 |
| My plum coloured RMB after restoration |
Roberts radio was founded in 1932 by Harry Roberts and Leslie Bidmead in Hill Place, London. By 1935 they were producing an average of 8 hand made radios a week. By 1951 they had released about 11 different models to date and in 1951 came the RMB (Radio/Mains/Battery). Similar looking mains/battery powered models had been produced earlier but RBM used the new low energy valves that would save on battery consumption. The valves had been designed as usual for use in small army back pack radios and were: DK92, DF91, DAF91 and DL94. Instead of 6.3V @1 amp heaters this model employed 1.5V @ around 200 ma. They still required two internal batteries, one for the HT (100v) and one for the valve heaters.
Inside the hinged back door is a place to wrap the mains cable (when using outdoors) and access to the mains/battery selector switch, this was a bit of a design fault as the unsuspecting public were libel to get a nasty mains shock when opening the back door with it still plugged in.
 |
| No light used on display - employs MW, LW & SW bands |
The design of the speaker window was aimed at the MG sports car market and some versions have been found with 'MG' printed on the speaker cloth. This one though was mainly sold in Harrods department store in London for the grand sum of £26 doesn't sound much but £1 then relates to £25 now, so 25 x 26 = £650, the same price as the MG car at that time? Queen Elizabeth II bought one from Harrods, it was available right until 1957. The colours I have seen around are red/plum, black, green and off white. In the days before ferrite rod aerials a few hundred feet of thin copper wire was wrapped around a box and hung on the wall, here the box or frame is fitted inside the cabinet around a slim wooden frame, seen edge-on above. There is an extra frame aerial also fitted around and behind the loudspeaker, possibly for short wave, not sure.
 |
| Some of the parts that needed attention after 64 years! |
When I purchased it, in around 2014, it cost me about £7, but had to buy 2 used valves for it, they cost about a total of £20, and it also needed some old wax capacitors and high value resistors replacing, oh and the metal disc mains rectifier I swapped for a BY127. In the days of valves the biasing was done with very high value resistors, that tend with time to go even higher in value, always worth checking them first. The one valve had a crack in it, so the air had got inside, thus burning out the heaters. You can very often spot a cracked valve by the inside top going white or clear instead of the usual blackness. The chassis was a little rusty, so I removed that with some wire wool, re-glued some of the PVC covering that was glued to an all wood cabinet and I re-stitched the two halves of the leather carrying handle back together, added some shoe polish and she looked lovely again. It's the first radio of this great age that I have restored, I tend to collect 60's forward looking designs, but something said 'buy me', lol
 |
| The inside before rust & dead spiders were removed |
If you wish to run this model on battery, some units are on the market that step-up a standard 9 volt battery to 90 volts and hides all electronics in a vintage looking battery box with it's own terminals, quite expensive to buy, but with the effort one can be made by 'the restorer' if he should wish. This is the only Roberts radio in my collection, but the company are still producing radios today, they are one of the most popular selling brands on the UK market and their best sellers are the retro remake ones.
 |
| Circuit for MW & LW version |
An 18-year-old Princess Elizabeth listens to an earlier non portable version
No comments:
Post a Comment