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A tuned radio frequency receiver (or TRF receiver) is a type of radio receiver that is composed of one or more tuned radio frequency (RF) amplifier stages followed by a detector (demodulator) circuit to extract the audio signal and usually an audio frequency amplifier. This type of receiver was popular in the 1920s.
This approach provided high performance with a minimum number of expensive vacuum tubes, but these receivers tended to radiate RF interference in their immediate vicinity. Consequently, there was a significant amount of hostility by neighbors of "regen" set users over maladjusted radios transmitting squealing noises and blocking reception [ d ...
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A number of AMers operate vintage vacuum tube transmitters in conjunction with separate receivers. Some operators have even obtained old AM broadcast transmitters from radio stations that have upgraded their equipment. Others build their equipment from scratch (called homebrewing) using both modern and vintage-era components. [15]
The RCA model R7 Superette superheterodyne table radio. This is a list of notable radios, which encompasses specific models and brands of radio transmitters, receivers and transceivers, both actively manufactured and defunct, including receivers, two-way radios, citizens band radios, shortwave radios, ham radios, scanners, weather radios and airband and marine VHF radios.
The sub-receiver tunes between 118 and 174 MHz, and from 220 to 512 MHz (VFO ranges). [28] The radio's main receiver uses DSP at the IF level, so a very flexible selection of bandwidths are available without the purchase of mechanical filters, as was necessary on past radios.
The receiver functions as a tuned radio frequency (TRF) receiver. The radio frequency (RF) signal from the tuned circuit ( bandpass filter ) is amplified, then passes through the high pass filter to the demodulator , which extracts the audio frequency (AF) ( modulation ) signal from the carrier wave .
Although the TRF receiver is used in a few applications, it has practical disadvantages which make it inferior to the superheterodyne receiver below, which is used in most applications. [9] The drawbacks stem from the fact that in the TRF the filtering, amplification, and demodulation are done at the high frequency of the incoming radio signal.