[ARC5] [Boatanchors] Coils and the winding thereof

[Michael Tauson]

On Tue, Jun 30, 2009 at 2:19 PM, Carl<km1h at jeremy.mv.com> wrote:
> I dont think Id use that material for any transmitting due to dielectric
> losses.

Likely.  The idea came from a gentleman who'd gotten his ticket in the
late 1920s and it was how he created coil forms when he couldn't find
(or afford) the ones he wanted.  Newsprint wasn't the only type of
paper he used but it was the cheapest.  One difference was that he
used shellac more than varnish though I'm not sure it should make any
difference.

> The pill bottles from the pharamacy work well at RF without Q degradation.
> They come in several size up to 2" diameter and are often free for the
> asking. They should handle at least 10W as long as copper losses are
> minimum.

True but in the 30s most prescriptions came in small cardboard boxes,
tins or envelopes for solid material and glass bottles for liquid,
something that continued into at least the late 1950s.

Some plastic coil forms were available as were phenolic and ceramic
but they were store bought and not everyone could afford that.  In
addition, I have no absolute verification of this but I think I
remember seeing spider web, basket weave and/or diamond weave coils
used in transmitters as well as receivers.

Speaking of ceramics, I wonder if there would be any problem winding
things like RF chokes (filament etc) on square rather than round forms
as long as the inductance works out.

I think part of the problem here is in thinking in today's terms
rather than in those of a young and basically broke ham during the
Depression like the gentleman I knew back in my small person days.
(He was the Depression era ham and I was the student, just to
eliminate any confusion.)  I'm using the same basic components and
techniques as found in the 1936 ARRL Handbook plus some earlier text
material and applying the lessons he taught ... some of which involved
words even the Navy didn't know.  ;-)

This is where having nice relatively modern test equipment fails.
While I've added both a capacitance checker and means to check
inductors to the want list, I have to keep in mind that the tolerances
then were a lot looser than they are now and that sometimes losses
were a fact of life.

Best regards,

Michael, WH7HG
-- 
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