Does the glass envelope actually break?
73,
Lee
-----Original Message-----
From: Steve Wedge <w1es1...@earthlink.net>
To: k4oah <k4...@mindspring.com>
Cc: Drakelist <Drakelist@zerobeat.net>
Sent: Thu, Dec 22, 2011 8:42 am
Subject: Re: [Drakelist] AC-4R Surprise
True.
I've seen 3-500Z's die that way, too, but that failure is usually a lot
more
exciting! You won't find a short with the ohmmeter, but you'll get a
nice bang
when you put the 3kV to the plate :)
Steve, W1ES/4
-----Original Message-----
From: Garey Barrell <k4...@mindspring.com>
Sent: Dec 21, 2011 10:11 PM
To: Steve Wedge <w1es1...@earthlink.net>
Cc: Drakelist@zerobeat.net
Subject: Re: [Drakelist] AC-4R Surprise
Steve -
Extremely high gain tubes mean extremely closely spaced grids! :-)
--
73, Garey - K4OAH
St Charles, IL
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Steve Wedge wrote:
If you can find a tube tester, test it. I find that 6HS6's get
shorts more
than most other
tubes. They won't show up until you light the filament. My
TV-10-D/U puts
line voltage on the
pins to check for shorts (to light a neon bulb), so you wouldn't
necessarily
see a short with no
power to it. Not sure why I see so many: if it's something in the
design or
just because many
people when they find these tubes are on the way out try to milk
them for as
long as they can
because they're so expensive.
From: <rhule...@comcast.net>
Sent: Wednesday, December 21, 2011 8:54 PM
To: <Drakelist@zerobeat.net>
Cc: <Drakelist@zerobeat.net>
Subject: Re: [Drakelist] AC-4R Surprise
Well, my nose detected burnt smell in vicinity of T4. R61, a
150ohm 1/2
resistor in the 250 volt
line to V8's plate is burnt to a crisp, resistance is zero. But
why?
Resistance to ground on V8
pin 5 is 15k per spec. But pin 6 screen grid resistance to ground
it 15k,
vs 90k spec.
Any advice? 73, Curt KB5JO
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