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.

Documents uploaded.

Not quite sure what they were up to here with EZ82, it seems to have only been manufacture here.

Looking at the specs. By wiring it the way they wired it that increases the plate resistance. Otherwise there is 100V difference between the heater cathode voltage 6V4 being 500V and the 6x5 mentioned 400V.

I would expect that if you wanted to emulate it a 5V winding would run the 6V4 albeit it may need a resistor for heater over voltage OR salvage a plug pack transformer.

Ah yes I remember the EZ82 being used with the heater connected to the cathode, which I supposed was to stop the possibility of the cathode shorting out like the early 6X5 was prone to do.

The EZ82 looked like the original version of the 6V4, which featured 2 half-wave rectifiers stacked one above the other, with a mica separator between them. The later, more familiar 6V4 version has the X-shaped anodes, just like the 6X4 and the last 6X5GT.

Hi Robbbert. Thanks for the email reply and explanation.

The question stills remains and maybe you can answer it. Can I use the transformer shown in photo two (which is not the original and was installed in the radio by a previous someone), to drive the radio?

If you use a 6V4 and not an EZ82 there should be no problem wiring it like the 6X4 circuit. But using pins 4 and 5 for the heater, of course.

You could also use a 6CA4 if you can't find a 6V4. It has the same connections but higher ratings.

As an aside: The Russians have made a ruggedised 5Y3 similar to the 6V4 etc. With what is not dissimilar to the shape of a tank stand with on up and one down. I strongly suspect there is a cathode sleeve as there is no surge, but the filament is a rod around 4mm in diameter. That seems to cure the issue of the sagging heater strip in a tube, shorting in all but one position.

Despite 6X5 apparently being designed for car radios; early versions with plates one above the other, were notorious for shorting & Zenith had them doing that, down to fine art.

Hi all. Sorry to be a pain and I appreciate your patients. I think the replies are missing the what I have asked therefore, just to clarify the help I need.

Photo-1 shows the original transformer connections from the schematic to a 6V4 valve or EZ82 rectifier valve of the MAS 1113-x radio.
(This Transformer is not installed)

Photo-2 shows the transformer which came installed already in the this radio.

These two transformer connections for the rectifier and radio circuitry are different.

My question is, can I wire the existing transformer to suit the MAS 1113-X radios circuitry. (photo-2) so the radio operates as normal. If so how? I have tried different ways but missing something.

Or, do I need to either purchase the correct type transformer or just strip the radio for parts.

Lets chat.
Thanks.

can I wire the existing transformer to suit the MAS 1113-X radios circuitry.

Yes

If so how?

Answered in posts 2 and 8.

purchase the correct type transformer

Good luck finding one.

strip the radio for parts

That won't fix it.

Vintage User, it seems you are missing something because your questions have already been answered, more than once.

My email address is un-hidden. If you drop me a mail we could arrange a "talk-through" your problem.

Special favour 'cos you are new!

Hi Ian.
Thanks for your kind offer and comment, but I think I will persevere with it. I have been doing these radios for 2 years so I guess I am new, hence using forums for expert advice and finding parts. But i'm not a novice in Electrical, 52-years to be exact and just finished my Electronics & Communication trade also.

After checking the schematic wiring again, I have found that two tuning coils are faulty, L4 of the BC aerial section and L8 of the BC oscillator section. All the others are ok. I will check the windings and repair them, or try to find some spares somewhere.

If anyone knows of any old 1951/54 Mullard or Philips for sale or parts, with the same coil design I would be interested. To finish I do have noise from the speaker but very low and no volume.

Hi Robbbert. Thanks for your answer. I have persevered and may have done it, we'll see.Selling for parts is an option as I will get my money back, but learn nothing. Yes, finding a transformer of this type will be hard but I won't give up.

Confucius said. “The man who moves a mountain begins by carrying away small stones.”