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Old 9th July 2012, 07:44 AM   #1
Zeta4 is offline Zeta4  United Kingdom
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Default WE448A data

Hi

Does anyone have data for triode connected WE448A? I have some
which I would like to try in a couple of applications. Curves etc would
be ideal but basic data like mu would be a help.

Thanks
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Old 9th July 2012, 08:15 AM   #2
guss013 is offline guss013  New Zealand
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You could try here...

Western Electric

hope it helps :-)
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Old 9th July 2012, 04:21 PM   #3
Zeta4 is offline Zeta4  United Kingdom
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Thanks, I have that data but its for the tetrode connection.

I did see one mention of a mu of 4.9 and an Ra of 4K
but surely the mu figure cant be right. Maybe its 49
which is much more likely.

Ah well Ill just have to experiment a bit.
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Old 9th July 2012, 04:33 PM   #4
kevinkr is offline kevinkr  United States
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I believe the data sheet here: http://www.westernelectric.com/spec_sheets/448B.pdf See figure 1 which appears to be curves with the plate and screen grid tied together. (Triode connection)

Make a simple test jig and do some measurements. If you use a good CCS load and tie plate and screen grid together with fixed grid bias you can measure mu directly.
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Old 9th July 2012, 05:17 PM   #5
Zeta4 is offline Zeta4  United Kingdom
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Thanks kevinkr, I hadnt noticed the apparent triode connection
in fig 1.
I guess I will have to measure it as you suggest.
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Old 9th July 2012, 08:38 PM   #6
7N7 is offline 7N7  United Kingdom
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Quote:
Originally Posted by kevinkr View Post
I believe the data sheet here: http://www.westernelectric.com/spec_sheets/448B.pdf See figure 1 which appears to be curves with the plate and screen grid tied together. (Triode connection)

Make a simple test jig and do some measurements. If you use a good CCS load and tie plate and screen grid together with fixed grid bias you can measure mu directly.
I don't think that is correct; I believe that they mean that both Anode and G2 are at 150V which of course is not quite the same as triode connection.

The valve appears to be very similar to the Swedish (Ericsson) A-1600 a.k.a. 7150 . I had some of these once, stubby bulb, Magnoval B9G base, Va (max) 150V etc. the data are in the Vade-Mecum section 108. I did make some curves but these are now lost I'm afraid. Mu was about 30 as I recall.

Paul
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Old 10th July 2012, 01:23 AM   #7
kevinkr is offline kevinkr  United States
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Quote:
Originally Posted by 7N7 View Post
I don't think that is correct; I believe that they mean that both Anode and G2 are at 150V which of course is not quite the same as triode connection.

<snip>
Paul
The curves do look triode like. The statement Eb=Ec2=X volts is a somewhat common nomenclature for triode connection here, (both WE and Sylvania were known to publish data sheets this way) and I interpreted the individual curves as being the combination of Eb=Ec2 at the plate voltage given to the right of the curve.

The curves certainly don't look that great, but may in fact be better than shown when actually measured. These might be good in something like a phono stage if the mu turns out to be reasonable.
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Old 10th July 2012, 09:05 AM   #8
7N7 is offline 7N7  United Kingdom
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Quote:
Originally Posted by kevinkr View Post
The curves do look triode like. The statement Eb=Ec2=X volts is a somewhat common nomenclature for triode connection here, (both WE and Sylvania were known to publish data sheets this way) and I interpreted the individual curves as being the combination of Eb=Ec2 at the plate voltage given to the right of the curve.

The curves certainly don't look that great, but may in fact be better than shown when actually measured. These might be good in something like a phono stage if the mu turns out to be reasonable.
No they are not triode curves; these curves - transfer characteristics with Va constant and varying G2 voltage and G1 voltage - appear regularly in pentode and beam tetrode data sheets. For example have a look at the nice set for the pentode section of 6AW8A here.

Paul
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