Looking on the internet deeply has found these results:

let you know when he comes back is the most popular phrase on the web.

when he get bak 19 results on the web	let you know when he comes back 1464,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It doesn't look like this phrase is very popular! The search could not find any examples on the internet.	I'll let you know what comes back. D'you let me know when you come back? I just came by to drop off this bag, so please let her know when she comes back. Let me know what comes back on those clothes. But let me know when they come back negative and I'll mock you. But let me know when they come back negative, and I'll mock you. You let me know what comes back from the... electrophoresis gel. I just wanted to let you know you can come back to the bar whenever you want.

when he get bak

19 results on the web

let you know when he comes back

1464,000 results on the web

More popular!

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

I'll let you know what comes back.
D'you let me know when you come back?
I just came by to drop off this bag, so please let her know when she comes back.
Let me know what comes back on those clothes.
But let me know when they come back negative and I'll mock you.
But let me know when they come back negative, and I'll mock you.
You let me know what comes back from the... electrophoresis gel.
I just wanted to let you know you can come back to the bar whenever you want.