I've always slept with the radio on very softly! In fact I can't easily get to sleep without it! Ok I'll get a battery smoke alarm and fire extinguisher and put it next to my bed..

A smoke alarm in the bedroom is always a good idea. When you're asleep you cannot rely on your sense of smell to detect smoke or burning odour.

Suggest you use a modern radio to help with your insomnia issue.

The issue of fire is an important one, especially when dealing with old appliances. Because valve radios have voltages inside that are higher than mains voltage there is an increased chance of a power transformer failing due to an insulation breakdown. Such an event happened to me back when I was serving my apprenticeship. On a nightly basis I also had the habit of using one of my radios to put me to sleep and on one occasion, the radio did almost put me to sleep - permanently.

The radio in question, a Kriesler 11-20, started to huff and puff an hour or two after I nodded off. Smoke filled the room and I only noticed because I needed to get up for a Jimmy Riddle. If I didn't need to pee then I may well not be here having this discussion now.

It took more than a week for the electrical smell to dissipate fully and I had to run all my clothes and bed covers through the wash twice, using all manner of detergents, fabric softeners and the like.

Whilst the use of smoke alarms is encouraged, it is still not worth the risk. Adults are known for remaining asleep when smoke alarms go off. In a deep sleep a person can be in a state of deafness even though their hearing is perfectly normal.

If you are still going to do it anyway, use a time delay to turn the radio off after half an hour.

I should also add that I had the same thing happen to the radio I used to run at work in my office all day, every work day. An AWA Radiolette 500M, its transformer gave away after being in that service for about four years. I am still yet to repair it even though I have a spare transformer. In the meantime I have cut the cord off it and left a note inside it so I don't forget that it requires repair.

I will never leave any valve radio unattended whilst it is operating. These faults are not commonplace but the results can be a disaster under the right circumstances. In reality, nothing that is electrically powered is failsafe. Not radios, any other appliance or even circuit breakers. I work as an electrician (and wear a few other hats) in a large hospital and I see major brand RCD/GPO outlets with biomedical rating, and the price to match, crap their pants after only a few years of operation. Nothing is good quality these days and older things that were good quality at the time are not 100% safe.

Update: To my knowledge, the codes for resistors with colour bars have always been the same. The colours might have faded with time, making them difficult to see correctly though.

Gee that's bad! Luckily we have an American staffy who sleeps on to of our bed who would wake us up, but a timer is a great idea, I could set it up to turn the radio back on half hour before my alarm, because I usually half wake up with the news broadcast, making the eventual alarm less traumatic!
As a mechanic I understand what you are saying, modern cars are unreliable, multiplied by every little electronic gadget... Working for the RAA, it keeps me busy!
I have a 52 Plymouth which I am rebuilding due to a rollover caused by a modern radial tyre bursting, prior to that over 11 years I drove it, a little thirsty but it only broke down once when the engine finally died of old age but with a rebuild... good as gold, turn the key and she started first spin... I still have the 6v Ferris valve radio and it still works!

On resistors, colour blindness is a factor and it affects something like 26% of the male population & 8% female. I trained in textile dying & aviation: Not in that percentage.

I have had new resistors where the colours are quite suspect & I actually sent one lot back, as not only were the colours way off they were out of spec.

Someone mentioned resistor colour charts: Some of the purveyors of parts have them: downloadable. I also have one for caps where there is a comparison with IEC, μF, nF, and then the colour bands written.

Whilst RCD's are mandatory now and may stop a leaky transformer, I have always insulation tested transformers, to ground & between windings. In 50 years I have never seen one in a valve radio actually burn, fuse yes. The 1937 specs actually specify that the material within a transformer must not support combustion.

I have an Astor JJ here (was in the shed) & it was never unusual for it to run for over 12hrs in a day, sometimes more.

Marc

Same advice about old radios applies to old TVs especially. I'd never leave one on when I was out of the room!

The issue is mainly the insulation in the mains transformer. Paper, wax, bitumen, linseed oil. They all burn fiercely! As the breakdown advances, the heat developed increases, increasing the breakdown, still more heat and so on.

In old TVs you also have the EHT transformer that can fail in a similar way. I used to repair many EHT cage fires back when. Mostly contained within the cage but it was always possible for burning wax to drop onto the cabinet or set fire to curtains.

In the UK, early 405 line TVs used mains-derived EHT. Not only was this guaranteed lethal but the transformers, which were usually potted in a wax-bitumen mixture, would regularly ignite, turning into a pot of flaming pitch and burning houses down!

Small transformers are difficult to protect with conventional fuses, any fuse rated to pop under fault conditions will also eventually fail with power-on surges. Modern designs use thermal fuses embedded in the windings and/or "intrinsically self-limiting" design with self-extinguishing plastics.

Yes I am colour blind to a degree, luckily my wife isn't! And she loves old radio's too! So she will be able to help me.
I have decided to test all my set's with an ammeter, to determine the exact current draw, when warming up and operating, this way I'll be able to install a fuse in each set, in case anything goes awry, hopefully this should protect us and the radio.
On the subject of resistors, I have found this site, which specialises in kits for valve radio restoration.
http://www.justradios.com/reskits.html
If any of you experienced restorers have a look, you will see lot's of kits. They all look pretty good.
The question is...
Which would be the best and most useful one for an amateur restorer like myself?
Any idea's very welcome.
Thank you.

I am thinking Slow-blow fuse might be best way to go.
I always believed that what wears radio's out is turning on and off, where the valves heat up and cooldown, whilst if it stays on, everything remains more or less constant... Voltage and temperature wise.

My mother was an artist & colour blind in one area. She would get really annoyed spending hours not matching a colour & I would come home & fix it before the kettle boiled.

Significant point: I do commercially repair: Therefore I carry stock. Stock is money. Think very carefully before you consider kits. This is a great way of building up stocks of what you will never use. I have pretty much a full range of 1Watt resistors as lower supermarket ones cannot hack the voltage. Not too many purveyors of such things tell you that & I do think they perhaps should advertise voltages, same as caps. Then we would buy them with a bit more confidence.

There are caps like 0.047mfd (473) (replaces 0.05) 0.1mfd not quite as many. Then one uses by the dozen and 47K (50K); 470K (500K); & 100K plus the odd cathode resistor & if you repair little nippers 61-52 etc where there is a10K resistor on the RF screens instead of the original 22K's in parallel. 10k 2Watt.

16μF & 8μF were common filters and 450V is not a value I use with 5Y3 / 80 25μF was common on OP valve cathodes.

So be careful; asses what you actually need if you are just hobby fixing. With valves 630V non polarised caps to replace wax paper.

this way I'll be able to install a fuse in each set, in case anything goes awry, hopefully this should protect us and the radio

Take note of what Ian has said above about fuses.

Also be aware that under some circumstances the secondary side of a transformer can be in distress long before sufficient current is drawn on the primary side to cause a fuse to blow.

Thanks for that, it makes perfect sense, so 1 watt resistors are not worth buying, I'd better opt for 2-5 watt and buy those values specifically in greater numbers rather than a kit full of ones I'll hardly use. That is exactly what I needed to know. The Blaupunkt has two fuses. one on either side of the mains transformer from memory, one even soldered in!
Thank you for your help. Much appreciated!