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Regenerative battery receiver with two valves
Cabinet made of mahogany, with Bakelite face plate; the controls and fittings are nickel plated. The radio was designed for use with headphones. On the left of the faceplate there are two small holes where the headset can be plugged in. On the right four antenna terminals, numbered 1 to 4, with a solid link that can be used to connect terminals 3 and 4. Connecting an antenna to these terminals in a number of different ways, the frequency range of the radio can be changed. This also affects sensitivity and selectivity, but is actually relatively straight-forward. The battery control knob (top left) is used to increase the voltage supplied to both tubes; the amplification knob (bottom left) decreases or increases the amount of regeneration. The station selector lever (lower right) selects the desired frequency.
The thick cloth cable coiled to the left contains the battery wires. The wires are individually labelled with small metal plates.
The tubes used (type 11) are quite scarce and filament breaks easily. In 1925 RCA issued a number of service sheets showing how to convert the Radiola III to the more reliable 199 type tubes.
This is a Swedish version of the Radiola III. The name "Radiola III" was removed in two places: on the face plate, below the RCA logo and on the back where the name "Radiola III" was painted over. In Sweden these radios could not be marketed, because SRA - Svenska Radioaktiebolaget - in Stockholm, already used this name for its products.

The real values for the capacitors below the four antenna connections were found by experimenting with an artificial antenna and measuring the frequency range; most circuits show the wrong values! (this is the correct circuit)

The original price was $35.
Data Valves
Serial number: none
Dimensions (whd): 20 12,2 16,7 cm
Made in: 1924
Purchased in: 2009
Click on a valve for more information

Circuit

What was broadcast in 1924?

 

Listen to "Terrible Blues" played by the Red Onion Jazz Babies, recorded in 1924

Inside
Circuit and connections
Antenna connections to different binding posts Battery connections
Transfer on the back. The name "Radiola III" was painted over.

Advertisement for the Radiola III, September 1925

This page was last edited on 28.04.2019