[Elecraft] Strong recommendation: MFJ 18xx-series single-band whips for KX3, etc.

[Brendon Whateley]

Jim,

Can you toss a capacitive hat on the top of the shorter vertical and see
what difference that makes? I've not figured out how to use the modeling
software yet!

- Brendon
KK6AYI

On Thu, Mar 24, 2016 at 11:14 AM, Jim Brown <jim at audiosystemsgroup.com>
wrote:

> On Wed,3/23/2016 7:12 PM, Wayne Burdick wrote:
>
>> I've been using an MFJ-1820T telescoping 20-meter whip for a few months.
>> Considering its length (48"), results have been excellent. I typically use
>> it with the KX3 on a picnic table at 15 W (with an external battery), or
>> hand-held at 3 to 5 W (internal battery).
>>
>
> As Tom Schiller, N6BT, famously noted, EVERYTHING WORKS, sort of. He
> demonstrated this by working all continents loading a lightbulb that he fed
> with coax. Tom is the designer of the excellent Force 12 antennas.
>
> I just did a quick NEC model of a 4 ft vertical with loading coil and a
> single quarter-wave radial laying on the ground, and compared it with a
> quarter-wave vertical (16.7 ft) with the same single radial. The model is
> for poor soil, which is typical of most mountainous QTHs. The full-size
> quarter-wave will be 7.4 dB louder than the shortened one. That's
> equivalent to reducing a 15W signal to 3W. The difference is slightly
> greater over better than average ground. The reduced efficiency is due to
> the greatly reduced radiation resistance of the shortened antenna.
>
> Bottom line -- yes, shortened antennas work, sort of, but full-size
> antennas work BETTER. If you can afford the weight of a means to support
> the longer antenna (typically a telescoping fiberglass pole), it's well
> worth it! And if a shorter antenna MUST be used, LONGER antenna, LESS coil
> is better.
>
> 73, Jim K9YC
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to brendon at whateley.com
>