+++++++++++++++++++ Or: Power Versus Frequency +++++++++++++++++++ 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 +++++++++++++++ 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 -=============================== 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 ++++++++++++++++++ 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 ++++++++++++++++++