Danger Mains electricity:
Valve radio's were produced at a time when constuction for safety was not as it is today.
It may be hard to think that even in the 1950's 240 volt DC was still in use. and therefore some radio's were AC/DC models, using mains droppers, giving of large levels of heat, others had a special mains cable that was resistive, meaning that the voltage was reduced within this cable, often people did not like having 6 feet or more spare cable and reduced it, resulting in short lived radio life. The most important, I have left until last. Most period radio's are using two core cable, live and netrual, if correctly wired this netrual is connected to a steel chassis ?. What does that mean; all the metal parts are connected to the mains and if the mains plug is wired incorrectly then a lethal situation has happened. Touch any piece of metal, perhaps even a screw, you will feel a slight tingle, if you are unlucky you will get the full inpact of mains electricity flowing through your body.
These radio's even where the screws hold the volume/tuner on to the shafts should not be assessable.The small Pilot radio's for example have the chassis fitted to the case via four screws underneath, these would have tape over them, for this reason.
Buying from auction:
When buying a mains valve radio with unknown history, always check everything before attempting to plug it in and wait to see what happens. If a radio has not been in use for many years, the capacitors loose their ability to work effectively, if we need to get technical, the dielectric dry,s up. This could mean damage to the components, with the smell of burning, worse case a large noise (bang). There are ways to safely supply mains voltage to the radio, at Classic Radio Shop we use a Variactor with a Avo 7 in series monitoring the current flow as the voltage is slowly increased. We often keep it low for a period of time so as to re-build the electrolyte in the capacitors and to date have never lost any. There are other ways to achieve this, if you do not have the test equipment. One way is by placing a 100 watt bulb in series, these details can be found on the internet. If you do not understand the concept of series, please do not attempt it.
Longevity: how long will my radio last
Your mains or perhaps battery radio was built when we did not live in a throw-away society, using components that were and still are available, despite first thoughts valves are still being produced with large numbers of the standard ones still being manufactured. So unless the mains transformer or choke has failed, there is little reason why the radio will not last another fifty plus years. I generally find that the jewel case radio's have had little use, these were after all, a second radio for most people at the time and when the batteries were no longer supplied, were then because of their compact size, put away in a cupboard not to see daylight until many years later.