Topband: Receive loop observations

[Richard (Rick) Karlquist]

On 4/3/2016 7:12 AM, Don Kirk wrote:
> Hi Herb (KV4FZ),
>
> You said "but the 50 turns is going to be a chore"
>
> The only problem I find with winding a core with many turns is keeping
> track of the number of turns.  What I do to solve the counting problem is
> that I take a zoomed in picture showing all the windings (using my smart

I have come to the same conclusion about turns counting.  What I do
is to calculate the length of wire needed and cut it to this length plus
10%.

Then I put the core at the midpoint of the wire and wind half the
turns passing one end through the core and wind the other half of
the turns passing the other end through the core.  When I get most
of the wire on the core, I look at the core through my stereo
microscope and count the turns.  Then I do the last few turns
actually counting as I go along.  When I think I have 50 turns,
I do a final recount.

Alternately, I could use the microscope camera to take a photo.
If I didn't have the microscope, I might get away with my
DSLR camera, using a "lens extension tube" to fake the lens into macro
focus lengths.  The lens extension tube is just a hollow tube
with bayonet fittings that goes between the lens and body.
It costs a few bucks, way cheaper than a $500 macro lens.

In most cases (other than my NCJ design), you are winding for
inductance or resonant frequency, so you just precut the wire,
wind it all onto the core, and then do: 1. Measure inductance,
2.  Remove a turn.  3. repeat...

If you want a really challenging coil winding experience,
build a pair of 5B4AGN filter boxes like I did.  Figure
an entire weekend just to wind the coils.

Rick N6RK