Trirdyn
The Trirdyn is a 3-tube radio built in 1924. This is a unique
radio as it incorporates some interesting technical features. The Trirdyn
is a regenerative and also has a reflexed stage. The signal path is
as follows:
The signal comes into the antenna terminals. It is then amplified (RF)
thru the first tube. This is a TRF stage tuned by the left tuning knob.
It is then coupled to the regenerative detector stage tuned by the
right tuning knob. The audio output of the detector is transformer
coupled back into the first stage which doubles as an audio amp. The
audio output of this reflexed audio amp is transformer coupled to the audio
output amp which drives a horn nicely even on the weakest signals.
The sensitivity of this set is very good, capable of getting down to the
background noise. It is a little trickier to tune than the typical
TRF set however. If the filaments are lit too hot, the gain increases
until a nasty howl results. This howl is due to the reflexing nature
of the set. Proper operation suggests to use only as much filament
that is necessary to receive the desired station with adequate volume.
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