Help- I can't even replace an antenna mast

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cleeve51

New Member
Joined
Jul 31, 2010
Messages
9
Location
Kingston upon Thames
Car
300SL & C Class
I have an 1989 300SL (W107) with a Hirschmann Auta 5090 power antenna. All the posts say the old mast just pops out and the new mast feeds in. But that isn't what happens. In fact, it looks wrong. When I loosen the top nut I can see the tube which extends from the motor, which has an external thread. But the new mast (6682 8037) has a fitting which seems to assume an internal thread on the tube from the mast. Is this the wrong part, or am I missing something?
old_fitting2.jpg
new_n_old2.jpg


The existing mast where And the proposed new mast
the nut fits on the outside

Can anyone help, please? And if I got the wrong part, what part number should I have got.
 
Hi Cleeve, the don’t look identical but the new mast may still fit, the images aren’t clear enough to make a comparison.

Can you remove the old mast, the radio needs to be switched ON at the same time as the mast tail is being pulled out.

You may find that by swapping over the old nut to the new mast that it may solve the screw thread issue.


Dec
 
The photo on the left is the old antenna and if it were better you would see the rusty bit is a screw thread. I'd slid the retaining nut an inch or so up the aerial and this is a standard nut with the the thread on the inside.

On the new mast, the base of the mast has collar with a nut welded to it and a screw thread below the nut. This should drop inside the motor assembly and screw to the inside.

There are slightly better photos at:
www.thedavenports.co.uk/images/new_n_old.JPG and .../Old_Fitting.JPG

When I turn the radio on the mast does extend (although it's already80% extended - permanently) to 100% but it doesn't want to leave the motor assembly. I'm concerned that even if it did pop-out as expected the new mast will have nothing to screw into.

I hope that clarifies the problem.
 
I see your dilemma, unless that mast is removed you won’t know if the new mast is the same as the old one.

It’s possible that you do have the wrong mast, hopefully someone else may be able to enlighten you further. Is this a Mercedes part or is there a brand name and does it claim to fit your particular model?


Dec
 
hirschmann antennas have a very small number stamped into the top of the antenna. I assume that the number on your existing antenna and the replacement are identical? You may need a magnifying glass like me to read it though. I was told last week that if the numbers match, then you are okay. Failing that the hirschmann website in germany has alot of pdf documents that may help. The most pressign problem will be ensuring that the old mast comes out cleanly. Mine was so welded to the tube that in the end I had to source another unit.
Les
 
Last edited:
The motor unit is definitely a Hirschmann 5090. The exisiting mast does not have any markings on the top (did they do that in 1989?). The new mast is stamped "h04" on top and is from a Merc dealer (and, from all the tables I've found, appears to be the right part number for the 1989 W107.
Even if the existing mast was a "compatible" (which I don't recall it ever being changed) it doesn't explain why the fitting on the new mast does not match with the fitting on the motor unit.
This "h04" mast clearly isn't right for the motor unit. I can't find the Hirschmann site which tells me the mast I need for the 5090. Please let me know the www.ref.
And finally, although the lowest two sections seem to move freely and I can hear the motor running (and moving the mast slightly), it doesn't just "pop-out" as everyone says it should. Maybe it is "welded/stuck" somewhere, or do I have to pull it past a retaining ridge?
 
Found Hirschmann

OK, thanks guys. I found the Hirschmann product page and it's clear that Merc have given me the wrong mast.

I think I need an 11 instead of an 04 - At least that has the right interface, fastened with a standard hexagonal nut. And it has a "contact clip" which is probably the bit that is preventing it from "popping out".

I'll try again when Merc parts dept. is open.
 
There are many sources in order to replace the Antenna Mast of the car. To remove it, there are the resources given to you. If you still cannot do it, try to really go to an expert or a mechanic to help you remove it.
 
What I learnt

Thanks for all the help. It took a while and I learnt a few things:

a) Not all Hirschmann masts have a letter on the top. The new mast (from Hirschmann), just like the old mast, had a plain chrome top.

b) If you remove the nut, turn the radio on and the mast doesn't pop-out, and won't pull out it probably means that the brass collar has corroded to the inside of the motor tube.

c) No problem, remove the motor unit by sawing off the mast if you have to. I'd suggest removing the fuse first to prevent damage.

d) Apart from one rusty self-tapper the motor unit opened easily to show excellent and precise German engineering. It's good that I opened it as I found about 3" of toothed, plastic feeder which had broken off.

e) After removing the tube from the unit I had to grind out the old brass collar, which took a long time and would probably have put it beyond economic repair had I gone to an aerial specialist (or cost a lot).

f) Finally, I put the motor unit back in the car, switched off the radio and the mast was sucked back into the retaining tube just as advertised.

Thanks to SIGNO communications Electronics who were very helpful in obtaining data and ultimately getting the correct mast from Hirschmann - which numerous Mercedes dealers had been unable to do.
 

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