Ham radio: Certain signals at roughly sunset

A quick question–with a part theory of mine:

I am a nerd [sub]father is geek, and mother nerd. I got his brains, and her looks[/sub], who built a shortwave listening radio, and enjoys ‘catching’ WWV out of Fort Collins, CO so I can double check the clock on my workbench.

Over the past few weeks, I’ve noticed I can get it relatively well around/just after sunset, and I have a theory on this. I think, because I’m at sunset, my atmospheric conditions change (deionization of the sky), and I can receive signals well. Further, because sunset hasn’t reached WWVB yet, it’s still broadcasting strong at it’s daytime power* and I can receive the signals at my location easier.

However, after a few hours or so, I can’t get WWV anymore–and I think it’s because sunset passes from GA over to CO, and WWV drops its broadcast power to the point that I can’t receive it anymore (too weak).

My theory is that the best time to SWL is just after sunset, where stations to the west of me are blastin’ out waves at daytime power, but I can receive them easier in nighttime conditions. So, does anyone else notice this, and does my theory hold water?

Yes, I’m a nerd. I logged signals from CO, OH, and some Voice of Russia too.

I don’t believe that WWV drops their power. They may, but I’ve never heard any say that they did. The reasons broadcast stations reduce power at night is because most stations, AM that is, share frequencies and reduce power to reduce interference with their “sister stations”. WWV is not sharing frequencies with any other US stations.

Their website WWV doesn’t mention any power cutbacks.

Radio reception on the HF bands is enhanced when both the transmitting and receiving station are on the greyline. This means the area of sunset/sunrise would be connecting the two points. If I find a better online explanation I’ll post it.

Obviously, I need to string up a higher antenna then–the one I’ve got now is 75’ of speaker wire (tied together at one end with a wire cap, so it’s more like 150’) strung up through the rafters of my attic. I’m going camping soon, and am gonna try to hoist one up on a baloon. . .

Is that because the transmitting station is still broadcasting daytime power, and the reciever is in nighttime conditions? Hey, if you do find more info, I’ll owe you one! :wink:

Still a nerd.

You’re experiencing what is known as grey line propagation (scroll down - there is a map showing the current grey line).

From the link:

Uh…you did want the official geek answer, didn’t you?

ETA: GaryM had the answer first. Damn you, GaryM! (shakes fist angriliy)

Ah, but I didn’t have a Greyline link, so we both win.

And Tripler, my greyline experience is on the ham bands, and we don’t normally cut our power at all. QRO all the way, which means 1.5 KW on sideband.

Man, Tripler, you’re this >< close to getting your license. Bone up on the FCC rules and operating procedures, take the test and get your ticket. We need more geeks like you.

And yeah, you’re experiencing greyline propagation. I’ve talked to at least a station in Argentina on greyline prop.


At least take the tech exam. It’s super easy.

Amateur General

Hijack! Anyone else going to Dayton this year?

Rico, that link is awesome, thank you!

. . . and an amateur license had been on my “when-I-‘settle down’-and-have-time-to-actually-have-hobbies” list of things to do. . . my private pilots license being on the list too. But being too damn busy with work and all, I just haven’t gotten to it yet. I’m loving SWL-ing, I just gotta get the gumption to go and invest some money into some used equipment (maybe next year’s b’day present).

Are the tests really that easy? I was under the impression I had to learn Morse Code, pick a band, study for that particular band, and pass that band’s test. I know the ARRL sponsors training, but is it just a matter of literally taking the test?

I’m such a nerd, I GeoCache, and even know how to wind a decent helical antenna.

They really are that easy. The tech license in particular is about one third common sense questions. I think you could read through a study guide one time and pass it right off the bat. Tech is (I think) 35 questions, multiple choice.

The license classes to get on HF (General and Extra) used to require morse code but this was dropped. There’s no band licenses or anything like that. The General ticket gets you most of the HF band.

I’m going to try, since I missed it last year. It’s worth the drive for the outdoor flea-market alone.