RD4 to RD45 upgrade. Antenna issues

[freddyokel]

My 2008 207cc has an RD4 and an EMF-C with v51.?? firmware.
Got an RD45 in the post this morning and an EMF-C with the later firmware is arriving next week.
Thought I'd give the RD45 a go and the first obvious thing is that the RD4 (and the loom) have White and Grey antenna connectors and the RD45 has just the White.
Connect the RD45 and the White antenna to the White connector on the RD45.
Power up, obvious beeping and errors (antenna 1 not responding, microphone not present, USB not present).
Use Diagbox (v7.57) to set the VIN, disable the USB and handsfree and we're error free.
But... I can't get the radio to work.
RD45 shows 'antennas 1' and allows me to configure active or passive on two antennas but still no radio, just static.
Any idea how to fix this? The Grey and White connectors are keyed and won't connect to the wrong one on the radio.

Edit: Forgot to mention that the RD45 works with the v51 EMF-C but obviously no Bluetooth menu. It plays CD's just fine. Setting antenna 1 to passive removes the antenna 1 not responding error.

[freddyokel]

A quick look at the wiring diagram indicates that the 207cc has two antennas.
The White is the front, conventional antenna on the windscreen bow and the Grey is built into the rear window.
Wondering if I just need some kind of reverse splitter.

[GiveMeABreak]

The White connection on the RD45 is for AM and FM1 combined.

[freddyokel]

Any idea which one is which on the RD4?
I'm guessing that the white one is the AM as it won't receive FM when connected to the RD45?

[GiveMeABreak]

RD4
"d" Aerial AM/FM1

[freddyokel]

Yeah, that's the white one.
But... I've just tried putting the RD45 in the car again and it's started working.
The v51 display is behaving a little oddly, almost like it's blurred but hopefully that'll be fixed when the new EMF-C arrives.

[xantia_v6]

Where 2 antennas are fitted, they are used in 2 modes, some of the time they are used as diversity antennas (FM) where both are receiving the same signal, but the radio switches to the one with better signal, sometimes the the signal is received using one antenna while the other is used for scanning other frequencies for a better signal. I played around with disconnecting one (a few years ago now) and the behaviour of a 2 antenna radio with only one antenna connected seemed a bit random, sometimes it worked, other times it didn't.

A single antenna radio should be able to work with either antenna, as long as it is configured correctly for active/passive, but performance on weak signals may be compromised.

Dual antenna RD45s are available, but much harder to find from Chinese vendors.

[freddyokel]

Single antenna (White) is working just fine now, it just doesn't receive as well as the RD4 (dual antenna) does.
On another note, I can maybe put to bed the rumour that an RD45 needs an EMF-C with a v72 firmware.
Mine (from a scrap 2013 C3 Picasso, not China) is working fine on a v71.3 EMF-C from a 2009 308.