Can anyone help me with a circuit diagram and any info on an STC 413 mantle radio

Valve lineup 6A8G 6B8SG 6V6G 5Z4G the label has 6G8G stamped over the 6B8SG

TIA

There's a schematic for the 413X downloadable at Radiomuseum here:

http://www.radiomuseum.org/r/stcaus_413x.html

Hi GTC, thanks for that but unfortunately it is somewhat different to the wiring in my set

I trust that your set's wiring is original?

Unfortunately, I cannot find a 413 schematic in any of the usual places.

Thanks GTC, there seems to little if any info on this radio.

Mine has had some rework mainly capacitors but some of the resistors that look original are not the correct value. eg 50K on cct and 500k in radio. The tone switch is completely differently wired.
If I cannot get any further info I might just rebuild it to the cct diagram. I suppose someone could have done work on it a long time ago before the new components using NOS components.

Any how thanks again for your help .

Never, as I have noted frequently, (and I have a HMV E43F as an example on the bench,) is it unusual to find parts that should have been changed in situ, are wrong, or it is wired wrongly. Parts of dubious origin, recycled of the bench are common. The best example I have seen was a Midwest, where every plate in the RF seemed to have a plate resistor of a different era and type and all were wrong. I also found one set with yesterdays RF section & tomorrows audio? Parts rundown.

There are several radios like Emmco, some Astor / Pye and STC (59 chassis being but one). I ended up reverse engineering it and the same for an EMMCO & others.

You may find that the circuit is similar to another as they all basically followed the same plot.

I have, especially with the EMMCO & STC 59, in realising the problem, used my ancient AutoCad to place principal parts (pre-drawn) as they are on the chassis and then play "join the dots". From that layout drawing you draw a circuit.

Whilst that may seem time consuming, mistakes become obvious, so you can end up finding the hard way is the shortest path to success Two of those circuits are on Kevin Chants site and are labelled on the document, how they were derived & any mods.

413X is in AORSM's.

Marc

STC were incredibly "flexible" with their models.

I have an STC mantle that belonged to my late mother, who acquired it during WW2. The internal circuit bears NO RELATION to the model number stenciled on the chassis. And it is definitely original. The valve lineup is 6A8G, 6G8G, EL3NG and 6X5. Electrodynamic speaker, volume control an early 30s vintage WW pot in the cathodes on the 6A8 and 6G8.

I'd say that many radios of that era were built using parts that were to hand at the time.

Ian, Youre not wrong about the changing of components as the supply became scarce, or substitute parts were more available.

The Kriesler 11-20 must be near the King of model changes with suffix letters near using the entire alphabet although I can not remember a 11-20Z model.

Clive,
Geting back to the STC, in the early days STC used the model number to discribe the chassis and the suffix to describe the cabinet it
was installed in. Thus we have a 413X and 413H mentioned in SIRWIN'S list of OZ made valve radios up to 1955 or there abouts.
He points to a schematic in the AORSM for 1940/41 page 299 applying to both models.

Cheers, Graham...

Many thanks to all for your replies.

I shall draw a circuit of mine and see how much difference there is and make changes as necessary.