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Old 18th September 2008, 03:01 AM   #1
exurbia is offline exurbia  Australia
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Question 311-b

I have been offered a large number of 311B valves. I don't know whether i should buy them, as i can't find any info on them. The type isn't listed in any of my books.
Can anyone help with info about them

Cheers,
Peter.
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Old 18th September 2008, 03:43 AM   #2
kevinkr is offline kevinkr  United States
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If I've got the right one it's listed in the vade mecum pages at Frank's right here: http://www.mif.pg.gda.pl/homepages/f.../054/2/231.pdf

It's a small beam power pentode with a grid cap (control grid) - it's capable of almost 2W, but at 14% thd..

Were the ones you were offered made by STC?

This type has a 10V 640mA filament and is designed for operation at extremely low plate and screen voltages ~ 135V.

Could be interesting as a driver for small dht depending on how linear it is, it's performance triode connected is anyone's guess, and it is not intended for operation with supply voltages in excess of 150V - 160V.

Cheap enough it might be worth getting a few to play around with.

Seems like it might be ideal for the tube/ss hybrid circuit George (tubelab) has been playing with.
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Old 18th September 2008, 03:44 AM   #3
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http://www.westernelectric.com/spec_sheets/311B.pdf

If they are made by WE then put them on ebay one pair at a time to finance something larger
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Old 18th September 2008, 04:01 AM   #4
kevinkr is offline kevinkr  United States
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Quote:
Originally posted by astouffer
http://www.westernelectric.com/spec_sheets/311B.pdf

If they are made by WE then put them on ebay one pair at a time to finance something larger

I agree, but I wonder how likely that is..

This is not the tube used in the WE91A, which is a 6C6..

Some Japanese designs use them to drive 300B, but I wonder how advisable that is given their ratings..
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Old 18th September 2008, 06:19 AM   #5
exurbia is offline exurbia  Australia
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Unhappy 311b

Oh well, not quite the bargain that they're made out to be by the seller
These are the stc/electronic enterprises model.
I might have a bash at a headphone amp with them
So, i'll buy a few and report back
TTFN,
Peter.
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Old 18th September 2008, 01:38 PM   #6
kevinkr is offline kevinkr  United States
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Default Re: 311b

Quote:
Originally posted by exurbia
Oh well, not quite the bargain that they're made out to be by the seller
These are the stc/electronic enterprises model.
I might have a bash at a headphone amp with them
So, i'll buy a few and report back
TTFN,
Peter.

Hi Peter,
Sorry to hear that, but a headphone amplifier does sound like a good possibility..

I have the same experience quite frequently, a deal that sounds "too good to be true" usually turns out that way unfortunately. I've had more than one deal where the seller told me they were selling something "cheap" that I needed fairly urgently only to be left gasping when the time came to actually write the check..
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