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THE AM BULLETIN BOARD => Technical Forum => Topic started by: W3SLK on February 17, 2007, 06:17:16 PM



Title: A Capacitance Question
Post by: W3SLK on February 17, 2007, 06:17:16 PM
I'm in  the process of rebuilding an HRO-50T. The electrolytic was shot so I went searching for a new one. I went down to my local parts jobber, (Moyer Electronics), and the closest thing Bill had was a 50 MFD/50 MFD @ 450VDC Photo Flash Mallory capacitor. I know the duty cycle of a photo flash vs. a standard electrolytic are different. The question is: Do I have any thing to fear by utilizing this cap? The highest voltage I can see being developed is about 270 VDC. I would like to know before I go through the trouble of installing it. TNX


Title: Re: A Capacitance Question
Post by: WBear2GCR on February 19, 2007, 09:31:24 PM
My understanding is that Photoflash caps are NG for high ripple currents.
They like being discharged though.
Makes them good after the ripple has been smoothed.

Best bet is the little caps they use for HV switching supplies... you can find some in those computer monitors that no one seems to think the parts are of any use but me...  ;)

Plus they are small... often found in the guts of computer power supplies too... and at hamfests...  ;D

        _-_-bear


Title: Re: A Capacitance Question
Post by: N2udf on February 20, 2007, 10:46:36 AM
Antique Electronics has a 50/50 500v cap that I have used(works great)....Lee,N2UDF


Title: Re: A Capacitance Question
Post by: k4kyv on February 21, 2007, 03:59:54 PM
I purchased an exact replacement for the multi-section electrolytic in one of my 75A4's from Antique Electronic Supply, or from Mouser (forget which).  It was identical in every respect to the original, except that the test and working voltages were about 100 volts higher.  If I recall, it was a Mallory, but under a different brand name.  The well-known original manufacturer apparently discontinued the line or went out of business, but a new company claimed that they took over the entire product line and still makes them.


Title: Re: A Capacitance Question
Post by: Rob K2CU on February 23, 2007, 09:29:07 AM
If the caps are not shorted or too leaky, just buy 47 or 56 uF  350 V or higher, radial lead caps from Digikey and solder them to existing terminals.

Some people have puled the guts out of old twistlock caps and replaced insides with individual caps.
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