[ARC5] Use of a Variac

[Mike Feher]

Most of the reforming I did, I used my time. I would start at a low voltage at a comfortable current like about 5 ma and then wait and do something else. Come back to it and if the current went down I would increase the voltage for the same current, and so on. I kept it up till I reached rated voltage. Sometimes I gave it about 8 hours on average. If I was able to reach rated voltage, I never had a problem with that cap again. Most of these were WWII vintage. Resting current when done was a function of capacitance. 73 – Mike 

 

Mike B. Feher, N4FS

89 Arnold Blvd.

Howell NJ 07731

848-245-9115

 

From: arc5-bounces at mailman.qth.net <arc5-bounces at mailman.qth.net> On Behalf Of Mark K3MSB
Sent: Thursday, April 23, 2020 7:09 PM
To: Robert Nickels <W9RAN at oneradio.net>
Cc: ARC5 <arc5 at mailman.qth.net>
Subject: Re: [ARC5] Use of a Variac

 

Hi Bob

 

Very nice video.   To test capacitors I do pretty much the same thing with either my Heath capacitor tester or HV power supply and some meters.   You have nudged me to build a meter box like you did.

 

What I cringed at was you reformed a 30+ year old capacitor.  It worked for a few minutes.    What kind of longevity testing have you done?    Say after 100 to 200 hours at rated voltage?     

 

I still have to philosophically disagree with capacitor reforming.   I feel that the availability of new and inexpensive capacitors make reforming unnecessary,  and provides a more robust solution.    If I'm rebuilding a transmitter,  I would simply not feel good about putting in 30+ year old caps (reformed) when a short after hours of operation can take out something made of unobtainium.

 

Mark K3MSB.

 

 

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