QRP and Direct Conversion

摘要

Over the years QRP constructors have used direct conversion techniques in many of their simpler designs for receivers and transceivers. To put it simply, the radio (RF) signal is mixed with a local oscillator to convert it directly to an audio (AF) signal. One of the results of this simple technique is that both of the signal sidebands can be heard. When I built my first direct conversion receiver many years ago and applied power, I thought I had a very lively receiver; lots and lots of signals. I had yet to become used to hearing all the signals twice!