[Amps] Homebrew is back..

[Diane & Edward Swynar]

Hi Carl,

"...Tap the 10M coil in the center with the Tune cap which gives a 4X stepup
for the required C. Do not add a seperate L coil. The last 4x 813 amp I
built used the vacuum variable with the tap and it ran full power even at
the high end of 10M."

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Yes, thanks for that info...

A very nice classic example of that very technique may be seen in early/mid
60's editions of the ARRL HANDBOOK: the piece I'm thinking of deals with
mono-band amplifiers, all employing paralleled 813s...

MUST READING if you're thinking of ever using one of these venerable jugs on
10...!

BTW Carl, have you ever seen an 813 WITHOUT that rugged graphite plate...? I
found a couple at a Hamfest a few years ago wherein the plates---I
swear---look like the plates used in 811A's, only fed with steroids!

"Tin plate" construction all the way. How they can dissipate the graphite
plate's 125-watts I do NOT know...

I've never tried them on the air yet---and can find no reference in the
books on them either...

~73~ de Eddy VE3CUI - VE3XZ