22 or 24 gauge wire?

[PRR]

> a true breadboard build?

Yes. All plastic-stuff is fake.

> The only time I have ever seen rectangular wire used in modern times was on the Hermes spacecraft

JBL (not JPL!) and probably others mill round wire to a rectangular shape for loudspeaker voice-coils, to get more Cu/Al in the costly magnetic gap space.

Large power transformers are wound with ribbon to get more copper onto the iron core.

The one-turn secondary of a spot-welder is usually a flat strip (or stripS to improve flexibility).

Bus-bars are often rectangular for easier tappings and improved heat dissipation. In power stations they may use *hollow* rectangular tubing. Short HIGH-current busbars are often designed for very-high current density (to save cost) and heat dissipation becomes the main limit, hence flat and hollow instead of round and compact. Maximum surface area per dollar of Aluminum.

The buses in your cellar circuit-breaker box are surely stamped from flat sheet, though this is more for fabrication convenience.

Thanks for the Hermes reference.

Lovely terminal splay on those audio transformers.

[amptramp]

If you want the schematic for the Hatry & Young receiver, here it is:

http://www.sparkbench.com/homebrew/Hatry/hatryschema0520.gif

It used a newfangled thing from 1929 - tetrode tubes.