A mate gave me a radio today which he received from a deceased estate. There is only one mark on the dial escutcheon, AC, there are 3 valves one is an 80, I can't make out the 2nd, it clearly shows E something 5, the other one is missing. The speaker is also one I've never seen before, the cabinet it is stamped "Made in Germany", it is a separate speaker box mounted inside the cabinet. I've looked at most Australian manufacturers with the 2 known valves in mind but nothing matches. I'd like to restore the radio but my hands are tied without knowing what I'm looking at.

I should have mentioned that I checked every valve in the Miniwatt book that begins with E and ends in 5 with 5 pins, E415 is the only one.

The EF5 is a P base valve. Used in sets around 1936.

Might help.

Wayne.

Sorry. I missed the bit about five pins.

Wayne.

Photos uploaded.

Did a bit of searching to identify the speaker, this what I found. Any thoughts would be appreciated.

https://www.antiqueradio.org/art/Kleinempfaenger08.jpg

"This type of speaker was new to me. When I queried the rec.antiques.radio+phono newsgroup, I got the following explanations of how they work.

They did not use the common today "voice coil" to drive the speaker's
cone or diaphragm, but had a flat piece of metal (a reed, I suppose) connected
by a mechanical link to the cone or diaphragm. This piece was mounted at one
end to the speaker's frame. The other end (the one connected to the cone) was
free to vibrate, just a few thousandths of an inch from the iron core of an
electromagnet driven by the radio's audio output stage. Sounded a bit like an
Edison cylindrical record phonograph.
From another contributor:

They were in common use in the UK for battery sets pre-war. They were
quite sensitive and did not need an output transformer due to their high
impedance and enabled a more compact form than was possible with a horn.
And another:

Phil, there is nothing wrong with a reed speaker. They were very common
in the 1920s. They can even sound quite nice, certainly much nicer than
horns of that period. I think the big drawback was the limited volume.
They initially attempted to make them louder by increasing the cone size,
which could measure several feet in diameter.

Simply put, a dynamic speaker can out-"volume" and out-"bass" this type
of speaker."

Sending 2 more pictures of the inside of the metal box and also multi taps for AC inputs. I'm starting to think that it's a European radio. I have checked with Radio Museum for every well known 3 valve radio in the 20s and 30s for the same valve line up with no joy.

Interesting old radio. The E415 was made by Philips from 1928 to 1932, being a detector and triode. I expect it serves the purpose of an output valve in this case.

https://collections.museumvictoria.com.au/items/411813

I'm starting to think that it's a European radio.

The photo did say, "Made in Germany".


I need to check my valve book next week to find a probable type that could perform the function of RF amplifier for a regenerative receiver.

The right-hand variable capacitor will adjust the sensitivity to a point just before it squeals.

Photos uploaded to Post 7.

I'll check these out tomorrow, they could be close, maybe the 80 could have been a 280 or 1560?


Stromberg Carlson
Year Model no Chassis no Description V no IF (kHz) Valve Line up Circuit ref Page Alt circuit ref Alt Pg Picture Page_ Orig price Notes
1929 A31 AC BC Table 4 Regen E415 E415 C603 280 W.W. 31/5/29 21/15/0
1930 A22 22X AC BC Table 3 Regen E415, B443, 1560 14/7/6
1930 A22C 22X AC BC Con. 3 Regen E415, B443, 1560 SC 11/01 84 18/0/0

Couldn't wait till tomorrow, the A22x is very close, maybe the E415 was in the wrong socket ?

https://www.radiomuseum.org/r/stromberg_midget_two_a22.html

I think it's the speaker only that was Made in Germany. The body of the speaker is Pot Metal, not good as I can't see it being used, I'll wait till I pull it to pieces.

Trying to figure out what some of those parts are...

The metal box behind the tuning gang is a capacitor, which will have to be replaced. The size printed is 1μF, which is about all they could manage in those days. If it's just a filter cap, you might be able to use a normal high voltage electro in that position.

The box between the 2 valves is a mystery, as is the odd switch arrangement underneath it. I'd have to see the schematic before making a comment.

In the 7th photo is a dropper (resistor with multiple tappings), which was a common arrangement back then. You'll have to check for continuity in the the sections, as they frequently burn out.

Also, check for continuity in all transformer and speaker windings. Apart from those things, there's not a lot left to go wrong.

Robbbert, there 5 electros, 2 x 1 ufd 500 volt that can see, on the other side there are 2 x 4 ufd 1500 volt and one under the chassis, don't its value yet. I'll have a look at the box between the valves. My other concern is the speaker, if you look at the photo you'll see pot metal, don't know the effect of it yet.

Hi Rudolf,

I can't help with the maker but I can tell you that the radio is almost certainly Australian made if the E415 is original. As far as I am aware Australia is the only country that used Philips valves on UX bases. European radios would have used British B4 and B5 bases which are completely different.

The missing valve could be a B443 / C443 or something similar if it is wired as a pentode and has 4 volts on the filament. If the filament voltage is 2.5 volts and it is a pentode it will be a 47.

The filament wiring will give a big clue. If the two valves are both powered of the same filament winding the missing valve will be one of the "443" pentodes almost certainly.

Regards, Frank.

Hi Rudolf,

The radio is most certainly an Airzone cub (AC) in console form. I think I have an advert for one somewhere. I will try and find it. The chassis is very similar to the mantle Cub cathedral, but the layout is different. It uses similar components, but different valves. I'd guess the speaker is not original to the set. I'll see if I can dig up some more, but start searching for Airzone - probably 1932 - 3.

Robert