Mystery Crystal Radio

[Godefridus]

I got hold of an old crystal radio and I wonder if anyone recognises the set. See fotos. I found a few surprises when I had a closer look. The little brown box marked Graham Farish Mica Condenser does not actually hold a capacitor. I found a germanium diode OA47 when I lifted the box. I also noticed that the Eddystone Radio coil was not connected to anyhing. When I removed it I discovered a toroid transformer underneath. The set works quite well, even with only the ground wire connected to a radiator. Does anyone have more information? Is there a reason why some connection wires are coiled?

[G6Tanuki]

It's a "retro"-styled recreation of an old-style crystal-set; someone's got together a few old bits and some newer ones and made something that looks vintage but isn't.

Treat it as an amusing and entertaining toy but it doesn't have any historic significance or value.

[SiriusHardware]

'Graham Farish' were / are, to my limited knowledge, manufacturers of Model Railway track, rolling stock and locomotives, especially 'N' gauge.

A while ago (2000?) they were absorbed by Bachmann but the Graham Farish brand is still used on the N scale product range.

However, on looking around it seems that up until the 1940s Graham Farish were better known as makers of radio components for home constructors, so that part at least is potentially quite old.

https://www.brightontoymuseum.co.uk/...:Graham_Farish

[Herald1360]

The OA47 is possibly the best Ge diode that you could have found there. It's a gold bonded type with very low forward voltage drop, which helps quite a bit with sensitivity.

I doubt the curly wires have any significant effect. The one in series with the headphones might be a passing nod at an RF choke, but its inductance would be too low to have any useful effect.

If you want to make it look a bit more in period, you could change the ANT label to AERIAL or A and the GND label to EARTH or E. The old bits are UK parts but the ANT GND (ANTENNA< GROUND) terminology is US or at least certainly would have been in the 1920s. Mind you, the variable capacitor is much too recent anyway to match the old coil former and condenser box.

[VT FUSE]

That creation would have appeared on a popular auction site quite recently,a search under Crystal Radio will show regular offerings with identical Chinese 4mm terminals and paper labels.Have just looked but none listed at the moment but they often have the trademark coiled hookup wire and OA81 etc.

The seller states in adverts that a long antenna and earth connection are required.To my knowledge,these have been appearing regularly in various forms for around 3 years or so.

[crackle]

To me it looks like someone is knocking these up in a shed.

Mike

[Radio Wrangler]

That sort of toroidal core only got common from the mid 70's onwards in homebrewed amateur radio gear. The variable capacitor and knob are WWII styles, and look original. The eddystone plug in coil and the Graham Farish box are pre-war.

I reckon it was knocked up fairly recently given the Chinese terminals.

It must have taken significant time and effort to have got the wiring on the underside as untidy as that. It looks like there has been a lot of messing around trying different arrangements. Anyone producing them would have been a lot neater.

It seems a shame to waste an eddy coil as just an ornament.

David

[60 oldjohn]

The base board reminds me of the wood that electric sockets & fittings were bolted to in the 1940 & 50s. Of course would not be a big job to make using a router, so could be newly made.


John.

[Peter.N.]

I remember Graham Farish, used to pass them on my way to Bromley.

Peter

[SiriusHardware]

They still have a distinct identity as probably the leading supplier (in the UK) of 'N' gauge model railway items specifically, but everything is almost certainly made in China for Bachmann nowadays.

I wasn't aware of their 'hidden' past as hobby radio parts makers though.

[G8HQP Dave]

It is sad to see genuine old components misused to make junk like this. It is a variant of 'steam punk'.

[wd40addict]

Yes, a new term is required: 'Craposet'?. They seem to be the radio equivalent of the Crapophone: vintage parts put together to make something that appears even older to the unwise.

Attached shows another example.

[John M0GLN]

Originally Posted by Peter.N.

I remember Graham Farish, used to pass them on my way to Bromley.

Peter

And if you wanted one of their capacitors in 1930 it would have cost you as much as 2/6 for three.

John

[Herald1360]

I read that as 2/6 each for 3-off.

[Herald1360]

Originally Posted by G8HQP Dave

It is sad to see genuine old components misused to make junk like this. It is a variant of 'steam punk'.

In this case, it's a working crystal set- not exactly junk. There's nothing here to get very excited about unless it's being passed off as vintage rather than pastiche repro.

At least one of the parts isn't being misused- unless you reckon using a twin gang cap to tune a single circuit is misuse. That's nothing new though- ever looked inside a "Roamer 7"?

[John M0GLN]

Originally Posted by Herald1360

I read that as 2/6 each for 3-off.

So do I now that you've pointed it out.
Thanks
John

[Godefridus]

Thanks guys for all the useful replies. I paid £8.50 for the set, which is probably a good price for any of the vintage parts only! At least those look genuine.
I was reading about Graham Farish, who was a fascinating character and a real entrepreneur. The company was apparently famous for making parts such as the mica condenser in the early days of radio. Even Marconi was using those parts. The condenser was advertised in the Radio Contact magazine.

[paulsherwin]

I think some posters have been overly critical about this. It is what it is, just a bit of fun. It's only a problem if it's been sold under false pretences, or if a genuine old crystal set has been ripped apart for the parts, which seems unlikely. My guess is that someone is knocking them together using the contents of their junk box.

£8.50 is certainly not an unreasonable amount to ask for such a thing.

[Godefridus]

It was advertised as a vintage crystal radio, so that was misleading indeed. I could not find a detector, so I reverse engineered a schematic diagram. I then discovered that the Eddycoil was not connected and there was no condenser under the Graham Farish box! It must have been quite a bit of work to built the thing.

I built a crystal radio in a jar when I was still in primary school (in the Netherlands), many moons ago. I understand that many people also built their own sets in the 1920s. I have an old homemade box that may well be from that era. It has a genuine crystal and a "cat's whisker". The tuning is by a variometer, i.e. a small coil that rotates inside a larger coil. The aerial wire forms the capacitor of the tuning circuit. Does this sound familiar?

[julie_m]

Unlike some modern crystal sets, this one actually stands a fighting chance of picking up a signal.

The variable capacitor probably came out of a valve set, but maybe its cabinet was turned into some sort of retro-looking Bluetooth thing, in which case it's not quite so much of a waste.