] ----S. W. A. G.---- ] ] These were both factory B-C band adaptations of Q5-er used to home on ] BC stations rather than NDBs. ] ] Go figure Well I just looked @ a Surplus Conversion manual & it shows every R-24 BCB set as a "navigation rx." Hence loop/wire switch. All I can say is they might have been raries & ARC built 'em on demand on handy, pre-ink-stamped chassis. Or something