[Elecraft] Toroid Question

Fri Feb 14 17:39:01 2003

I think the main reason for winding the torroids at 80% is to make the leads
come out cleanly to the pc board holes....I would say that you should be
able to work it to at 95% of the area.

Gregg R. Lengling, W9DHI
PSYCHOLOGY:  The science of inventing words for things that do not exist.

----- Original Message -----
From: "Parker Buckley" <[email protected]>
To: <[email protected]>
Sent: Friday, February 14, 2003 4:33 PM
Subject: [Elecraft] Toroid Question

> I'm winding a 50mH inductor for use on a 160 meter antenna
> (for my K2, of course).  Something I got out of Moxon's book
> for using short, elevated radials.  This worked great on a
> 30M antenna.   Anyway, I recall many instances in building
> the K2 where the instructions were to cover approximately
> 80% of the core.  Is there a reason for that?  Using a
> T200-1 core, I need 47 turns.  With #14 wire, that's almost
> close-wound on the inside; consequently, the leads come off
> very close to each other.  I attempted to measure the
> inductance using an MFJ 259B, and get something like 6 mH,
> and only over a very narrow frequency range.  My Autek RF-1
> does a lot better, indicating about 30 mH, still frequency
> dependent.  The leads are still about 10 inches long, and
> I'm wondering if stray capacitance is the culprit, whether
> or not having the leads coming off the toroid in close
> proximity to each other could be a problem, or whether the
> antenna analyzers are not capable of providing a good
> measurement.   Comments welcome.....I have time to ponder
> this while waiting on the freezing rain and snow to arrive
> for the weekend.  Maybe I'll do the A to B mods this
> weekend.
>
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