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Re: [Amps] IM distortion and such

To: "'R L Measures'" <>,"'W2RU - Bud Hippisley'" <>,<>
Subject: Re: [Amps] IM distortion and such
From: "Dave" <>
Date: Tue, 27 Jun 2006 01:29:45 -0400
List-post: <>
Who designed the SB220?


      Dave, AA6YQ

-----Original Message-----
From: [] On
Behalf Of R L Measures
Sent: Monday, June 26, 2006 23:39 PM
To: W2RU - Bud Hippisley
Subject: Re: [Amps] IM distortion and such

On Jun 26, 2006, at 1:30 PM, W2RU - Bud Hippisley wrote:

> Tom W8JI wrote:
>> One of the best engineered amps on the market was the
>> SB220. It was amazingly cheap for the results, and they had a very 
>> good service life when operated according to manufacturing specs. 
>> That amp is a prime example of good engineering for the market place.
>> By the way, when all the patches and fixes that are touted as 
>> life-improving mods are added to an amp in amateur service the 
>> primary failure mechanisms will still be uncontrollable. All those 
>> cost adding mods wouldn't do a thing in the big picture.
> With respect to Tom's first paragraph above:  I still have the
> SB-220 I
> built more than a quarter of a century ago.  I think I've replaced a
> grand total of one tube in all that time, despite pounding it to death
> in contests, DXing, and general operating over the years.  During that
> period, I have transmitted into the wrong antenna or no antenna more
> times than I care to remember.  it still has the original cooling fan
> and it's the quietest legal limit amplifier I've ever owned, used,  
> or heard.
> With respect to Tom's second paragraph above:  Once upon a time I
> owned
> an ETO PA-76.  I didn't keep it because it kept "breaking" despite the
> (excessive) control circuitry in it.  I currently also own an  
> AmpSupply
> LK-550 (to operate 160) and its unnecessarily complex interlock
> circuitry frequently keeps the Operate / Bypass relays from energizing
> when requested.  One of my pending shack projects is to "gut" the
> control section of this amplifier so it approaches my SB-220 in
> simplicity and reliability.
> For *me* (and I emphasize "me"),  3-500Z amplifiers represent the best 
> available combination of reliability, resilience to dumb operator 
> errors, tube (valve) replacement cost, TVI minimization, and required 
> drive levels (relative to my favorite transceivers) for amateur MF/HF
> amplifiers.    After my first PL-172 failure, I used to cringe every
> time I turned on my old HT-33A, and I developed similar reactions to
> firing up the PA-76.    By contrast, I don't live in fear of  
> energizing
> my SB-220, and it is, consistent with remarks by both Tom and Rich at 
> one time or another, one of the best values I've ever found in any
> of my
> hobbies.

Amen, Bud, and the few needed mods to the SB-220 are minor.
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R L MEASURES, AG6K. 805-386-3734

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