Different wavelengths of radio propagate much differently from each other and that means that some times of day are better for one band than another.
Daytime Bands
20m is generally a daytime band, but dissolves into just noise as the sun goes down. You can watch your signals just stop going anywhere following the grayline on the PSK reporter map. There’s a short after dark burst of signal propagation, but generally you can see a distinct pattern change and then it dies abruptly.
The reason for this is that one of the layers of the ionosphere that bounces 20m waves just quits being formed after the sun is not directly blasting the earth during daylight.
30m is another daytime band, where you’ll find a lot of hams making contacts. It tends to die off a little later in the evening, and sometimes I’ve been still making contacts at 9:30pm, but usually the pickings get slim by then.
“Night Clubbing” on 40m
And then there is 40m. Yesterday was my first day (or night) working digital on the 40m band and it was a lot of fun!
40m is really where the “night life” of ham radio takes place. My friend with the wall and boxes full of QSL cards tells me that you can usually find someone to make contact with on 40m even at 4am if you can’t sleep.
I had not previously been working 40m because when I got my hamsticks for the window installation experiment, every single ham radio outlet from here to the moon was out of stock on the 40m sticks. (Could we stop with the Covid hysteria now, please? I’m getting tired of this being the excuse for every problem that occurs into the next decade– and the excuse for not fixing it.)
Yesterday I got the bright idea to remove one of my hamsticks from it’s installation plank, and replace it with a Wolf River Coil Mini Bullet– one of two I own as part of an Otophone. I tuned it for 20m first, as proof of concept since that band is fairly easy to get going, and made a bunch of contacts during the day.
40m Antenna Setup
Then in the evening, I tuned the mini-bullet for 40m. I had to make some changes to get an acceptable SWR, including adding a longer radial wire. The one I’m using for 20m wouldn’t get me any closer to the 1:1 SWR ratio we shoot for than 3:1. My radio’s tuner is good, but not that good!
I ended up raiding my larger wolf river coal for a precut radial, and just unwound it partway, threaded it around behind my bookcases and tossed it, still on it’s spool on my bed. That worked better than I expected.
Once I had it tuned up on 40m I started transmitting. I discovered a couple of other little glitches.
I find the RFI problem that wreaks havoc on my rig control over USB on my laptop is WORSE, MUCH WORSE at 40m than at 20m.
Initially I wasn’t able to set the radio for more than 12watts without the USB port going wacky and WSJTX shutting down.
On 30m, I start seeing this behavior at around 40watts, including messing with my laptop trackpad while transmitting at even lower levels.
At 20m I was able to resolve it for the most part with ferrite beads place on every cord and cable I own. But that just doesn’t work on 40m.
After being frustrated with no one being able to copy me, even on digital at 10watts, I installed a LDG choke on the line, and was then able to work with a more reasonable 25watts before the USB started going crazy again.
The 40m Contact “Booty”
I made about 20 contacts on 40m while I was working last evening, and have confirmed 7 states so far. Not bad for a first experiment with a new antenna setup and rolling with the punches to resolve issues the first time.
I had to jump off as it got later and a big weather-alert-generating storm rolled in about 10:30pm. (Hurry up and Haul in the antennas to keep them dry, and to keep lightening from frying my shack! Arizona monsoon storms can be pretty electrifying!)
Overall, it’s been fun to sample the ham radio “night life” so far and I’ll definitely be working more 40 digital after dark.