People are staring to take the computer predictions, simulations and
forecasting too seriously. Atmosphere and ionosphere are very complicated
and are run by Sun and not some wiz programs.
Before the computer models, we used to OBSERVE and LEARN about propagation
from our activities on the bands. Changes with sunspot cycles, time of year,
day etc.
So forget the computer prescriptions and observe and make notes what is
happening when Sub is doing what. One general observation I have found that
with low sunspots in a cycle atmosphere shrinks, angles get lower and
antennas with low angle lobes work better. At High sunspot, atmosphere gets
higher and angles get higher and higher frequencies come to live.
The best, unpredictable and unbehaved band is 160 m, you never know what
happens, just need to be around when IT happens.
Check out http://members.aol.com/ve3bmv/bmvpropagation.htm
on my observations and notes on ducting and refraction.

73 Yuri, K3BU
"C. J. Clegg" wrote in message
news
On Sat, 16 Dec 2006 01:22:44 +0000, Jim - NN7K wrote:

Owen is correct- and anyone operateing 10& 6
meters will tell you the same thing!

Good morning, Jim.

What I'm trying to figure out is the effect of sporadic E on the lower
bands, e.g. 75 meters.

I was on a military net on a frequency somewhat above 4 MHz and was able
to work a station 70 miles away, well after dark when the critical
frequency was below 3 MHz. According to everything I know about critical
frequencies and MUF (which isn't very much), my NVIS signal from my
17-foot-high dipole should have gone right off into space, and the
70-mile-away station shouldn't have heard a peep out of me (and vice
versa).

I'm trying to figure out if the solar storms of the last few days might
have something to do with why I was able to contact that station when
every indication was I shouldn't have been able to. Sporadic E? I dunno,
maybe, but it seems like quite a stretch...