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KF5JRV > TECH 14.02.17 13:24l 22 Lines 1192 Bytes #999 (0) @ WW
BID : 10407_KF5JRV
Read: GUEST
Subj: TRF Receiver
Path: IW8PGT<IR2UBX<IW2OHX<UA6ADV<CX2SA<VE2PKT<N9PMO<NS2B<KF5JRV
Sent: 170214/1115Z @:KF5JRV.#NWAR.AR.USA.NA #:10407 BPQK6.0.13
Once the triode was established as an amplifier it made a tremendous difference
to radio receiver performance as it allowed the incoming signals to be
amplified. Previously most sets used crystal detectors and even with a large
aerial, the signal levels were low. The introduction of the triode valve
enabled signals to be amplified so that more distant or weaker stations could
be heard. However in virtually all cases the valve was used as an audio
amplifier because of the stability problems with these early devices.
To be able to achieve sufficient gain, more than one valve was needed, and as
their cost was very high, people looked at making the most efficient use of
them. One way that proved very successful was introduced in 1913 and involved
the use of positive feedback in the form of a regenerative detector. This gave
significant improvements in the levels of gain that could be achieved.
These regenerative receivers proved to be very successful. The amount of
feedback could be adjusted to the point of oscillation, and this greatly
increased the gain and selectivity, enabling this type of receiver to
out-perform all other forms.
73 Scott KF5JRV
KF5JRV.#NWAR.AR.USA.NA
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