Re: Neurotic about Toroids

[n7on]

Lee--

I felt precisely the way you do now when I received my K2 in July--the
toroids appeared daunting for a novice kit builder who'd never wound and
tinned one.

Take some enamalled wire and practice tinning (don't burn your fingers).
Then wind and tin a few and see how you feel.  I liken the process to
sewing wire around a small doughnut.  It's easy to get the hang of it.
I've only had one toroid problem, and I quickly caught it--be careful to
put the leads in the properly numbered through-holes, especially with
bifilar windings.

A few of my tricks:

--make the windings symmetrical.  If the instructions call for seven
turns, I try to make sure there are three turns on the right, three turns
on the left, and one turn at the top of the core.  With an even number of
turns, half are on the right, half on the left, and the top of the core
is between windings.

--someone mentioned wire-winding direction:  be sure to refer to the
manual's photos and make sure the leads enter and exit the core properly.
 I believe all Elecraft toroid leads enter and exit the core with the
same winding "sense."

--the wire will have a natural bend or curve.  Try to sew the wire in the
direction of the bend--that'll reduce the likelihood of kinks and
simplify winding.

--Elecraft's Gary reminded me to be reasonable with the tightness of the
wire around the core.  A small amount of "give" will permit you to
fine-tune the wire spacing before installation.

--my toroids always look better once they're installed.  Before
installation there's no tension at all, so it's normal that they may not
appear perfect (just close to it).

--tinning:  there are probably as many methods as there are kit builders.
 I bought four small standoffs and a small PC board from Radio Shack and
made a small platform.  After melting a solder blob on the board, I
proceeded with the already-mentioned solder blob enamel-stripping method.
 Works like a charm.

--use your DMM to check for continuity after installation, pad to pad,
not lead to lead.  Once while building the K2 I thought I'd shorted the
bifilar windings on a toroid because there was continuity between the red
and green wires.  A quick check of the Elecraft reflector archives and
the K2 schematics showed everything was fine--there was supposed to be
continuity.

--take your time.  The more meticulous your construction method, the less
time you'll spend troubleshooting.

The Elecraft website has many toroid photos.  I took photos of most of
mine during K2 construction, let me know if you'd like me to send you
any.

Never hesitate to ask questions on the reflector or to contact Elecraft
for help.  Both are superb resources and have been of great assistance to
me.

I'm absolutely delighted with my K2 and don't understand why every active
HF'er doesn't have one.  My second kit, the KPA100, arrived Friday.

Finally, keep this in mind:  if you can identify, install, and solder the
first K2 component, R5, you can successfully build the kit.

73,

John, N7ON
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