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[Fwd: TC help]

Original poster: Edward Wingate <ewing7-at-rochester.rr-dot-com> 


After repeated attempts to answer this off list e-mail and getting
bounced by (Grummans?) mail server, I am forwarding it to the TML and
hope Terry will post it.

Ed Wingate RATCB

-------- Original Message --------
Subject: TC help
Date: Fri, 18 Jun 2004 12:45:04 -0400

-------- Original Message --------
Subject: Re: Arc'ing in my variac
Date: Fri, 18 Jun 2004 12:43:01 -0400
References: <>

Pat Masterson wrote:

 > >Ed Wingate RATCB
 > >
 >   Ed, I agree fully. I was just starting to tune a new configuration and
 > noticed (luckily) the little sparks dancing around the variac windings.
 > of course I turned the power off right then. I would never operate the
 > variac in that mode. My problem is how to proceed from here. I need to
 > get the coil tuned. Should I put a 3-wire AC line on the variac and
 > ground its fram to the ground wire? Should I also need some RF chokes
 > in the AC line from the NST? Thanks Ed.  -pat


I use EMI filters between my power cabinets and line. I never really had
a need to use them between the transformer and power cabinet. I do use a
filter between my rotaries and the speed control Variac because there is
a bridge rectifier in the circuit to run the rotary on DC. Bridge
rectifiers don't tolerate transient spikes well!

I'm not sure I would ground the frame of the Variac at this point. That
might increase the chances of damaging it. You should be able to run the
system at a power level below that which causes the Variac arcing and
tune for best output, then increase power in increments until you're
tuned for best output at full power. That's how I always do it. If the
coil is tuned for best output at full power, all the arcing on the
Variac and other bad behavior the coil might be exhibiting should stop.


Ed Wingate RATCB

 > *  Pat Masterson  V01-01,  Northrop Grumman,     *  Ham:KE2LJ
 > *  1 Grumman Road West                           *  President Grumman 
 > *  Bethpage, NY 11714                            *  Radio Club  WA2LQO
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