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My car is making a whining noise which changes pictch when I rev.

It is something on the aux drive train. I have taken the belt off and nbotice that there is abit of axial play in the PAS pump but no radial run out so I think the beraings are alright.

The alternator seems fine and turns fairly easily with no deflection on the pully.

ANy ideas?

Did you run it with the aux belt off?

Could be either, but... when my alternator bearings were shot there was a fairly loud whining noise when the engine was running. This disappeared when the engine was run without the aux drive belt. After removing the alternator from the car there was no obvious roughness or play on its pulley so I don't think you can tell for sure just by feeling for play in the pulleys. With the alternator on the car I used a long screwdriver to "stethoscope" the PAS pump and alternator - although both made some "bearing" noise but it was pretty obvious that the alternator was the main culprit.
If you take the alternator out its quite a tight fit so out put some cardboard over the radiator to prevent damage to the fins on it.
hope this helps

As Steve says, try running it with the aux belt off. If it stops, it could be the tensioner/idler if you've not tried them... Also it's been known for the crankshaft pulley to break - the rubber dampener can perish and split causing it to slip. To check it, grab some tippex/paint and run a line from the centre to the outside. If it's slipping the line will be broken

Well,

I've run without the auxy belt and the engine is sweet!

I've fitted a new crankshaft pulley when I did the timing belt, so I know that this is not the cause.

I have stripped and rebuilt the PAS pump, whitemetal bearings, no wear at all.

Tensioner and idler seem O.K

Sandin aircaon compressor is fine.

Alternator feels a little rough sitting on the work bench. It also has an overrunning pulley which I can't remove arrrrgggghhhh!!

Looks like it is going to be a recon alternator for £162 + VAT, al for £30 worth of bearings!!! - This goes against every principle I have as a tight scotsman!

I took my alternator off and took it to a local auto electrician who replaced the bearings - it only cost me £20. BUT, after about 14 months it started making a nasty noise again so I threw in the towel and got a Lucas remanufactured / exchange one from a local factor. So far so good...