since NSW been in lockdown since mid-June, I taken opportunity of having the 4wd in the garage and in pieces, doing lots of upgrade and modifications including, fixing 12v DC cabling for radios, doing measurements of DC cable feed losses to radio with load and without load, one thing I discovered was that I had added two big 60amp relays evenly feeding the radios in the car, these are switched via the Accessories switching 12v direct from battery feed, via 300amp distribution box (which feeds battery to radios, spotlights and radiator cooling fans, essentially additional high current devices not handled by main fusebox) to the radios and split by the two relays to share the load between all the radios. Looking at volts at the battery and measuring at the radio, I only seeing a couple hundred mV losses end to end, at full TX power, most of that loss is across the relay. The 4GA cable is doing its job. I did add two new brass battery terminal connectors to replace the crappy terminal connectors supplied by Isuzu.
Realistically, I could have fed all the radios via one relay, as I not expecting to run multiple radios at once, even though two radios are for VHF & HF APRS, but they are short term bursts of Tx, anyway, I played safe by having two 60amp relays in case a relay failed, then I don't lose all communications, which is very important if travelling in the outback. Having overkill on the relays means not pitting contacts from on-off keying of relays every time I go in the car. The idea of the relays was ability to isolate radios from power, i.e I don't want a radio to fail or have it keying up by itself when the car is parked, so if I not in the car, then all radios are isolated, same applies to all other electronics in the car, isolated when switched off.
Also replaced some older antenna sockets, they manage to get moisture in the SO-239 bases, the gold centre pin plating gets tarnished, replaced them, now distant repeaters are much better in signal strength.
Did some more under body coating with Tar based paint, it 's to reduce the pitting of underbody frame and panels from driving on dirt roads, the paint inside the rear bumper looked like 20 years of sandblasting. I first cleaned it all up with high pressure water cleaner, repainted with satin black rust guard, then coated over with Tar paint. This should slow down the damage to underbody paintwork from driving on dirt roads. I also custom made some smaller mud flaps to go underneath, minimize rocks flying up and hitting things, particularly to protect things like brake and fuel lines and wiring near fuel tank.
Looking forward to lockdown ending one day, so I can take the 4wd out in the country. The guys in my local radio club itching to go away somewhere too. Hopefully, we can coincide a trip away with a radio contest.
