[Elecraft] On hand-twisting wires for bifilar windings...

[Don Wilhelm]

Folks,
Actually with the length of the wires used in the K2 for the bifilar
windings, I find them easier to do by hand twisting.  Cut the wires to the
length stated in the manual, then start in the middle of the wires - hold
the wires with one hand while overlaying the wires for approximately the
proper twist pitch with the other hand.  When you finish from the center to
one end, start in the center again and wind to the other end.  It would take
me longer to gather up a vise, seldom used pliers, cordless drill, etc. than
it does for me to hand twist the wires.

If you should try this method, the key to success is to let the ends of the
wires dangle free as you are twisting - that allows the wires to rotate as
they will while you twist and they will not have a tendency to 'spring back'
when released.  The exact turns per inch is not really that critical.  The
impedance of the 'transmission line' produced would be better if the wires
were not twisted at all, but laid perfectly parallel.  Twisting the wires is
just one way to keep the wires in close proximity to each other while
winding onto the toroid core.

As always, your mileage may vary, but that is the way I do it - and I have
never had a problem at HF (VHF and UHF would call for more critical
techniques).

73,
Don W3FPR

----- Original Message ----- 

| Just a note on Twisted Bifilar windings, when building my K2 and some
other
| stuff, I found my old hand drill, (with the crank on the side), works
ideal.
| I simply put a screw eye in the chuck, put the wires through the screw eye
| and attach the other end of the wires to a vise.  It makes it easy to get
| uniform, even twists of the wire and you have direct control as you crank.
| Obliviously you should not try this with a power drill, or even a power
| screw driver as you want to be able to slowly make the twist of the wire
to
| control the turns per inch.
|