PMR446 means "Personal Mobile Radio", two
way radios with 8 channels and 38 subtones, transmitting in a
little slice of frequencies large less then 90 KHz, from
446.00625 to 446.09375 MHz, under the frequencies of the TV UHF 4
band.
One of the very interesting features of PMR446 radios is the low power used: if in Citizen Band (CB) the maximum "legal" power is 4.5 Watt (in Italy), with Personal Mobile Radio446 (PMR446) the "legal" power is lowered by 10 times, that is 0.5 Watt and several limitations were imposed (as short antenna and, sadly, with no possibility of change it) to limit the interferences with other users.
But we don't think that 0.5 Watt are too few to make very good long distance communications: with good propagation, we can do several hundreds km link and, apart from less interferences, we have less battery drain and consequentely lesser physical dimensions of the radio to contain the batteries.
Here by the side, a photo that compares dimensions of my Midland Alan 38 and my TwinTalker 3600. It seems that were passed centuries between the two but were passed 15 years only...
Since 2004, with a friend, I started to experiment with PMR446. For who comes from CB, the one absolutely different thing in propagation is that PMR446's radiowave is very similar to the light's behaviour, therefore, if two antennas see one the other, then the signal will pass, else...
When I'm home, my PMR446 is in forever scanning... but nobody speaks. So, because I live in the country and there is nobody near me with this passion, just for fun and for experiment, first I started with building a 1/4 wave long (a ground plane), continuing with a Yagi 9 elements, then a Yagi 13 elements and finally a completely new 14 elements Yagi.
And these are my PMRs:
In the middle the famous TwinTalker
3500, my first radio, bought for only 5 €. I removed its
antenna and replaced with a BNC
so I can connect a Yagi antenna.
Later, I bought 2 TwinTalker 3600, @ Lidl for 39 € (in Germany the same radios were sold for 25 €!!!). And some years after, I bought (always in Germany... @ Ebay) many other TwinTalkers 3600 and a TwinTalker 4700 and TwinTalker 4710 DCP.
Now my PMR446 family is really grown ;-)
One on them was modified with a BNC connector, for experiments, of course, but I saw that coupling the original antenna with a yagi antenna, the results were near the same.
Personally, I like these radios, they are very sensible and not power and battery hungry. They are microscopic radios, very light weight and them fit very well in every pocket. When I'm on bike, TwinTalker 3600 is always in my pocket, ready to make a bicycle-DX.