DIY spectrum analyser input protection

Spectrum analysers such as the SIGLENT SSA3000X and SVA1000X series are extremely useful instruments that can provide invaluable insight into broadcast signal performance, transmitter troubleshooting and interference, RF device characterisation and EMC testing.

However, like other spectrum analysers, they are very sensitive and can be easily damaged if the appropriate precautions are not followed.

The devices have standard protection elements such as a DC blocking capacitor and an automatic attenuator that prevent damage from low frequency and higher power signals. There is even an audible and visible warning if the ADC (analogue-to-digital converter) is overloaded.

In addition, adding external attenuation and protection can be useful to prevent further damage, especially when connecting to unknown sources such as antennas, transmitters and LISNs.

One of our customers, Mr Jeff Covelli (WA8SAJ), is a HAM (Amateur Radio Operator) who recently introduced a very simple protection box that can be useful to keep the sensitive front end operational when connecting to unknown signal sources.