[Amps] Plate impedance

[Will Matney]

Rich,

*********** REPLY SEPARATOR  ***********

On 4/10/06 at 6:07 AM R; Measures wrote:

>On Apr 9, 2006, at 10:17 PM, Will Matney wrote:
>
>> All,
>>
>> I started reading through the RCA Radiotron Handbook this evening 
>> looking for where the factor of 1.8 is listed for calculating the 
>> plate impedance of a class AB amplifier, and I can not find it.
>
>A factor of 1.8 is close enough.  The exact factor is dependent on 
>ZSAC, so there is no magic number written in stone.


I understand that as it will never be exact as there's too many variables involved. That's about like designing transformers. By the way, the old formulas in this edition of the Radiotron Designers Handbook on transformers, I don't agree with. Where they came up with those figures I don't know, but they differ from every book on the subject I've read. They only mention using iron up to 10 kilogauss, which today is low. Most now run from 12 kilogauss (as conservative), on up to 15 kilogauss (some higher). These formulas will get you lost more than the old 5 / A formula when you try to plug the result into the long formulas.


>
>> The edition I have was the older one back in the 40's with the black 
>> cover. The red one was from the 50's and had more in it if I recall, 
>> but I don't have it. I was wanting to find where it gives this factor, 
>> and the ones for Class A, AB1, AB2, B, and C. Bill Orrs handbook gives 
>> the factor of 1.8 on his Pi tank values table, but doesn't mention 
>> anywhere in the text where it came from. I also looked in a RCA 
>> receiving tube book and could not find it there either, or I am 
>> overlooking it somewhere. I could have sworn it was in the Radiotron 
>> Handbook. The Handbook does say that the plate impedance is twice the 
>> peak voltage swing times the peak anode current. What I'm wanting to 
>> know is where are these factors located in print, as I'd like to read 
>> the whole texts concerning this? Any help
>>   would be deeply appreciated. Thanks to all in advance.
>>
>> Best,
>>
>> Will
>>
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>
>
>
>Rich Measures, 805.386.3734, AG6K, www.somis.org