[Amps] SB-220 and Xfrmr Smoke...Part 4

[Jim W7RY]

I think you have an intermittently shorted tube. This is why your old 
filament transformer smoked.  There is a reason for re-wiring the antenna 
relay to keep from burning up the filament transformer. Details are on Rich 
Measures site. (I know I know....)

If a tube shorts, it also shorts out the filament transformer. I don't 
remember the exact current flow but Rich explains it.


73
Jim W7RY

----- Original Message ----- 
From: "Jeff Carter" <amps at hidden-valley.com>
To: <amps at contesting.com>
Sent: Wednesday, February 04, 2009 8:51 PM
Subject: [Amps] SB-220 and Xfrmr Smoke...Part 4


> Okay, the replacement transformer is installed, and life is
> good...except I'm beginning to think this amp is haunted.
>
> All voltages were checked and are present.  Never again when working
> on an amp will I assume that just because somebody sold me something
> that it's good.  I should have known better.
>
> The haunted part:  At odd intervals, the meter needles will *twitch*.
> The plate current, which is sitting on zero, twitches up to maybe 50
> milliamps, the HV needles twitches down a few volts, and then, as
> quickly as it started, everything goes back to normal.
>
> What's going on with this?  Do I have another problem to find?
> Nothing's hot, nothing's smoking like before, this just seems odd
> behavior to me with no drive or anything.
>
> Has anybody seen this problem?  Or is it just a normal thing when
> everything is new like this, with things settling in?
>
> Thanks again,
> Jeff/KD4RBG
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>


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