Manufacturer: Hallicrafters, Toronto, Canada
Model: 5R40
Approximate Date Of Manufacture: 1955
Type: 4-tube Superheterodyne AM BC band 3-way portable radio
Tube lineup: 1R5, 1U4, 1U5, 3V4 (miniature)
Status: working, partially restored
Where purchased: eBay, March 2006
The radio operates on batteries (one 7-1/2V "A" battery and one 90V "B" battery) or AC operation. The AC power supply uses a selenium rectifier. It covers the AM broadcast band plus one shortwave band. The radio uses four low-voltage miniature tubes.
As received it was in pretty good shape but was missing the knobs and the internal ferrite loop antenna. There was one bad tube - the 1R5 had an open filament (but I still have a nagging suspicion that my tube tester may have burnt out the tube as it has happened before). I installed a ferrite loop antenna from a junked radio, put on some spare knobs, and touched up the alignment and it worked on AM. It is still not very sensitive and may have weak tube and I don't think the shortwave is working but it needs an external antenna.
I found some pictures of the radio on the Internet that will help me determine what the original knobs looked like. The case was cleaned and some loose pieces glued back.
The radio is described as a "3-way portable". Why 3-way? Because it runs on batteries, 110 volts AC and 110 volts DC.