A Long Tail Phase Inverter ???? ......... strange schematic ????

[kagliostro]

Which kind of PI is this ????

Kagliostro

[DummyLoad]

Long tail with a current source. Each phase drives a cathode follower. Each cathode follower drives the grids of the output tubes.

--DL

[RicharD]

I don't see any cathode followers. ????   

[DummyLoad]

I don't see any cathode followers. ????   

you're right... haste post ry50 are the output tubes...the lines off the cathodes threw me. my apologies. notice that bipolar power supply is required. more of pain than it's worth.

i guess ry are cyrillic alphabet for GU in english alphabet?

--DL

[RicharD]

I see the neg 120V but I also see that resistor connected to the positive lead of a filter cap.  That doesn't seem right to me.

[kagliostro]

I've find the origin of that schematic

this is the page (in russian - you must use google translator to try to understand something - russian to italian isn't good)

http://sergeev21.narod.ru/gu50pp.htm

the author say there is an NFB and also a positive current feedback in order to have a low output impedance

this schematic was after changed and not used

Kagliostro

[kagliostro]

I think I've find the answer

wrong or not I think the intention for that circuit was a CCS for LTPI

http://www.freewebs.com/valvewizard/ccs.html

Kagliostro

[sluckey]

Yep. Just like DummyLoad said in reply #1.

[kagliostro]

sometimes the truth is near but hides

Kagliostro

[sluckey]

One mans 'sink' may be another mans 'source'.