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Or: Power Versus Frequency
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From: "Billy G. Echols, Jr., Ph.D."
Organization: BellSouth Email Account
To: elecraft at mailman.qth.net
Date: Fri, 17 Jan 2003 15:52:32 -0500
Subject: [Elecraft] Practical K2 versus K2/100
Subject: Practical K2 versus K2/100
The attempt here is to examine the 160- and 10-meter claimed scores from the ARRL contests
conducted in the fall of year 2002 for how differences in power affected the results. The
hypothesis is that higher power is required on the lower frequency bands to overcome the effects
of noise and vagaries of propagation.
Figures 1 and 2 show the 160-meter and 10-meter claimed scores for the 2002 contest as extracted
from the ARRL Contest website. The first figure shows the minimum, average, median, maximum and
number of log entries; the second depicts the same data divided into quartiles. Figures 3 and 4
show the same data averaged and segregated into high, low, and QRP categories for 160- and
10-meters.
Figure 1: Minimum Average Medium Maximum #
160MultHi K-VE 756 91531 68015 407712 55
160MultLo K-VE 1680 24270 23040 53650 14
160MultHi DX 1458 756 1458 2160 2
160MultLo DX 0 0 0 0 0
160SnglHi K-VE 520 70256 44815 650750 225
160SnglLo K-VE 18 28378 16285 177120 347
160QRP K-VE 2 12256 7846 73536 57
160SnglHi DX 16 15331 1535 152000 37
160SnglLo DX 4 529 178 3900 13
160QRP DX 0 0 0 0 0
10MultHi K-VE 210 821783 653544 3083876 91
10MultLo K-VE 308 148770 100672 610458 43
10MultHi DX 6272 929830 763504 3812476 56
10MultLo DX 23680 260705 175984 879552 13
10SnglHi K-VE 792 504024 299756 4479522 359
10SnglLo K-VE 36 159670 72444 1928320 832
10QRP K-VE 18 109070 41844 851894 121
10SnglHi DX 198 462925 329784 4966670 254
10SnglLo DX 1 147841 70176 2386020 605
10QRP DX 364 71345 43378 436182 80
Figure 2: Quartile0 Quartile1 Quartile2 Quartile3 Quartile4
160MultHi K-VE 756 24079 68015 130049 407712
160MultLo K-VE 1680 12000 23040 35685 53650
160MultHi DX 756 1107 1458 1809 2160
160MultLo DX 0 0 0 0 0
160SnglHi K-VE 520 19373 44815 100548 650750
160SnglLo K-VE 18 6923 16285 39078 177120
160QRP K-VE 2 2083 7846 15484 73536
160SnglHi DX 16 404 1535 5002 152000
160SnglLo DX 4 74 178 362 3900
160QRP DX 0 0 0 0 0
10MultHi K-VE 210 207510 653544 1180829 3083876
10MultLo K-VE 308 37044 100672 206459 610458
10MultHi DX 6272 272972 763504 1297935 3812476
10MultLo DX 23680 79120 175984 376908 879552
10SnglHi K-VE 792 93118 299756 750416 4479522
10SnglLo K-VE 36 25084 72444 197896 1928320
10QRP K-VE 18 15708 41844 154760 851894
10SnglHi DX 198 103832 329784 640260 4966670
10SnglLo DX 1 20956 70176 209124 2386020
10QRP DX 364 13892 43378 94992 436182
Additionally, Figure 4 shows the overall scores divided by the number of submitted logs. Also, the
headers are in assumed maximum power levels of 1500 watts (about 61 dBm), 100 watts (about 49 dBm)
and 5 watts (37 dBm); this does not take into consideration the relative gains, losses, or
inefficiencies of the antenna system in the respective frequency band.
Figure 3: Quartile0 Quartile1 Quartile2 Quartile3 Quartile4
160 High 512 11241 28956 59352 303156
10 High 1868 169358 511647 967360 4085636
160 Low 426 4749 9876 18781 58668
10 Low 6006 40551 104819 247597 1451088
160 QRP 1 1042 3923 7742 36768
10 QRP 191 14800 42611 124876 644038
Figure 4: Quartile0 Quartile1 Quartile2 Quartile3 Quartile4
160. 61-dBm 98.62 272.07 551.58 962.77 3873.32
160. 49-dBm 30.09 220.70 426.58 672.34 1160.64
160. 37-dBm 0.02 18.27 68.82 135.82 645.05
10. 61-dBm 29.32 1955.75 5737.28 10191.14 33500.07
10. 49-dBm 457.19 1753.11 4020.38 8594.45 22029.02
10. 37-dBm 2.35 151.73 444.02 1233.20 6246.36
It is interesting to note the 12-dB difference in power levels between the three
categories, high, low, and QRP shown in Figure 4. It is obvious no matter the power level that
10-meter scores are substantially higher as compared to the 160-meter scores; this indicates that
more power is required within the power link budget on 160-meters to produce the same claimed
score. Generally, the difference between 160- and 10-meters is an order of magnitude no matter the
power level; 160-meters requires somewhere between 16-dB and 24-dB more power than 10-meters. Some
of this difference arises because antenna gain is easier to attain on 10-meters (how many hams do
you know with three element Yagi antennas on 160-meters?); let us assume the average 10-meter
antenna gain is 8-dB. Some of the 160- to 10-meter difference is attributed to inefficient
160-meter antennas; let us assume the average 160-meter antenna loss (inefficiency) is 3-dB. The
remaining 5-dB to 13-dB difference remaining between 160- and 10-meters is caused by noise and
propagation difficulties.
The conclusion is that for decent performance on the lower frequency bands, 160- and 80-meters,
more power is required. If you operate mainly on the 14- through 28-MHz frequencies, a K2 has
sufficient power for most operations; however, as sunspot activity declines and activity moves
downward in frequency, the higher-powered K2/100 will be required to maintain the level of
performance the standalone K2 attained on the higher frequencies.
This report would have been produced sooner but the ARRL 10-meter claimed scores
were just posted several days ago. If you are interested in the full spreadsheet
send me an email at ni5f at arrl.net and I will email you the Excel spreadsheet.
Bill, NI5F
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Reply-To:
From: "Ron D'Eau Claire"
To:
Subject: RE: [Elecraft] Practical K2 versus K2/100
Date: Fri, 17 Jan 2003 13:35:51 -0800
That's an interesting report, Bill.
One thing to consider (because it plays a HUGE role in my small QTH) is
that it's the "Effective Radiated Power" (ERP) that is a big issue.
Most ops can put up an antenna for 10 meters, or even as low as 20
meters, that has an ERP equal to a dipole in "free space" - or very
close to it. Indeed, a fortuitous height in the under 40 foot range can
produce significant low angle gain for a horizontal 20 meter dipole -
several dB over a dipole.
But it's a different story down on 80 and 160. Dipoles at 1/2 wave high
(120 to 240 feet up!) are not too common. Full sized 1/4 wave vertical
out in the clear and with good high-efficiency grounds or 1/2 wave
vertical (120 to 240 feet to the top) are probably no more common.
Almost all ops work with a fairly "lossy" antenna at 80 and 160 compared
to the higher frequency bands.
So 5 watts on 10 meters into a good dipole might be 10 or even 20 watts
ERP.
The same 5 watts into a doublet or vertical on 80 or 160 might produce 1
or 2 watts ERP, or less. That's an S-unit or two on most "meters".
Then, as you point out, you have to add the higher band noise covering
up those weaker signals down on 80 and 160...
Ron AC7AC
K2 # 1289
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Subject: Practical K2 versus K2/100
The attempt here is to examine the 160- and 10-meter claimed scores from
the ARRL contests conducted in the fall of year 2002 for how differences
in power affected the results. The hypothesis is that higher power is
required on the lower frequency bands to overcome the effects of noise
and vagaries of propagation.
...
Bill, NI5F
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From: "Dave Sergeant"
To: elecraft at mailman.qth.net
Date: Sun, 19 Jan 2003 06:48:12 -0000
Subject: [Elecraft] Practical K2 versus K2/100
Billy G. Echols wrote:
>The attempt here is to examine the 160- and 10-meter claimed scores
>from the ARRL contests conducted in the fall of year 2002 for how
>differences in power affected the results. The hypothesis is that
>higher power is required on the lower frequency bands to overcome
>the effects of noise and vagaries of propagation.
Thankyou Bill for posting these figures, I will have to have a closer
look at the ARRL site to find how I really did, but certainly my
effort in CW ARRL 10m QRP where I put in a claimed score of 119,712
looks in the upper quartile. In last years results it would have been
in the top 10 DX.
It is difficult to draw too many conclusions though from the figures
as the two contests are totally different. Also it doesn't list the
CW, SSB and mixed sections separately and I am puzzled why there are
five columns for the quartiles!
The 160m contest is a DX works USA/VE only contest - as such it
really rules out any QRP participation in Europe as even the well
equipped stations will only manage a handful of contacts. From my
postage stamp garden I would be lucky to QSO any USA stations at all,
although my friend across town has worked W9 with 10W. By contrast
the 10m contest is an everybody works everybody else contest and
working USA is pretty straightforward.
I did not even attempt an entry in the top band event, but my results
in the 10m one show that even a modest QRP entrant can have a
reasonable bash in this event and the other big contests. I would
like to encourage more entrants to the QRP sections of these contests
which seem to be relatively poorly supported. Last time I checked I
was the only G entrant in the 10m QRP CW section. In CQWW CW there
are only 5 Gs listed in the QRP all band section. Come on chaps, it
can be done. Willingness to devote the time and operating skills are
far more significant than the difference between 5W and 100W, and
active participation in these events gives excellent publicity for
Elecraft products.
73s Dave G3YMC
dsergeant at iee.org
dsergeant at btinternet.com
http://www.dsergeant.btinternet.co.uk
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