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