Mullard MA3 Receiver

 Searching for a set I'd stored away a few years ago, I found this Mullard radio from 1935. I think I'd been concerned about woodworm so put this set together with a Lotus radio from 1931 in plastic bags in the loft over my workshop. I'd then forgotton about it. It's in very tidy condition and I can see the cabinet top has been revarnished. Many a set from the 1930s supported an aspidistra or something similar and due to over-watering ended up with a stained top.

 

 You can clearly see that it's a mains receiver and has an isolation transformer making it fairly easy to bring back to life in a safe state.

An early Health & Safety feature found on the minority of sets is the rear cover can only be removed once the 2-pin mains connector has been unplugged. The mains voltage adjuster setting is visible with the back in place but can't be altered without first removing it.

 

 It's a 3-valve plus rectifier TRF design and uses all Mullard valves of course, two early-shaped gold-metalised B7-based valves, a VP4A and an SP4 for RF amplification and a B7 based PENA4 audio output valve. The rectifier is a B4 based IW4/350. I like the screw top valves because it's less easy to pull off the cap although, in this set the top of the VP4A needed super-gluing back on. The pair of copper cans carry accurately matched coils for aerial and RF amplifier ganged tuning. Early sets needed separate tuning knobs.

 

 The loudspeaker is a mains energised type whose coil doubles as an HT smoothing choke.

 

 The designers cheated when it came to tuning because, although the dial has a very contemporary oblong shape, the pointer travels in an arc.

 

 

The usual labels about patents and the dire warning about not selling the set combined with a free gift etc. Reading it carefully suggests that a dealer could diddle the buyer and sell it for more than the manufacturers list price.

Again, the notice about BVA valves. You shouldn't use foreign valves! Not exactly an illegal practice to do so but the implication is that the set wouldn't work too well unless you used British Valves.

Below, the model and serial number plate.

 
 

 Below, the circuit diagram of the Mullard MA3

 

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