01-09-2022, 12:35 AM
An RF or an AF transformer can be used to invert the phase of the signal by 180 deg. If such an inversion is made to a circuit, the circuit could oscillate or degenerate. Depending on how the design of the stage is using that transformer.
Some restorers of 20's era battery sets have found this to be true with the audio transformers. For example some reflex receivers must have the 180 inversion or the set will oscillate uncontrollably. Other radios with an audio transformer that has a common core and two bobbins each, a primary and secondary must be "phased" properly or the AF amp becomes an audio oscillator.
IMHO such an inversion in an RF or IF coil may cause a similar oscillation issue. IMHO it is better to pay attention to winding direction and circuit connection rather than have to guess and make transformer wiring swaps, which may not be practical because of physical layout.
YMMV
Chas
Some restorers of 20's era battery sets have found this to be true with the audio transformers. For example some reflex receivers must have the 180 inversion or the set will oscillate uncontrollably. Other radios with an audio transformer that has a common core and two bobbins each, a primary and secondary must be "phased" properly or the AF amp becomes an audio oscillator.
IMHO such an inversion in an RF or IF coil may cause a similar oscillation issue. IMHO it is better to pay attention to winding direction and circuit connection rather than have to guess and make transformer wiring swaps, which may not be practical because of physical layout.
YMMV
Chas
Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”
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