partial feedback stuff

[dave dove]

guys

refering to Broskies version of PF:

in his article he uses just a resistor
from 300B plate to before coupling cap
in effect the driver's plate
and gives the maths for calculating R

http://www.tubecad.com/march2001/page8.html

in t.rex he uses 47K followed by 2.2uf
from 300B plate to 300B grid

http://www.enjoythemusic.com/magazin.../trex/fig1.jpg

does anyone have an opinion as to why the two topologies
and
in the second instance how he calculated C

looking forward

dave dove

[SY]

I get a 403 error from the second link.

[dave dove]

SY

i just tried it and it works fine

try this:

http://www.blackdahlia.com/html/tip_50.html

dave dove

[Bandersnatch]

Hey-Hey!!!,
I have not read the article in question. I do use the general topology quite extensively in one form or another.

Make sure the provided math accounts for the plate Z of the driver tube. The plate resistance forms a voltage divider and the NFB amount is reduced.

Pentode drivers are excellent choices, and for the same reason, the cascode.

One can also do away with the driver stage voltage supply speerate NFB resistor, and go to a tap on the OPTx plate winding. This is the nuts and bolts to the E-Linear topology. I enclosed a basic PP schematic.
cheers,
Douglas