|
Without measuring, we only have opinions. The ARRL Test Procedures Manual is a nice place to start. Some homebrew as well as boat anchor equipment are used in the ARRL lab. Some of my lab equipment are also boat anchors. I am a firm believer that you must understand the inside workings of your test equipment in order to utilise them meaningfully. In this way, the vintage of the test instrument will not be much of an obstacle in your quest of obtaining the desired test results. Recently, I had the fortune of being asked to commission a GE/MaaCom MASTR3 UHF repeater system with 2 satellite (diversity) receivers. The receiver sensitivity and SINAD test setup was comprised of an IFR AM/FM 500 Test Set and a HP8903A Audio Analyzer. I had an enjoyable time doing the tests and made some videos for you, just so that you can experience what 12 dB SINAD sounds like. Generally receiver specs seem to allude that the input impedance is 50 ohms. Looking at the input circuits, I have my doubts. I decided to hook the input of my TSC100RA scanner to my network analyzer and find out the truth. Before you view the movie, I would like to mention what I learnt: a. You will hear the sound of the network analyzer scanning, very interesting b. The input impedance changes as you switch bands, due to the switching in of input circuits for different bands. Note that before you try that with YOUR receiver, you must lower the output level of the network analyzer so that the receiver is not damaged. Hope you enjoy the movie.
|
|
Receiver Measurements |