Yeah, that's a low Q coil on a short antenna ... it's not going to be
very efficient.
Dave AB7E
On 7/20/2015 2:35 PM, Rick M0LEP wrote:
The one I got bitten by was the one reviewed here:
http://www.eham.net/reviews/detail/1378
It isn't too bad for the top end of HF when most of the adjusting coil
is not involved, but performance drops off dramatically once more than
about a third of the adjustable coil is exposed. If you've got 100 watts
(or more) to drive it with then I guess you might get somewhere with it,
but with the KX3 it might as well have been a dummy load on 40 metres,
never mind with the add-on coils for the lower end of HF.
On Mon 20 Jul David Gilbert wrote:
In general, properly built coils aren't nearly as bad as you say they
are. It is possible to build coils with a Q of several hundred, and if
you do the math you'll see that the resulting loss is essentially
trivial. It all depends on the rest of the antenna, and yes, a very
short antenna with a crummy coil in the wrong place is going to suck.
But some of the best antennas on the market right now use coil loading
very effectively.
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