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Re: [Amps] [Heathkit] The SB-220

To: "RICHARD SOLOMON" <w1ksz@q.com>, "Amplifier Reflector" <amps@contesting.com>
Subject: Re: [Amps] [Heathkit] The SB-220
From: "Carl" <km1h@jeremy.mv.com>
Date: Sun, 23 Aug 2009 13:09:12 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Do you have Google available?

I do have the hard copy.

Carl
KM1H


  ----- Original Message ----- 
  From: RICHARD SOLOMON 
  To: Carl ; Amplifier Reflector 
  Sent: Sunday, August 23, 2009 12:41 PM
  Subject: RE: [Amps] [Heathkit] The SB-220


  Do you have a copy of that Heath Service Bulletin ? Or know if
  it is on-line ?
   
  73, Dick, W1KSZ
   
  > From: km1h@jeremy.mv.com
  > To: w1ksz@q.com; amps@contesting.com
  > Subject: Re: [Amps] [Heathkit] The SB-220
  > Date: Sun, 23 Aug 2009 10:24:08 -0400
  > 
  > Amen to that.
  > 
  > The huge majority of amps that I buy for 6M conversion are 100% untouched 
by 
  > voodo science and have no signs of problems ever.
  > 
  > OTOH, a few with directly grounded grids Ive bought real cheap since a 
tube, 
  > meter, bandswitch, zener, or all the above is blown.
  > 
  > I can guarantee that any SB-220 that is acting up can trace the problem to 
  > out of tolerance suppressors, dirt, nicotine. Voodo kits will work and so 
  > will new resistors, its a matter of choice as neither offers more than the 
  > other.
  > 
  > Keeping the grids above ground enough to reduce tube gain a bit is still 
the 
  > best way for long term stability with any brand and combination of tubes.
  > 
  > I realize that most on here dont own a spectrum analyzer and many dont have 
  > a clue about neutralization. While the SB-220 is pretty stable as designed 
  > it can take off under some tuning conditions, tuners, antennas, etc. No 
  > amount of nichrome will help. Reducing gain will. Or adding a neutralizing 
  > circuit which isnt worth the effort.
  > 
  > If some want to create a cottage industry by offering unneeded 
modifications 
  > to the unknowing then go for it. Its the American way and P.T. Barnum would 
  > be proud.
  > 
  > Thats simply not my ethic.
  > 
  > Heath had a service bulletin to keep the filament transformer from burning 
  > out when a fault occurs. This affects 240V operation only and is a simple 
  > rewiring at the switch. Later kits had the change.
  > 
  > Carl
  > KM1H
  > 
  > 
  > ----- Original Message ----- 
  > From: "RICHARD SOLOMON" <w1ksz@q.com>
  > To: "Amplifier Reflector" <amps@contesting.com>
  > Sent: Saturday, August 22, 2009 9:09 PM
  > Subject: Re: [Amps] [Heathkit] The SB-220
  > 
  > 
  > >
  > > I must lead a charmed life ... in 54 years of Hamming and three
  > >
  > > SB-220's along the way, I have never had such catastrophic
  > >
  > > failures as I have seen described. In fact, several of my friends
  > >
  > > who also had SB-220's have experienced similar luck. And we
  > >
  > > were not known for treating these amps with kid gloves.
  > >
  > >
  > >
  > > There must be some random failure mechanism that has not
  > >
  > > migrated to One land ... perhaps the cold ??
  > >
  > >
  > >
  > > That being said, insurance is always a good thing and I have
  > >
  > > already installed the AG6K suppressors in my 6 Meter Conversion
  > >
  > > and the bias mod will be next. Can't be too careful you know !!
  > >
  > >
  > >
  > > 73, Dick, W1KSZ
  > >
  > >> Date: Sun, 23 Aug 2009 08:59:34 +0800
  > >> To: amps@contesting.com
  > >> From: vk6apk@bigpond.com
  > >> Subject: Re: [Amps] [Heathkit] The SB-220
  > >>
  > >> Good on you Lon. Well said.
  > >>
  > >> My experiences are similar to your's. In every amplifier that I have
  > >> installed Nichrome, whether commercially made or home brew, the
  > >> change has been very noticeable.
  > >>
  > >> I don't care who invented the idea or how it works. I don't care
  > >> about others who say it doesn't work and that it is snake oil. I just
  > >> know that I'll continue to use it and enthusiastically recommend it to 
  > >> others.
  > >>
  > >> Whether it cures the cause or the symptoms, is totally irrelevant to
  > >> me. The science and the maths are of no concern either.
  > >>
  > >> I compare it to silicon sealer, self drilling screws, battery drills
  > >> and the like. Life would be dreadful without them.
  > >>
  > >> 73, Alek
  > >> VK6APK
  > >>
  > >>
  > >>
  > >>
  > >> At 03:13 AM 23/08/2009, k5jv wrote:
  > >> >Greetings to all,
  > >> >
  > >> > I usually do not comment on topics like this but could not resist
  > >> >this time. I, also, have been repairing amps for about 40 years -- have
  > >> >probably worked on 100 SB-220's. I think it is the best watt/dollar
  > >> >available in an amplifier today. However, as it was originally 
designed, 
  > >> >it
  > >> >is just an accident looking for a place to happen.
  > >> >
  > >> > I use nichrome wire (nichrome ribbon in larger amps) in the anode
  > >> >suppressors, not because it is the best material, but because, as 
  > >> >Richard
  > >> >Measures said nearly thirty years ago, it is relatively easy to work 
  > >> >with,
  > >> >readily available, inexpensive, and does the job. In all my years in
  > >> >working on amps, I have never had, even one, come back for service, of
  > >> >parasitic related problems, after installing Measures parasitic 
  > >> >suppressors.
  > >> >I personally think that input network changes are as helpful, or more, 
  > >> >than
  > >> >the anode changes.
  > >> >
  > >> > After parasitic suppression, I think the most important modification
  > >> >is the bias mod. I do not know how many filament transformers I have
  > >> >replaced in SB-220's over the years, but it is safe to say that not one 
  > >> >of
  > >> >them would have needed replacement if the bias mod had been done. If you
  > >> >want to really make a nice amp out of your SB-220, you might want to
  > >> >consider Richard's QSK mod. It is relatively cheap, not too difficult to
  > >> >install, and really works.
  > >> >
  > >> > Another great amp is the Kenwood TL-922. Of course, it is nothing
  > >> >but a cleaned up SB-220, but, it is even more parasitic prone, due to
  > >> >placement of components in the final compartment, than the SB-220. It,
  > >> >also, needs the bias mod and a soft start mod. QSK makes this amp a
  > >> >pleasure to operate.
  > >> >
  > >> > I have known Richard Measures for nearly forty years. He is one of
  > >> >the real thinkers in the Amateur Radio field. I do not agree with
  > >> >everything he says, but I have never, not even once, found him to be 
  > >> >wrong
  > >> >wrong. No one else has either. Remember, they almost burned Galileo at 
  > >> >the
  > >> >stake for saying that the world is round.
  > >> >
  > >> >73 de Lon, K5JV
  > >> >
  > >> >_______________________________________________
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  > >> >
  > >> >
  > >> >
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