If you took out the right-hand horizontal bar of the grill that would make AD for autodyne.

STC, clever idea.
Fred.

One of the things with glass tubes is that the vast majority were built without internal shielding and it was not until the miniature's that that was added to a few.

The other undoing is the modern capacitor with no outside foil. I am working on a wireless set 19 and in common with a BC-221-N frequency meter it has metal jacketed "Oil filled" caps. That jacket can act as a shield. It is unfortunate that the centre is waxed paper relying on the PCB oil as the self healing agent. These are no more reliable than the ordinary waxed paper and everyone in the WS19 is a resistor or open in the case of electrolytic's.

Most interesting autodyne was a MIdwest with a Colpitts Oscillator. Interesting when you see a four gang tuner and the oscillator uses two. Also the band switch was also switching oscillator cathode resistors.

One notes here and is applicable to Pentagrids of which 6SA7 is very different, is the Midwest. Here the switching of cathode resistances is related to maintaining not only oscillation, which goes high but enough drive to sustain adequate modulation in the mixer. A separate exciter is recommended for 6SA7 as it has no true oscillator grid, and is best with a tapped Hartley oscillator, even then it can be cranky.

We note that the higher the frequency the lesser is the modulation which is where Midwest were going with the cathode resistance change and very likely why they chose the separate exciter. One could actually introduce stability by voltage regulating (LR8, or tube) the voltages to the oscillator.

I have had a lead dress issue in an STC Autodyne relating to an oscillator wire & the screen & plate wires running parallel for a distance, to the point where I replaced the screen wire with shielded cable to shut up a secondary oscillation.

Some cranky sets can keep one entertained for hours.