Hi all. Recently I bought a Mullard, which was sold as a MAS-1110, but since I found it's a Mullard MAS-1113-X SW/BC.

Issue: The power transformer installed is not original for a Mullard of this type form 1951/54 which has three secondary windings sec-1 for HT, sec-2 for the 6V4 rectifier heaters and radio circuit and sec-3 for the other heaters and dial lamps. The one installed is a popular used transformer but with only two secondaries, sec-1 for HT and sec-2 for the heaters and dial lamps. Both the AC primaries are the same. I have included two photos. Since the 6V4 (in the original cct) has a separate heater supply which is also connected to the plate pin7&3, Can separate these and still place the 6.3Vac lamp cct to the heater and the plate pin-7 to the cct?

I have followed the schematic and tried to connect this intruder as best I know how but have had no luck, I get no noise at all. I placed the DC from the 6V4 pin 3 to the circuits +B, pin 4&5 for lamps and heater and 1&7 for the diodes.

The questions are: Can I still use this unoriginal transformer for my Mullard 1113-X radio? If so,dose the radio circuit require changing and what changes do I need to do? I decide to change the valves out 1 x1 and when I reached the 6M5, I got a real loud sound but I was not quick enough to turn the radio off so I think it blew the 6M5. I'm lost now so asking for some advice, but be polite please.
Regards.
Paul

The heater of the 6V4 should be wired on pins 4 and 5, in parallel with the heater circuit for the rest of the radio. Don't connect the heater to any other pins.

The HT winding will connect to pins 1 and 7.

Pin 3 is the rectified output which becomes B+ .

The centre-tap of the HT winding might go to ground, or it might be used as a negative power supply with a small-value resistor to ground.

But let's see these photos when they become available.

I would expect the transformer to be salvage from a set with a 5Y3, or similar filament rectifier. That would have a 5V winding, 6.3V winding and a centre tapped HT winding. With a 6V4 the 5V winding would be superfluous and not needed. There may be a wire with seemingly no owner and open circuit? If so that is a shielded trans former & it goes to ground.

The transformer is possibly original and that might have been got at. The original 1113x circuit shows an EZ82 (6V4) on a separate winding as the cathode (which positive comes from) tied to that winding, which is floating like a 5Y3 does. Ie.it is not earthed.

That is how I wired the tube feeding the 6L6 in my bench power supply and is to stop a heater to cathode flash over.

Do wire it as per circuit before daring to power it again.