Kolster K-22

[Electronic M]

Have you ever worked on a superhet with an RF amp tube before the converter (or mixer/osc.) tube. If so a TRF is basically 2-5 of those RF amps cascaded feeding the detector. Each amp has a tuned LC filter that tunes the AM band, and an amp tube the L part of the LC should be a transformer to couple the cascaded stages. If the tubes are good the L not open, the C's not shorted, the PS detector and audio good then it should pass signal. TRFs tend to be less selective and sensitive so unless there is a reasonably powerful station close by you will need a long wire antenna (50'-150') to get proper reception.

TRF radios with single knob tuning also can benefit from an alignment of sorts...If the tuned elements (L or C) are not ganged disconnect the mechanical linkage from one at a time adjust for strongest reception of a station, reconnect linkage and proceed to the next tuned element until all have been adjusted...If the tuned elements are ganged there likely will be individual trimmers to adjust to achieve the same thing.