[emeritus]

I don't have a Hacker, but I run my bedside radios from D cells using external battery packs consisting of battery containers from Maplin fitted with a lead and plug to fit the radio in question. I used to have a regular supply of part-exhausted D cells from our family's cycle lamps, but now that we use LEDs, that source has dried up. I use a 3 cell box for my 4.5 V radio when using new batteries, and a 4 cell box to use up the remaining capacity of almost-exhaused cells. No problem with hum!