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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