www.wexphotographic.com/buy-kenko-teleplus-pro-300-dgx-2x...
I'm not saying I recommend it, it's that you have asked where you can buy one from.

I bought mine off Amazon.com

Thanks, What converter would you recommend ?

Avoid to use a 2x tc, the IQ will be badly effected. At any rate the Kenko DG Pro300 and the Tamron SP Pro ones are compatible.

With a 1.4 tc you will get 280mm f/4, not really a great difference in terms of focal length. You could avoid to buy a tc at all and thinking about another solution according to the kind of shoot you want to do. This solution could be interesting mainly to the users whose cameras (such as Pentax or Sony) have a built in stabilization.

www.flickr.com/groups/tamron_70-200/discuss/7215762527103...

If you want more reach, as you're a Nikon user I'll suggest you to get a look here www.flickr.com/groups/d7000-club/discuss/72157629782277263/

will not work ..tried it at photo show last year at Javitts..the 1.4 works good.

I have the Tamron SP 2x works fine with this lens

Thanks for the Comments!

I bought mine here:

www.digitalstreet.nl/product_info.php?products_id=3106

For my tamron 70-200 2.8 on the Nikon D90.

But can someone tell me, what to use, how to use it.
F=? iso=? etc.

On tripod it works. But somehow ??

Frank