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[AMPS] HA-10 Warrior Parasitic Supressor Inductor Values

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Subject: [AMPS] HA-10 Warrior Parasitic Supressor Inductor Values
From: (2)
Date: Mon, 3 Sep 2001 11:10:53 -0700
>Tom Rauch wrote:
>>> > One factor that apparently 
>>> >increased the Warrior's VHF instability was so-called
>>> >"neutralization". 
>>> "So-called" is correct. According to the schematics, it consisted of a
>>> feedback capacitor from the output end of the pi-tank, back to the
>>> cathode. This will produce feedback of variable amplitude and phase,
>>> depending on the settings of the bandswitch and the tuning and loading
>>> controls. It's hardly surprising that the amp was more liable to
>>> oscillate at some frequency.
>>That is NOT correct Ian. Bad enough that Rich says things without 
>>being fully aware what is going on! 
>>The feedback in the Warrior is from the anode, through a capacitor, 
>>through a phase inverting transformer, to the filaments.
//  Rich is fully aware that the 811's filament is the "cathode" (Ian). 

>>The tuning of the tank has a very minimal effect on phase shift. 
>>This is a simple modified bridge system.
>>I think you are wrongly confusing it with the system in a Yaesu 
>>572B amplifier where feedback is taken AFTER the output tank, 
>>which of course WOULD shift phase with tank tuning and 
>>destabilize the amplifier at HF with some tank settings.     
>Sorry, it appears I was confusing the Warrior with another amp... maybe
>the Yaesu, though I don't recall ever seen that schematic.
//  The Warrior and the Gonset 4, 811A amplifier used the same 
neutralization scheem. 

>I agree that a phase inverting transformer, coupled as you describe,
>produces a bridge neutralizing arrangement which is pretty much as
>broadband as the transformer itself.
//  However, there must be a frequency-dependent phase shift somewhere 
since such is known to regenerate above HF. 

>>> >Gonset also used neutralization in their 4, 811 amplifier.  
>>> I'm not familiar with that schematic: would that be real
>>> neutralization, or more of the bogus kind?
>>Before you say "bogus", you should look at the system. It works 
>>very well in Heath's amp and other amps. It has nothing to do with 
>>VHF oscilations, it is to stabilize the amp at upper HF.
>I applied the term "bogus" to the system I described, not the one that
>is actually in the Heath Warrior.
//  blowin' smoke

>>Let's not feed people trying to learn misinformation Ian!
>Sorry, I was misinformed myself!
//  perhaps not.

cheers, Ian

-  R. L. Measures, 805.386.3734,AG6K,  

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