G811a Triode Driver

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darkspeed

G811a Triode Driver « on: 2010-03-22, 06:07:48 »

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Posts: 812

Waiting on parts.....

To build a 160w hv hf supply from four g811a triodes

UPDATE:
Built most of it today.. Still waiting on the 10a variac, fans, and I need to build the control plate and screen that will enclose it.

2 CH @ 160w filtered DC supply.

Grids can be driven from a signal generator or from a feedback loop.

Added two banks of RF capacitors so the primary of each triode can be tuned

If it works well I may build a bigger one from a 833A tube

G-811.pdf (10.76 kB - downloaded 860 times.)

« Last Edit: 2010-04-15, 18:50:12 by darkspeed »

darkspeed

Re: G811a Triode Driver « Reply #1 on: 2010-03-22, 06:20:30 »

Hero Member

Posts: 812

1 - 2000v microwave oven transformer

2 - 6.3v 20a triad filament transformers

2 - 4 pin tube bases

2 - triode caps

2 - G-811 Russian Triodes

3 - 1.8nf 10kv capacitors

2 - 30ohm 20w resistors

1 - 5kohm 50w resistor

1 - 20kv vacuum variable capacitor

1 - 140v variac

1 - BNC connector

3 - 4000v 1uf filter capacitor

4 - 16kv diode

1 - 20a RF filter

3 - cutting boards

4 - WC float rods

1 - 3kvdc panel meter

1 - filament power switch

1 - mot power switch

1 - 120v pc fan

« Last Edit: 2010-04-15, 09:34:30 by darkspeed »

darkspeed	Re: G811a Triode Driver « Reply #2 on: 2010-04-15, 08:12:25 »
Hero Member Posts: 812	.. G811a Triode Driver CIMG5860.jpg (565.08 kB, 1280x960 - viewed 1962 times.) G811a Triode Driver CIMG5872.jpg (526.96 kB, 1280x960 - viewed 1714 times.)

darkspeed	Re: G811a Triode Driver « Reply #3 on: 2010-04-15, 08:13:00 »
Hero Member Posts: 812	.. G811a Triode Driver CIMG5874.jpg (440.87 kB, 1280x960 - viewed 1721 times.)

Grumpy	Re: G811a Triode Driver « Reply #4 on: 2010-04-15, 13:16:07 »
Group: Tinkerer Hero Member Posts: 4265 tExB=qr	Nice cutting boards Why do the two resistors have coils wrapped around them?

stprue	Re: G811a Triode Driver « Reply #5 on: 2010-04-15, 13:45:28 »
Full Member Posts: 221	Very nice build Darkspeed....I bet those vacume cap's wern't cheap!

darkspeed	Re: G811a Triode Driver « Reply #6 on: 2010-04-15, 17:32:49 »
Hero Member Posts: 812	Quote from: Grumpy on 2010-04-15, 13:16:07 Nice cutting boards Why do the two resistors have coils wrapped around them? Thanks guys.. G. - the resistor / inductor act as a choke if the tube tries to become a spark gap normally its a bad idea to use metal case resistors in this function but i paint them with corona dope so they are ok.

Grumpy	Re: G811a Triode Driver « Reply #7 on: 2010-04-15, 20:52:38 »
Group: Tinkerer Hero Member Posts: 4265 tExB=qr	Quote from: darkspeed on 2010-04-15, 17:32:49 Thanks guys.. G. - the resistor / inductor act as a choke if the tube tries to become a spark gap normally its a bad idea to use metal case resistors in this function but i paint them with corona dope so they are ok. why wrap the coil around the resistor? does it have ferromagnetic material in it?

darkspeed	Re: G811a Triode Driver « Reply #8 on: 2010-04-15, 21:11:58 »
Hero Member Posts: 812	Quote from: Grumpy on 2010-04-15, 20:52:38 why wrap the coil around the resistor? does it have ferromagnetic material in it? Honestly its an old tube thing.. RF builders have been doing that forever, i think it just makes a handy former..

Grumpy	Re: G811a Triode Driver « Reply #9 on: 2010-04-15, 22:35:32 »
Group: Tinkerer Hero Member Posts: 4265 tExB=qr	Quote from: darkspeed on 2010-04-15, 21:11:58 Honestly its an old tube thing.. RF builders have been doing that forever, i think it just makes a handy former.. yes, but you only have a few turns, not hundreds. Hi freakin' freq choke.

darkspeed

Re: G811a Triode Driver « Reply #10 on: 2010-04-16, 03:15:11 »

Hero Member

Posts: 812

Quote from: Grumpy on 2010-04-15, 22:35:32

yes, but you only have a few turns, not hundreds. Hi freakin' freq choke.

Yes! correct! when a triode arcs out the RF between the internal parts is in the very high MHZ...

If you over drive the plate voltage it can arc out and the choke will most of the time save the tube from failure

The 811 is good to 30mhz but the grid will free resonate at 100mhz so choking above 30mhz is a safe bet.