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[AMPS] Parasitic suppressors/another question,

To: <amps@contesting.com>
Subject: [AMPS] Parasitic suppressors/another question,
From: measures@vc.net (Rich Measures)
Date: Thu, 8 Apr 1999 17:38:31 -0700


>
>>>> Having designed commercial 800 MHz amps in the past, I prefer to have 
>>>> them stable (as much as possible) across all possible load conditions.
>>>> 
>>?  However, in uhf amplifiers the anode-resonance is the tank.   In hf 
>>amplifiers there are usualy two resonant circuits connected to the anode. 
>
>Agreed. Still you can design an HF amp to be unconditionally stable and 
>test for that condition as well.

?  Tuning the HF tank circuit and disconnecting the hf load have 
virtually nothing to do with what is happening in the anode-resonant 
circuit where the parasitic oscillations take place.  
>> .  
>>>And if it is with no drive applied and the neon glows
>>>orange it means it is oscillating on or near the band selected - not so?
>>>
>>?  In my experiences, g-g triodes can occasionally oscillate in steady 
>>state without drive above the grid self-resonance.  In a 3-500Z, this is 
>>approx. 80MHz. 
>
>Well, then those amps have design problems.  Did those oscillations that 
>you mention from your experience occur with our without your nichrome 
>suppressors?  

?  Both.  Resistance-wire suppressors lower VHF gain compared to 
copper-wire suppressors.  



Rich...

R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures  


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