Showing posts from September, 2022

Modulated Signal Source

 A short project for a modulated, portable signal source, ideal as the "other end" of an antenna test range. Anyone who has tried to measure the performance of an antenna knows there are 2 halves to the problem ... detecting the signal and sending the signal.  Detecting and accurately measuring the signal is a well solved problem, the venerable HP415E is the weapon of choice.  The '415 is self-contained, battery powered and very accurate. With a simple diode detector it makes an ideal portable measuring device and has been the backbone of many professional and amateur test ranges for many decades.  The problem with the '415 is it needs a modulated signal source, 1kHz of AM is needed on a carrier of the desired frequency. There is little point having a portable detector if you have to lug 20 kilos of bench equipment out into the field and provide it with mains power to generate the test signal. To solve this, I used a cheap synthesised signal ADF4351 signal source from