Stuck Ferrite Cores

Hello all friends of tube radios! It happens all over again when tampering with these old tube gadgets that some of the filter ferrite cores will break when trying to adjust them by force. My remedy here has been bying a cheap similar set but it seems not to be a good solution on the long run. So, my question is; what is the best solution to loosen a ferrite core from its stuck position? I read somewhere that a ear wax remover would be a good way, but before bying this sort of stuff, I'd be appreciated to hear your oppinion. With Kind Regards Lars-G.

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Hello Lars,

I have used a variety of methods and usually succeed in the end. The following order is suggested.

1.  If it is accessible, place tip of hot soldering iron on the core for a few seconds.  Care needed as can damage plastic or change permeability.

2.  Lighter fluid or iso-propyl alcohol - a few drops and allow to penetrate.  Ear wax solvent would have the same effect and I have heard that it has been used.

3.  Small spot of WD40 if above techniques do not shift.  Allow to penetrate for an hour.

If possible attack from both ends - only occasionally possible.    The correct trimming tool is essential of course, it is all too tempting to use a screwdriver on a hex core!

Regards,

Roy

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Hi, Lars,

in Addition to Roy's suggestions, here is, what i have been succesfull with:

- If the Core is not visible, because of Wax above the Core, i first remove this Wax carefully with a selfmade tool ( looks like a Screwdriver, but made out of Plastic, so it won't scratch the Core.)

- then i heat up a matching tool ( out of metal ) by putting it in hot Water ( 70 - 80 °C ). When hot, i put that tool into the core, to melt the Wax in the slit of the core. It is important to have a tool, that fit's into the core very good.

- then i try, with a limited Force, turning the Core clockwise ( the Core will move down easier than up ). Most times it takes a Minute or two, until the core starts to move.

- when the Core has started moving, i gently try to keep it moving, going back and forth, until the Core moves easy. Don't get too far "down", to avoid Contact with the second Core.

- then i remove the Core. 

Statistics with this Method: only one broken Core within the last five Years.

Hope this helps,

Best Regards,

Henning Oelkers, Berlin, Germany 

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Hello Roy and Henning! Thank you very much for your advices. Going to try them out as soon as possible on my Philips 433A prensently on my work bench with two cores badly jammed. Regards Lars-G.

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