National Instruments 782549-01

The National Instruments 782549-01 RF Preselector Module, also referred to as the PXIe-5693, is a high-performance solution for enhancing the capabilities of spectrum analyzers through effective preselection and preamplification. This module operates over an extensive frequency range, offering a low frequency bypass from 20 Hz to 30 MHz and a preselector path from 20 MHz to 7.0 GHz, as well as an external filter path extending from 20 MHz to 3.0 GHz. Its integration of various notch filters significantly enhances signal clarity by effectively rejecting unwanted signals in designated frequency bands, exemplified by the N1 notch filter that provides over 38 dB rejection between 55 MHz and 75 MHz while retaining a passband from 32 MHz to 44 MHz.

The gain performance of the 782549-01 is finely tuned to optimize different frequency ranges, delivering typical gains exceeding 23.5 dB for frequencies between 20 MHz and 950 MHz, with positive gain exhibited across most frequency bands even when the preamplifier is disabled. This module is engineered to accommodate high input power levels while minimizing loss and features a noise figure ranging from 12 dB to 19.1 dB based on the frequency. Critical for fast frequency analysis applications, the 782549-01 is equipped with rapid switching capabilities, allowing transitions between preselector bands and notch filters within 200 microseconds. Furthermore, the module demonstrates excellent linearity, characterized by third-order intercept points typically around -2.0 dBm to 0 dBm for signals up to 7 GHz.

Designed as a robust, single-slot PXI Express module, the 782549-01 has compact dimensions of 21.6 cm × 2.0 cm × 13.0 cm and weighs 465 g, making it suitable for various industrial applications. It operates effectively at a maximum altitude of 2,000 meters and within a temperature range of 0 °C to 55 °C. The module's connectors, including RF input and output, are SMA female types with a reference impedance of 50 Ω, ensuring reliable performance within specified power limits.