[Patrick Turner]

On Wednesday, 28 November 2007 02:57:13 UTC+11, The Phantom wrote:
I recently ran across a 1933 paper by W. N. Tuttle, of the General Radio
company titled "Dynamic Measurement of Electron Tube Coefficients". It's a
14 page, approximately 2 megabyte, pdf file. It describes a General Radio
instrument. It's a very detailed paper. If you would like to have a copy,
post an email address (encoded in such a way as to foil the email address
harvesters), and I'll send it your way. It will probably be up to 3 megs
as an email attachment.

I guess the meaning of "Dynamic Measurement of Electron Tube Coefficients" is the measurement of the µ, gm, and Ra of any given vacuum tube, presumably with a sine wave signal which translates to "dynamic" ie, measurements were not done using varied levels of grid dc voltage while measuring anode Vdc change across an anode resistance from which current change can be calculated.

The tube coefficients might be now called tube parameters. They all are variable depending on the Idc anode current, so the more Ia you have, the higher the gm, lower the Ra, with µ being the most constant parameter. There are limits for gm increase which are reached when Ia approaches the maximum possible, which is usually far more than any tube idle currents.

I should not assume any more than I already may have about a 1933 paper I have never read. Perhaps you'd like to describe what you learnt when you read the paper, and what conclusions can be reached and what use these could be towards anyone trying to design and build an amplifier.

Was there something that tube engineers of 1933 did better than what their sons were doing in 1963? ( apart from cringing and leering at transistors )

Patrick Turner.