[AMPS] neutralization

[Ian White, G3SEK]

Rich Measures wrote:
>  
>This circuit is not found in *Care and Feeding of Power Grid Tubes*.     

So? 

If it isn't in "C&F" or some other 30-year-old publication, does that
mean that it can't exist or can't be correct? A few new things have
happened since then.


> I liked Ian White's comment that, due to phase shift, every 
>negative-feedback [neutralization] circuit (at the fundamental frequency) 
>becomes a positive-feedback [regeneration] circuit at some higher 
>frequency.   

No, not "some higher frequency": I said "some DIFFERENT frequency".
My own main concern is with VHF/UHF amps that need to be stabilized on
LOWER frequencies. It just shows that you have to consider each case
very carefully on its own merits.

I still have to smile about the alleged damage caused by VHF
oscillations to tubes such as the 3CX800 and 8877, which will happily
pump out 1kW or more in amplifiers for 50, 144, 220 and even 432MHz.


73 from Ian G3SEK          Editor, 'The VHF/UHF DX Book'
                          'In Practice' columnist for RadCom (RSGB)

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