It would help if I was one of those people that you could tell something to and I would just go and do it. It would save everybody a lot of hassle especially me! Put the amp and the radio back in th car and earthed the amp to the chasis at last. Every other thing had brought the SWR down with the amp on bit by bit and now it is right on 1.5. The earthing at the antenna still needs to be improved with a lead from the mag base to the chasis somewhere. Will probably drill a hole in the roof and bolt it. DX500 and DX1600 amps do not have a dedicated earth post but I found a suitable hole on each to take a 5/16" bolt and a couple of nuts so that has been taken care of…Still need to ground the battery better at the terminal. Before too long I will have done everything and the SWR will be 1:1 with the amp on and maybe the on board computer will not reboot each time it keys up.
Not much propagation yesterday but got through to Darwin and queensland in the morning and Europe Ok in the afternoon driving home. Locally the 400W on SSB covers the city with a good signal from 40km out mobile. Certainly makes a big difference.
Next time somebody asks I can give them the benefit of my experience and tell them exactly what I was told…
Mag mounts and High power are a problem
Earth the magmount to the chasis
earth the amp to the chasis
Earth the negative post to the chasis if not already done
Run the leads off the battery
Fuses at the battery on both leads
Hopefully they will do the lot all at once and use other folks experience to get it right first time!