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Re: [Amps] Retraction with regard to the SB220

To: Jeff Carter <>
Subject: Re: [Amps] Retraction with regard to the SB220
From: "Roger (K8RI)" <>
Date: Fri, 28 Mar 2008 00:26:51 -0400
List-post: <">>
Jeff Carter wrote:
> Okay, someone just told me I've committed a faux pas.  I've come here
> to correct myself.

You being new didn't make any mistakes. We just have some people who are 
too sensitive about some things.  When a newbie asks a question it's not 
the same as an "old timer" who is well known asking  the same thing.
> There's a subject regarding my two project amps (both SB-220's) that
> just isn't discussed in public anymore due to some sort of argument
> that happened long before I ever knew this list existed.  I didn't ask
> about it to start another fight, I was merely trying to gather
> information, and for those who were offended, I can only offer my
> apologies.  I will try to avoid any mention of it in the future and I
> retract my former mention of the subject.
You asked only natural questions for someone starting out and 
particularly after looking at what you see in commercial amps.
> Now that *that's* out of the way, I would absolutely love to visit any
> links or read anything anyone has to say about their personal
> experiences with the SB-220, which I am about to spend a lot of money
> lovingly refurbishing in the attempt to learn something about HF
> Amplifiers.   Anything, of course, which does not approach That Which
> We Don't Talk About Anymore.
   It's always easier to start out rebuilding, or restoring something 
that already works.  Although that is not among your options I think you 
have chosen one of the best projects to start  out with, *dangerous* 
voltages aside and the 220 does indeed contain some very dangerous voltages.

The SB220 is a very simple, straight forward circuit, while the amps and 
tubes are widely available at reasonable, or even inexpensive prices.  
They make a good restoration or even modification project and it's not 
one so complicated as to cause the builder to  give up in frustration.  
(you should try thousands of hours building or rebuilding an airplane 
that is going to be supporting your backside one or two miles above the 
ground) <g>

Study the manual, and I'd suggest the ARRL Hanbook sections relating to 
construction, safety, and trouble shooting practices.  Then when ready 
to reassemble, do it in stages.  Starting with the power supply make 
certain the voltages are what they should be.  Be neat and methodical 
and safe.  Remember you will be working with voltages that can kill 
almost instantly.  AND for the just-in-case something goes wrong there 
should be a way of removing the voltage from the amp without someone 
else having to come near it such as a kill switch or even extension cord 
that could be pulled out of the outlet.

Good luck in your project es 73

Roger (K8RI)

> Thanks in advance,
> Jeff/KD4RBG
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