[Sideband]

So have you measured your actual mains voltage? It might be low. In any case I would think the 220-230V setting was appropriate but it's worth checking your actual mains voltage and use the best setting. Don't assume that the mains is 240. Typically here it's usually around 230 - 236. Don't forget that the average owner of these sets (or more likely the supplier) would have set the mains to the appropriate mains voltage for the area and it would have been left at that. The radio would have been designed to cope with drops in mains (except very big drops) and continue to work. The original owner would not have been expected to check the mains each time he used the set and then change the setting! So a mains variation of + or -5% would be easily handled in normal use. I'm pretty sure mine is on the 240-250V tap.

I've not actually measured the voltages from the power supply on my BAC31 since it gives plenty of audio output on mains but I can do so when I next get in to the workshop.