1940 Two Tube Shortwave Receiver

1940PS2tubeThis cute little two-tube broadcast/short wave receiver appeared in Popular Science 75 years ago this month in the June 1940 issue.

1940PlugInCoilsIt used  ready-made coils which plugged into the top of the set to change bands. Back in the day, you could buy the coils pre-wound, such as the ones shown here in the 1940 Allied catalog. A set of four coils covering 17-270 meters would cost $1.80. If you wanted to get the bottom of the broadcast band, the coil covering 250-650 meters would be an additional 75 cents.  Plug-in coils are unobtanium these days, but AA8V has a good description of how to make your own forms from a defunct tube and section of PVC.

A 1N5 tube was used as the regenerative detector, with a 1A5 serving as an audio amplifier to drive a built-in speaker. It was powered by a 1.5 volt battery for the filaments, with a 90 volt B battery, also tapped at 22.5 volts.

The builder of this set probably heard a lot of interesting signals on the shortwave bands during the war.

The 1N5 and 1A5 tubes are available at Antique Electronic Supply.  All other parts are readily obtainable, other than the plug-in coils, which you can wind yourself. For ideas on where to find parts, visit my crystal set parts page or my how to stock your junk box page.

1940PS2tubeSchematic

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  1. Pingback: 1940 “Mighty Midget” One Tube Shortwave Receiver | OneTubeRadio.com

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