[ARC5] An "Extra Class" Question:

[Geoff]

Yep, they do go bang when run outside their narrow optimum window. When in 
doubt read the spec sheets and do the calculations.

Carl

----- Original Message ----- 
From: <wb3fau55 at neo.rr.com>
To: "David Stinson" <arc5 at ix.netcom.com>; "ARC-5 List" 
<arc5 at mailman.qth.net>
Sent: Saturday, February 09, 2013 5:37 PM
Subject: Re: [ARC5] An "Extra Class" Question:


> oh yea, real cool. MOVs have a  tendancy to explode in applications 
> involving
> high excursions in voltage.  Have fun,  enjoy the smoke...



> ---- David Stinson <arc5 at ix.netcom.com> wrote:
>> I have really messed this thread up!
>> You got it exactly right, Mike.
>>
>> Sorry, guys.  I was intending to get fresh insights on
>> a problem, so was intentionally vague, but that didn't
>> work-out so well.  Please let me explain.
>>
>> I meant "Extra Class Question" in the sense of it
>> being the sort of question one might see on the test,
>> not that it actually was.
>>
>> Here's the situation:  the AN/ARC-5 MD-7 modulator
>> has a G.E. "Thyristor" across the secondary which damps
>> modulation excursions over 300 V RMS.
>> I'm rebuilding an MD-7 for a friend which had a blown
>> mod. transformer.  It was blown because yet another
>> doofuss decided to whack it out of the modulator,
>> break off the mounts for it and doubtless try to modulate
>> his pair of  P-P 813s with it.
>> I've got the modulator restored and worked except that
>> the "Thyristor" and its mounts are missing.
>> It was dumb luck that I found a replacement
>> modulation transformer and finding another is unlikely,
>> should this one blow from not having the device installed.
>>
>> At the moment, I have two series-connect 200 V MOVs
>> across the secondary.
>> This is unsatisfactory because that's 400 Volts, not 300.
>> Are MOVs rated RMS or Peak anyways?
>> I probably knew 20 years ago.....
>> And can you series them?  Like a 200 and a 100?
>>
>> Whatcha think?
>>
>>
>>
>>
>>
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