The cabinet will need to be refinished at least on the top. In the meantime, I used the appropriate color of Old English scratch cover on the cabinet.
Several of the capacitors had already been replaced many years earlier. However, the originals were lying loose in the cabinet. Among those that I replaced were a pair that had been replaced earlier.
"Licence" to listen
Also lying loose in the cabinet were radio receiver licenses complete with the name and addresses of the original owner. Apparently, Canadians had to purchase annual licenses in the 1940's in order to own and operate a radio receiver.
Even though it is located quite a distance south of the Canadian border, this radio still likes to listen to the "All-Time Favourites" on AM-740 from Toronto . It apparently recognizes much of the music from its youth ;-)
25 cycle power from the "Hydro"
Another clue to the radio's early life was its use of a 25 Hertz (cycles per second in that era) power transformer. These can be recognized by the very large lamination stack as can be seen in the chassis picture. A 25 Hz transformer will happily work on 50 or 60 Hz but not vice versa. The Niagara power grid (referred to by Canadians as the "Hydro" for its hydroelectric generation) in the 1940's used 25Hz as its standard.
The power cord was replaced. The rubber covered wires from the loop antenna were almost completely bare because the rubber insulation had hardened and fallen off. I used old-style braided black "spaghetti" to cover the existing wires. None of the chassis wiring had this problem. I performed the usual safety checks to determine if any leakage existed between the power line and the chassis. As usual, I used a bit of deoxit on all the tube sockets and controls. Then the rectifier tube was pulled and the power transformer and filament circuits were tested. I reformed the electrolytic with an external variable power supply. After all these checks, I powered the set with a variac while monitoring B+ and current draw. The set powered up well but was quite weak in sensitivity. I checked the 6SK7 RF amp tube and found it cold. Pulled that tube and checked its filament with an ohmmeter. Filament was intact. Wiggling the tube in the socket brought it up to power and the radio suddenly had all the gain and sensitivity as expected. Followed up by thoroughly cleaning the 6SK7 tube socket pins and slightly crimped the socket openings a bit to assure a proper fit and good connections. Did some voltage checks on the working set to determine the quality of bypass and coupling capacitors. Replaced several including the critical audio cap to the input grid of the 6F6 audio power tube. Was quite pleased with the performance of the set after these repairs. The tuning eye was nice and bright for the vintage. The dial cord was broken. I had earlier made notes of the placement of the dial cord from what was left of the broken cord. Restringing is not a simple task. I used 65 pound fishing line purchased at Wall Mart to replace the cord. The heavy line works quite well as a replacement.
The cone of the electrodynamic speaker was broken and had apparently failed some years before. That original speaker with its field coil used as power supply choke was still present in the set although the actual speaker in use was a permanent magnet Jensen replacement. I decided to leave both the original and the replacement in the cabinet as found in case a future owner wanted to restore the cone of the electrodynamic speaker. The field coil continues to serve its purpose as the power supply choke.
One of the fun side-benefits of restoring old radios is the information that can be gleaned for an old set. Many thanks to Tim C. for giving this set a good home.
The National NC-33 was the previous item "on the bench".