Keith, KD1E wrote: K1 or K2. Hmmm, the debate continues. But wait, we're approaching a sunspot min. My antennas are pretty limited. I have a 28 foot vertical (fed with a tuner near the base) for 40 thru 15 and a dipole at 25 feet but that is about it. No towers, no high wires, no yagis. How limiting will 5 or 10 watts (even with that Elecraft Mojo) be under current conditions? Are we entering into conditions where QRP with simple antennas will become rather frustrating? Is it K2/100 time?
--------------------------------------------- The difference between 10 and 100 watts (10 dB) is about 1.5 "S" units on most receivers. Band conditions changing from hour to hour will cause a much bigger variation that that. The biggest difference will depend upon whether you focus on working DX as you primary activity. Overall, signal strengths will tend to be slightly lower than we see on 10 meters during the sunspot maxima, so it is true that QRP may suffer slightly. Unless you're trying to bust a pileup for a rare DX station you shouldn't notice a lot of difference in your ability to make contacts, even good stable contacts for long-winded rag chews if you want, as long as you adjust the bands your using to follow the changes in propagation and the maximum usable frequency (MUF). What you will notice about the sunspot minimum is that the 10 through 18 meter bands will be open less often than they were. Indeed, in the years around the minimum, you may find that 10 meters is open only sporadically for short periods of time. Even 20 and occasionally 40 may shut down to long skip for days. The issue isn't whether a particular band is 'open' but rather the maximum usable frequency (MUF). Fifteen and ten meters have been great DX bands during the sunspot maxima because they're typically close to the MUF. On occasion the MUF even gets as high as 6 meters, and long skip contacts suddenly become easy there. During the sunspot minima the MUF will drop down to 14 MHz and, on occasion, even 7 MHz. When that happens those bands are roaring with DX much like 10 has for years throughout the sunspot maxima, and the higher frequency bands will be quiet except for locals. Still, there's a couple of big differences. First, the ionization of the lower atmosphere affects lower-frequency signals more. That's why you don't hear daytime "DX" on the AM standard broadcast band (550 - 1700 kHz) but it often booms in at night. The ions produced in the lower atmosphere by the sun absorb those frequencies, but as soon as the sun sets those ions dissipate and the atmosphere becomes transparent to RF. That effect extends up to, typically, somewhere between 7 and 15 MHz. As the frequency goes up the absorption drops. That's why you can work distances with 5 watts on 80, 40 or 20 in the day that no amount of power from a station in the broadcast band will cover, and the DX gets better as you go up in frequency (as long as you stay below the MUF). That's also a large part of the reason why, after dark, better and better DX starts being heard on 160, 80 and 40 meters. The other big difference is that the typical Ham antenna is much less efficient for DX work at the lower frequencies. Vertical antennas suffer greater ground losses and, typically, horizontal antennas are too low for best DX. A horizontally polarized antenna, no matter the type, needs to be close to 1/2 wave or higher above the effective ground for best DX coverage. Most Ham antennas meet that criteria at 14 MHz and above. An antenna 35 feet up is a full half wave high on 20 meters, for example. Down at 7 or 3.5 MHz, the antenna needs to be 60 to 120 feet up to be an equivalent electrical height! That's above what most Hams can manage. Still, lower antennas are excellent for short skip out to 1,000 or 2,000 miles. They can even do better than antennas mounted higher up. So, no matter the power, if you're looking for consistent DX performance with a "typical" Ham installation, your bands of choice will shift down toward 20 and 40 meters instead of the higher frequencies during the sunspot minima, and your DX opportunities will appear more commonly along the gray line or during the hours of darkness when atmospheric absorption is a its lowest. For casual contacts and rag chewing, 80 will start to act a lot more like 40 meters has in the past and even 40, 30, and 20 meters will see a lot of stable short skip at times. A little extra power is always a help, but it's often only a psychological help. My K2/100 is at 100 watts a lot simply because in working a lot of stations, they "like" to know that I'm running a comparable power because they hate digging for signals near the noise. My power is always down at QRP levels when I'm around the QRP calling frequencies (7040, 14060, etc.) One time I called an OT retired radio operator I know and we had a nice long rag chew. Predictably, he thanked me for running "decent power", grumbling about all those QRPers who expect him to try to listen to their peanut-whistles down in the noise. As always, I just ignored it and we chatted about things a couple of OT's would normally talk about from their childhood: the war of independence, the civil war, Teddy Roosevelt and other icons of our youth <G>. After a half hour of chewing the rag we signed off. It was only then that I noticed that I had forgotten to turn the KPA100 on. My output wasn't 100 watts as I had reported. It was 10 watts. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
