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Looking for some advice on establishing a ground plane for a Power Antenna replacement on an 80.
I bought a reproduction power antenna for my 1980 from Zip Corvette several months back and only got around to installing it this week. Below is the antenna I bought. It is sold as a reproduction and has the correct three wire (grey, white and green) harness.
The problem I've run into is that this model has nowhere to attach the earth strap that runs up from the rear driver side frame rail. The lug visible at the bottom of the above picture is for mounting to the chassis and is not connected to any metal part of the antenna. There is no mounting point on the antenna shaft and nothing useful under the rubber boot. I went back to the Zip site and noticed that they have discontinued the model I bought and replaced it with one that has an obvious ground attachment point in the form of a tab attached to the shaft. See pic below...
I'm pleased that the model is improving over time but it doesn't help me with the $200 prior model I'm the proud owner of! I can easily fabricate a metal clamp that goes around the shaft of the antenna similar to above and provides a point to connect the ground wire to, but I'm not convinced creating a ground plane is as easy as that unless the antenna was specifically designed to have the ground plane introduced that way. Has anyone used the model in the first picture (with the rubber boot)? How did you connect the ground?
Some GM antenna models like the second pic you show don't use that bracket attached to the mast tube.
They use a stiff strap attached to the rivet you can see to the right of that bracket that extends to the mounting point at the bottom of the antenna.
When you bolt it to the frame bracket you also have the strap bolted up. The ground strap is at that bolt also.
Are you sure you don't have a strap like that under that rubber shroud?
Some GM antenna models like the second pic you show don't use that bracket attached to the mast tube.
They use a stiff strap attached to the rivet you can see to the right of that bracket that extends to the mounting point at the bottom of the antenna.
When you bolt it to the frame bracket you also have the strap bolted up. The ground strap is at that bolt also.
Are you sure you don't have a strap like that under that rubber shroud?
Thanks for the good info. I'm positive there is nothing under the shroud. I pulled it right off. The only thing under it is the motor, plastic mast housing housing with recessed black painted screws and a plastic terminal block where the 3 wire harness enters. There are two screws at the bottom of the aluminum shaft that could potentially be intended to hold a tab similar to the one in the second photo in my post (i.e. the new model). I guess its possible the tab was missed on mine. I think the fact that Zip changed the model is suggestive that the model I bought has a problem.
That ground bracket in your second pic sometimes turns up on ebay.
If nothing else connect the ground to one of the screws at the co/ax connector or to one of the holes you say is at the bottom of the mast tube.
As long as it's connected to the mast tube it's good.
The ground isn't really electrical but for radio reception.
Thanks for the photo - helpful to see. The problem with the "reproduction" antenna is that the point on the antenna where your ground connects to is plastic and there is no continuity between that mounting point and other point on the antenna including the co-ax shield and shaft. So if I use the same location yours does it will have no effect. As I look at your photo the circular mast housing appears to be metal which explains why that location works for you.
That ground bracket in your second pic sometimes turns up on ebay.
If nothing else connect the ground to one of the screws at the co/ax connector or to one of the holes you say is at the bottom of the mast tube.
As long as it's connected to the mast tube it's good.
The ground isn't really electrical but for radio reception.
Thanks for the info. I'm going to use a water pipe ground clamp around the bottom of the shaft and see if that works as a grounding point.
My antenna has a metal plate with a hole directly under the hole in the fiberglass. I thought that was the ground.
That is normally how the ground is introduced with a manual antenna. The aftermarket power antenna uses insulated spacers at the top either side of the hole in the fiberglass so a plate there wouldn't contact the body of the antenna.
Power antenna ground conundrum
