PMR range doubling tip for UV5R type HTs

[Lightspeed]

We continuously test the local coverage of our PMR446 equipment by transmitting with a standard PMR446 compliant hand held to a UV 5R type radio as the wandering receiving station. This gives us a good understanding of what we can hear from the local area, and where the dead spots are.

Coverage has been increased 50% by simply repacing the UV 5r's stock antenna with a Nagoya NA774. This is a telescopic antenna approx 41cm long when fully extended. This antenna is specified for Ham VHF and Ham 70cm bands. Although not specified to 446 Mhz, it does an excellent job in receiving.
see http://www.ebay.co.uk/itm/Nagoya-NA-774-...2a21398a1c


Coverage can be extended even further using one of these:

http://www.ebay.co.uk/itm/Ham-Amateur-Ra...20c8a3eab3

Occasionally this seller offers antennas tuned exactly to PMR446 band. This is the product that we use. Its 60 cm long when fully extended, and fairly rigid, so not really stable enough for hand portable use as it puts excessive strain on the radio's antenna connector. We use ours when at fixed location for monitoring.

If ordering either of these, make sure you specify the correct connector for your radio.
Consider purchasing a BNC adaptor for your radio(s), then additional antennas can be ordered with BNC connectors to allow interchangability.

LS

[NorthernRaider]

I get a similar range extending reception from putting a 52cm rubber duck on the hand held CB.

[Paul]

Good reasons for extending aerial length but I always worry about bolt on telescopic goodies not specifically designed for that particular gear. Two reasons.

How can you tell it's providing a good SWR for the transmitter?
Handheld twigs are notoriously hard to tune effectively unless the rig has a built in SWR meter and the bigger the twig the more it's surroundings ( i.e. YOU) affect it's SWR.

Then, especially if there is exposed metal and you're transmitting, one flick against a metal fence, live wire, or something like that and the output transistor could go pop.

Now if your lucky the receiver still works, or not.

[Lightspeed]

(14 August 2012, 09:11)Paul Wrote: Good reasons for extending aerial length but I always worry about bolt on telescopic goodies not specifically designed for that particular gear. Two reasons.

How can you tell it's providing a good SWR for the transmitter?
Handheld twigs are notoriously hard to tune effectively unless the rig has a built in SWR meter and the bigger the twig the more it's surroundings ( i.e. YOU) affect it's SWR.

Then, especially if there is exposed metal and you're transmitting, one flick against a metal fence, live wire, or something like that and the output transistor could go pop.

Now if your lucky the receiver still works, or not.

What you say is correct Paul.

That's why I'm sharing this information here. I've tested the antennas in question and they appear to be giving correct SWR to the transceivers..... so far so good and no destroyed output transistors. Of course there could be variences between individual antennas, but that's the same even with high end gear. I guess the logic here is to get the extra antennas and test them straight away while replacement equipment is still available.

By the way, it appears that the Thailand based supplier does SWR his antennas as part of the manufacturing process.

You make a very good point about metal antennas coming into contact with metalic wires and other metalic structured. In contact these will become part of the antenna and so detune the whole system with potentially damaging results.

WARNING: DO NOT LET ANTENNAS TOUCH METAL OBJECTS WHEN TRANSMITTING!