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PJL · 11th Oct 2018, 6:16 pm

Bought this from a local auction based on a very poor picture in the electronic catalogue. It's a 1932 EMI set and is a clone of the Marconiphone 256 using a 7 valve chassis that is more commonly found in radiograms. It is an early superhet with 125KHz IF, a separate oscillator and mixer utilising the early pre-B MS4 and VMS4 valves, and a PX4 output.

I won it for £12 and needless to say when I collected it the PX4 was long gone along with the back but I had expected this for the price and was pleased to see it was not a rust bucket, all other valves were present, and it looked fairly untouched. I have a few spare power triode's so was happy to donate an AC044 to this set.

One of the original block capacitors had been replaced with a 50's dual-electrolytic, now bulging wildly, and there were a few 'danglers' where a previous repairer had tacked on extra capacitors across the leaking ones. The resistors were in pretty good shape with all but a few still in tolerance. The original volume control was a dual comprising a 20K wirewound for cathode bias adjustment and a 100K for the gram input, now without the gram part.

The missing block was on top of the chassis so I constructed a rough replacement from brass sheet, patched in a 100K resistor so the gram input is always full volume, re-stuffed the other two capacitor blocks, and switched on monitoring the HT. It was a slightly scary 350V instead of 300V and a quick check on datasheets revealed this was to be expected with the UU5 it came with as it is far more efficient than the original U12 and this set takes almost 100mA due to the HT fed field coil. A 150 ohm resistor in the centre tap to earth fixed most of it.

First results were disappointing as it just squawked at me but cleaning the waveband switch got it working weakly but a full alignment, the IF was wildly out, was needed to bring it to life. The 85 year old valves are all working pretty close to specification which is just as well as they are pretty rare now.

I decided to go for the authentic look, covered up a few of the scratches and dings, gave it a treatment of linseed oil followed by bees wax, and washed the moth eaten cloth.

This is a fairly rare, very stylish and solidly built, read seriously heavy, set. I love it...

11th Oct 2018, 6:16 pm	#1
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Columbia 356 Bought this from a local auction based on a very poor picture in the electronic catalogue. It's a 1932 EMI set and is a clone of the Marconiphone 256 using a 7 valve chassis that is more commonly found in radiograms. It is an early superhet with 125KHz IF, a separate oscillator and mixer utilising the early pre-B MS4 and VMS4 valves, and a PX4 output. I won it for £12 and needless to say when I collected it the PX4 was long gone along with the back but I had expected this for the price and was pleased to see it was not a rust bucket, all other valves were present, and it looked fairly untouched. I have a few spare power triode's so was happy to donate an AC044 to this set. One of the original block capacitors had been replaced with a 50's dual-electrolytic, now bulging wildly, and there were a few 'danglers' where a previous repairer had tacked on extra capacitors across the leaking ones. The resistors were in pretty good shape with all but a few still in tolerance. The original volume control was a dual comprising a 20K wirewound for cathode bias adjustment and a 100K for the gram input, now without the gram part. The missing block was on top of the chassis so I constructed a rough replacement from brass sheet, patched in a 100K resistor so the gram input is always full volume, re-stuffed the other two capacitor blocks, and switched on monitoring the HT. It was a slightly scary 350V instead of 300V and a quick check on datasheets revealed this was to be expected with the UU5 it came with as it is far more efficient than the original U12 and this set takes almost 100mA due to the HT fed field coil. A 150 ohm resistor in the centre tap to earth fixed most of it. First results were disappointing as it just squawked at me but cleaning the waveband switch got it working weakly but a full alignment, the IF was wildly out, was needed to bring it to life. The 85 year old valves are all working pretty close to specification which is just as well as they are pretty rare now. I decided to go for the authentic look, covered up a few of the scratches and dings, gave it a treatment of linseed oil followed by bees wax, and washed the moth eaten cloth. This is a fairly rare, very stylish and solidly built, read seriously heavy, set. I love it... Attached Thumbnails Last edited by PJL; 11th Oct 2018 at 6:25 pm.