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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 04:22:42 -0700
>My old Warrior's parasitic supressors need to be
>changed and I need to know what the optimum value of
>inducatance is for the supressor.  The carbon type
>resistors are showing their age as well.  Not one is
>even close in value.
>The amp runs four 811A tubes.
>Bill Smith
//    Suppressor resistors (Rsup) typically increase in resistance during 
an intermittent parasitic oscillation condition.  Thus, it seems likely 
that you had one or more.  For instance, I have seen Rsup in a MLA-2500 
increase from 100-ohms to c. 400-ohms.  
-  Designing suppressors is not a black art.  Lsup needs to have enough L 
to cause Rsup to become quite hot on 29MHz.  This situation yields 
optimal VHF suppression -- i.e., reduction in VHF gain at the VHF anode 
resonance of the tube(s).  At this frequency, the reactive-ohms of Lsup 
and the resistive-ohms of Rsup need to be roughly equal.  The only test 
equipment needed is a dipmeter.  However, my guess is that the Warrior's 
anode resonance is c. 80MHz.  If this is the case, roughly 0.18uH and 
100-ohms would be about right.    In a nutshell, more L gives better VHF 
suppression with the tradeoff of more heat in Rsup at 29MHz.
-  One factor that apparently increased the Warrior's VHF instability was 
so-called "neutralization".  Heath did not use neutralization in its 
subsequent models of GG amplifiers.  Gonset also used neutralization in 
their 4, 811 amplifier.  From personal experience, I know that the Gonset 
intermittently oscillated at VHF.  The fix was lower VHF-Q suppressors 
and removal of the neutralization circuitry.  
-  For improved transient regultion on SSB, the Warrior's HV supply's 
filter choke needs to be resonated at c. 150-Hz.  If 572Bs are used, the 
filter choke can be shorted out to increase the anode supply voltage and 
PEP-out on SSB.  However, the increased voltage may necessitate raising 
the  voltage capability of the filter C.  
- For SSB, 811As should be tuned up with a tuning pulser or a keyer 
sending 50-wpm dits. 

cheers, Bill

-  R. L. Measures, 805.386.3734,AG6K,  

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