What do you mean by "load and tune caps, 100 and 500 pf caps?? the tune
cap is about 250 pfs, and the load cap is a dual or triple cap of about 1000
pf or so max. something doesn't look right there.!!! Just wondering.!!!!
carl / kz5ca>The load and tune Caps (both the 100 pf and 500 pf caps)
test good. No
----- Original Message -----
From: "R.Measures" <r@somis.org>
To: <Ka7lpo@aol.com>; "AMPS" <amps@contesting.com>
Sent: Thursday, March 04, 2004 5:47 AM
Subject: Re: [Amps] SB-200 80 Meter Dilemma Update
>
>
> >Here is an update on my 80 meter dilemma on my SB-200. Originally, I
posted
> >that my SB-200 was working great on 40-10 meters but not good on 80. I
had a
> >high swr and any noticeable power output above 150-200 watts immediately
> >dissipated.
>
> ** This suggests that your drivermight be throttling back to protect
> itself.
> >
> >The load and tune Caps (both the 100 pf and 500 pf caps) test good. No
> >apparent damage to bandswitches. The Plate choke looks good.
> >
> >I inspected the tuned input C30 cap and added an additional 200 pf to the
> >470
> >pf mica cap. My swr on 80 meters is now much improved. I now have
noticeably
> >greater output power BUT the power still quickly dissipates or diminishes
> >while keyed down. It peaks then quickly drops.
> >
> ** strange
>
> >Are my grid-ground caps off both tubes suspect? I do have two well worn
> >tubes that show excessive heat damage. Can the 572B tube work great on
40-10
> but
> >become dysfunctional on 80?
>
> ** No.
> - I would try a Pi-network 80m tuned-input with a Q of 2. (Xc!=25-ohms)
>
> good luck, Don
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