[Amps] Peter Dahl / Harbach SB-220 transformer

[Carl]

----- Original Message ----- 
From: Gudguyham at aol.com
To: km1h at jeremy.mv.com ; jim.thom at telus.net ; amps at contesting.com
Sent: Friday, June 11, 2010 7:02 PM
Subject: Re: [Amps] Peter Dahl / Harbach SB-220 transformer




In a message dated 6/11/2010 9:20:21 A.M. Eastern Daylight Time, 
km1h at jeremy.mv.com writes:
I guess Jim doesnt understand that more RF places more stress on an already
marginal bandswitch Lou to say nothing about increased gain can result in
instability as proven in many amps.

Some like to go for the most meter wiggle and the heck with reliability(-;

Carl
KM1H

Carl, I would be the first one to agree that the band switch in the SB-220 
is marginal for the total power that a pair of 3-500's can produce.  I 
suppose the thought process by the designers was that since I KWDC input was 
the "law" and about 600 watts out being the norm, the band switch was fine. 
Moving forward to today's law everyone was kicking the power output up and 
the band switches were failing.  I would say that about 7 out of 10 of the 
amps I gut for 6 have a band switch issue with one or more contacts. 
Usually 10 meter contact.  Sometimes 10 and 15.  Although Denny cut corners 
here and there, he did supply a much better band switch in the Dentron and 
AS amps.  Drake also had a very good band switch, rarely did I ever see a 
bad one.  The bigger Ameritron amps have a good band switch also.  If you 
want to go for that "meter wiggle" you had better build up for it.  Just 
like the days of drag racing, MO power, bigger and more HD clutch and gears, 
wider tires traction, bars etc etc. Lou


Agree Lou, the biggest problem with the 220 is the switch indexing, you can 
see that the blown ones barely have the rotor touching the contact. A couple 
of years ago I bought 200 contacts from Electroswitch and am now running 
low; the rebuilt switches go as fast as I can do them.

Dont get me going on drag racing, Im back into it in the vintage classes for 
the past several years.This may be the last season.

Carl
KM1H