This Mills Radio Corp. receiver was found at a yard sale in Wilmington back in 2019. The company is believed to date back to late 1923, or early 1924.
The only information found on the Mills Radio Corporation is a listing in a 1924 Raleigh City Directory giving the business location and the names of three principal officers. It lists: Mills Radio Corp. 109 E. Davie - Daniel Mills - v-p & gen manager - h 211 N Blount., Mills John M, pres Mills Radio Corp h 317 S Boylan Av, Mills Walter H (Mills Tire Co), sec-treas Mills Radio Corp h 418 S Boyland Av.
This set appears to be a 'non-infringing' design, (i.e. No regeneration) incorporating two plug-in broad band RF transformers made by the Radio Instrument Co., Washington, DC. An antenna connected to a parallel tuned circuit with signal capacitively coupled to a variometer. From the high side of the variometer the signal is connected to the grid of the first UV-199. The plate of this tube drives a broad band RF transformer feeding the grid of the second UV-199. The plate of this second tube drives a second RF transformer coupled to the grid leak detector tube. The audio signal is now coupled to a standard audio transformer for amplification via two-stages using UV-201A tubes. It is unusual to see a mix of UV-199 tubes and UV-201A tubes in a receiver. The three parallel connected filaments of the UV-199 tubes are controlled by a single rheostat in series with the 6 Volt storage battery connections. To avoid applying over voltage to the tubes, the rheostat has been modified with a band of iron wire wrapped around the resistance element forming a bump that blocks complete rotation of the rheostat wiper towards zero ohms. I don’t think I have seen such a modification before.
There is a 50pf. variable capacitor
obviously kluged into place on the panel.
Note that a ‘gimmick’ capacitor is in
parallel with this part. The severe lack of
selectivity in this design would have
destroyed its market value by mid-1924
when the Department of Commerce
started allocating more broadcast channels. Three of the tubes carry paper stickers dated late 1927 from a shop in Morganton, NC. So, it seems as if this radio was in use for at least three years. If all you wanted to do was hear a local station in the daytime, I guess this set would still have some utility.
The hard rubber panel is made by Radion and extruded with chips of various brown and red to suggest a colorful mahogany style look and, no doubt, they were the ones that would engrave whatever you wanted on the panel for a fee. The knobs are also made of multi-colored hard rubber.
The cabinet seems to have been made at a local cabinet shop. Kind-of odd in having the veneers on the top lid and the base of the cabinet oriented along the narrow dimension. There was lots of veneer delamination to repair on the top and base. Half the bottom board veneer was missing. The chassis is yellow pine; a common wood for North Carolina.
I find it curious that the tube sockets and RF transformers are isolated from the pine board by a 1/16” thick sheet of red, rubber gasket material. This material is not necessary for insulation and it is not anywhere near thick enough to provide even minimal microphonic isolation or to compensate for shrinkage of the pine board. The only effect it had in the long run is to provide a source of Sulphur that
heavily corroded the phosphor bronze tube socket contacts. Fortunately, while heavy, persistent cleaning in the ultrasonic cleaner removed virtually all the oxidation.
The battery connections on the back of the cabinet have no identification except for hand embossed script into the wood veneer. The way the terminals are wired-in, it leaves one to think that not enough thought was put into ease of assembly for the layout.
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