Broken core

[recarter]

While winding the cores on my KPA100, I pulled too hard on the wire and broke one in the low pass filters.  I ordered a replacement from Elecraft.  I continued assembly as far as I could.  After staring sadly at the three core pieces, I thought of super-gluing the core back together.  My thought was to replace the repaired core with the replacement part when I receive it.  I fixed the broken core and finished assembly.  Gluing it back together was easy, but getting my fingers appart was a trick.  I think these things are just metal filings glued together anyway.  Is there any reason that the repaired core would have to be replaced?

Rich - KE1EV
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[Vic K2VCO]

[hidden email] wrote:

> While winding the cores on my KPA100, I pulled too hard on the wire
> and broke one in the low pass filters.  I ordered a replacement from
> Elecraft.  I continued assembly as far as I could.  After staring
> sadly at the three core pieces, I thought of super-gluing the core
> back together.  My thought was to replace the repaired core with the
> replacement part when I receive it.  I fixed the broken core and
> finished assembly.  Gluing it back together was easy, but getting my
> fingers appart was a trick.  I think these things are just metal
> filings glued together anyway.  Is there any reason that the repaired
> core would have to be replaced?

In my opinion, a super-glued core is just fine.  I've done it with no
ill effects (although not in my K2).  You are right that they are made
of metal particles glued together (and insulated from each other).  I
will be interested to hear what others say.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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[Alexandra Carter]

I'd NOT use super-glue, sheesh!! It amazes me how people think this
stuff is a cure-all. It gets brittle, outgasses, and I'd not let it
anywhere near any beautiful Elecraft product!  I'd use J-B Weld, which
is a very strong epoxy glue and should make the core good as new. 2nd
choice is just regular old 2-part epoxy glue. 73 de Alex NS6Y

On Mar 15, 2006, at 6:20 AM, [hidden email] wrote:

> While winding the cores on my KPA100, I pulled too hard on the wire
> and broke one in the low pass filters.  I ordered a replacement from
> Elecraft.  I continued assembly as far as I could.  After staring
> sadly at the three core pieces, I thought of super-gluing the core
> back together.  My thought was to replace the repaired core with the
> replacement part when I receive it.  I fixed the broken core and
> finished assembly.  Gluing it back together was easy, but getting my
> fingers appart was a trick.  I think these things are just metal
> filings glued together anyway.  Is there any reason that the repaired
> core would have to be replaced?
>
> Rich - KE1EV

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[Stuart Rohre]

Super Glue should be fine.  Some epoxies however, have fillers in them and
might NOT be passive to the RF specs of the core.

I saw this happen while working in the EMC field.  We were testing a
transformer for a customer that had to attenuate RF passage thru its core
and windings.  It was a three phase power unit for a LORAN station.

They potted each phase core in a chassis with epoxy and sand mix.
Unfortunately, there were some ferrous rocks in the mix and, the RF
attenuation was affected such that the transformer FAILED the RF attenuation
test.  It passed LORAN signals like a tuned circuit!

Made me realize that colorant in an epoxy might mean there are things other
than adhesive in the mix.

Stuart
K5KVH



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