Antenna operation ins & outs.
 

Hi, ultimately when the ignition is turned I would like the antenna to be always extended. Currently it extends only when listening to the radio and retracts when switching to CD. As I hop between CD & Radio all the time, this becomes annoying. Does the radio maintain a constant 12v signal to the antenna when it wants it up OR does it send a 12v blip? If it's constant, then using the switched 12v line would achieve my aim wouldn't it? If it sends a blip to extend it and a blip to retract it, could I perhaps use the radio's amplifier turn-on lead to make it do what I want? Thanks.

You didn't mention what car you're referring to, which would provide helpful info, but I think I might have some insight. The 12v turn on lead to your antenna is constant; my car is this way, and I assume they're all the same (feel free to prove me wrong though). From the sounds of it you're not using any of your stock stereo setup, but if you are, you might have an amp in the rear with a 12v lead that you could easily tap into to potentially save effort. I never knew my car had a stock amp in the rear untill I installed my basslink.

I had quite the reverse of this problem with my car. I rarely use the radio, and I got sick of listening to the antenna go up and down when I turned the stereo on/off while listening to CDs so I wired a switch into the turn on lead to disconnect it, but to still be able to use it when I want to. My antenna no longer goes up at all, unless I tell it to.

My 420SEL had a really cool feature; there was a three position rocker switch on the dash that controlled the antenna. I could keep it all the way down, all the way up, or adjust it inch by inch to any position in between. Supposedly this was to avoid interference or distortion or something from having too long of an antenna (one of the longest telescoping antennas I've seen). I think it applied more in Europe though, for whatever reason.

Thanks for the reply. The car is an 89 300e by the way. The constant voltage thing would make sense, especially if you have a switch. ie. a switch could vary the output voltage but it probably wouldn't have the ability to send a burst of voltage would it. I wonder if most of the MB antennas had this ability to vary their heights and if anyone installing one of these switches could take advantage of this?

HA.

I wish my mercedes antenna worked like yours did. One of the reasons I dumped it was because I HATED that it was still up during CD mode. I believe all 94-97 mercedes had the 1492 or 1692 Alpine or becker. If the radio was powered on, the antenna would stay up regardless of mode.

Again, simply connecting the antenna to the amp lead would do the trick. Of course, test all wires with a volt meter before changing things around.

To my knowledge only the W126 cars had this feature. It's possible that it was only present on the post '87 cars as well, I know they made plenty of changes for the '88 model and I believe that was the year they updated the stereo. I had never thought of it, but it would be a really cool idea to wire up this feature on a newer car. I'd be pretty impressed with anyone who went to the trouble of doing this. If I actually used my antenna I know I'd be looking into it. Then again, I would be damned impressed if someone went to the trouble of figuring out how to install an antenna from a new MB in an older car, if it's even possible; I believe they're inside the glass on the rear window...? No more motor at all, and with a little bodywork and paint you could have a smooth rear fender:D

My power antenna was working when I installed my Alpine in my E320 but now it stopped working at all. I guess i have to check my connections.

Problem Solved. I wired it up to a three way switch for selectable "off", "on only with radio" and "always on with head unit power" operation!

That sounds interesting, how does the switch look?

My Becker made the antenna go up and down with the radio, my Aiwa wouldn't conrol it so I had to wire it so it was up with ignition unless the switch in the console said not to. My Kenwood was wired so it only stays up with the radio on I believe. I guess some radios have an output for controlling power antennas, others don't.

I've got a similar thread going on the antenna thing
 

Pardon me if I butt in here, but I can't help it. I'm looking at a way of keeping my antenna up all the time when I want to, but easily being able to get it to go up and down with the radio going on and off. (See 'Winterizing an antenna')

From the interesting posts I've read on this subject, here are what I believe are the facts:
- Most antennas have a trigger wire, a constant wire, and a ground.
- In most cases, applying 12V + to the trigger wire makes the motor turn in a direction that extends the mast.
- In most cases, applying 12V + to the constant wire makes the motor turn in a direction that retracts the mast.
- After retracting or extending the mast fully, a circuit in the antenna disconnects power to the motor.
- Some antennas use 12V - for the trigger and constant signal. Using a relay will enable you to flip this to 12V +.

So, regardless of how the source of the 12V is switched on or off (radio trigger wire, IGN or ACC switch, remote amp lead turn-on wire), any 12V signal fed to either wire will make it go up or down. If there is no signal to the trigger wire, but 12V to the constant wire, it will stay down. If there is no signal to the constant wire, but 12V to the trigger wire, it will stay up. If both 12V sources are removed, it will remain in the position last in when the sources are disconnected.

Here's a speculation:
- The switch on the older Mercedes that allows you to 'bump' the mast up or down is a combination momentary contact/on/off that inches it down with 12V pulsed to the trigger (up) wire, or the constant (down) wire.

True
Yes, as long as the ground wire is grounded and there is 12v to the constant wire.
I don't think so. I believe that having the 12v to constant with ground wire grounded and no 12v to trigger makes the antenna go down.
True
Yes... from what I understand, this is typical on old Mazdas. That is having a negative trigger wire. The constant wire is still 12v +.
I don't think so. Again, constant wire should have 12v and ground wire should be grounded. The trigger with 12 volts makes antenna go up. No power on trigger makes it go down.
Don, have you actually tested this? I think if you cut power to the constant wire, the motor is disabled. No up or down happens.
True, but again, I believe if you just remove the constant wire (or ground), it will stop the motor.
I think the way the swith works is this.
Switch off: No power to constant (trigger is irrelevant)
Switch down: 12v to constant, no power to trigger.
Switch up: 12v to constant, 12v to trigger

Someone please correct me if I'm wrong.

BoostnBenz, the switch looks crap! But it's out of sight down near the steering column, so it doesen't really matter. A bit later I might try and get one of the factory switches and integrate it in a nice way.

donbryce & wjm, interesting! If true then the possibilities for total antenna control are limitless! I'll apply your thoughts/findings in the next couple of months and check back.

WJM, re. testing: When I was trying to get the antenna I had working, on the bench, I discovered that it had a faulty circuit board, so had to return it to the supplier. A replacement is on the way. The bad board confused me, though.
My gut feel is that you are right about the mast not going up with trigger connected and constant disconnected. That's real easy to test. I will when my new unit arrives...

Replacement antenna has arrived, and testing completed
 

However, the clutch drive pin broke after it had worked for less than 5 up/downs! More on that below. Here's an update on the previous discussion.

WJM, you are right on both points. I had stated:

Your comments were:

The constant and the ground must be connected for the trigger to have any effect.
If the mast is up when the constant is disconnected, when it is re-connected, and the trigger is not supplying 12V, it goes down.
If the mast was down when constant disconnected, the trigger won't make it go up until constant is re-connected.

So, I think that also answers my other question about how to keep it up so as to ignore the trigger, whether it is powered by the radio switch or an IGN source. A simple on/off switch to the constant wire (or ground for that matter) will, as you say, disable the motor. For me, I can switch 'off' for 'up' all the time in winter. For the OP above, he can switch off for up all the time, and/or transfer the trigger to IGN instead of radio for up when the car is on, down when stopped.

Now, on to the repair of the clutch, which would be the sheared off pin in the leftmost pictured gear, the one on top of the drive when you open the case.

(My picture didn't get captured, so I'll post a reply to insert it. Can't add a picture with the edit mode for some reason)

I used a fantastic German made glue to initially get the pieces back in position, then drilled a very small hole enlargement in the slot to allow inserting a tiny bolt/nut to re-inforce the plastic pin. Did this to both antennas, first to the cheapo for a proof of concept. Time will tell, but I'll bet it will last a long time.

I also transferred the circuit board from the cheapo to the Hischmann, since mine was burnt up, and it works great too! The cheapo is in fact a carbon copy of the Auta 6000, so the electronics don't know the difference.

Hope this helps someone else.[B]

Here's the missing picture (I hope)
 

Last post was referring to repair of the gear clutch drive pin:

power antenna switch problems
 

On my 1977 450sl the antenna switch started to shortout and the radio volume would drop drastically (antenna operated normally) By bypassing switch, antenna comes on-off with radio on -off. However the antenna height is limited to only 15 inches I was advised that there is a cam in the housing (Hirschmanpower unit) that can be flipped to run antenna to upper limit. Questions 1) how tall is full lenght? 2) How to get unit disassembled to flip cam 3) is this the only fix? Any help apprciated. Abe G