[Elecraft] Toroids

[Don Wilhelm]

Edward,

This subject comes up from time to time on this reflector.  Inductance
meters seem to vary all over the place depending on the variety.
Inter-winding capacitance and many other factors will have a great influence
on many meters which makes them frequency dependent.  You likely do NOT have
a problem.  You could double check the core type you actually used and
recount the number of turns (count the wires through the center of the
toroid rather than the turns on the outside).  I will believe the inductance
tables published by Amidon before I believe my inductance meter for all but
very low frequency inductors.

If you used the correct core material and put the number of turns specified
by Elecraft on it, then it will work in the intended application - ignore
your inductance meter readings.

You generated a bit of my curiosity though by your timely question - I am
building a K2 for another ham and he ordered the toroids from 'The Toroid
Guy', so I pulled out the ones for the noise blanker and put them on my
inductance DVM adapter - nothing fancy, the one that has been in the ARRL
Handbook for a few years - measures at about 60 kHz. -  L1 and L2 measured 2
uH and L3 measured 123 uH - go figure!!!

73,
Don W3FPR



----- Original Message -----

> I decided to take a break from building the main K2 and thought I'd build
a
> couple of the options, so I built the noise blanker. I wound the three
> toroids and thought I'd done a pretty good job - right number of turns,
> pretty tight, reasonably well spread over about 85% of the toroid. So
> imagine my surprise when I measure their inductance. So the two toroids
> shown as 1.2uH actually measured as 4uH; whilst the 40uH toroid measured
as
> 80uH.
>