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Sun spot activity in the ARRL Letter

Apr 5th 2012, 21:33


Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
I would really appreciate a qualitative summary of the Solar Update Column in the ARRL Letter.
As presented, the isolated facts about Sun spot numbers, Solar flux, etc. leaves the reader attempting to discern for oneself a probable HF propagation forecast in practical terms from the data presented.
While all that data is valuable and should continue, it would be extremely helpful to have a qualitative presentation vs. frequency, MUF and so forth based on the raw data.

Pat, W2YX
Apr 6th 2012, 02:10


Super Moderator

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0

The challenge of putting together a qualitative description is that it is highly location and station dependent. For instance, when I operated from Pacific Heights in Hawaii--I was lucky enough to have a 10 meter beam on steeply sloping ground--with a great view of the Pacific Ocean. I could actually work rare African countries while running QRP that were hard for folks on the Honor roll--it is quite likely that my antenna had an unusually large amount of gain at very low radiation angles due to its unique location.

At the other extreme might be folks at high latitudes, who have to constantly deal with aurora. In Connecticut, if the band isn't open to the Far East, Europe will often be just fine. Even better are paths to the Carribean--the bands have to be real lousy for us not to hear them. For folks in Alaska, choosing an aurora free paths may not be an option! I recall Bob Brown NM7M(SK) suggesting that one do a scatter plot of the variables for your station, so you can determine what works for you. A station with a big antenna is likely to have a wider range of "good" conditions that someone who has severe antenna restrictions to deal with.

The desired mode of operation is also a big factor--you typically need much better conditions for casual voice conversations than CW contesting or PSK31 (keyboard to keyboard chats).
This propagation prediction page can be useful for turning the data into estimates based on the exact path and the antennas on each end.

Zack Lau W1VT
ARRL Senior Lab Engineer
May 11th 2012, 01:20


Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
I think propagation will ALWAYS be something we have to chase, which to me is part of the allure of amateur radio. It wouldn't be as much fun if too predictable. Yes, I could have picked up a cell phone rather than wait to get through to South Pole Station on 20m, but where is the challenge in that?

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