-----Original Message-----
From: measures <2@vc.net>
To: AMPS <amps@contesting.com>
To: <amps@contesting.com>
Date: 13 September 2000 14:43
Subject: Re: [AMPS] Blown TL922A... What to do?
>
>>
>>
>>-----Original Message-----
>>From: measures <2@vc.net>
>>To: AMPS <amps@contesting.com>
To: <amps@contesting.com>
>>Date: 13 September 2000 02:36
>>Subject: RE: [AMPS] Blown TL922A... What to do?
>>
>>
>>>
>>>>
>>>> I like the idea of modeling the circuit. However,
>>>>much of the circuit is not considered. People often don't realize that
>>>>that there are additional inductances due to the current paths thru the
>>>>chassis and often these impedances are in both the input and
>>>>output circuits. I have seen many amplifiers that have very long paths
>>>>from the anode (PLATE) thru the coupling capacitor, PI input capacitor,
to
>>>chassis and
>>>>back to the grid and cathode circuit. Sometimes this path is a foot in
>>>>length or more
>>>>. This single loop amounts to nearly a uH of inductance with
>>>>who knows what other impedances tied to it and signals sharing the path.
>>>> My electronics instructor used to say often the problems with a
circuit
>>>>is the component you can't see. Especially with RF circuits.
>>>>
>>>Amen to that, Bill. Who would ever have guessed that there is a
>>>Z-step-up L-network hidden inside the Tune-C in a 922?
>>
>>
>>C'mon, Rich, make with some details. Where's the L, where's the C, what
are
>>their values, and do they predict the required voltage step up?
>>
>Good point, Steve. This is perplexing. The tune cap. connects to c.
>27mm of #12 busswire, so that could be involved with the series
>resonance. The trouble with schematic diagrams is that they are quite
>accurate.
> I have heard of many 6000v tune caps that arced over in TL-922s. The
>peak potential at C-Tune should be no more than 2800v. Something weird
>has got to be stepping up V.
wierd or not, can you detail a theory we could test?
Steve
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