I've run them longer at times, mainly in my office at work, where a Radiolette 500M would often be turned on at 06:30 and off at 17:00. A radio should reach its peak temperature in the first half hour of use so running it any longer than that shouldn't have an undesired effect.

One exception however applies to those who just grab a radio and juice it up without restoring it and making sure it is still electrically safe.

10 hours! That's a long time.

A well restored radio is a good soldier most of the time.

Put the chassis back into the case. The temperature at the inside of case up left back corner is 60C after a while.

So the transformer is hotter.

Look at some pictures in eBay listing and I found heat damage to the case in the same area in two of them.

It looks like this radio is hot by design.

Some radios are not designed to be used for long time.

Anyone know a radio that runs cooler by design?

Probably only those that have no backs on them and with the larger transformers that will run on lower the 40Hz mains supplies that existed in the 30s and 40s.

Doubt all radios designed to run that hot?

Valve televisions get hotter. Something like 18 valves including the screen and poor ventilation in some models. Even those with holes in the bottom still got fairly hot because the PC board obstructed the convection air currents.

Heat damage to the cabinet from the rectifier & OP tube is common in many of the smaller physical sized plastic radio's. Some had an Asbestos panel at the top.

One thing with them is not to run them in poor ventilation locations and never lift them from the top even when there is what looks like a hand hole.

As said the physically larger transformers tend to be the ones closest to "continuous rated". Doing crazy things like putting the hottest tubes next to them and in their field was never clever.

Marc

I've just been checking the power transformer on a 11-81 chassis wreck I have for spare parts. This one has obviously been very hot as melted wax has been dripping from it. One side of the HT winding is also open circuit. Someone has tried to get around this with a single silicon diode (0A210), replacing one half of the 6V4. The back cover of the radio (plastic) has shown signs of heat and is distorted. I have another complete 11-81 pending restoration, so it'll be interesting to see how hot the power transformer gets in this one when I get around to it.

On the subject of 40Hz power transformers. I've been reading a list of electricity supplies throughout Australia in the late 1930's. Back in those days electricity supplies throughout Australia were anything but standard. AC supplies, depending on where you were, could be anywhere from 200 to 250 volts. Western Australia, particulary around Perth, the electricity supply was 250AC, 40Hz. Radio manufacturers of the day did cater for the wild variations of electricty supplies going by service manuals and parts lists.

We have a few active members here from Western Australia. I wonder how they go with restoring radios designed to work on 40Hz and if there are any pitfalls with this. We are much more mobile today and radios originally set for a for certain supply voltage and frequency could end up anywhere. I've heard of instances of where people have stupidly connected battery sets to the mains and blown them up. What about a radio designed to work on a different mains frequency - could this be a trap for the unwary?

Western Australia, particulary around Perth, the electricity supply was 250AC, 40Hz

WA's power has been a problem for decades. In the 1970s, when we were first installing computer terminals (or VDUs as they were then called) the VDU manufacturer's WA field service crew were always attending to failed units with physical evidence of over voltage mains. Same with modems.

Even as recently as the 1990s I had a war of words in letters to Western Power about blown up UPS units where the manufacturer, after inspection of them, said "typical symptoms of over voltage mains". WP denied it was their fault until one day the substation kiosk itself had a meltdown. They ate their words over that!

I remember back to when this country made light globes and the factory had a line making globes specifically for the WA market. To allow for tolerances WA's globes were rated at 260v and 250v for all other states and territories.

The drivers in LED globes now can operate between 100v and 250v, like most things with a modern switchmode power supply. I think the dimmable LED globes have market-specific ratings though.

I wonder how they go with restoring radios designed to work on 40Hz and if there are any pitfalls with this.

At my last job I had an AWA 500M in my office for seven years and nine months. It had 40~ stencilled on the chassis. Now the transformer did end up burning out only a few months before I changed jobs but I doubt that would have been due to the 40Hz issue. If anything, it would handle 50Hz better than a transformer designed for 50Hz, like the smaller ones fitted to the similar 516M.

It was simply a radio that I used in my desk daily for a very long time and at the end of the day that radio was around 60 years old. I still have the radio, and luckily enough a spare transformer for it.

I would think that the same rules apply at 40Hz as it does for any transformer with Silicon iron, it was well known before WWII that the higher the frequency (up too a point with the material) the more efficient was the transfer and the less copper etc needed. So vibrator transformers were smaller & ran at around 150 -200Hz, The bombers ran alternators at around 400Hz and I think automobile alternators similar, and they don't have a lot of wire in them, compared to the DC Generator.

So a 40Hz transformer may actually put out slightly more volts a 50Hz. One of the biggest killers of HV secondary windings is failed capacitors.

Marc

Hi Monochrome625,

Hope to hear from you soon about the restoration.