[AMPS] Amp using 833A

[W8JI@contesting.com (Tom Rauch)]

>    I don't think anyone has done any calculations:
> I used to run a pair of 250TH's in parallel grounded grid in the 60's. I
> then did not know that it would n0ot work since the mu was only 37 or so.
> They worked fine driven by my home brew pair of 6146's and my 20A exciter.
>    Now the 833 has a mu of about 35. Indeed you can't operate it at zero
> bias and the input impedance is  higher than 50 ohms and power gain a bit
> low. 

Everyone keeps talking about "mu".

Why?

In grounded grid, it is the ratio of cathode impedance to anode load 
impedance that primarily sets the gain. That impedance ratio sets 
the amount of negative feedback. 

Those ratios can be different with tubes of the same mu, and GG 
gain can be different.


73, Tom W8JI
w8ji@contesting.com

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