C43 Antenna Adapter

[Mitch H]

So I recently installed a C43 head unit, and am still trying to work out how to connect up my antenna. The antenna is your standard Motorola male connector. The picture below shows what terminals are on the back of the C43. The connector on the left is a euro connector, and I tried a Metra 40EU20 adapter, but the shape of the plastic part of the euro connector wasn't right. I suppose I could get a Metra 40EU10 and use a Motorola female to female adapter to connect the male Motorola pins together, but that is a lot of extra wire to run behind my head unit.

Anyone know what the terminal on the right is, and if it's an antenna in if there is an adapter to connect to a Motorola antenna? Does anyone know if there is an adapter that actually fits in the euro connector on the left?

[Dirtboy]

Anyone know what the terminal on the right is, and if it's an antenna in if there is an adapter to connect to a Motorola antenna? Does anyone know if there is an adapter that actually fits in the euro connector on the left?

Terminal on the right is for the diversity antenna. There is an adapter that fits the euro connector, just not sure where to find it in the states (got mine in Germany).

[Mitch H]

Here's an update in case anyone else runs into this problem in the future (I know the C43/CD43 replacement is popular).

The bottom line is that I used Metra P/N 40-VW20 to adapt my motorola male terminal to the large coax connector on the back, and now I have great radio reception. For those who are interested, I did some more research on the C43 antenna scheme because I didn't have anything to do at work.

From what I can gather, the C43 is designed to be paired with an antenna amplifier that uses an antenna diversity scheme (using a roof mounted antenna for FM/AM and antennas along the rear window for FM). Each will likely pick up the broadcasted radio signal in a different way based on location, polarity, pattern, etc. and one will pick it up better than the others. So the amplifier switches to output the strongest signal with the least noise to the radio.

Now as far as what the two different sized coax connectors do, I think the large one is the output from the diversity amplifier and the small one is the communication line to the diversity amplifier. This page appears to confirm that, but this explanation of the E87/E90/E91 diversity scheme only shows one connection to the radio (the ZF line, over which all the communication happens). I'll bet the diversity scheme has just changed between the E36 and the E87 etc. and that the diversity amp runs the communication and radio output all on one line. The communication frequency they use (10.7 MHz) wont interfere with either the AM (531–1,611kHz) or FM (88.1–107.9 MHz).