Vehicle & Technical > Discovery
Roof bars. will they conduct electricity?
NeilWilson:
--- Quote from: "thermidorthelobster" ---Stick a multimeter on and you'll find out pretty quickly.
--- End quote ---
Just checked on mine and the bars are earthed (or if you prefer, negative terminal connected).
Neil
muddyjames:
cool wicked. thats a good start. just hope my roof mount grips now!
Tyke:
You need good bare metal contact when dealing with earths on radio equipment. We are dealing with RF currents at very high frequencies and what is fine for a DC system may offer such a high impedence to the flow of RF current that a normal DC earth may be all but useless.
Doubt that the roof bars would provide a good enough earth for efficient working of the radio. This could show up later as very high SWR readings when you are setting up the system and in severe cases, operating with high SWR's can cause heat build up in the radio set and effectively burn out the output transistors.
Don't worry too much though, just take advice from the guys who have them fitted and working ok . there's loads on here.
All bit complicated if you are not into radios but here is a site that may help you understand a little better.
http://www.k2bj.com/Ground.htm
NeilWilson:
--- Quote from: "Tyke" ---You need good bare metal contact when dealing with earths on radio equipment
--- End quote ---
True enough, although lots of people get away with mounts on roofracks with rubber gutter feet ends and various other mechanical contraptions. You can counteract some of the SWR with suitable aerial tuning. Any earth is going to be better than none at all. I have mine mounted on the spare wheel carrier.
Neil
muddyjames:
how do you mount yours Niel? I thought about that but my spare wheel has the grey plastic trim on it and i cant be bothered to take that on and off after every trip or unless it will mount on and then leave on and be hard for light fingers to take of I may leave it thee.
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