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

[Gene Gabry]

It's all about making contacts anyway you can and having fun doing it!

Gene, N9TF

-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Wayne
Burdick
Sent: Friday, March 25, 2016 10:00 AM
To: jim at audiosystemsgroup.com
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] Strong recommendation: MFJ 18xx-series single-band
whips for KX3, etc.

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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