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[Amps] Hard-drive Dive

To: <amps@contesting.com>
Subject: [Amps] Hard-drive Dive
From: 2 at vc.net (2)
Date: Sun Mar 23 10:45:34 2003

>2 wrote:
>
>K7FM had written:
>>>I do have a Collins 30S-1 amplifier.  It does
>>>not have parasitic suppressors.
>>
>>**  Vern Baumgartner, a friend who worked as an engineer at Collins 
>>Radio told me that Ni-Cr alloy was used as a conductor in the 
>>4cx1000A's anode circuit.
>>
>Let's be careful with the facts here. Looking at the schematic of the 
>30S-1, there is no conventional R/L parasitic suppressor. 

**  who said there was a R/L suppressor in the 30S-1 ?

>There is an 
>"L101" between the anode connector and the HV blocking cap, right where 
>you would expect a parasitic suppressor to be. The photograph shows a 
>substantial inductor of 3-4 turns of thick wire, about 0.75-1in diameter 
>and 2-3in long.
>
>This is the only place where it could make any conceivable sense to put 
>a parasitic suppressor; but what L101 is made of, the manual sayeth not.
>
>At a glance, there's something connected to the anode called "Z-101" 
>that looks like a parasitic suppressor, but it is in the path to the 
>capacitive divider that provides RF negative feedback. In that location, 
>Z-101 cannot damp the VHF parasitic resonance of the plate circuit. 
>However, this deliberate additional RF feedback path will also make the 
>30S-1 behave differently at VHF than amps that don't have this feature.
>
>The 30S-1 is a unique amplifier. It contains many RF, power-supply and 
>mechanical features that were highly innovative and individual to that 
>amplifier. Some of these features will only work together as a 
>"package". Attempts to copy individual aspects have generally not been 
>successful, because the copiers weren't as smart as the original Collins 
>engineers, and didn't understand how everything interacts.
>
>In short, the 30S-1 is a dangerous precedent for *both* sides of the 
>nichrome controversy!
>
**  I was unable to confirm Vern Baumgartner's (W6HW) statement about the 
30S-1, which is why I omitted it from the January, 1994 QST article.    
However, in the 8169 and 8170 amplifiers I built, instead of a 
conventional R/L suppressor, I tried the idea of a resistive anode 
circuit conductor.  It seemingly worked.  In the 8170 amplifier, there 
were several big-bangs before I switched to a more resistive conductor.

-  R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K, 
www.vcnet.com/measures.  
end

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