VHF/AM air-band converter - can also be used in the 2 m amateur band

can also be used in the 2 m amateur band Many enthusiasts would be in- terested in listening to what goes on in the v.h.f. air band of 108 . . . 132 MHz were it not that receivers covering those frequencies are fairly expensive. Fortunately, air communications use amplitude modulation and if you therefore have a good short-wave receiver it is pretty straightforward to connect a suitable converter to it. And that"s what this article is all about . . . The converter actually covers the fre- quency range of about 106 . . . 150 MHz so that apart from the air band it covers a small part of the broadcasting band (up to 108 MHz, but that"s mainly f.m.) and the 144 . . . 146 MHz (that is, the 2 m) amateur band. The converter consists of a v.h.f. amplifier, a mixer, and an oscillator. After it has been amplified in T1, the input signal is applied to a MOSFET mixer where it is combined with the output of crystal oscillator T3. Three tuned circuits between the aerial in- put and mixer ensure...