The principles discussed in this chapter apply to receivers for the VHF and higher frequency ranges, although somewhat higher values of intermediate frequencies may be used.
Alternatively an HF receiver may be used on the higher frequency bands by means of a converter. This is a separate unit consisting of an RF stage. a mixer and crystal-controlled local oscillator. Typically this may convert 144-146MHz to 28-30MHz, the output from the mixer at this frequency being taken to the antenna input of a receiver which tunes over 28-30MHz.
Such converters are commercially available to convert the popular VHF and UHF bands to a number of different output frequencies.