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
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
Message-
From: kc9...@aol.com
Sent: Dec 22, 2011 11:49 AM
To: w1es1...@earthlink.net, k4...@mindspring.com
Cc: Drakelist@zerobeat.net
Subject: Re: [Drakelist] AC-4R Surprise
Does the glass envelope actually break?
73,
Lee
-Original Message-
From: Steve Wedge w1es1...@earthlink.net
All,
Well my luck or lack thereof continues... I pulled the 6HS6 and then
referenced my Eico 625. Of course the 6HS6 isn't mentioned anywhere in any of
the charts I have. So, based on some results of a search, tested it as a 6AU6
and then a 6HR6. Former showed good, latter showed marginal,
I still believe that R61 and the AC-4 were both victims of the same failure.
And I still would not trust that 6HS6. Did you recheck the resistances with the
6HS6 removed?
73,
Bob WW3QB
All,
Well my luck or lack thereof continues... I pulled the 6HS6 and
, and I remember seeing
4200 from typical new ones).
Good luck.
Steve, W1ES/4
-Original Message-
From: rhule...@comcast.net
Sent: Dec 22, 2011 1:33 PM
To: Steve Wedge w1es1...@earthlink.net
Cc: Drakelist@zerobeat.net, kc9...@aol.com, k4...@mindspring.com
Subject: Re: [Drakelist] AC-4R
, and I remember seeing
4200 from typical new ones).
Good luck.
Steve, W1ES/4
-Original Message-
From: rhule...@comcast.net
Sent: Dec 22, 2011 1:33 PM
To: Steve Wedge w1es1...@earthlink.net
Cc: Drakelist@zerobeat.net, kc9...@aol.com, k4...@mindspring.com
Subject: Re: [Drakelist] AC-4R
...@comcast.net
Sent: Dec 22, 2011 1:33 PM
To: Steve Wedgew1es1...@earthlink.net
Cc: Drakelist@zerobeat.net, kc9...@aol.com, k4...@mindspring.com
Subject: Re: [Drakelist] AC-4R Surprise
All,
Well my luck or lack thereof continues... I pulled the 6HS6 and then referenced my Eico 625. Of course
the 6HS6
I've checked all of the tubes with my old emission tester, all test good
except for the OA2 which lights up but tests bad. Not sure how valid that is.
And with V8 removed, the resistance at pin 6 is still 15k rather than 90k per
the manual. I'm in process of resistance checking the rest of the
: [Drakelist] AC-4R Surprise
Steve -
The resistor in question is a 150 ohm decoupling resistor, not a plate
load resistor. It's not all that unusual for the low value carbon comps
to fail shorted. Enough current to melt the binder into a lump of coal
('tis the Season) rather than enough to just
Curt -
The 0A2 is always difficult to test, as most inexpensive testers don't have enough high voltage DC
to fire. As I said earlier, I think you have a problem with your Pin 6 of V8 resistance
measurement. There is a 6.8k and 6k resistor in series between that pin and the +250 bus.
Hello Gary,
Yes, that is what I've concluded too though haven't confirmed with measurements
yet. I know at one time you repaired Drake equipment (maybe you still do), so
would appreciate any words of wisdom about finding and correcting a short in
the B+. Nothing obvious on visible
: Dec 21, 2011 8:17 AM
To: Gary Poland gpola...@cinci.rr.com
Cc: Drakelist@zerobeat.net
Subject: Re: [Drakelist] AC-4R Surprise
Hello Gary,
Yes, that is what I've concluded too though haven't confirmed with
measurements yet. I know at one time you repaired Drake equipment (maybe you
still do
are blessings: they generally stay around until you find them!
73,
Steve, W1ES/4
-Original Message-
From: rhule...@comcast.net
Sent: Dec 21, 2011 8:17 AM
To: Gary Poland gpola...@cinci.rr.com
Cc: Drakelist@zerobeat.net
Subject: Re: [Drakelist] AC-4R Surprise
Hello Gary,
Yes, that is what I've
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
It's interesting that the pin 6 resistance to ground is so low since it passes
through a 82K resistor. Do the values change if you remove V8? I sense a tube
short.
73,
Bob WW3QB
Well, my nose detected burnt smell in vicinity of T4. R61, a 150ohm 1/2
: 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
Curt -
If this is a 'new' transmitter to you, the most likely cause of a crispy R61 is that someone shorted
one of the trimmer caps in the PreSelector plate circuit to the chassis. Easy to do, especially
when guys use a metal screwdriver to adjust those trimmers through those little holes.
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
My T-4X quit working today, the 250V supply was gone. Filament, bias, and 650V
supply normal. On investigating the AC-4R board in the AC-4, found two
parallel 5W 200ohm metal oxide resistors in the 250V supply circuit OPEN.
Suspected a shorted capacitor, but the cap is not shorted. Anyone
A short in the B+ line within the T-4X will open the resistors. It used to
happen a lot when people would change the blue filter in S meter of TR-4’s and
pinch the wires reassembling the metal cover on the S meter. Look for a short
in your T-4X.
73, Gary
http://home.roadrunner.com/~w8pu
R-4A
20, 2011 8:25 pm
Subject: [Drakelist] AC-4R Surprise
My T-4X quit working today, the 250V supply was gone. Filament, bias,
and 650V
supply normal. On investigating the AC-4R board in the AC-4, found two
parallel
5W 200ohm metal oxide resistors in the 250V supply circuit OPEN.
Suspected
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