Re: Level shifter inrush current

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "G by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bog-at-cinci.rr-dot-com>

Weazle,

I have not had any problem with blown diodes. Thanks to Steve's 
recent research on charging chokes, the diodes are getting even less 
of a beating.

I do have one question to throw out to the list: I keep losing MOTs 
to the magic smoke in the sky. The secondary wire just seems to burn 
apart. They are under oil and wired in the traditional series-opposed 
arrangement (cores wired together). Perhaps the poor transformer 
performance is why they are in the garbage in the first place? I have 
lost 5 this way. BTW- one mot secondary is epoxy potted and has yet 
to fail.

Good luck,
Gregory



>Hello Coilers,
>
>Are those of you who are running twin MOT level shifter type supplies
>having any problems with inrush current at switch on?  Checking in my
>ARRL Handbook and other technical manuals, I'm finding recommendation
>to use some resistors in series with the diode strings to limit large
>inrush currents from blowing the diodes.  However, the supplies shown
>have much larger filter caps than what we are using, and perhaps that
>and the winding resistance of the MOT secondaries is enough to act as
>built in limiting.  Comments, suggestions....
>
>73, Weazle, VE3EAR/VE3WZL
>
>Listening: 147.030+ and 442.075+
>E-mail:    weazle-at-hurontel.on.ca
>            or ve3ear-at-rac.ca
>Web site:  http://www.hurontel.on.ca/~weazle