The bare receiver chassis last seen at
now has a power supply and an audio amplifier. Here is the finished circuit board prior to installation…
Construction is conventional point-to-point wiring except for the upside-down chassis box.
Here is how the board looked after being flipped over and screwed in place.
The mystery speaker has been uncovered. The lid certainly saved the speaker from damage during assembly!
The amplifier is a 6AK6… a parsimonious power-sipping power pentode (PPPP) that spares plenty of plate and filament current for the circuits that will be added later.
The power-supply uses a choke-input rectifier filter. This improves voltage regulation and increases the available HV current. The 65mA DC output rating of the transformer (with a capacitor-input filter) is boosted to 110mA. This is not a free lunch of course… the rectifier output voltage drops from 250V to 170V.
My next task will be the design and construction of the local oscillator. Maybe an electron-coupled Clapp using a pentode… I’m certainly open to ideas and suggestions!