Rf parts house brand has a good warranty, have been told they ask no
questions you tell no lies if one goes south..
73's,
Gary...wa6fgi
----- Original Message -----
From: "Darryl Kwasny" <djkwasny@yahoo.com>
To: <amps@contesting.com>
Sent: Tuesday, October 16, 2007 8:11 AM
Subject: [Amps] SB-220 Still testing
> Well, I'm slowing overcoming my problems with the SB-220. I ran both tubes
> for several hours yesterday. With the plates disconnected. I then removed
> one tube and connected the plate. Fired it up and got about 100ma without
> drive. Tried driving it and the plate current would just drop to 0.
> Checked all the mods from Rich and everything looked good. So I sat around
> and pondered it for a while. I figured no ground to grid. Looked again and
> was disappointed to see that there was indeed a 30 ohm grid resister.
> Pondered some more and then checked the grid to ground. Nothing! I checked
> right across the resister and nothing! That resister was new and not
> smoked. It was a bad resister right out of the box. I suppose the warranty
> from Rich is long gone. :-)
>
> Anyway, replaced the resister this morning, popped one tube in and gave
> it some drive, drove it a little harder and it responded will. Drove it to
> about 250 to 300 watts out then shut it down.
>
> Took the tube out and put the other one in the other socket. Turned the
> amp on and it took out that grid resister. I suspected that tube might be
> bad because of the small bang a few years ago.
>
> Would everyone agree that the tube is belly up?
>
> I am going to look around for new Chinese tubes. Is any one manufacture
> any better than the others, if so which one. I am going to contact a guy
> that gets Pentas, are they one of the preferred brands?
> If not, which ones?
>
> Thanks, Darryl - K5WAS
>
>
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