Thread: UHF Advice please...

I can speak for the Icom IC-440:

The speaker is in the hand piece but there is a jack for an external speaker.

I have an ARB winch bar and there are two tabs on the top rail each of will accept the antenna unit.

The antenna I chose was:

Prestigecom.net.au 3 & 6.5db Ground Independant 4WD Antenna Package - $115.00

The 6.5db aerial is good for flat country/highway use and is also designed to resist bending at speed. The 3 db is good in hilly country.

Thanks Mahn,
Since posting earlier Ive found the speaker is in the Mic on the Icom and not (I dont think, on the GME), so all other things being equal I think the Icom would be better for me.

As for the antenna(s), is there much real-world difference between the 3 & 6dB's? Im assuming you get more distance with the 6db on the flat highway?

What sort of distance can you get with the 3dB vs 6.5dB?? Presumably the 4.5dB is inbetween the 3 and 6.5 in terms of distance??

Also, do you simply unscrew one antenna from the ARB bar and screw the other one in?

Thanks
Jon

You will also find that the chassis of the Icom is a lot better than the GME.Making for a more solid and more robust unit.

Hi Jon,

Think of the aerial as the center of a donut.

The higher the db the flatter the donut...therefore the horizontal range is greater.

The lower the db the more spherical is the distribution around the aerial.

In hilly country I change the antenna to the smaller one. It screws onto the top of the choke. Too easy.

I'll take a photo tomorrow.

The Icom units are a very solid unit, I don't have one but if I was going to upgrade that would be my choice.

The antenna questions you ask; does brand matter? No, if they are for the appropriate frequency band then they will work with any transmitter. Brand might be associated with different build quality but there is not much between them.

I went with a Mobile One, I am told they supply the antennas used on the police cars so they can't be a total dog.



As for the gain vs distance question, 3 db extra gain is the equivelant of doubling the power output of the transmitter but only in the direction of maximum gain. UHF propagation is closely approximated by free space propagation where distance and power density are related by 1/r^2 (one on distance squared) law, therefore double the power (3db) will get you 1.4 the distance.

For bullbar mounting you will want to use a ground independet anntenna, the higher you mount the antenna the greater the line of sight distance to the horizon.

thanks guys, thats of great help.

now why dont the manufacturers talk in donuts & 1/r^2 - easy peasy!

Jon

I recently bought a IC 440 after looking at both the Icom and GME. As mentioned the ICOm has the speaker in the handset the GME does not. As my 101 is very noisy I have set up the Icom with an external speaker as well. This does not disable the handset speaker which means I have no problem hearing.

The Icom cradle is great - allows the radio to simply unclip for use in other vehicles (I bought a second cradle for my other car.

I have a 6.5/9.5 db GME aerial combo and it works great.

Radio was $410 and aerial $79 from Prestige.

The only down side is that you need to carry the manual with you to use the Icom for its fullest functionality but basic functions such as search, vol, squelch and change channels are easy to use - however I think the GME is the same.

I think the main advantage of the Icom over the GME is the speaker in the handset - works well even in my 101 so you really do not need to worry about an additional speaker. I could have got a GME on Ebay for about $375 delivered.

Garry

Garry, thats helpful. The mic in the speaker is a great plus for me but it also means that with the icom I can use one of the spare external inputs on the back of the stereo for extra speaker if need be.