Need to purchase a separate ground cable - from my TT to my Phono Preamp

when I made mods to segregate ground cable from Technics 1200 MK2, I just used normal black piece of wire terminated with spade all found in my tool bins. My signal tonearm wires are vintage NOS Ortofon 26AWG

Any basic wire can be used for a ground between the TT and the phono preamp.  I have made some with spade termination and have used some with just raw wire terminations.  It is not in the signal path. 

Generic hardware store copper wire is fine.

If you don’t want to make one Audioquest makes a inexpensive ground cable that you can buy off Amazon…

Any bit of metal wire will work - light cord or mains - outside the audio loop but eliminates hum if there’s an earthing issue