> >Thanks for the input. Are you saying there is a big problem with the
> >811H or did they fix this problem?
> >
> >Mike
> >W0MU
> I have no idea what the failure rate is, Mike. The apparently
> parasitic-related failure I saw may have been the only one---or it could
> have been one among many.
> You might try asking Mr. Rauch which type of VHF suppressor is currently
> being used.
> Rich---
Hi Mike,
Parasitics do not cause filaments to break in a tube. Those claims
are silly.
Filament breakage is due to mechanical shock or weak mechanical
points in the filament.
The original 811A Chinese tubes fropm one vendor (like the
3-500Z's) had poor mechanical construction. Filament breakage (as
well as glass failures and arcs due to out-gassing) were common.
Ameritron switched to another tube manufacturer that used better
materials.
73 Tom
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