| |
KF5JRV > TECH 14.02.17 13:23l 9 Lines 1192 Bytes #999 (0) @ WW
BID : 10407_KF5JRV
Read: DK3UZ DF7EAV GUEST
Subj: TRF Receiver
Path: DB0FHN<DB0PM<OE2XZR<OE5XBL<F1OYP<ON0AR<VE2PKT<N9PMO<NS2B<KF5JRV
Sent: 170214/1115Z 10407@KF5JRV.#NWAR.AR.USA.NA 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
Read previous mail | Read next mail
| |
