Wednesday, January 10th, 2018
On PMR446
~~~~~~~~~
Solderpunk responded[1] to my older post about common interests[2] on
gopherspace with a nice long post, which was pleasure to read - we
indeed share view on many things. But today I'd like to elaborate on
a topic, which we do not share yet - PMR446 radio.
I'll start with a bit of history. Until November 1989, Czech Republic
(then part of Czechoslovakia) was a socialist country and to say it
gently, personal freedom of its citizens was very limited. It was not
possible to own and operate a transmitter without license by ministry
of interior and it wasn't easy to get that license. So when in 90's
all that ended, huge boom of CB radio started. Tens of thousands of
people bought CB transceivers, put antennas on their roofs and if you
visited any bigger city, you had to wait couple of minutes on almost
any channel to get the possibility to speak, because they all were
simply full. There were CB clubs, contests every month, people on
portables every weekend...
The situation however dramatically changed. Majority, that used CB
radio just as a mean of communication with friends or family, soon
replaced bulky transceivers with cell phones or Skype and those few
newcomers didn't compensate the loss. Today there is just one active
CB club, maybe two dozens of people doing portables and handful of
contests every year.
When the CB was just slightly over the peak (around 2002/3), some of
CB users with HAM spirit noticed the new PMR446 standard (Personal
Mobile Radio, 446 MHz) and decided to try it on portables. PMR is
limited to handheld transceivers with fixed antenna and transmit
power 500 mW E.R.P. Until 2016 there were just eight channels in the
range 446.0-446.1 MHz usable with analogue FM modulation, in the last
revision another eight were added in the range 446.1-446.2 MHz and in
these new channels digital operation was allowed. Since 2018/01/01
all channels can be used either in FM or in digital (DMR, dPMR) mode.
The band itself is not much affected by atmosphere conditions and the
propagation is very straight, almost in the line-of-sight range,
without significant reflections or diffraction. That makes it good
for the intended local usage (low interference with distant signals),
and in together with the usual small size of transceivers interesting
for QRP portabling, especially from a mountain to a mountain.
So the band took over in portables here in the Czech republic and
today there are more portables every weekend on PMR446 than on CB.
From a good QTH it's not a problem to make 50-60 QSO on a single
afternoon, I just did it last Saturday[3] and it's even better during
summer. As our country has mountains on almost all of its border, we
can here do quite a long distance QSO, considering the band, transmit
power and transceiver type. According to Wikipedia, the world longest
QSO on PMR446 was over 500 km. My personal record is cca half of that
and I witnessed some QSO over 300 km long, which really is across
the whole country from west to east. All of this on stock PMR446
transceivers bought around 50 USD a pair.
I don't know whether PMR446 is used this way anywhere else than in
Czech republic and Slovakia. In Poland CB is still a big thing
(I haven't yet seen a polish car without a CB antenna) and I heard
just two or three Germans on the band during last six years. Outside
Europe PMR446 even isn't free to use, so possibly this is just our
weird little thing. But for sure it's fun.
[1]
gopher://sdf.org/0/users/solderpunk/phlog/on-common-interests.txt
[2] see the bottom of this file
[3]
http://www.cbpmr.cz/deniky/5434.htm
