W126 Hirschmann Antenna

A couple of months ago an eagle eyed viewer of my Instagram feed asked my why my 560SEL doesn’t have a Hirschmann Antenna.    Given how original the car is, it was a good question.  I had never really noticed what antenna the car had, other than it worked.     Since I have the original Becker, I really should have the original Hirschmann Antenna to go with it.

I had a look at the car, and saw that while it did have a Hirschmann branded antenna, it was the wrong one.   It was one of those generic antennas sold in the 90s.   Quite a lot of original Hirchmann antennas got replaced with these as they were not much more than the cost of a new mast.   I have one on my 450SLC, as when I got the car the original Hirchmann was long gone.  Sadly, it had been replaced by something cheap and nasty.

Since I planned to sell the 300SE, and I wanted to sell it with a working power antenna, I swapped out the 90s Hirschmann antenna with the proper 80s unit that no longer worked.   Since the 300SE was no longer sporting its original Becker, it seemed like a reasonable swap.    I also had one in the 420SEL parts car.    As the harness had been cut on the 560SEL, I was able to grab that piece of harness from the parts car.

That harness piece let me test both antennas.   The great news was that both of them moved a bit, they just had bent and stuck masts.    I had bought an aftermarket mast to try with these antennas, so I started with the antenna from the 300SE.   It was actually worse, even though the one that came out of the 420SEL was really dirty.    After a clean up they both looked pretty good.    I was pleasantly surprised, as I had low expectations of even having one working antenna from the two.

I set about opening up the Hirchmann antenna from the 300SE.   While you don’t strictly have to open up the case to change the mast, I wanted to inspect the inside and lubricate the gears.  Opening up the antenna case is very easy once you’ve done it once.  You have to release the plastic tabs.  I found the best way was to use a medium sized flat head screwdriver and lever each one carefully from the top.   I tried for a while to push them from the bottom but that never worked.

Overall, I was pretty impressed with the internal condition of the antenna.   It was a bit dirty, and there was a very small amount of moisture inside the case.   That was all cleaned up.    You need to be careful not to lose the little rubber rings that locate the motor.   There are three on the front and three on the back.

The actual process of removing the mast is well covered in various youtube videos.   I found once I had loosened the top of the mast and removed the mast carrier, I had to run the antenna to get the toothed belt out of the housing.   Its possible with one person but would have been easier with an assistant to hold it.   I also had to run the antenna to feed in the new mast.  I went with a cheap aftermarket mast, primarily because I had fairly low expectations that my antennas would work.

The mistake I made first time, was to feed in the new mast fully before re-assembling the housing.   The best way is to feed it in about 80% and then cut the power.   If you feed it in all the way, the motor runs to the end and pulls itself up too far and off its mounting points.   This means the belt doesn’t line up with the bulge in the case to accommodate it.     If you only feed it in 80%, you can then locate the motor properly in the case, check the rubber rings are all located properly, and then put the case back on.   Once the case is on, I then tightened up everything else, and ran the mast up and down a few times to test it.

From there it was a fairly simple matter of installing the antenna in the 560SEL.   I forgot to order a new rubber grommet to locate the antenna in the rear wing.  The one from the 300SE was a bit hard, but generally ok, so I re-used it.    I first spiced in the harness from the 420SEL into the 560SEL, and was a bit perplexed why it didn’t work.   After a few minutes of checking fuses, I remembered that the trigger wire to the old antenna was separate.  It wasn’t using the blue wire from the factory harness.

I suspect this is because the Becker 868 is a two piece unit, and the antenna trigger wire comes from the secondary box, which is located in the boot on my car.    I’ve left this wire with a quick disconnect. I often park the 560SEL under the hoist, so it can be useful to disable the power antenna.

I’m going to purchase a new grommet and new genuine mast to have on hand.   The old grommet was quite hard, and I’m not sure how long this aftermarket mast will last.   Now i’ve done it before, it will be a simple job to replace them if I have to.   The car is all ready for a club run tomorrow.