RadioBanter - View Single Post

May 2nd 06, 01:23 PM posted to rec.radio.amateur.dx

wrote:
I am a SWL from Bangalore,India, and i heard from the HAMs here that it
is difficult to have QSOs in 40m band like they used to do some 5 years
back. It seems that they were able to have QSOs with just 5w (distance
of 400KM and more), but now even if they are pumping 50W SSB they are
not able to have comfortable QSOs seperated by a distance of just 50KM.
I designed and built a super het receiver and i am not able to receive
anything in the 40m Band. Are there any reasons for the above said
experiences?

If it is more difficult to have QSOs on 40m than it was 5 years ago, I
would say local conditions (noise, interference from broadcast stations)
are to blame. At least here in the eastern US I've heard some of the
best conditions in my 35 years in ham radio on 40m recently.

Generally, the 40m band is almost *always* open to somewhere. During
the day, distances between zero and 700-800km should be common; at
night, strong signals should be available over distances of as much as
8,000km or more.

We are in fact at the sunspot minimum. There is an 11-year cycle to
sunspot activity; these sunspots influence the ionization of the
ionosphere and affect the ability to communicate over long distances on
high frequencies. For example, there will be little or no long-distance
propagation on the 10m band for a few more years.

However, it's pretty rare for the activity to get low enough to make the
40m band completely dead.

Sometimes (and especially at sunspot minimum) the 40m band can develop a
"skip zone". (this is pretty common at higher frequencies) Signals
from stations that are too close will shoot right on out into space -
you can communicate with stations 3,000km away, but those 200km distant
cannot be heard. I suspect this is what's going on: the stations in
your area are too *close*. They could communicate effectively with
other stations in other Indian cities and nearby countries, but not with
stations in the immediate Bangalore area.

I am not familiar with activity levels in India, but I would expect
there to be *some* signals (at least broadcast signals) on 40m at all
times, 24/7. To be honest, if you're hearing nothing, I would suspect
your receiver is not working properly.

--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com