Unfortunately it appears no one sells the whip and base, don't need the NMO mount but I may be stuck buying all of it. Tomorrow I will call STI-CO directly.
I found the cut guide on the website.
The mast length (includes whip and what they call mast adapter (I would call it base)) for 145 Mhz should be 19.8". Do you recall what you wound up with?
I reread your results above and did so a bit slower and I became a bit confused by your saying when you trimmed/tuned for 146 Mhz the 70 cm went useless at worse than 3:1. But farther down I interpret the trimmed whip for 146 Mhz yielded a SWR of 1.2:1 and the resulting SWR for ~445 Mhz was slightly more than 1.5:1. It seems like SWR for that portion of 70cm actually improved over the original length. Maybe I am missing something
Sorry, not trying to be a pest.
1996 LX 450 OME heavy front/med rears, factory e-lockers, 285/75-16 Discoverer STT, home made t-case skid plate, ARB front bumper, XD9000i, Redline sliders, HID off road lights, Kenwood TM-D710
"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." -- Benjamin Franklin