As part of something else on the reflector I was in PM with Luc ON7DQ. He wondered when I said my Linx 1010B didn't work if I had tried just a TRRS plug or a headset. I told him I tried a headset and it didn't work.
Now I am a curious person and I thought why does Luc's Linx 7 work and my Linx10 doesn't when to all intents and purposes the hardware is similar. Strikingly similar. So I did some digging about at home in the 'modern junk' drawer. This is the place old phones and their ancillaries go to die..... I've owned plenty of phones in my time and they always used to come with a headset. I have plenty of Nokia headsets but they have a 2.5mm TRRS plug. I found another headset with a 3.5mm TRRS plug in the junk drawer to try.
So plugging the original into my 7in Hipstreet (same hardware family as all of these Win8/Win10 tablets but small RAM and FLASH) and it doesn't work. Tried it in the Linx 1010B and it doesn't work. So I then did what I should have done and plugged it into one of the bazillion Android phones I have and.... well I wasn't sure if it was working or not. Hmm! Excitedly I tried the newly found one and it worked on the Hipstreet and then tried it on the Linx 1010B and it worked there. Not surprisingly it worked on the phone.
So there's a lesson I should know. Don't assume anything works because it's new and not been used. I'd be surprised if there were 2 TRRS wiring standards so I am assuming the one that doesn't work is just duff in some way and I should have tested it further. Mea culpa.
Anyway, from a test with a headset that probably came with an Android phone, I can confirm that plugging it into a Linx1010b caused the microphone in the headset to drive the soundcard and disabled the onboard microphone.
Before everyone gets too excited, the standard soundcard hardware that all these Atom based Win 8 / 10 tablets use only works at 24kHz sampling. This means they will not work with WSJT software as that needs 48kHz sampling. I have used the on board microphone to drive fldigi running on Win8 on the Hipstreet for PSK etc. and it worked fine.
If you want WSJT, you need a USB soundcard which will set you back one whole British pound!