Reflex RECEIVERS were sets that used one of their valves to
perform several functions. In fact, some early receivers had more than one stage
reflexed. In the case of the Astor KM, it’s the intermediate frequency (IF)
stage (6B8G) that performs several functions – ie, IF amplifier, detector, AGC
and first audio stage.
Despite using quite conventional components, radios with
reflexed stages were not particularly popular with servicemen. To understand
why, read the early "Serviceman Who Tells" articles in "Radio and Hobbies" which
came out from 1939 onwards (now available on DVD from SILICON
CHIP). My own experiences with this set back up those early Serviceman
The servicemen of the era were usually self-taught. Some of
them had a good understanding of the radios they serviced but others were purely
"valve jockeys". A "valve jockey" had no understanding of the workings of the
receiver and just replaced valves until (hopefully) the receiver worked. Valves
weren’t as reliable back then as they were in later years and valve jockeys
often got sets going reasonably well, even if the real cause of the fault had
not been found.
Another problem for early servicemen was the lack of test
instruments. During the 1930s, even a basic multimeter was an expensive item and
this situation persisted right up until the 1960s.