Did the regulator have proper bypass in the first place or was this a problem
just waiting to pop out? Capacitor-to-regulator distance is critical. I've
never known a regulator go funny if it was properly set up in the first place.
As Pease would say "do what the manufacturer tells you or all bets are off."
David
G3UNA
>
> From: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
> Date: 2008/12/09 Tue AM 08:39:07 GMT
> To: amps@contesting.com
> Subject: Re: [Amps] Fwd: rx noise?
>
> David Robbins K1TTT wrote:
> >I think the noise in that one is solved... take a look at the scope pic
> >for a 12v regulator with a 2v p-p oscillation on it at:
> >http://wiki.k1ttt.net/2008%20Maintenance%20and%20Upgrade%20Blog.ashx?NoR
> >edir ect=1#Bottom That's one repaired, another one tested clean for
> >now, and 5 more to go.
> >
> Glad you found the problem, Dave. By coincidence(?) someone recently
> found a similar problem with a 78xx in a GaAsFET preamp that had been OK
> for years, but then decided to become unstable.
>
> Any thoughts about what changed to trigger the instability? (Aside from
> it being CQWW weekend, and the regulator having poor stability margins.)
>
>
> --
>
> 73 from Ian GM3SEK
> http://www.ifwtech.co.uk/g3sek
> _______________________________________________
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> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
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