Hello,

I posted this on the audio forum but got no reply so I will repost here hoping someone can answer my question.

I'm working on the Hirschman antenna on my 1981 240D. Trouble extending or contracting the mast. I think it's the antenna mast and I ordered a new one. I have a question about what's inside the antenna case. The antenna is a U6000-485, On top of the spinning plastic gear assembly is a bright metal tab that eventually opens the contacts to stop the motor. About 90 degrees to the left of this tab is a copper colored, lighter duty bendable tab. What does this do? Is it necessary?

Thanks

You might post some pics. As I remember on my 6000 there are about three or four sets of "points" or long arms with contacts underneath. Much like the points on old carb gas engines. You can short a screwdriver on them and the mast will go up or down. I never figured out if there was a way to adjust the gap other than maybe bending an arm which is probably not a good idea. This is on a 1981 300SD.

Pics might help. Also you might just have a mast that is not quite straight and that would keep it from going up and down.

In general, if the motor works all you needs do is remove and replace the old antenna shaft, I find it much easier to use an abrasive device to round the square end of the white nylon leader so it slides into place .

This is how the originals were made, not sure why they changed .

Remember to keep it clean ! .

hirschman says lubricate with silicone, I've heard others use different lubricants .

If you insist on taking the cover off or the motor apart, BE GENTLE WITH IT ! .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

OK, here's a photo. Orange arrow is the copper colored piece I mentioned. Blue arrow is the heavier, chrome-ish tab that interacts with black star wheel (yellow arrow) that opens points and shuts off the motor. The copper tab appears that it should also work with/on the black star wheel but I don't know why.

You can hook it up to a 12v car battery charger and watch it work. Do not remember what those tabs do but you should be able to figure it out by watching.

Depending on where you position the three position dashboard switch, the antenna will raise half way or fully ~ I ass-U-me that's what these contacts are for .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

So default position of the mast is about 15" up. Assuming thats the switch default position. If you want it to be in a different position, the dash switch sends power to a different circuit so it runs as long as the switch is held up or down.

OK, I received the new mast and installed it and everything works as it should. I bench tested the unit with a 12V battery and on the bench the mast still was not working correctly but once in the car all was fine. I still don't know what the copper colored tab does. I moved the tab to various positions and it didn't seem to matter. It still isn't clear what this tab is supposed to do.