[AMPS] neutralizing

[measures]

>
>There is no reason that all amps, GG or otherwise, can't be or shouldn't
>be neutralizied.  

At the same time one must understand that while some
>tube and circuit designs are known to function quite well without
>neutraliziation, others (those where there is a high grid to anode C
>value) do require it.  
>
>However, don't confuse the need for neutralization with the need for
>parasitic suppression.  They aren't the same by a long shot. 
>Unfortunately, both show up as an instability......flash, bang!
>
>To see if neutralization is required, a study of IMD products must be
>undertaken.  
>
>A truly stable amp must be able to operate without any evidence of
>instability regardless of the input load or output load and with any
>combination of tuning adjustments.  Stable is stable.
>
>73
>Bob K4TAX
>
>carl seyersdahl wrote:
>> 
>>  I've known about neutralizing amps for many years, and repaired many of
>> them for the gov't but I don't recall ever seeing a GG amp neutralized.
>> Since the plate and cathode ckts. are in phase with each other, and 180
>> degrees out of phase with the grid, it follows that , directly from plate to
>> ground one would need a phase inversion. this of course could be done with a
>> coil and a cap, but it doesn't seem to me that the feedback would remain
>> exactly what it needs to be on all bands in a bandswitching amp. in the old
>> days, with grid driven amps, and single band, it seemed to work well, but
>> today it's a different story. all this is what I learned over the years, and
>> of course I could be slightly off base or have forgotten my basics(it's been
>> a looong time) and I was out of the game for nearly 30 years!!!I've recently
>> repaired some sb200's and one sb220 and the owners are happy with them(and
>> the amps aren't neutralized), so maybe I haven't totally lost touch with
>> reality.Any comments?? (I can still learn!!)       carl / kz5ca
>> 
>> --
>> FAQ on WWW:               http://www.contesting.com/FAQ/amps
>> Submissions:              amps@contesting.com
>> Administrative requests:  amps-REQUEST@contesting.com
>> Problems:                 owner-amps@contesting.com
>
>
>--
>FAQ on WWW:               http://www.contesting.com/FAQ/amps
>Submissions:              amps@contesting.com
>Administrative requests:  amps-REQUEST@contesting.com
>Problems:                 owner-amps@contesting.com
>
>


-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


--
FAQ on WWW:               http://www.contesting.com/FAQ/amps
Submissions:              amps@contesting.com
Administrative requests:  amps-REQUEST@contesting.com
Problems:                 owner-amps@contesting.com