>From: Rich Measures[SMTP:measures@vc.net]
>Sent: Monday, December 08, 1997 11:38 AM
>To: Ian White, G3SEK; amps@contesting.com
>Subject: Re: [AMPS] parasitic suppressors
>
>>Peter Chadwick wrote:
>>>
>>>Just to add to the debate, I haven't seen anyone come up with a boiling
>>>point temperature for gold in a vacuum
snip......
>My understanding is that severe grid overdissipation, which may result
>from overdrive, underloading, lack of adequate HV (all interrelated), can
>evaporate - or if you prefer, boil or sputter or whatever - gold off the
>grid.
This was Mr. Rauch's position during the grate parasitics debate,
however, he never produced a reference.
- I do not believe that it's possible the gold with the output from a
typical transceiver. The mass of an 8877 grid is such that an
extraordinary amount of power would be required to elevate the
temperature high enough to rapidly boil off the gold plating.
>A grid surface without gold falls prey to secondary emission which screws
>up linearity, Ig, etc. To the extent that errant gold lands on the
>cathode, it tends to "poison" the oxide and in extreme cases literally
>kills emission.
Secondary emission could well be a contributor. Does it seem likely that
electrons which strike the anode during a VHF parasitic oscillation would
be capable of producing secondary emission?
Rich...
R. L. Measures, 805-386-3734, AG6K
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