National Instruments 782549-01 RF Preselector Module

The National Instruments 782549-01 is an advanced RF preselector module designed to enhance the performance of spectrum analyzers by adding preselection and preamplification capabilities. It is also known as the PXIe-5693. This module operates across a wide frequency range providing a low frequency bypass path from 20 Hz to 30 MHz, a preselector path from 20 MHz to 7.0 GHz and an external filter path from 20 MHz to 3.0 GHz. The 782549-01 module offers a variety of notch filters that improve signal clarity by rejecting unwanted signals within specific frequency bands. For instance, the N1 notch filter effectively rejects frequencies between 55 MHz and 75 MHz, offering a rejection of over 38 dB, while maintaining a passband from 32 MHz to 44 MHz.

The gain characteristics of the 782549-01 are optimized for different frequency ranges providing typical gains of over 23.5 dB for frequencies between 20 MHz and 950 MHz. The module offers positive gain across most frequency bands even with the preamplifier disabled. The module is designed to handle high levels of input power with minimal loss and it has a noise figure that ranges from 12 dB to 19.1 dB depending on the frequency. The 782549-01 module is also equipped with rapid switching capabilities that allow it to transition between different preselector bands and notch filters within 200 microseconds. This feature is critical for applications requiring fast and dynamic frequency analysis. The module's third order intercept points indicate its high linearity that shows typical values of -2.0 dBm to 0 dBm for frequencies up to 7 GHz.

This 782549-01 preselector module is a robust, single slot PXI Express module with a compact design. It measures 21.6 cm × 2.0 cm × 13.0 cm and weighs just 465 g. It supports a maximum operating altitude of 2,000 meters and operates within a temperature range of 0 °C to 55 °C. The module’s connectors including RF input and output are SMA female type with a reference impedance of 50 Ω and are designed for safe operation within specified power limits.