mini displayport to HDMI cable into micro converter :-(

Hi,

I've searched the forum and can't find anything that's helped so far. Apologies if this is a noob question.

I'm trying to mirror the display from a MacBook Air, which has a mini displayport output. My signal path is:

mini displayport - HDMI cable // HDMI to SDI micro converter // BNC cable // SDI to HDMI micro converter // HDMI cable into display

When I plug the mini displayport - HDMI cable directly into the display, the MacBook Air recognises that it's connected to an external display and behaves as I would expect.

When I plug the mini displayport - HDMI cable into the micro converter, the MacBook Air does not recognise that it's plugged into an external display (and also makes the mouse pointer really jerky)

I know there's nothing wrong with everything from the HDMI to SDI micro converter onwards, because I've tested them with a MacBook Pro, using its HDMI output. When I do this, the MacBook Pro allows me to mirror the display to "BMD HDMI". On the MacBook Air, it's as if it doesn't know that it's connected to the micro converter as it does not appear as a connected display.

The differences between the MacBook Air and the MacBook Pro are:

Different output ports (mini displayport vs HDMI)
Different operating system versions (High Sierra vs Sierra)

So I believe that my problem is either due to the operating system or the mini displayport to HDMI cable (even though it's working when plugged directly into the display - is it possible that it could be compatible with the display but not with the micro converter?)

Has anyone used the micro converters with High Sierra?

Thanks for reading - I'm hoping someone here knows something I don't!!!

Steve

Well, I have excellent news. I bought a mini displayport to HDMI converter (iWantit is the brand), and it works! So there was an issue with the mini displayport to HDMI cable I was using - although it worked when plugged directly into the display, it didn't work when plugged into the micro converter. I have no idea why, but there we go. Hope this helps someone in the future when they have as much of a panic as I was having last night

By the way, the cable that DOESN'T work is the Rankie R1101 1.8 m cable on Amazon. So don't get that one if you want it to work with a micro converter!