Valve Socket - UK Vintage Radio Repair and Restoration Discussion Forum

boiss · 1st Aug 2012, 10:15 pm

Well I have knocked up a valve socket and the bottle fits not sure of where I will use it yet, A case of have valve will power it up, Hmmm!

Sean Williams · 2nd Aug 2012, 9:37 pm

Looks like an 833, therefore you must use it!

boiss · 8th Aug 2012, 2:14 pm

Yup, It's a GU48, Russian 833A, picked it up in Lithuania for 20 euros. Had a few probs with it in the airport, finally they believed it was just a bigger version of what they had in their old radios.
Got power to the heater so now I need to find something OTT to do with it.

boiss · 9th Aug 2012, 2:24 pm

Well it's not a very good replacement for an SET triode strapped EL84, On 280Volts HT, Ia was about 10mA, in order to increase the Ia it was necessary to run Ig and then the matching on the driver stage goes up the tubes. without positive bias on the grid O/P was around 200mW with significant distortion, increasing Ig by biasing reduced the O/P undoubtedly due to loading effects. Need to follow up on power drive ccts to run grid current etc.

PJC58-Hythe · 14th Aug 2012, 8:02 pm

It won't be, it not designed for that sort of thing! It's typically used as an RF triode with a maximum output of 1KW or a modulating triode (in a push pull arrangement) delivering upto 2.5KW. The supply voltages are likely to be in the region of 3KV and the drive for maximum output is around 35W. If you want to see a slightly insane audio application using it single ended I found while googling it go here...

http://www.tubelab.com/833SE.htm

Peter

tri-comp · 18th Aug 2012, 11:31 pm

Quote:

Originally Posted by boiss

....On 280Volts HT, Ia was about 10mA

You're missing a Zero here; should be 2800V

Anyway; this triode is not made for 200mW or even 200W. 1000W in Class AB2 Push-Pull is more like it. Gates used it as modulator (and RF-amp) in their BC-1H 1KW AM-transmitter-series.
I have the schematics for that so you can see how it's put together if you're interested.
Takes some heavy Va and some powerfull cathode-follower drive to take into class AB2 and then it starts singing.

What puzzles me is why anyone would want to waste 100Watt (10V/10Amp) into the filament to extract 200mW of output-power...

rgds,

/tri-comp

boiss · 31st Aug 2012, 3:47 pm

Here is another amp SE 833 for only $69000 per channel
from WAVAC. They also do a complete Stereo amp for a
mere $350000!!!
Review of monoblocks http://www.positive-feedback.com/Issue21/wavac.htm
The Fun is in doing it and they look great!
Boiss

1st Aug 2012, 10:15 pm	#1
boiss Pentode Join Date: Jun 2006 Location: Malaga, Spain. Posts: 235	Valve Socket Well I have knocked up a valve socket and the bottle fits not sure of where I will use it yet, A case of have valve will power it up, Hmmm! Attached Thumbnails

2nd Aug 2012, 9:37 pm	#2
Sean Williams Dekatron Join Date: Feb 2005 Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW Posts: 3,518	Re: Valve Socket Looks like an 833, therefore you must use it! __________________ Engineers make things work and have spare bits when finished

8th Aug 2012, 2:14 pm	#3
boiss Pentode Join Date: Jun 2006 Location: Malaga, Spain. Posts: 235	Re: Valve Socket Yup, It's a GU48, Russian 833A, picked it up in Lithuania for 20 euros. Had a few probs with it in the airport, finally they believed it was just a bigger version of what they had in their old radios. Got power to the heater so now I need to find something OTT to do with it. Attached Thumbnails

9th Aug 2012, 2:24 pm	#4
boiss Pentode Join Date: Jun 2006 Location: Malaga, Spain. Posts: 235	Re: Valve Socket Well it's not a very good replacement for an SET triode strapped EL84, On 280Volts HT, Ia was about 10mA, in order to increase the Ia it was necessary to run Ig and then the matching on the driver stage goes up the tubes. without positive bias on the grid O/P was around 200mW with significant distortion, increasing Ig by biasing reduced the O/P undoubtedly due to loading effects. Need to follow up on power drive ccts to run grid current etc.

14th Aug 2012, 8:02 pm	#5
PJC58-Hythe Heptode Join Date: Sep 2010 Location: Hythe, Hampshire, UK. Posts: 632	Re: Valve Socket It won't be, it not designed for that sort of thing! It's typically used as an RF triode with a maximum output of 1KW or a modulating triode (in a push pull arrangement) delivering upto 2.5KW. The supply voltages are likely to be in the region of 3KV and the drive for maximum output is around 35W. If you want to see a slightly insane audio application using it single ended I found while googling it go here... http://www.tubelab.com/833SE.htm Peter __________________ Peter - M0HYT - BVWS Member - GQRP Club http://www.retroworkshop.co.uk

31st Aug 2012, 3:47 pm	#7
boiss Pentode Join Date: Jun 2006 Location: Malaga, Spain. Posts: 235	Re: Valve Socket Here is another amp SE 833 for only $69000 per channel from WAVAC. They also do a complete Stereo amp for a mere $350000!!! Review of monoblocks http://www.positive-feedback.com/Issue21/wavac.htm The Fun is in doing it and they look great! Boiss