[GreenKeys] Model 26 Update

[Roy Morgan]

On Feb 19, 2015, at 9:13 AM, Doug Alderdice <ka2wft at arrl.net> wrote:  
> 
> ...the damage to this coil was such that it wasn't too hard to repair. ... I was able to find two ends with enough lead on them to be able to test continuity and more importantly, tack solder a splice to them.

There’s a trick to soldering to fragile enameled wire, including litz wire (which is nearly impossible to strip):

Put a common aspirin under the end of the wire and apply the solder pencil to the wire onto the aspirin.  The insulation should come off.  Carefully clean the wire and coil area well and solder.  (This may not work with modern high temperature magnet wire.)

I suggest making very sure the new lead wire can’t pull on the fragile winding.  A bit of epoxy, or maybe transformer tape applied very carefully might be in order.

Further, rewinding such a solenoid coil should not be impossible.  Getting a good measure of the original wire diameter/guage is important, then just fill up the bobbin with the wire to the original thickness.  I’ll bet our favorite transformer rewinder in Maine would be able to rewind magnet coils at modest cost:

Gary Brown, WZ1M,  
Transformer Rewind Service
478 Forest Ave.
Orono, Me.
04473
xfrmrs at roadrunner.com
http://members.tripod.com/tubes_tubes_tubes/transformerrewindingservice/

Roy

Roy Morgan
RoyMorgan at alum.mit.edu
K1LKY Since 1958