Armed with all the information I headed to the Kia Carnival to do battle. Started by pulling the Mag mount to pieces to see how it was put together. Pretty basic but lots of room to attach earth leads to. Used Sticky aluminium tape to run from the pl259 down to the roof and accros to the roof rack mounts on both sides. Luckily I was able to ground it to the roof at this point.
Put the antenna back together and hooked up the radio, amp and SWR meter.
Radio all OK SWR 1:1.2 or so.
Turned on the Amp and the SWR came in at about 1:1.2 also at lowest point but the curve was very sharp.
Resonant frequency seems to have gone down 300k/cs but reluctant to cut more off the whip until I get it out in the open. Testing it too close to trees, wires and house right now. Didn’t make much difference with the 30w but could be affecting readings with hi power. Battery must be a bit flat as lights dimming. Still it was putting out 320W or so FM with 30W drive. Checked the voltage drop at the amp and it was 13.8 dropping to 11.4 with Engine running. Power had gone up to 400W FM. Checked the leads and they were warm. Oops. I had doubled them up and they looked pretty big but they were quite flexible so did not have much density. Luckily I had bought some thicker wire just in case. The new wire was just under 1/4" diameter. The copper part and quite stiff. Ran it back to battery and wrapped the cables in the sticky foil as well. Bit of heat shielding for the wires in the engine compartment.
This time the lights don’t dim and the Amp is reading close to 500W. Car radio comes on but as the vehicle is diesel I hope it can’t do much else. Need to find an open area to check the SWR properly before cutting any more off the whip. I did not earth the Amp but I will when I work out where I will put the amp in the car. It is nice to have it visible so you can turn it off and on easily and still be able to take it out without too many hassles when needed.
Starting to wonder if the hassle of having the amp in the car is worth it…..
But we are well on the way to fixing the hi SWR with the magmount. Definitely needs earthing on the roof.
Just need to trim it too frequency and earth the amp to a pillar or chair bolt.
Thanks for everyone’s help especially Aja and Glen from down in the land of the kiwi.