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Re: plate load-"brilliant" question

i think you may be confusing a few different ideas...

for parafeed on the plate of the tube we want infiniate inductance in the plate so the VR tubes probably are not ideal as a load.

but we could look at VR tubes in the cathode to bias the tubes but this is a different issue than parafeed and will work similarly for both parafeed and direct feed... there are issues with doing this, but i have never tried it so i don't know if any of the "issues" are really issues..

now onto the good stuff...:-)

with that 5Y3... there are a couple of cool things you could look into...

first, be a man and use a 280 :-) looks count for something.

seriously, what voltage drop are you getting the book says 60V @ 125ma so run 70ma and you might be close to -40V???

also you can use one tube for a pair of outputs, somehow there has to be beauty to that approach...

and finally... try tweeking the filament voltage to adjust the bias... you should be able to trim the filament voltage by 10% or so and get pretty close to the book points for the 2a3, and the rectifier should still be operating linearly... it might be a very easy way to build a simple amp??? also using an indirectly heated rectifier will give you a nice slow turnon... but as it looks now the 5Y3 80 5Z3 family looks best someday i'll scour the books a bit more and see what turns up...

also how about an 83 to bias up a 12B4 linestage for a nice fixed 10-15V bias??? a friend said some industrial applications used mercury tubes for bias due to the huge currents, a resistive load would dissapate too much heat..

just food for thought.

dave


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