Hi guys

Does anyone here know how to, or have any idea as to how a valve, with no markings left on, can be identified? I just got a radio, recently, and two of four valves have no numbers. These are the 1.5v octal types.

Thanks!

One way is to analyse valve lineups. A few weeks ago Marcc helped me out this way in this thread regarding a radio featuring as Radio of the Week.

After Marcc suggesting what valve it might be I compared the unmarked one to one of the suggested type and the 'guts' inside the valves were identical in every way. This isn't always an accurate way of telling, as many valves have innards that look similar, though it is a start.

Another way is to provide details of the radio (and if you have a photo of it you can e-mail it to me and I will include it in your post). Another member or visitor may be familiar with the set and offer you some assistance.

Perhaps the identity and model number of the radio would a good start ?

Rudy

Hi again

I couldn't find any obvious ID markings on the radio. It's a blue leatherette (Currently being restored from being painted red) box-like radio. The door swings open, which contains the aerial, and the speaker, 2 knobs and dial are on the opposite side. It takes 4 valves, 3 with top-knot thingos (One is a 1h5gt, one has ...R5... , one has ...6...G...) and runs from a battery supply of 90 and 1.5 volts. The valves are octal. I recently opened up the 'door' part and found 'RCS' (A parts supplier and radio buisness in glebe, the radio was picked-up from Foster) stamped on the bakelite form of the spiderweb antenna coil. There is an ARTS&P sticker, which is either C or G, and it has a 3 digit serial number (I'll send that and the number of the other valve next post).
The speaker is an 8k ohm Audiotron. Inside the chassis, it looks professionally made, and the cap's have just been replaced. The valves also need a replacement, as they're duds.

Thanks, if anyone manages to get through that.

Ahhhhhh I see now. I still don't know what the valve value are though the 90 volts is your high-tension voltage. The valves will have 1.4 volt filaments which work fine from a 1.5 volt D cell, or several wired in parallel.

If you have some GT valves in the receiver then the licence transfer prefix will likely be a G, dating your set to 1940.

RCS Radio was a company that mainly made components such as valve sheilds, dial glasses and the like. They are still in business and make PC boards for kits described by Silicon Chip and other publications.

I just sent the photos Brad - And the other valve is a 1a7gt

You sent them via e-mail? If so, I haven't received them yet. You might need to check the address and try again.

Perhaps the valves could be 1R5-1T4-1S5-3V4.
If its AC/DC then maybe 6V4-6X4

Rudy

Possibly, if they were made as octals, one is a 1H5GT, another is a 1A7GT. They're the 1.5v types. The ones with the missing numbers is the one with no top-knot, the pwr amp, and the tall Ken-Rad one.

I have a G-mail kind of e-mail thingo, so check your spam folder, Brad.

I got a huge old rectifier yesterday - The screw-in base is the size of a base for an 01A, the box is twice the height of an 01A, and the filament is 90v at 6 amps. And it says to run off batteries!

G'day Chirpolo,

My mail server currently blocks both yahoo.com and gmail.com due to excessive spam from those domains. Can you please resend the e-mail to chatbotbigpond.com? This is my webmail account that I only use in an emergency.


Brad.

Here are the photos:

As they are octal sockets then it has to "C" not "G" which would date it a 1936 model. I'll go through my list and have a look at all models from that year and let you know.

Regards

Rudy

Going by the markings on the box, the valve with the Edison Screw (ES) cap on it is a half-wave rectifier valve, meaning that only half of the AC waveform is converted to DC, with the other half simply not being used. Any radio using that would need a very good DC filtering system to stop mains hum coming through the speaker.

I have no idea of what the object with all the brass binding posts are though. Just a wild guess here but it could be a morse key - chances are that I am wrong though. It looks like what ever it is is spring-loaded and is some sort of switch though.

The photos 6-11, from the top, are of the unnamed valves.

That mystery object is definitely some kind of spring-switch thing. When the contact thingo, between the two poles, is on the right hand side, the two right hand terminals connect with the two on the opposite side and vice versa.

Mabye something to do with high voltages and earth connections?

Now that I think of it, that coil of wire looks like resistance wire. Still no further clues as to what it is though.