[HBR] Need advice on Miller 1730 transformers

[Bill Cromwell]

On 01/13/2014 05:09 AM, Werner, HB9BNK wrote:
> Back around 1970, I built a HBR-13C (with great help from Alex 
> Stewart). Having studied the valuable reflections-CD and the 
> discussions here, I recently pulled the receiver from the attic and 
> try now, to get it running again - and improve, if possible.
>
> Now, I found, that some of the I.F.filters cannot be tuned, because 
> the core's are locked by whatever ...
>
> Can someone give me an advice, how to free the core ?
>
> Thanks and 73
>
> Werner, HB9BNK

Hi Werner,

I haven't done this because I haven't had the problem. Other hams have 
reported success using heat. They use something like a metal allen 
wrench or a small screwdriver - NOT to force the slug (core) - to apply 
the heat. Do not use the the metal tool to force the slug or you will 
break the slug. You probably already knew that. Apply heat from a 
soldering iron or solder gun to the metal part of the tool to transfer 
heat to the slug. The heat will transfer from the soldering iron, 
through the metal tool, and into the slug. Be careful, of course, to not 
let the hot metal or iron touch anything else. Try just a little heat at 
first to see if some of the wax has migrated into the 'threads' and to 
soften it. More heat if needed. The expansion/contraction you hope will 
break the 'bond' and free the slug.

If the slug is already broken you will have to crumble it out of the 
form and replace it. You probably already knew that, too. I mention 
those things since there will be readers of this thread who would not 
otherwise know.

Good luck with your HBR project. Let us know how this goes for you. I 
have been accumulating parts in a bin for an HBR or my own. I am interested.

73,

Bill  KU8H