Hello. Have just purchased one of these, a 1920's 6 valver TRF type. Also an external speaker was with the radio. The speaker is of a type predating moving coil speakers.
Naturally the radio is very dilapidated but appears to be complete.
Would anyone out there have a circuit diagram or be able to point me in the right direction.
The dial cord for the four tuning capacitors is broken. Would any details be about as to how to restring these.
Think I have a fair amount of work ahead.
Thanks for your help with this.

Several if's buts & maybe's

I assume that speaker is a Horn or armature type. It will highly likely high impedance magnetic.

One may be extreemly lucky & get a circuit. do we assume it is battery, or has it got a 280 in it?

The valves are?

Most of this type of set used transformer coupled Triodes, so the circuit ain't going to be complicated, unless they used AC filaments.
There is not a huge amount to actually go wrong.

One would need to see the engineering, to even contempate a wild guess on the string: They are rarely overcomplicated. Some use fine string like heavy fishing line others .... I did use parachute cord on one.

Marc

Thanks Marcc for your help so far. The speaker is a RCA Model 103 high Z type.
The valve line up or at least what is there are as follows starting at the front end.
V1 A615, V2 B605, V3 A609, V4 A609, V5 A609 ?, V6 B605 (missing).
There is a dilapidated Udisco information card giving some info on operating procedures.
Two audio transformers in the audio stage. At the front end there is a early type rotary switch which probably is for different aerial matching.
Four coupled variable capacitors with their coils.
Some evidence of the set having been "got at". Will be a long job getting this set going. Some vermin entry and a lot of dirt. So far have have removed the baseplate from the cabinet and just making notes before pulling bits out. Much of the wiring needs replacing.
Thanks again for your interest.

I have had sets where the Monkeys rather than the mice have been the problem, more so than anything else.

Those are all Philips valves http://users.bigpond.net.au/emmerik/catalogue/valves83.html Will get you the minimum info on the valves. I would expect them to be in the Phillips valve data books.

Some photo's of the inside are probably in order, before you start.

If you cannot find a circuit? I normally draw up the valve & transformer positions on an AutoCad & then play join the dots.

The last big TRF I played with is in Jul "Silicon Chip".

Do be aware that if the valve filaments are run on DC they may have to be wired "polarised". ie neg & positive on specific pins as that can be part of the grid bias.

Sounds like a project.

Marc

Thanks Marcc for your observations. Yes they are all Philips valves and fortunately have the data on them.
Guess it will be a tedious task of tracing out the circuit. As yet have not found any info on the Udisco brand. Probably one of the many of small radio builders in the 20's. Long gone.
Yes the valves are 6v d.c battery types and thanks for the reminder about polarisation of the supply.

Tks, Nick