[Heath] SB receivers and in general ferrite coils

[G3OOU at aol.com]

As Glen has already said, you can pick the core out in pieces - I use a  
very sharp scriber to break pieces off but it requires a lot of patience. If 
the  cores are ferrite they are nearly impossible to drill out but if they 
are dust  iron that is much softer and easier to remove.
 
I have had some success moving broken cores with a metal Allen key of the  
correct size - it needs to be a very snug fit. Once you have all of the 
broken  pieces removed clean the inside of the former to remove any debris.
 
Most cores will break if you apply force to them that is not evenly applied 
 across the entire contact surface. A poor fit trimming tool or one that is 
too  small will almost always cause core breakage. Some of the original 
Heathkit  trimming tools in my collection appear to have shrunk slightly over 
the ages and  are now a sloppy fit in the cores. These should not be used.
 
I have also tried using silicon tap grease when placing a good core back  
into the former with some success. I never use miniature rubber bands as they 
 can jam in the threads.
 
73

Bob

Bob F Burns
C Eng,  FIET, MSE
Amateur Radio Callsign: G3OOU
Registered RSGB  Instructor
G-QRP Member No: 6907; Zone: 14, QRA: IO91WH; WAB:  TQ25
Secretary of Crystal Palace Radio & Electronics Club: _www.g3oou.co.uk_ 
(http://www.g3oou.co.uk/) 
Technical web site: _www.qsl.net/g3oou_ (http://www.qsl.net/g3oou) 
Follow G3OOU as  @BobFBurns on Twitter _Http://twitter.com/BobFBurns_ 
(http://twitter.com/BobFBurns) 
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