[Chas]

Looks like an aftermarket BFO (Philco maybe) (beat frequency oscillator) for listening to CW (code signals) on the Ham bands... Without the BFO code signals would just "clickity, click" unless the beat against another radio station carrier, (messy).

Nice addition if one can read code or put the tones into the computer to decode. The BFO would also make listening to Single-Side-Band voice, those sound like Donald Duck without the carrier (BFO) turned on. The radio may be hard to correctly tune the SSB but it is possible.

Remove if you like, I would buy for another Philco shortwave in my collection

YMMV

Chas