[Heath] SB-610 focus problem?

[G3OOU at aol.com]

Hi Sandy
 
I have the same problem on my SB610 which I suspect is due to out of  
tolerance resistors around the tube voltage divider circuits. Heath never  
provided any form of astigmatism control on those scopes so that meant that some  
of the control voltage divider resistors had to be 'averaged' for best 
focus.  The resistors have probably aged upwards over the years so a good idea to 
check  them all with a meter.
 
The later scopes like the SB614 had an astigmatism control so you could use 
 that information to add one to your SB610 with a new preset on the rear  
panel.
 
73

Bob

Bob F Burns G3OOU
C  Eng, FIET, MSE
G-QRP 6907
Secretary of Crystal Palace Radio &  Electronics Club: www.g3oou.co.uk
Technical web site:  www.qsl.net/g3oou
@BobFBurns on Twitter: http://twitter.com/BobFBurns  

 
In a message dated 28/10/2013 15:18:31 GMT Standard Time, ac1wye at gmail.com  
writes:

 
Hi,  folks,


I've  been using my '610 for a long time and it's always been reliable, 
especially  after I recapped it.


I'm  wondering about something. For those who run these, have you ever 
noticed how  the trace line can be focused real sharp in the center and it gets 
out of  focus at the edges? Not by a whole lot, but it's noticeable.


I  also have a HO-10 I've rebuilt and I use that on my bench with my dummy 
load  for testing. The horizontal trace on that is clean all the way across 
once the  focus is set.


Is  there something I need to get into and check on the '610, maybe an 
out-of-spec  resistor(s) or something else in the Focus circuit? Anybody have a 
thought on  this?



 
 
 
 
 
 
 
Thanks es  73,   Sandy AC1Y



Alexander N. Gerli,  Sr.

548 Allred Mill  Road

Mount Airy, NC  27030-2202


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