Yet another old radio (Crosley JM8GN "Magic Mood" portable)
I recently acquired an interesting radio from my late grandfather's estate.
This is what collectors would call a "novelty radio" -- it's a battery-powered portable shaped like a book. Made in the late 1950s, the instruction sheet proudly declares it to be a TRANSISTOR radio, but it's actually a tube/transistor hybrid, with three subminiature tubes and two transistors.
Here I've closed the cover and placed it alongside a typical 1950s tabletop radio; you can see it actually is quite compact for its day, although it would have soon looked like a huge battery-eating beast compared to the fully transistorized radios that were about to appear on the market.
The front panel is very simple, just two controls -- frequency and volume. Note the triangles on the tuning dial, which mark the CONELRAD frequencies, intended to be used in the event of a nuclear attack. These marks were required on all radios manufactured between 1953 and 1963.
Removing the large screw in the center allows the chassis to be removed from the case for battery installation or repairs.
All the circuitry is on a single etched circuit board at the bottom of the chassis, a relatively new innovation at the time that greatly sped assembly and reduced wiring errors. Earlier radios were wired point-to-point by hand. There are three very small tubes, each about the diameter of a Sharpie pen; this was about the pinnacle of tube miniaturization. There are also two germanium transistors in metal cases, type 2N109, one of the first types offered for commercial sale.
The circuit is quite conventional. The three tubes are in the RF chain -- a 1V6 mixer/oscillator, a 1AH4 IF amp, and a 1AJ5 detector. This is a fairly similar lineup to that used by a lot of tabletop radios. The two transistors are connected push-pull to form a class B audio amplifier. This likely saved a lot of battery power compared to a typical class A tube amplifier, but its main goal was no doubt to let them claim the radio was TRANSISTORIZED, a major selling point. This was close to the height of high tech, at the time.
So does it play? I don't know yet. As was typical for tube portables it takes a high-voltage "B" battery, in this case 45 volts, and a 4-volt "A" battery for the filaments. These are no longer made and modern equivalents wouldn't fit in the case; however, I may power up the bare chassis at some point just to see how it does. The set appears to have been used at least once but, like a lot of tube portables, doesn't appear to have seen much use.
This is what collectors would call a "novelty radio" -- it's a battery-powered portable shaped like a book. Made in the late 1950s, the instruction sheet proudly declares it to be a TRANSISTOR radio, but it's actually a tube/transistor hybrid, with three subminiature tubes and two transistors.
Here I've closed the cover and placed it alongside a typical 1950s tabletop radio; you can see it actually is quite compact for its day, although it would have soon looked like a huge battery-eating beast compared to the fully transistorized radios that were about to appear on the market.
The front panel is very simple, just two controls -- frequency and volume. Note the triangles on the tuning dial, which mark the CONELRAD frequencies, intended to be used in the event of a nuclear attack. These marks were required on all radios manufactured between 1953 and 1963.
Removing the large screw in the center allows the chassis to be removed from the case for battery installation or repairs.
All the circuitry is on a single etched circuit board at the bottom of the chassis, a relatively new innovation at the time that greatly sped assembly and reduced wiring errors. Earlier radios were wired point-to-point by hand. There are three very small tubes, each about the diameter of a Sharpie pen; this was about the pinnacle of tube miniaturization. There are also two germanium transistors in metal cases, type 2N109, one of the first types offered for commercial sale.
The circuit is quite conventional. The three tubes are in the RF chain -- a 1V6 mixer/oscillator, a 1AH4 IF amp, and a 1AJ5 detector. This is a fairly similar lineup to that used by a lot of tabletop radios. The two transistors are connected push-pull to form a class B audio amplifier. This likely saved a lot of battery power compared to a typical class A tube amplifier, but its main goal was no doubt to let them claim the radio was TRANSISTORIZED, a major selling point. This was close to the height of high tech, at the time.
So does it play? I don't know yet. As was typical for tube portables it takes a high-voltage "B" battery, in this case 45 volts, and a 4-volt "A" battery for the filaments. These are no longer made and modern equivalents wouldn't fit in the case; however, I may power up the bare chassis at some point just to see how it does. The set appears to have been used at least once but, like a lot of tube portables, doesn't appear to have seen much use.