[AMPS] Parasitics and Blown Filaments

[km1h@juno.com]

Hi gang...

I actually read Tom's response and laughed so hard that I accidentally
deleted his message. 

Blown filaments are absolutely possible due to an internal tube failure.
Consider the failure a parasitic, gas, lousy assembly, etc. Any one of
those can do it. 

A case in point is the huge number of Svetlana 572B's with blown filament
failures....I had a least 2 dozen happen to me and my customers. Put them
in a known stable amp such as a SB-200, turn it on and everything looked
fine. Key the relay with NO DRIVE and "Bang".  Svetlana has acknowledged
the stability problem and has redesigned the tube. It was an acknowledged
parasitic problem based upon internal geometry, not gas or poor
construction. 

I feel that Tom's response is irresponsible and is strictly a
MFJ/Ameritron CYA  smoke screen. 

My congratulations to Svetlana for not only quickly responding to the
problem but also admitting the reason. Eimac, etc could learn a lesson
about customer relations. 

73...Carl   KM1H

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