After connecting the HV 90V battery pack accidentally to the filament lead consequently frying all of the bottles, I replaced them to no avail.

I then bought another one on ebay for $15 apparently not working as a spare chassis. My first one is really nice tan leather in great condition however the new one is a vinyl type covering and a little bit in not as good condition. Last night on a whim, using the mains cord for the first one, I powered up the new one just to see what happened, Yes I know not a great idea, but I was ready to yank the plug immediately, but the unthinkable happened.... It burst into song as soon as I moved the dial. Noticing it was very quiet, I turned the volume towards what I thought could only be down, thinking I had it on full, only to find that it got louder! Hmmmn The volume is actually back to front to what I had expected! So realising my mistake, I plugged in the first radio to the mains only to find it working fine as soon as I turned the volume the correct way, it burst into song! I'd been testing it on volume zero, Silly old me...

So now I have two good working 581P's and as the battery plugs were removed on the second one, I soldered the wires to my 7.5 and 90V battery packs, popped them nicely inside the back and hey presto, it's working like a treat on battery power. Quite chuffed! Now I can go camping!!!

Now I can go camping!!!

I wish I could do that. No chance for the next three weeks at least. I am reliving my boss at work and that means "don't leave town". Apart from that, school holidays are not far away and that means packed camping grounds, which I am not fond of. After Term IV begins I will make plans for a three nighter somewhere.

The volume is actually back to front to what I had expected!

Pot wired back to front. Easily fixed.

Or does it also have an on/off switch?

Yes but the on/ off switch is on the side with an "activate" "AC" "off" "Low" "High" power setting, not sure what activate does as nothing actually happens with this, but the others are self-explanatory, the volume pot is vertical with the wheel rim attached protruding from the face, so looking down on it, it's wired right, I think my brain had a dyslexic moment lol. Yes my psychology studies and part time job mak camping a long shot, but hey at least there's an incentive now I have a battery radio! I just have to work and study like crazy to cut some slack!

I meant the pot having an on/off switch (i.e. on the rear of it), but I see you've sorted it out.

The "Activate' function recharges the batteries. You can do this with carbon-zinc cells if they aren't too flat and get a bit more life out of them.

I once had a Ferris cradle car radio and they claimed recharging of the 9 volt battery as a feature.

A great radio, built like a tank with a die cast case.