21-00 UTC I worked with Uruguay, CV5D,
operator Lu. The same story, at 5 watts no QSO, at 10 watts 579.
21-00 UTC the 20 meters band was closed.
Vladislav, RX3ALL 72!--
Vladislav met with a very interesting phenomenon, which
is named (by me) nonlinear
propagation of radio- wave in ionosphere. The phenomenon
is, that at some small power (say 5 watts, as Vladislav had) it
is impossible to do a QSO, nobody answers, however,
if the power is a little increased (say to 10 watts, as Vladislav
did), the QSO is going on 59. As a rule, this phenomenon is observed
at DX QSO, if the distant is more than 2000 kms.
I have noticed
this phenomenon in 1980s. At the times I had ham call UA3ZNW
and I often sent CQ at 10 meters using a home brew transistor AM
transmitter. 12 Volts from a PSU with manually variable voltage
was going to the PA of the transmitter, and I had 3- watts RF power.
So, at the
times I have met the same phenomenon as Vladislav met at 2005. When
12 Volts feed the PA, nobody answers, BUT, when 16 Volts feed the
PA, I have received 59 from far stations. My transmitter runs 5
watts when 16 volts were across PA. So, it impossible explain, why
at 3 watts GUHOR, but at 5 watts- 59. Usual theory of radio- propagation
has no answer on the question.
I have noticed one more interesting effect of nonlinear propagation of radio- wave in ionosphere.
It is possible to name this phenomenon as a trigger effect.
The phenomenon is that at some small power (say 1 watt) nobody answers.
However if the power is a little increased (say to 2 watts) you
have received 59. Then power decreased (say, again to 1 watt) but
anyway you have received 59 from your correspondent.
At first I noticed trigger effect at 10 meters band. Since
an RF transistor of my PA was overheated at 16 volts, I worried,
that it would go out of operation during QSO. In 1980s the RF power
transistor costs pretty penny. So, I called my correspondent when
my PA was fed by 16 volts, after that reduced voltage to 12 volts,
and made QSO. As a rule, the QSO was completely done. The truth,
sometimes during QSO my signs were ceased, then I again increased the voltage to 16 volts for a while.
A power radio station located in my city also could be
the cause of the trigger effect. For example, I for a long time
call DX station, no answer, then power station from my city have
made QSO with the DX, after that the DX gives me 59. Such phenomenon
often is observed by me in contents, when I try QRP. I call for
a long time a far station, no answer, then
a powerful station has made QSO with the DX. That is all, the DX
gives me 599.
At first I thought that these strange things are only on
10 meters. But then I observed the phenomena on others amateur HF
bands, from 160 up to 10 meters. The truth, on the 10 meters these
phenomena are more sharply than on low-frequency HF ranges. Lots
of hams and professionals also are familiar with the strange phenomena.
My attempts to find a science explanation to these interesting phenomena
Professionals and scientists in personal talking about
the phenomena sad me, that it is a whim of propagation or lack of
my antenna or lack of the receiver of my correspondent. May be...
But by me this effect was marked at various receivers, both self-made
and professional, at different antennas, on diverse bands, and at
stable (for the time) propagation...
... It seems to me this riddle
is still unsolved...