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Dynamic Mutual Conductance Valve Analyser

Valves, Transistors, IC's and Components. Bench test techniques, Test Gear - Valve Testers, Scopes, CRT Testers, Bridges, Sig Gens, Pattern Gens, Workshop tours etc
 
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Dynamic Mutual Conductance Valve Analyser

Post by Sparks » Sat Feb 20, 2016 5:48 pm

I found this article in the Radio Constructor June, 1956, the following link to the article online:
http://www.r-type.org/articles/art-118.htm
All very simple to build, but the calibration of potentiometer R9/R10 baffles me. :ccg Has anyone any idea of what it means?
Bob

 
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Re: Dynamic Mutual Conductance Valve Analyser

Post by Cathovisor » Sat Feb 20, 2016 6:24 pm

It's an odd way of expressing it, but the scale seems to be the ratio of the values as measured between the top of the pot and the wiper (R9), and the bottom of the pot and the wiper (R10).

R9 + R10 must always equal 50kΩ so when the pot is at its midpoint, R9 = 25kΩ, R10 = 25kΩ so the ratio is 1.

If the pot is turned so that R9 = 10kΩ and R10 = 40kΩ then the ratio is 0.25.

Similarly, if R9 = 40kΩ and R10 = 10kΩ the ratio becomes 4. The ratio will go from zero to infinity.

I think that's what they're trying to say.

 
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Location: Lancashire

Re: Dynamic Mutual Conductance Valve Analyser

Post by Sparks » Sat Feb 20, 2016 6:39 pm

Thanks. I am glad I am not the only one confused! I will study it a bit more tomorrow!
Bob

 
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Re: Dynamic Mutual Conductance Valve Analyser

Post by Ed Dinning » Sat Feb 20, 2016 8:47 pm

Hi Gents, a sort of standard way of expressing bridge balance points to make calculation of unknowns easier, and this tester relies on bridge principals.
Looks as if it could be useful as it allows various quiescent points to be set up (DC conditions) and mutual conductance taken at those points, not some arbitrary values as used by many valve testers.

Ed


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