[Elecraft] Practical K2 versus K2/100

[Billy G. Echols, Jr., Ph.D.]

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@arrl.net and I will email you the Excel spreadsheet.

Bill, NI5F