Campagnolo Khamsin asymmetric wheels, done around 200 miles, fitted with an 11 speed SRAM rival cassette.

When I ride, I get a 'tick tick tick' sound every revolution. Sometimes the frequency increases, but mainly stays at 1 tick per revolution. It's definitely coming from the rear wheel, I took the wheel off and fitted it to a friends bike and the noise was the same.

Current fault diagnosis has been:
Check tyre for damage or signs of noise inducing debris - nope.
Valve stem, attached a nut - Noise still apparent.
Possible spoke crossing/touching - negative, spokes not touching.
Removed skewer - noise still apparent.
Fitted to another bike - noise still apparent.

Anyone got any ideas?

I haven't taken the tyre and tube off yet to check for debris. However, whichever way I ride, in or out of the saddle, freewheeling or pedalling, the sound remains.

It almost sounds like when you have a stone in your car tyre.

If it's a bearing then I'll just return the wheel. Far too early for that to be going.

Thanks for any help in advance.

Make sure the RDER isn't touching a spoke.

The spokes don't have to touch each other to make noise. It could be the spoke/nipple interface or the nipple/rim. I had an old Velomax wheel that made a noise because the spoke threaded into the hub and was not Loctited properly. Does the wheel make noice when it is spun in the air?

Negative. No noise whatsoever when not fitted to a bike.

Rear dérailleur isn't touching the wheel.

I suppose the next option is to remove tyre and tube and have a look.

Often these ticks are tire/pavement noises. There might be something embedded in the tire, or some film or whatever, or sometimes a small area where the tread isn't as firmly bonded to the body plies. Before going nuts, try a different tire on the wheel.

Otherwise apply a tiny drop of oil where each nipple exits the rim, spin the wheel to drive it into the hole and test ride. I do this once a year or so anyway using a bit of grease dissolved in naphtha to coat the area and prevent corrosion from winter road salt.

Sounds a plan.

I completely stripped the wheel today and was a bit miffed to see that campagnolo use a 'bonded' rim tape. I'm sure I could have ripped it off, but didn't really want to, as I didn't have a spare piece of tape.

Couldn't see anything wrong.

Cassette came apart fine, no grit or obvious signs of debris.

Freewheel removed and bearings checked which also looked fine. No signs of brinelling or pitting (although these were sealed, so only gauged this on spinning the wheel with my fingers acting as axle.

It's absurdly annoying, especially when climbing at low speed. All I can hear is the tick of my wheel.

I'll oil the nipples when I'm back home. Fingers crossed.

You can save yourself some work in the future by being more analytical. For instance freehub or cassette issues, would manifest when coasting or pedaling, but not both, and the cassette would never tick when coasting because it's not moving. Also bearings rarely, if ever "tick" they may make other sounds when failing, or grit make make noise but it won't be a synchronous tick.

As I posted before, I lean toward the tire. Ant it might not only be the tread. Sometimes seat funny and you'll get a tick as that spot comes underneath. One hint might be higher or lower pressure, which might change the sound a bit.

In any case, since you have the tire off, see if you can find another tire and see if that solves it.

BTW- one other thing to try, so simple it's worth it even if the odds are low. Remove the valve nut, and jam a toothpick between the valve stem and rim. Takes a second, and beats finding out it was so simple AFTER tearing your hair out.

Since the wheel is off of the bike and the tire removed give the wheel a shake in a couple of different orientations to see if there is a piece of debris or a stray spoke nipple rattling around inside the rim. Place the edge of the rim on a soft material on the floor (carpet, rag) and press down on the top in a few places to stress the wheel and see if you can make a spoke or nipple tick. Put on some gloves and squeeze pairs of spokes together hard as an additional test.

As someone who's been riding since the days when loose crap in rims was just about assured, I can tell you that stuff in rims rattles at super low speed, but once you get rolling it stays put, pressed against the outer surface like the people on the spinning carnival ride. (except that it doesn't scream).

I don't see that anybody asked, so I just want to check.

How is the rim closed, pinned somehow, or welded. I'm just wondering if it's possibly a joint issue. If it's welded you can 99% rule that out, but it's on the suspect list for non-welded rims.