[Elecraft] Neurotic about Toroids

[Ron D'Eau Claire]

KI6AZS wrote:

 But how do you know you have not tinned the enamel, since the whole thing
is covered in solder?

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Use you ohmmeter to confirm continuity from one end to the other. 

The biggest mistake most builders make tinning the toroid leads is that they
fail to tin them close enough to the body of the toroid. You need to tin
right up to the core! Unwrap a part of a turn so you can tin he wire without
burning the adjacent turns, then reposition it so the solder starts where
the wire leaves the side of the core. 

When the wire isn't tinned up high enough, it's easy to pull the tinned
section all the way through the board so you're trying to solder to the
un-tinned wire above where you stripped it! 

Also, it is NOT necessary to pull down hard on the leads when mounting the
toroids. Just pull all the excess lead through the hole, so the toroid is
sitting or standing as indicated against the board. 

As a final check BEFORE soldering, look to see if tinned wire is visible at
the edge of the pad on the toroid side. IF you see enameled, un-tinned wire
going into the PCB hole, you didn't tin it far enough up. Remove the toroid
and tin the lead closer to the core. 

It's really harder to describe than to do, but some ops find it simply not
much fun to wind and tin toroids. That's why the "toroidguy" is around. You
should have found a flyer in your kit box advertising his services. You can
also find his info under Builder's Resources on www.elecraft.com. He'll send
you a set of pre-wound, pre-tinned toroids all ready to drop in to your kit
if you want. 

About the I.C. concerns, simply following the grounding procedures given in
the book and you'll be fine! The big issue, if you aren't wearing a ground
strap, is to touch something unpainted and GROUNDED before picking up an
I.C., and touch it AGAIN regularly, especially after getting up or squirming
around in your seat. A little clothes-to-vinyl or cloth friction on the seat
can quickly produce a static charge. 

If you aren't sure about the ground, the mains ground is FB, if it is
grounded. A cheap tester from your hardware store can confirm whether your
mains ground circuit is properly hooked up. 

Ron AC7AC