Transient Limiter with built-in 10 dB attenuator, 9 kHz to 30 MHz
The Transient limiters protect a spectrum analyzer input from high-level transients from the line impedance stabilization networks during EMC conducted emissions testing. It has a combined frequency range of 9 kHz -30 MHz. The built in band pass filter attenuates the out-band signals at more than 20 dB/decade.
The LIT-930A features a broader frequency range than the LIT-153A, in that the low end of the its operation extends down to 9 kHz. The unit also features higher maximum input level ratings, as it can withstand input levels up to 4 watts CW (+36 dBm), +/- 15 Vdc. Its VSWR is less than 1.1:1. Other than these differences, you connect and use the LIT-930A spectrum analyzer transient limiter in the same manner as the LIT-153A.
Conducted EMI emissions measurement are conducted using Line Impedance Stablization Network (LISN). The EMC receiver input is connected live and neutral line of the product via the LISN. The LISN blocks the supply voltage from LISN RF portt but allow the RF signal to pass without much attenuation, so that it can be measured with a EMC receiver. Because the RF signal must be passed through, any short transients (a few microseconds or less) on the power supply lines will also be passed through. Transient limiter LIT-930A protects the EMI receiver input from these short transients A transient with high enough energy will damage a unprotected receiver input.