[QuadList] 15 mil Headwheels ?!?!?!?!?!

[Don Norwood]

This is a new discovery for me.  I knew that between air and ball bearings, 
10 and 5 mil tips, and threee different preamp modules, there were lots of 
variations of the Ampex MK-X head.  All of them were pt# 1800705-xx with the 
dash number differentiating the configuration.

But.......what I had not seen until looking in an Ampex catalog is that dash 
numbers from 209 thru 239 were 15 mil heads!  Yes, that's not a typo that 
should have been 5, it is actually 15.  What were these for?????

This only seems to apply to the MK-X heads.  I do not see 15 mil offered for 
the MK-XI, XV or XX.

Don