File this under "Nothing to do at home so I am making up shit to do...."
I tried to use a +12 Acc signal from my Yatour "CD Changer" to activate a relay to make the antenna go up and down.
Unfortunately, it didn't work, because the Acc signal from the Alpine MBUS protocol (which the Mercedes Benz MX3192 translates) is at +12 whenever the Becker 1432 system is on..... no matter if the input source is AM, FM, Cassette, or CD.
I did map out the connections between the Alpine MBUS 8-pin DIN connector (on the MB MX3192) and the Yatour "CD changer" --- posted here for posterity:
 
I made a cable adapter to "steal" +12v and ground from the MX3192 --- and used nice Molex connectors.  My first time using Molex a connector crimping tool.  THIS THING IS AWESOME.  Why didn't I get one earlier?
 
Note for posterity ---- especially for 
@darek_u - 
The MX3192 spits out +12V on Alpine MBUS DIN pin 6 at all times, regardless if the car is on or off.  Pin 7 (Acc) spits out +12V when the Becker 1432 is turned on (and doesn't matter what source is selected).  
Now that I got all Molex Crimping tool happy, though, I didn't want to waste my efforts. In search of something to do, I decided to replace the Yatour bluetooth receiver, seen here:
I was always slightly annoyed that it had a tiny bit of noise.  100% of the time when driving, I did not hear any induced noise.  95% of the time when listening to audio in the car, I did not hear any induced noise.  However, when sitting in a quiet garage with the car off, and when listening to a quiet passage (say, Mozart's Mass, Barbara Bonney / Claudio Abbado, Berliner Philharmoniker - 1991 - Track 1 from 2.00min - 3.00min) I could hear noise.  It was a subtle static overlaid with a "dit dit dit dahhh" type of noise.  Irritating.
I deduced that it was the Yatour bluetooth receiver causing the noise, because when I jacked my phone into the 1/8" audio input into the "CD Changer," the noise disappeared.  Enter the JL Audio MBT-RX.  This thing is well received by many for its superlative sound quality.
Note that the original Yatour bluetooth receiver uses a 4 pin connection --- the Yatour bluetooth receiver can handle not only audio but also phone calls, and has provisions for a microphone and an extra control button.  I was not using the Yatour receiver to place/receive phone calls, so I decided that I could just jack the JL Audio MBT-RX into the 1/8" audio input.  And, of course, the whole reason for doing so (aside from eliminating noise) was so that I could crimp on more Molex connectors and not let my cable adapter go to waste..... my 2-pin molex connector pulling +12v (on pin 7) and ground from the MX3192 to power the MBT-RX.
 
 
Result -- not only did the noise go away, but I noticed a great deal better stereo separation!  I was quite surprised!  Lesson learned - Bluetooth Receiver quality makes a big difference.  You get what you pay for.  There is a BIG BIG difference in bluetooth receivers wrt sound quality.