Basic parafeed plate choke calculations?

[Jim R.]

I'm tackling my first parafeed design project -- a SE 12b4a amp using MQ exo-45s and I would like to know how one goes about calculating the values for the PF choke and cap.

Any guidance appreciated.

Thanks,

Jim

[nullspace]

Hi Jim,

Here's Paul Joppa's Rule of Thumb crica Dec. 2007:
Parafeed cap: C = 2*L/(RL squared). C is the capacitance in microfarads (uF), L is the plate choke inductance in henries, RL is the nominal load resistance in kOhms. Example: for the Paramour upgrade, L=40 henries, RL=3K, C=8.9uF. Usually half to twice that value is reasonable, i.e. 4.5 to 18uF; we use 10uF.

In terms of choosing a choke, the other Paul lays out some thoughts on choosing a choke interspersed with other interesting stuff here: Parafeed Fun. In short, minimum 8-10H/1kOhms of nominal load. So, for EXO-45, at least 40-50H.

Hope that helps.

John

[Jim R.]

Thanks, John -- helps a lot.  I also bookmarked VS's page.

Thanks again,

Jim

[jazbo8]

Bumping an old topic... but does anyone still have the image files that go with VoltSecond's Parafeed Fun article? I tried archive.org, but all the image files were missing.

TIA,
jaz

[Paul Birkeland]

Try this spreadsheet.

-PB

[jazbo8]

Try this spreadsheet.

-PB

I already have the spreadsheet, but would like to see the whole article, I think the images were from the PSpice simulations...

[jazbo8]

Bumping the thread in the hope that someone has saved the image files from VoltSeconds' parafeed page...