10 M Wattage

[Glen Zook]

Actually, a dB is a dB is a dB.  If you double the
power, the increase is 3 dB.  If you quadruple the
power, the increase is 6 dB.  And, if you go 10 times
the power, the increase is 10 dB.

Now, as for "S" meter readings:  A lot of the older
gear had fairly accurate readings.  Most were set with
a value of 50 microvolts for an S-9 reading, and
virtually all of the remainder were set at S-9 = 100
microvolts.  When you use a calibrated attenuator on a
signal generator you get one "S" unit equal to 6 dB of
signal.  That is, when you reduce the signal 6 dB from
50 microvolts (to 25 microvolts - remember, when
dealing with voltage 1/2 voltage = 6 dB reduction)the
"S" meter drops to S-8.  And so on.

Now, on many of the newer units I have seen a signal
of as low as 10 microvolts produce an S-9 reading and
increasing it to 20 microvolts produces a "40 over"
reading.  Even on those that require 30 microvolts for
S-9, increasing the signal level to 100 microvolts
will read as high as 60 dB over S-9!

Too many manufacturers like to say that their
equipment is "more sensitive" since the "S" meter
readings are higher.  This is nothing more than a
"ploy" to get the unsuspecting to buy their products.
There is no "rhyme or reason" to the "S" meter
readings and actual signal strength.

Thus, what is often an S-6 reading on a Collins 75A4
is a "30 over" signal on one of the "latest and
greatest" rigs.  Quite often, the actual
signal-to-noise level on the signal is better on the
old Collins than it is on the newer equipment.

Now, when 10 meters is open, you can work the world on
a few watts.  When it is closed, you can't work
anything running a KW.  I have worked well over 100
countries mobile on 10 meters running 25 watts PEP
into a loaded Larsen antenna (3 dB loss when compared
with a full size quarter-wave whip).

I agree that the antenna is a very good place to
improve your signal.  Of course, if you have both the
antenna and the power you suddenly become one of the
"big guns".  Also, especially if you build your own, a
good antenna is normally a lot cheaper than going for
high power.

Glen, K9STH


--- Ed Wright <edwardwright at HOME.COM> wrote:

Remember if you are at N watts you need to double that
to pick up a db on the other end

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