On Oct 1, 2005, at 6:35 PM, k7fm wrote:
> " This was c. the same time that I found out that General
> Electric Medical had cancelled a contract with Dick because he failed
> to fix the problem of sudden 8877 failures in a MRI amplifier that he
> was manufacturing for G. E."
>
> As I recall, the "parasitic" problem with the Alpha amps occurred at
> exactly the same time that Eimac made a batch of bad ceramic tubes (in
> particular, the 8877).
True, but according to Dick, the (damned) heat dam problem lasted about
13 months, so it's an inadequate excuse. When G. E. said there was a
design problem, Dick should have listened. Afterall, Fyler was a G. E.
guy. Also, Dick wasn't the only 8877 amplifier designer that ignored
feedback-C, on Friday I tested an 8877 that came from a Dentron
DTR-2000 and it exhibited gold-sputtering with the Joe Funderberg
(W6IHA) test.
> At the same time you were analyzing the problem, Eimac changed the
> construction of the tube.
Are you sure about this?
> I am still amazed that your analysis of the parasitic problem in the
> Alpha amps resulted in reduced problems for Alpha owners, even though
> Alpha did not implement your ideas.
My ideas and analysis did not result in reduced problems for owners,
reducing the VHF-Q of the suppressors used in Alphas resulted in
reduced problems because less VHF-Q means less Rp, and that means less
VHF amplification.
The puzzle here is why do some people still believe that it okay for a
dampening device to have high Q? This is like selecting a
shock-absorber for an automobile that is very springy and lively.
cheers, Colin
>
> Colin K7FM
>
>
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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