Paul,
I made the measurements myself. The inductor was in the open, sitting on
a wooden baseboard. It had a "tapered pitch".
The Qs I measured seem to be similar to those measured by Tom W8JI who
says this on his web site:
"The trend of Steve's data agrees with my measurements, although there
are differences in data because I measured different inductors. I
measured less peak Q, but also significantly higher minimum Q in the
inductors I tested. While the inductors I measured has less delta in Q,
they also had a serious dip in Q up near 25-35 MHz when near
half-inductance."
73,
Steve G3TXQ
On 29/11/2010 17:50, Paul Christensen wrote:
> Steve,
>
> Do you know if the plots were obtained with the roller inductor placed away
> from surrounding objects -- or placed within a metal cabinet? The Q looks
> pretty pathetic above 40m.
>
> Also, anyone know if Q improves toward 10m when using a roller inductor with
> a non-linear turns count that allows for more turns per unit of inductance
> at one end? (e.g., Cardwell 229 series)
>
> http://www.cardwellcondenser.com/PAGES/md04g.html
>
> Paul, W9AC
>
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