On Mar 28, 2:10*pm, Cecil Moore wrote:
wrote:
... has anyone had experience
using a *toroid wound with the correct amount of reactance installed
on the element to to achieve resonance instead of a coil and how it
has been for them.
I've only one data point based on measurements made
at a California 75m mobile shootout.
K7JEB had this one mounted on a full-sized pickup.
An 8.5 foot whip using a 75m Texas Bugcatcher coil
at the base outperformed my antenna by +7dB.
I had this one mounted on a full-sized pickup.
An 11.5 foot whip using an SG-230 autotuner at the
base.
Not exactly the comparison you are seeking but the
SG-230 did use #2 iron powder toroidal inductors.
One might assume that the 6 inch long air-core
bugcatcher coil contributed more radiation than the
toroidal inductors. Seems to me the large air-core
coil occupies a greater number of degrees of antenna
than does toroidal inductor. This could be proved
(or disproved) by making delay measurements on both
coils using traveling wave current.
Previous such measurements are worthless for such
because the total current used was primarily standing-
wave current and was changing phase by only ~1 deg
for every ~30 degrees of antenna wire or coil.
--
73, Cecil, IEEE, OOTC, *http://www.w5dxp.com
Thanks for your reply and the information you provided, it was very
useful as well as the link, it will take me a bit to check it out LOTS
of info there as well.
I'm trying 40/80/160M trap vertical ,i'm experimenting with the low
pass filters in the vertical as coil and cap hats as opposed to coils
and coax capacitors or mica caps which ever. I would like to use the
hats to distribute the current along the radiators more uniform as
opposed to linear. The insulator i have on hand for the top hat is
physically not long enough for the air core inductor, this is why i
was wondering about the toroid at the top. 40/80M works great for dx
with a 100W not bad on 15M either despite propagation lately. I should
also mention its noisy on rx, i see it sometimes has 40db more noise
then the loops that i used for rx, thanks again, 73 vo1bbn