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

[Wayne Burdick]

Jim,

Like I implied in my posting, portable operation is often more about convenience than signal strength. 

Your estimate of around 7 dB sounds reasonable. That's about 1.5 S-units, to use the vernacular. When a band is open, this loss still allows a lot of contacts to be made.

Example: A couple of months ago my son and I were doing a bit of hiking/bird watching at Redwood Shores. While Griffin stalked hooded mergansers with his camera, I quickly set up my KX3 at a picnic table. I attached the whip with a right-angle BNC, along with the 13' counterpoise wire. 20 meter CW was very active with EU contest stations, most of them probably running a KW ("or so"). I called several of them running 5 W, and worked most of them on one call. 

I may have been down 7 dB from a full-size vertical, but I got through nonetheless. And I didn't have to frighten any birds away with my usual weight-tossing wild-west antenna deployment routine.

Sometimes size doesn't matter.

Wayne
N6KR


On 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
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