I have no data that would support the 6%/dB rule of thumb, but I
absolutely agree with the slides in your presentation, Doug.
For many years I was constrained to simple vertical antennas due to
neighborhood sensitivities at my Scottsdale QTH, but adding a used Henry
2K-4 I bought for $600 (i.e., about $60 per db) made all the difference
in the world for contest scores and general DXing. The downside, of
course, is that an amplifier puts you in a higher category so
competitively you don't gain much, but actually being able to work
people is a lot more fun.
The old adage that you should always put your money into your antenna
first doesn't really hold water once you get above a pretty simple
setup, as your slides show. Above about 5 or 6 db, getting additional
signal strength from a tower and antenna is probably the LEAST cost
effective path on a dollar per dB basis. My comparatively simple setup
(OB16-3 and OB2-40 on a 70 foot AN Wireless HD-70 tower) at my current
QTH cost me well over $1,000 per dB (possibly pushing twice that)
compared to the simple dipoles I previously had strung from a 55 foot
length of guyed 4" irrigation tubing. That being said, it does make you
more competitive for contesting since by itself it doesn't bump you into
a high power category
Lastly, I didn't move to this hillside QTH purely for its usefulness as
a ham radio location, but it truly does make a difference. Check out my
HFTA terrain files at http://www.ab7e.com/HFTA/AB7E_HFTA.html ; On 20m
through 10m my major lobes are 4 degrees or less. Too bad I'm not a
better operator to make good use of it ...
73,
Dave AB7E
On 8/22/2019 10:03 AM, Doug Grant wrote:
On Thu, Aug 22, 2019 at 4:00 PM W3LPL wrote:
These recordings are an impressive demonstration of the benefit of
one dB of signal strength improvement in a weak signal situation.
Click on the links on this website:
www.ab7e.com/weak_signal/mdd.html
Many years ago, Clarke Greene, K1JX, casually mentioned that he had
determined adding 1dB to your signal strength would result in a 6% increase
in your contest score (mostly applied to DX contests). I filed that away
for future reference.
Test cases are hard to find, but I found one in 2014 when N1UR switched
from Low Power to High Power in the CQWW. Same op, same QTH, same antennas,
and very comparable propagation near the top of the cycle.
My conclusion: the K1JX "6% per dB" rule was about right.
The exercise for the reader is to figure out how to add dB at the best "dB
per dollar" ratio. Not all dB cost the same!
You can find some hints in a presentation I did a while back at CTU:
https://www.contestuniversity.com/wp-content/uploads/2017/06/K1DG_CTU_2015_Ten_Ways_to_Improve_your_Contest_Score.pptx
Slides 5-22 cover this topic.
73,
Doug K1DG
.
_______________________________________________
CQ-Contest mailing list
CQ-Contest@contesting.com
http://lists.contesting.com/mailman/listinfo/cq-contest
_______________________________________________
CQ-Contest mailing list
CQ-Contest@contesting.com
http://lists.contesting.com/mailman/listinfo/cq-contest
|