Posted: 8/21/2011 9:47:50 AM EDT
| Whats the story about use of this band. I read that its best for short distance signals and in periods of low sunspot activity but after 1920 was allocated to other users. |
| 40m. During day and early evening I can work pretty much most of the US from MS on 40m . At night you get DX. Other countries have Shortwave stations that broadcast in the 7.250ish area and they can be loud at night. They are AM. I enjoy 40m. Closest I have worked on 40m is probably 175 miles from me. |
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All HF bands are subject to tremendous variation due to the daily day/night cycle of the ionosphere plus whatever daily solar variability, with large variations in trends based on the sunspot cycles.
The 40m band is particularly difficult because it's not allocated the same around the world. Part of what is allocated to amateur radio in North and South America is allocated to shortwave broadcasters in other parts of the world, which results in severe interference. |
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2 blocks. Last week.
We started out on 75M; this to sked with another area friend who was mobile in IL at the time. Myself and the 'neighbor' were both 60dB/S9 to each other and S9 to 10dB/S9 to our buddy in 9-land. All of us switched to 40 to try condx there. Same antennas (multiband dipoles and a Tarheel) were used, and the power levels at each station were unchanged. The neighbor dropped to 40dB/S9, as did I. Our friend reported that we both jumped to 20-30dB/S9 at his end. Lower radiation angle (relative to antenna height) tends to do that. We each have a definite NVIS component to our antennas on 75, and given the height they're at this is no surprise whatsoever. |
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Closest I have worked on 40m is probably 175 miles from me. I've done 2 miles (same city, in fact). Oh, yeah? Well get this! I talked to myself once. 
I used to hear my Dad in his workshop, talking to himself. I thought he was nuts. "OK, that's 7/8", I need to take off 3/16"... that makes it 11/16"... ok, right there... that should do it." Then as I got older I realized that was a way that some people think things out. Then I had heard people argue with themselves. I thought THAT was nuts. But then I realized this is how some people work things out and find the best solution to a problem. Now when you argue with yourself and you lose the damned argument... now THAT'S NUTS!!! |
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If you could only have an antenna for one band, 40 meters would be the best bang for the buck. I've done Ireland, Scotland, and Italy on 40 meters. Yup. 40 is (almost) resonant on 15 meters*, too, enough so that only minor tuning is necessary. My first CW contact was Los Angeles to Nagasaki on 15 meters on my dad's 40 m dipole. It can also be used with an antenna tuner for other bands. Odd-numbered harmonics are resonant. So the 3rd harmonic of 7 MHz is 21 MHz; the third harmonic of the 2 meter band (144-148 MHz) is found in the 440 MHz band. |
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If you could only have an antenna for one band, 40 meters would be the best bang for the buck. I've done Ireland, Scotland, and Italy on 40 meters. I'm with AFM on this one. No matter what the time of day or the conditions, it 40 is almost always open to somewhere. From regional communications during the day to DX at night, 40 has it all. Even a couple of weeks ago during the big geomagnetic storm and I couldn't hear a soul on 20, I still heard plenty of stations on 40. |
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I love 15 and 17 m during the day, so quiet, and great dx. But they shut down before sundown.
20 meters, quiet but crowded, especially during contests. Again, a daylight band. 80/75 meters is dead in the daytime. And sometimes noisy at night. 40 meters, as said, is open somewhere around the clock. Sometimes goes dead in the middle of the day, but the rest of the time, works. |
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I love 15 and 17 m during the day, so quiet, and great dx. But they shut down before sundown. 20 meters, quiet but crowded, especially during contests. Again, a daylight band. 80/75 meters is dead in the daytime. And sometimes noisy at night. 40 meters, as said, is open somewhere around the clock. Sometimes goes dead in the middle of the day, but the rest of the time, works. and then there's the much forgotten 160M.
Not many use it due to the larger antennas needed. I like to hop on there from time to time. Lots of older guys running older broadcast equipment. |
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Yeah, I listen, and learn a lot about amps, antennas, etc.
But I asked an older ham about running on 160 m. He said, "I don't know... I've never had enough real estate to work 160 meters." 
But here is a coil loaded dipole for 160 meters. Will also work 40 meters due to the placement of the coils, acting as chokes, or traps. And if it will work 40 meters, it should do 15 meters, too. Overall length is the same as an 80 meter dipole. 
I don't know who drew this up, found it on a ham forum somewhere. |
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I used to hear my Dad in his workshop, talking to himself. I thought he was nuts. "OK, that's 7/8", I need to take off 3/16"... that makes it 11/16"... ok, right there... that should do it." Then as I got older I realized that was a way that some people think things out. Then I had heard people argue with themselves. I thought THAT was nuts. But then I realized this is how some people work things out and find the best solution to a problem. Now when you argue with yourself and you lose the damned argument... now THAT'S NUTS!!! I am vocal. I do this quite a bit. When I argue with myself it is a case of throwing an idea out, shooting it down, turning it into a Phoenix and making it fly. SOmetimes an idea can get shot down and fly out of its own ashes only to be shot down again and fly again several times before it either flies or stays in the dust. It works for me, but I will admit if I heard someone else do it I would seriously wonder about them. |