[CQ-Contest] CQ-Contest] Impressive demonstration of one dB of signal strength improvement

David Gilbert xdavid at cis-broadband.com
Thu Aug 22 14:42:49 EDT 2019

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 ...

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
> .
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