When I started working at Leeds University Television Service in 1974, we had a pair of Ampex 650
2" helical machines, (the Euro version of the 660).
These machines ran at fairly slow linear tape speed of about 3.3/4ips as far as I can remember
and took large reels that could record over 3 hours on one reel.
They had a really nice solenoid controlled smooth transport, much better than the transport on
the later Ampex 1" type A machines that we also had.
https://www.google.co.uk/search?q=am...=1547322871207
Rod