"Bill Carpenter" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Power supply seems OK. Bias adjusts from -49 to -90 and voltages at 279 and
682. Both a little high but seem OK to me. Anything else I should check
before I try replacing the cathode resistors? Gotta wait to order some
anyway.
----- Original Message -----
From: "Garey Barrell" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, January 01, 2008 10:34 AM
Subject: Re: [drakelist] T4B Trouble
Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist
gang
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Yep, that's it. It's adjustable to set the idle current for the finals.
No bias voltage = full plate current!
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>
Bill Carpenter wrote:
"Bill Carpenter" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Thanks Gary, I'll look at the AC-4 though I replaced the electrolytics a
few years ago. Which pin is the bias measured on? It looks like pin 9
to me at -45 to -65 volts against pin 1 which is ground?
----- Original Message ----- From: "Garey Barrell" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, January 01, 2008 9:46 AM
Subject: Re: [drakelist] T4B Trouble
Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist
gang
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Bill -
Sounds like you lost the bias supply in the AC-4, electrolytics and/or
rectifiers. There has been some discussion of this over the last few
weeks on here.
The AC-4R kit from The Heathkit Shop is the best answer for AC-4's that
still have their original electrolytics.
You got lucky in that the cathode resistors opened! Carbon comp
resistors are pretty hard to find. Best replacement is the Ohmite OX
ceramic composition resistor available from Mouser and others.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B & C-Line Service Supplement CDs
<www.k4oah.com>
Bill Carpenter wrote:
"Bill Carpenter" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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I was enjoying SKN last night on 40M with my Bline but decided to
switch to my K2/100 to use a more effective NB against bad powerline
noise that has popped up here recently. I left the Bline on and was
happily CWing away when the Bline kind of "blinked" so I turned it off.
Later I found no output at all so suspecting finals I checked them and
yes they were bad. I put good ones in and still no output. There had
been no noise, smoke or burned sound so I had not looked under the
finals. I did that this morning and found R32 and R33 (1 watt 15 Ohm)
both burnt and testing very high or open. Obviously I need to replace
these but is there anything else I should check first to see what may
have caused this to happen?
Any help appreciated.
Happy New Year! 73
Bill
NZ0T
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