>
>on 11/17/99 6:35 AM, measures at measures@vcnet.com wrote:
>
>> ? Would you be surprised to learn that the person assigned to the
>> rewrite is from the Marketing Department instead of the Engineering
>> Department?
>
>Common practice in the industry, Rich.
? My 1967 Edition of Care and Feeding says it was 'prepared by
laboratory staff". This does not sound like it was a bunch of sales
folks, Jon. . // Why does "Care and Feeding of Power Grid Tubes need
to be updated? Sure, the Class C stuff is mostly a relic. The only two
errors I am aware of in the book is the minor error in tank calculations
caused by not taking the stored energy in C2 into account for the tank Q
calculation, and the statement in section 2.4.2 /p.16/ about the purpose
of tungsten di-carbide in the emission process. Eimac essentially
states that the carbide layer serves to reduce the thorium evaporation
rate and extend the emissive life of the cathode. . However, without
the carbide layer, emission is reduced to c. 0.5%, so the statement does
not check out. Tungsten di-carbide is responsible for 99.5% of the
electrons coming from the cathode. When the carbide layer is used
up/evaporated, recarburization with acetylene gas (when the filament is
hot) restores full emission.
>Many marketing/sales folks are
>former engineers. It generally pays better. It's not a conspiracy so that
>false information goes out to customers in order to hide the fact that Eimac
>builds their tubes with built in parasitics in order to sell more tubes in
>the long run.
>
? According to QST Magazine's Paul Pagel, Reid Brandon told the powers
that be at QST that Willis B. Foote, Chief Specifications Engineer, Power
Grid Division., was not authoriaed to release the information about grid
gold-sputtering to Richard Measures. Go figure, Jon.
- Foote's unathorized letter can be read at:
http://www.vcnet.com/measures/EimacF.html
- My guess is that there was no conspiracy. Eimac apparently never had
a good handle on the problem of parasites. Care and Feeding's sketchy
treatment of parasitics suggests that the boys at Eimac either never read
or never understood Mr. G. W. Fyler's classic article about parasitics in
the 1935 IRE journal. I have never seen an Eimac Engineering Bulletin
that addressed this knotty subject.
cheers
- Rich..., 805.386.3734, www.vcnet.com/measures.
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