Rich Measures wrote:
>>> The event that causes the damage apparently happens suddenly.
>>>- IMO, overdrive tends to dislodge patches of cathode coating, without
>>>damaging the gold plating on the grid. {photograph in September 1990
>>>article "Parasitics Revisited".}
>>
>>That's my problem: how can you know these things?
>By looking at the photo. The cathode coating is flaking off, the gold
>plating is not.
All you know for sure from the photograph is - quite literally - that
"The cathode coating is flaking off, the gold plating is not." That is
ALL you know for sure. The evidence is not sufficient to prove
conclusively WHY it happened.
>>We can only see the
>>after-effects, and have no direct evidence about the causes... it's all
>>a matter of interpretation and "IMO".
>>
>If overdriving killed the tube, why is the grid in mint condition?
Rich, you're arguing in circles. I didn't claim that overdriving killed
that tube: YOU did (count the quote marks). It's a fair question, but
you have to answer it.
You seem to have a real problem in separating evidence (the physical
condition of the tube, which everybody can witness and agree) from your
own theories about the causes.
Read my fingers: what you see under the microscope does NOT include the
cause of the event.
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.demon.co.uk/g3sek
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