Agree with JN on the MR-1, it sounds much better on CW than phone
But the little mobile setup is fun to use and I have made a number of 75 and 40 meter QSO's with mine. I picked mine up at a hamfest and the UT-1 power supply is built into a MR/MT-1 case with a clock on the front panel so I have a really large clock radio.
I later picked up the cosmetically similar HX-20/HR-20 SSB mobile twins and paired them with a HA-14 "compact KW" amp. I haven't tried to go mobile with them but they have been on the vintage SSB net a few times.