Electrical interference with HF radio

[PeeBee]

I was away last week and found my Codan Hf dead to the world, hissing and no legible voice transmissions heard. I had the radio working a couple of weeks earlier, clear as a bell in Melb. I started on the troubleshooting route whilst camping and swapped out antenna, cables, isolated voltage booster, still high noise signal on all frequencies. i rang the Codan rep and he suggested powering up the radio with an 'isolated battery'. and disconnect the other vehicle batteries. result, radio full receive and next to zero background noise, beacon requests from 4 stations across different frequencies - great, must be something in the car or atmospheric getting into the antenna. So, start putting things back one at a time and monitoring the interference, bugger me, everything dead quiet and crystal clear, except around the 7-8.5MHZ area, which was still full of noise. prior to this everything was noisy from 3 - 29mhz. To my surprise the Corrosion device had little if no impact on the noise level, but it remains disconnected for the time being.

Problem I have now is I have not changed anything apart from disassembly and reassembly of the battery connections. All earths are fine and there are a number of links between body, chassis and batteries. So now its a hunt to find a frequency generator in my local area around this 8meg point. I will need to go for a drive into a 'quiet area', free from power supplies, cables and transmitters to see if this is resolved, but again, bit at a loss as to how it has 'fixed' itself in most regards except the 8meg area - annoying, but have another 6 weeks now to sort it i guess.