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[AMPS] Suppressors, measurements, and acrimonious blather

To: <amps@contesting.com>
Subject: [AMPS] Suppressors, measurements, and acrimonious blather
From: i4jmy@iol.it (i4jmy@iol.it)
Date: Thu, 3 Aug 2000 11:37:30 +0200
Mostly correct as general statement but also some tubes mechanical 
construction (internal electrodes or wires, socket dimensions and 
shape) lead to inherent stability problems and the best RF designer 
can't do anything else than trying to lower the amplifier gain at 
critical frequencies.
On the other hand I've seen a number of professional grade HF tube 
amplifiers totally without any VHF suppressors personally verifying 
they never had any single problem, including those that might be caused 
by VHF parasitic.


73,
Mauri I4JMY



 


> For myself, once I began designing with valves whose dimensions were 
less 
> than 1/8 wavelength at my operating frequency, I determined that all 
> instances of parasitic oscillation were due to poor component 
layout.  Pay 
> particular attention to where ground currents flow.  That tuning 
capacitor 
> has a grounded end.  Where does that ground current need to flow?  To 
the 
> grid of the grounded-grid valve!  Is that distance short?  What about 
the 
> load capacitor?  Do you know where that ground current must flow?  
Yes, to 
> the output connector!  You see, star grounding is not necessarily 
correct 
> all the time.  Just because a component has a short connection to the 
> chassis does not mean it's well grounded.
> 
> Whew.  Enough for me for now, I'm at risk of being called the 
Deuteronomist.
> 
> FF
> 


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