radio aerial problem

[Rusty47]

On my 1977 Dolomite 1300,someone snapped off the front wing mounted aerial,and I am replacing it with a new aerial.The radio is Sharp LW/MW,and it worked OK before.I have replaced other aerials on other cars,since 1955,and never had a problem.However,I am puzzled as to why I am getting no reception with this aerial extended,but when I touch the extended aerial with my hand,perfect reception,but when I take my hand away,nothing.I have wire brushed the inner wheel arch,back to bare metal for a good solid earth,still nothing .Please tell me what I am doing wrong,or what I have missed.Thanks a lot for previous advice.Joe

[matt of the vivas]

Sounds like a faulty aerial. The co-ax cable may not be properly joined inside the aerial.

[marshman]

Appreciate that you cleaned the bodywork to tensure a good earth but did you check this with a meter? A good check is to measure the resistance from outer part of the plug that goes into the radio (disconnect it from the radio) and the car body, or even the case of the radio. You should read pretty close to 0 Ohms on a test meter. The fact that when you touch the aerial you get good reception says to me the aerial and central core are connecting to the radio, but there is an issue with the earth. The aerial needs a "ground plane" to work properly, in this case a good earth to the bodywork which you are aware of. When you touch the aerial you I assume you are effectively creating this ground plane enabling enough signal to be fed into the receiver. Are you sure you assembled the fittings at the base of the aerial correctly and things were making contact where they should and insulated where they should be as well. 'lectrics are mysterious, radio 'lectrickery doubly so!

Roger

[dollyman]

Hi Joe, aerial has a bad earth as Roger say's. I have had this problem many times over the years. I take it you have a good earth on the radio itself as well? We did used to get this sort of problem with cheap and nasty aerials as well. Not saying you bought as such but they are getting harder to get these days and you might not have been sold a good one.

Tony.

[Rusty47]

Thank you all so much for great advice.I removed radio,fitted a good earth from it to the body,removed the aerial,rearranged the aerial fittings to the wing inside the wheel arch,and the radio is now working fine.It was obviously an earth problem as you suggested.I could have fitted a modern radio,but the period one looks just right for the car.Once again,thanks for your time and knowledge.Joe.

[dollyman]

Thank you all so much for great advice.I removed radio,fitted a good earth from it to the body,removed the aerial,rearranged the aerial fittings to the wing inside the wheel arch,and the radio is now working fine.It was obviously an earth problem as you suggested.I could have fitted a modern radio,but the period one looks just right for the car.Once again,thanks for your time and knowledge.Joe.

We love it when a plan comes together Joe.

Tony.