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PMR446 & eQSO
PMR446
is a European licence-free radio service offering 8 channels
in the 446Mhz band, PMR446
radios can be bought from as little as £30 a pair. All
PMR446 sets must use an integrated antenna and the max ERP (Effective
Radiated Power) is limited to 500mw (0.5W) which gives a realistic
range of approximately 0.5 to 1 mile around town and up to 2
miles in open country. In line of sight conditions and at high
altitude some people have managed a range of over a hundred
miles.
eQSO
Internet Gateway
I run the UK095-L eQSO
Internet Gateway in Warrington, Cheshire, UK which you can
find on Channel 4, CTCSS 19. The radio in use for the link is
an Xtreme XT1000 which is mounted in the loft on the end of
a 4.5' long plank of wood so it is right up in the apex of the
roof.
More information
and coverage maps here.
eQSO is a "voice-over
IP" system - that is, voice delivered using Internet Protocol.
People all around the world are connecting their PMR446 sets
(and UHF CB in Australia) up to their internet connected computers
to form a network which allows people from all over the world
to communicate via PMR446.
As
an example of what this does, someone within range of my gateway
link can talk through my link radio, over the internet, and
out through another gateway in, say, Belgium or Australia. Someone
within range of that second repeater gateway can then communicate
back and thus establish a conversation.
Even
if you don't have a PMR set yet you can still participate in
the network using
your computer with a microphone and speakers.
Unoffical
Conventions for PMR446
A few unofficial conventions are now becoming commonly used
on PMR446:
-
Calling
Channel: Channel 8, CTCSS 8
-
Data
is confined to Channel 1
-
Activity/DX
on 1st Sunday of each month
-
DX
Weekend: Sat 2nd and Sun 3rd August 2003
External
Antennas & other mods
Warning: Any modifications to a PMR446 set renders its type
approval void making the set illegal. The biggest improvement
to range on 446 is to be found by mounting the radio and thus
antenna up as high as possible, whilst this might be fine for
an eQSO link where the radio isn't touched once set up it may
not always be practical in other situations so quite a few people
add an external antenna to their set, mounting the antenna high
up and having the radio in a position where it can be operated.
70cm ham band antennas are ideal for PMR446 use although using
one would entail fitting a BNC or similar socket to your radio.
SWR is not really critical as PMR446 uses such low power a high
SWR is highly unlikely to damage the radio, but of course a
high SWR would affect the signal output so getting it as low
as possible is still advantageous. One possible problem with
adding an external antenna is impedance matching, a communications
transceiver usually expects to output to a 50ohm load and so
antenna designs are based on this assumption. However, there
is no guarantee that this stands for any particular 446 radio
so it is a bit of a 'suck it and see' situation.
eQSO
Links
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