Don't you think the HV filter will generally discharge much faster than
the cathode will cool down & lose emissivity, Peter...? Even if the HV
contactor/relay takes 50 ms to open and the tube(s) look like ~1k dc load
without bias, I think the HV is pretty well gone in another 50-100 ms.
Don't think much cathode cooling occurs in 100-150 ms. HOWEVER, if there's
any solid evidence to contrary it's something I'd sure like to know!
73, Dick
-----Original Message-----
From: Peter Chadwick [SMTP:Peter_Chadwick@mitel.com]
Sent: Tuesday, March 30, 1999 5:15 AM
To: 'amps'
Subject: RE: [AMPS] Re:HV on tube w/o filament voltage
The problem I could see is when switching off: if the bias goes down while
the cathode ( rather than filament) is hot, it could lead to problems with
stripping. It might not do a thoriated filamenmt much good, because you
start running out of emission, but generally, their thermal time constants
are much less than cathodes.
73
Peter G3RZP
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