Crosley Super Trirdyne Special

This is a 3-tube, c. 1925, battery-powered TRF receiver that employs an interesting reflex regenerative circuit. (It seems like “Trirdyne” has one-too-many Rs and that “super special” has one-too-many superlatives, but I digress.)

 The first stage is an RF amplifier, followed by a detector stage; the AF from the detector is fed back to the RF amplifier tube, so that tube does double duty—it amplifies the incoming RF and also serves as the first audio amp, making it a reflex-type receiver. The AF then goes to the power output tube. In essence, we have a 3-tube receiver working like a 4-tube receiver. Crosley was famous for making the most out of a circuit, saving cost, and making radios more affordable to the masses. 

Like many TRFs, this set has two output connections: one, for earphones, comes after the “first audio” stage. The other output connection, for a loudspeaker, is after the power tube. When earphones are plugged into the front-panel jack, the output tube’s filament is turned off, saving A-battery power.   

There are six controls on the front panel: a power switch, two RF tuning capacitors, two rheostats for adjusting filament voltages, and a tickler coil position for adjusting feedback from the detector to the RF stage. A seventh control is on the chassis, inside the cabinet: a variable mutual-inductance antenna coil. The schematic in Rider’s does not exactly match my set; this one is closer: http://www.crosleyradios.com/battery-sets/TRIRDYN-1.pdf

This radio has enough volume for use in your living room, but for placement in a guest bedroom, it’s a little too complicated to operate!

© 2005, Doug Criner