21-07-2015, 04:18 PM
I have found that floating heater supplies are bad news from a hum point of view.
If you adopt Murphyv310's suggestion - floating DC supplies (batteries?)- be sure to tie one side of the supply to a point which has a low impedance to 0V. As the cathode is several tens of volts 'up', it makes sense to use a potential divider across the HT rail, to bias the battery roughly similarly. Then decouple it to 0V with a chunky electrolytic.
Batteris aren't practical long-term I guess, but this will at least help you to identify if you are barking up the right tree.
If you adopt Murphyv310's suggestion - floating DC supplies (batteries?)- be sure to tie one side of the supply to a point which has a low impedance to 0V. As the cathode is several tens of volts 'up', it makes sense to use a potential divider across the HT rail, to bias the battery roughly similarly. Then decouple it to 0V with a chunky electrolytic.
Batteris aren't practical long-term I guess, but this will at least help you to identify if you are barking up the right tree.
