Wednesday, October 21, 2009

Propagation "words of wisdom" from an Old Timer

Old Timer does not necessarily refer to the age of a person, although it can. It normally refers to the person's experience.

I have 32 years in the hobby, some would refer to me as an Old Timer (OT) even though I am only 45 years old. (Such a reference to me would be a compliment, OT hams are looked up to with respect and deference as those who have "been there, done that")

Anyway, I have had an excellent exchange with an Old Timer, Jim W9VNE, in Cincinnati, Ohio. Jim and I worked each other last year on the ham radio satellites (a future post on this is coming from me). Well, after I worked TX5SPM, I saw Jim spot the DX and added the comment "long path" on the DX Cluster network.

Since I worked TX5SPM on my vertical, I wondered how Jim could tell it was long path. My confusion is taht I thought the DX (Marquesas Island) was not too far from Hawaii, so it had to be a daylight propagation path. What did the path look like at that time?

So I was confused. I did not think that my signal from my vertical could be travelling LP! I have worked Laura, 3A2MD, via LP because she has mountains to her west headed from Monaco to US. We did this when my Hex Beam was up, back on 1 January 2008 in the morning local time.

I decided to ask Jim, W9VNE, for his thoughts on this. Jim has been in the hobby for more than 50 years and he is on the DXCC Honor Roll at #1, so he knows what he is talking about!

Jim provided me some GREAT information, and with his permission I am posting his thoughts here, bceause I find this fascinating:

How do I know that the path was long path (LP) ? That is a good question. Two ways of knowing. First is turning your beam and peaking them. If LP then you will not hear them SP. While that sounds simple it is not intuitive. Sometimes a station will be both SP and LP. You can tell that too without much trouble (to the educated ear). The signal will have a flutter or echo on it. One signal coming from different directions will be out of phase since one is going 5,000 miles from Eastern Europe to USA and the other signal from the same station is going close to 20,000 miles. The 15,000 mile difference divided by the speed of sound 186,000 miles will give you that delay in the fraction of a second.

There are patterns (long established) about LP and SP. From the Eastern USA short path (SP) to the Pacific Islands occurs on 20 meters late in our evening from around midnight until it gets daylight. Since this QSO that I made occurred around 3 PM Eastern time it would not be short path. It was over South Africa. Other well known LP paths are into Europe from Midwest and Western states in dead of winter (late Dec into Feb) when it is getting dark in Eastern Europe 3 to 4 pm it is 9:30 or a little later in the morning. Turning the beam to Europe and you do not hear them and beaming to the South West you will hear them. Early sunset for EU but late sunrise for USA.

A good DX station; 3A2MD (a YL) is active on 20 cw. Her location in Monaco prevents her 2 element beam from doing much good as she is beaming directly into the high hills of Monaco City. She turns her beam about 10 AM my time and beams the long way around and I hear her out of the South West.

So how do you tell. Turn the beam. If no beam, become familiar with the times when this phenomena does occur. The Western Pac into NA is well known about 3:30 PM. I work many VK stations then on LP. I have worked Japan LP on Ten Meters about 9:30 AM when it was 9:30 PM in JA land. Beam is over Africa. You would not hear a thing if beam was on JA SP. Often you can work South East Asia in the morning by beaming into the South East. Stuff like HS and 9V1 9M2 can be heard on LP but not SP.

I look at the Terminator (grey line where the sun is just starting to shine or just starting to set. There is always a grey line around the globe. When you are in it (the grey line) you should look for stations on the other end of the grey line. The path will always be LP. I used to work JA on forty meters about 4:30 PM on forty meters and that would be 4:30 AM in JA land. It is dependent upon frequency as much as time of day. LP propagation is most prevalent on 40, 30 and 20 meters. As I noted I have experienced it on 10 meters but that is very rare.

I akso asked Jim to comment on my earlier post on this blog regarding my JA long path QSO on 17 meters. Jim kindly responded with some more TERRIFIC analysis:

I did a cursory view of your blog. Working LP on 40 and 30 in the late afternoon is fairly routine. It is LP. Because it does NOT have flutter does not mean it is not LP. You can go over the pole(s) and not have flutter too. Flutter does occur on polar paths but not always. Depends on the amount of magnetic activity then and there.

A SKEWED path is something that is used to refer to an anomaly i.e., neither LP or SP. I have seen that with extreme magnetic activity. The signals from EU or AS can start off and then be DEFLECTED from their routine paths. An example is to receive EU from a direction of 70 degrees when it normally is 40 degrees. The signals peak at 70 and fall way off at normal 40 degrees. All of that occurs with high sun spots and high solar activity. Same occurs from JA.

So the term SKEWED should not be used as you used it. It was LP for sure at that time of day YB and 9V come in on 30 and 40 from the SOUTH EAST at that time of day.

So there you have it, excellent words of wisdom from an Old Timer. Thanks, Jim!

73 and good DX

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