[Elecraft] Miniature self-supporting HF antennas

[David Gilbert]

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.