Believe it or not, back in the '50s the "electrician's knot" was the CODE REQUIREMENT for power cord strain relief! Usually used with a rubber (natural of course) grommet that prvided a cushion between the CLOTH insulation and the nasty sharp edges of the hole in the sheet metal. While on the topic of ancient history, the moving-coil meter movement had a name (eponymous with the inventor): D'Arsonval. I still have quite a few Bakelite "terminal strips" for the RIGHT way to do the point-to-point wiring; flying connections were amateurish (no slur on hams, BTW; I've been licensed since 1957, ARRL Life Member). Also ground lugs, along with some military-grade insulated standoffs for the same purpose as the strips (but single-point with a turret top compared to the multi-point terminal strips). Despite the relative fragility of the vacuum tubes, the rest of the typical constructions of that era were pretty rugged, as they had to be with several hundred volts and high currents everywhere.
Well done mister C you have found another monster! A truly scary-looking lump of hardware that deserves to be torn down and buried in ten different places. It looks like something reclaimed from the chamber at Abu Ghraib. Did I spot a half-hitch tied in the mains cable to provide strain relief? Nasty nasty. KILL IT WITH THE BIG HAMMER!
Mine was a slightly later tube model. Looked the same except the meter bezel was transparent. Pulled it out after many years of storage and it was still in working order. Dont really have a use for it anymore so I sold it on eBay for $25.
I'm still using mine. It's not an antique, because if it is then I'm...........
Yes I built mine. It was the second Heathkit I built. It still has the original 6AF4 in it but the selenium rectifier has been replaced with a silicon diode and the power filter cap as well.
I remember seeing a few articles way back then that had conversions detailed to put JFETs in place of the triode. One even went so far as to replace the power transformer with a basic 12.6/6.3 filament transformer so you could eliminate the high voltage (at least on the secondary side).