I finally sorted my problems with my Alinco DR590,
fixed the UHF PA, the radios that were imported into Australia are T model for 440-450 and the 70cm PA is guaranteed to cook itself, hence you could never get more than 30w at 433-434 Mhz, now I put the correct E model components into UHF the PA it can do 42w at 13.8v, (the actual RF block is rated at 45w at 15.2v) but I wound it back to 30w and she runs cool now on high pwr, the way it should be. The basic change is a couple of caps and an inductor, L4 goes from 1.25T on 3mm diam, to 1.25T on 4.0mm diam. It makes a big difference for such a small change.
Then I fixed the freq stability, it kept wandering off freq, it drifted about 4kHz from cold to warmed up, if give it a quick squirt of freezer spray, the TX freq would wander 10 kHz, found the soldering in the osc cct on the VHF main board was looking dry, so retouched the solder joints for all the components associated with the Xtal and it is now stable again.
Only one issue is the mic for the Alinco is crap, so I working on a better mic with DTMF, in fact, I am updating an old Philips FM-900 DTMF mic, a solid mic, with a much better DTMF operation, just replacing the old carbon mic insert with an electret plus resistor divider to supply the DC volts. The reason for this is the Alinco mic was so sensitive it picked up the echo inside the plastic casing, which overides the actual speech audio, plus the DTMF operation is garbled, as the DTMF tones are partially clobbered by the induced sound of pressing the DTMF buttons, so the DTMF tones were not clean.
Anyway, it is back in the car as of yesterday and I can get on 2m & 70cm mobile again. This compliments my mobile operation on 6m FM using the AWA RT85.