W8JITom@aol.com wrote:
>
> In a message dated 97-02-26 18:34:20 EST, k0wa@southwind.net (Lee Buller)
> writes:
>
> <<
> Several years ago, a CQ magazine writer extolled the virtue of the Sylvania
> or Amprex 3-500Z. he said it had heavier graphite on the plate and a
> different pate design which allows for more power dissapation. He also
> swore that they sounded better over the air.
>
> Has anyone any comments on this? Isn't a 3-500Z just that? >>
>
> That article was not so accurate. It told people to replace tubes after every
> so many hours because the "sound better". IMHO, thats bad advice.
>
> The dissipation is identical between the tubes. The thicker graphite anode
> has longer thermal lag, but is more prone to outgassing. I find no real life
> difference unless the tube is subjected to large short duration overloads,
> in that case the graphite anode is better.
>
> Eimac graphite anode tubes are about ten bucks more than the moly anode
> tubes.
>
> 73 Tom
I cant see how the material of the plate would have an effect on how it
sounds. The graphite plate is used a lot in RF sealing equipment. I
junked down several machines a few back, all used carbon plate tubes.
We had some equipment that was used for sealing baby diapers. I forgot
the number's but were Amprex, glass envelope about the same size as
3-500's and 3-1000's. All were low mu triodes. I think overload is the
main reason for that type of design also.
Ron W4WA
>
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