From: Garey Barrell 
Subject: Re: [drakelist] AC-4 power supply diodes


Garey Barrell  made an utterence to the drakelist gang
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The 1N4007 is fine.  The B5G5 is a 600V {at} 1A diode.

It's hard to determine the quality of the filter caps without an ESR 
meter or scope.  If they are original, they will fail sooner rather 
than later.   Don't forget the bias supply filter.  This supply can 
actually cause more damage to the transmitter or power supply when 
it fails than the HV supply.

Axial lead and Twist-Lok filter caps are getting very hard to find, 
so the board at

http://www.theheathkitshop.com/drakeac4rreplace.html>

looks to be a very good alternative that should last another 30 years!

73, Garey - K4OAH


Eric Webner wrote:
> I am working on my T-4XC (again!). I thought I would check out the
power supply first, to make sure all voltages are good. They all measured
(with DVM) good DC voltage, with very little AC (except for the filament
supply, of course). Will such a measurement be accurate, or do I need a
scope to check for AC?
>  
> There have been some discussions about replacing the electrolytic
filter caps and possibly the rectifier diodes. I see no leakage around any
of the caps, and would hope to not have to hassle with it. The diodes would
be much easier to replace, and I would like to know if it is practical to
replace them while the unit is open, or should I "not fix what ain't
broke?" If replacement is warranted, is there a suitable replacement
or cross-reference for the B5G5 diodes? I'd like to use my 1N400x
rectifiers that I have in my junk box, if that is appropriate.
>  
> Thanks for all your help!
>  
> 73,
>  
> Eric
> KA8FAN
>  
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