21. Crystal-controlled superheterodyne receivers with better selectivity and stability made control equipment more capable and at lower cost. 22. Modern radio tuners use a superheterodyne receiver with tuning selected by adjustment of the frequency of a local oscillator. 23. A single transistor combines the functions of amplifier, mixer and local oscillator of an otherwise conventional superheterodyne receiver . 24. The TR-1 was a superheterodyne receiver made with four n-p-n transistors and one diode. 25. Most superheterodyne receivers designed for broadcast FM ( 88-108 MHz ) use an IF of 10.7 MHz. 26. Dynamic calibration is needed when there are long waveguide runs between the antenna and first down converter ( see Superheterodyne receiver ). 27. Most receivers are actually superheterodyne receivers and they leak a little of their local oscillator frequency; this can be easily detected. 28. Early superheterodyne receivers used IFs as low as 20 kHz, often based on the self-resonance of iron-cored transformers. 29. For example, a key component of a superheterodyne receiver is a mixer used to move received signals to a common intermediate frequency. 30. Armstrong's concept of the superheterodyne receiver to filter out noise and amplify the original signal is used in the cordless phone.
