a few basics please, watt to watt compare

[MC Carpenter]

Can one of the more experience members help on this one,

watt to watt,  
meaning in the 3 to 5 watt range ,  the lower the frequency,  say 40 meters, at night the longer the skip, there fore the longest contact possible, except in summer when its best in early morning hours round four  AM or so. So anyone trying for contacts in mid day would be best to use 10 meters or higher  and in winter months,   Is this right,   the reason is that I never hear anyone on 80 or 160 meters but 10 meters in the day is a circus trying to sort out the over lapping  and all the signals sometimes.  I am wondering if this is the reason that Elecraft does not have 160 and 80 on there small CW units, I have never heard any signal from South America like Brazil , not even one when DX's,  yet I am told there is plenty of action on 160 and 80 in that region of the world
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[John J. McDonough-2]

MC

Pretty close.

Actually, on the lower frequencies, longer skip is always possible.  So is
shorter skip.  As you go up in frequency, shorter skip quits happening until
you reach the MUF, where essentially the minimum skip length becomes so long
that you can't get any skip.  So part of the problem is that, at the lower
frequencies, there is not only the long skip, but short skip as well.  Along
with it, all the noise from the short and the long skip that is also
reaching your radio.

You may have heard of the "Maximum Useable Frequency" or MUF.  This is the
frequency at which the minimum skip is the longest.  Above the MUF, your
signal just goes out into space.  As you get below the MUF, the long skip
remains, but shorter and shorter skip becomes possible as you get lower in
frequency.

However, there's a bad guy out there ... the D layer.  The D layer absorbs
your signal, and the lower the frequency, the more it absorbs.  Perhaps
worse still, the higher the solar flux, that same solar flux that makes the
MUF go up, the greater the D layer absorption.  So when 10 meters is open,
it's quite likely that 80 will be unuseable because of the absorption.

However, when the sun quits hitting the D layer, that layer's ionization
gradually fades, so conditions on the lower frequencies get better the
further past sunset.  And that is also why in the summer, when you have more
hours of sunlight and the sun is beating down on the D layer more directly,
the conditions on the lower bands tend to be poorer.

Of course, for the lower power signal, the D layer absorption is more
intolerable than for higher power levels.  That is why QRPers tend to go to
the highest frequency that's open.  On 10 meters, where there is virtually
no absorption, one watt is as good as 100.  On 80, though, it's a different
story.

Hope this helps a little

72/73 de WB8RCR    http://www.qsl.net/wb8rcr
didileydadidah     QRP-L #1446 Code Warriors #35


----- Original Message -----
From: "MC Carpenter" <[hidden email]>
To: <[hidden email]>
Sent: Wednesday, July 14, 2004 8:08 PM
Subject: [Elecraft] a few basics please, watt to watt compare


Can one of the more experience members help on this one,

watt to watt,
meaning in the 3 to 5 watt range ,  the lower the frequency,  say 40 meters,
at night the longer the skip, there fore the longest contact possible,
except in summer when its best in early morning hours round four  AM or so.
So anyone trying for contacts in mid day would be best to use 10 meters or
higher  and in winter months,   Is this right,   the reason is that I never
hear anyone on 80 or 160 meters but 10 meters in the day is a circus trying
to sort out the over lapping  and all the signals sometimes.  I am wondering
if this is the reason that Elecraft does not have 160 and 80 on there small
CW units, I have never heard any signal from South America like Brazil , not
even one when DX's,  yet I am told there is plenty of action on 160 and 80
in that region of the world
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[Stuart Rohre]

Bands such as 80m and 160m have a lot of thunderstorm static in summer, and
are best in that regard , (lower noise) in winter.   40m is more of a
daytime band for shorter ranges, and skip lengthens out at night.  If you
are trying to work in state, 80 and 160 m are best for that at night.

Bands above 40m, or 30m begin to be affected by the maximum useable
frequency effects.  Thus, 10m is a day time band, mostly.  Somewhat true of
15m, and of course the bands either side.
20m finally becomes a band with long DX skip day or for part of the night,
and is best all around DX band all year.  (IE open more of the year,
especially in lower sunspot times as now).

At dawn and dusk, you can get enhanced propagation on a number of bands.
The atmospheric noise of storms is less noticed on bands like 20m and above,
unless they are very close to you.

Hope that helps sort it out.  Buy the ARRL Handbook and read the propagation
chapter a couple of times to get a more in-depth understanding.
-Stuart
K5KVH


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