[AMRadio] High Voltage Power Supplies


Ed Swynar gswynar at durham.net
Sun Oct 30 09:08:11 EST 2005


'Morning All,

I'm curious as to why I have to replace the silicon diode strings in my 2500 VDC power supply about every 8-10 years, or so...I just went through the exercise again early this morning --- turned on the B+ to my 2 x 813 linear, & got nothing back for my trouble but smoke from inside the enclosed p.s. unit...

Opened it up, & the resistor across the relay in my time delay circuit --- transformer primary side --- was fried. I checked the conductivity of both legs of my diode string (it's a full-wave set-up), & sure enough, one leg was A-OK, but the other displayed conductivity on BOTH sides of each diode...not good.

Is this the reult of transients / voltage spikes somehow "overwhelming" the diodes...? 

It used to be more frequent prior to the incorporation of the delay circuitry --- but, despite its presence, this HAS to be at least the second time that a re-build was in order.

Any thoughts re. a dose(s) of possible "preventative maintenance" for the future...? I'm at a loss as to anything else here that I might try...

Thanks in advance...

~73!~ Eddy VE3CUI - VE3XZ




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