with a realistic set of parameters, then oscillation is a
> >practical reality. And if no set of reasonable parameters can be found to
> >support oscillation, then for practical purposes the circuit being
modeled
> >does not oscillate.
>
> Using such software, it was determined that the 8877 is likely to be able
> to oscillate above 100MHz.  In my opinion, corrective measures are
> indicated.

"is likely to be able to oscillate" is a subjective assessment; we seek
objective, repeatable proof. Either the model oscillates, or it doesn't.

> >Evaluating the effectiveness of suppressor circuits is a
> >similarly-objective excersize.
> >
> The intermittent nature of VHF parasites makes this difficult at best.

If the model oscillates, it will do so repeatably, permitting an objective
evaluation of suppressor techniques.

> >I suspect that neither combatant is truly interested in resolving the
> >underlying technical issue;
>
> €  not a good bet.
>

Fine. Publish a model that, with reasonable parameter values in a commercial
circuit simulator of your choice, repeatably oscillates.


    73,

        Dave, AA6YQ


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