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[AMPS] TL-922 Filament Transformer Protection

To: <amps@contesting.com>
Subject: [AMPS] TL-922 Filament Transformer Protection
From: measures@vc.net (Rich Measures)
Date: Mon, 7 Jun 1999 08:51:17 -0700


>
>Hi Jon,
>
.......
>> I disagree, Tom.  While some parasitic oscillations in amplifiers are well
>> behaved, some are not.  In my 4-1000A, for the longest time while building
>> it I had a slight oscillation that I could produce every time I brought
>> the tune C to minimum.  No bangs, arcs, etc.  
>
>Same in amps here. When I make them oscillate, they generate 
>trash and draw current. No bangs, no arcs, no bent tubes, etc.
> 
>> However, at one point I was dealing with a cavity resonance.  The amp was
>> stable w/o the cover.  Once I put the cover on, I got a big bang and it
>> wasn't from any gassing.  However, these sort of events are typically due
>> to some other problem such as a bad layout (the orignal problem in my amp)
>> or some other failure.  I would venture in a "normally" working amp that
>> big bang parasitics don't occur.
>
>Ahh. But that was likely a fundamental oscillation, or a low order 
>mode oscillation supported by the cavity. I can make an amp 
>"explode" by making it arc on or near the fundamental. I can wipe 
>out a bandswitch with a HF oscillation, or with excessive drive for 
>the amount of loading used.
>
>Everyone (except Rich) knows that happens. 
>
?  Rich knows that all power grid tubes have finite emissive 
capabilities.  He also knows that when over-driven, a TL-922 can not 
produce much more than 1800w-pep due the emissive limit of a 3-500Z.  
Arcing the 6kV Tune-C in a 922 would undoubtedly require over 6000w.  
>........
>What amazes me is how some people swallow his wild claims. PT 
>Barnum was right.
>
> 
>73, Tom W8JI
>w8ji@contesting.com


Rich...

R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures  


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