Radio Discussion Community

i've heard alot about aerials must have a good earth
i have a sirio mag mount ml145 so would perfomance be improved if i ran an earth wire to the mag mount? does anyone have any ideas? thanks

It's not something I've done to mine on my tractor for the simple reason I'm using awing mirror mount but I have seen it done for magmounts!

- Gordon

if you have mounted it on a good metal ground plane then adding an earth lead will not realy help

yes there is a good metal ground plane but the magmount isn't in contact with it because of rubber under the magnet

thanks for the help

And if you remove the rubber then you will have scratches all over your tractor!

Can the SIRIO ML-145 come apart from the mount? If so use it on a wing mirror mount!

- Gordon

the mag works through the rubber so will not make a lot of differance check for a short at the plug end if its a sirio ml1145 you should have a short if not check the connections in the mag base as these sometimes break


cheers and beers

b

A mag-mount uses the cars metalwork as its groundplane without the need to rub off half the roofs paintwork to make it earth properly. It's a bit like an electric toothbrush charges up, without a connector in sight..spooky! You could however if you wanted to, put a wire from the top of the magnet casing if it's metal (a lot of them are plastic nowadays) to the cars bodywork and it may help just a tad. Bolt an enamelled and black plastic coated wire from the magnet to say a point just inside the cars door opening, which you'll have to drill and clean the small area of paint. You could use a wire terminal so you can connect/disconnect it at will. The wire could be insulation taped alongside the existing co-ax so it wouldn't look messy. Cover all exposed wires and bolts with a coat of silicone adhesive. It may take you an hour or so to do it, but it may not make as much difference to the TX/RX as you hope for. Getting the existing SWR lower than it already is would make more difference if it's possible to do so. Also the positioning of the mag-mount determines the signals output range. If it's at the fron of the roof right by the windscreen, then the signal will tend to go towards the rear of the car. If it's on the rear boot, it'll go towards the front of ther car. If it's on one side, it'll go towards the opposite side of the car. (the reason lots of truckers have 2 aerials to equalise the effect!) The best place technically is therefore slap bang in the middle of the car, exactly halfway between the front and back bumper if possible. A lot of people though like to speak to others as they are heading towards them, so, like on the General Lee car on the Dukes of Hazzard, their aerials are towards the rear of the car pushing the signal forwards. Another reason it's good that way, is that you don't lose the aerial in multi-storey car parks as it's a foot or so lower ... looks like a dodgem with sparks going everywhere lol! and it's more pleasing to the eye