[Heathkit] SB 1000

Mon, 23 Feb 2004 20:47:24 -0800

Assuming that the tubes are ok, I would suspect that there is a serious
problem with the plate current metering like possibly a bad shunt or ?
Fern

----- Original Message ----- 
From: "Mark S Graalman" <[email protected]>
To: <[email protected]>
Cc: <[email protected]>
Sent: Monday, February 23, 2004 2:50 PM
Subject: Re: [Heathkit] SB 1000

>   150 ma grid current for a single 3-500Z at 200 ma
> plate current sounds high to me, I wonder if your
> grid meter and / or plate meter is lying, or maybe
> you're loading too heavy. Does the same thing
> occur on all bands?
>  What's the value of the primary fuses? Is it
> wired for 120 or 240? I guess the point I'm wondering
> about is assuming you aren't loaded too heavy or have a problem
> in the output network is at 200 ma plate current the amp is
> at roughly 600 watts input. Add in 75 watts for the filament,
> another 15% or so for losses I would think the primary
> current on 220 would be about 3.5 to 4 amps and twice
> that if you're on 110. If the primary fuses are 10 or 20 amp
> units I can't help but think your meters are lying to you.
>
>
> On Mon, 23 Feb 2004 15:59:05 -0600 Charles W BWW Burkhardt
> <[email protected]> writes:
> > I should have made myself clearer. The normal operating current for
> > this 3-500z is about 400 ma in CW service. If I get anywhere near
> > this plate current-even 200 ma- I blow both fuses. The plates become
> > orange at 200 ma. and I've learned when to stop. The grid current
> > stays about normal, say 150 ma. Maybe this will clear things up .
> > Thanks, Charlie K0GPF
> >
>
>
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