The National Instruments PXI-5691, identified by part number 781035-01, is a high-performance PXI RF amplifier designed for a wide frequency range of 50 MHz to 8.0 GHz. This module features two channels: one fixed and one programmable, enabling versatile application configurations. Channel Zero supports a level calibration range of ±0.9 dB with a maximum absolute input power of +30 dBm, allowing for robust signal integrity. The maximum output power achievable without risking damage to the module is +20 dBm, while it can deliver up to +25 dBm under specified conditions. Channel One, serving as the primary path, offers a gain range of +31.5 dB with a fine adjustment step size of +0.5 dB. The level setting time is impressive at a maximum of 4 µs, maintaining calibration accuracy within ±0.9 dB. This module’s relay switching time is optimized at 5 ms, ensuring quick response times for dynamic applications.

At lower frequencies (10 MHz), the gain variation is minimal with an upper bound of 0.40 dB and a lower bound of -0.60 dB; conversely, at the higher end of the spectrum (8 GHz), the upper bound is -0.60 dB and the lower bound is -3.40 dB. The RF amplifier operates with a power requirement of 2.9 watts at 12 volts, drawing a current of 99 mA. It is equipped with four SMA female connectors for each channel input and output, all designed for 50 Ω impedance with AC coupling. The physical dimensions of the PXI-5691 are compact at 21.6 cm × 2.0 cm × 13.0 cm (8.5 in. × 0.8 in. × 5.1 in.), and it weighs 263 g (9.2 oz). The module is rated for operation at an altitude of up to 2,000 meters (800 bar) at an ambient temperature of 25 °C, with operational conditions ranging from 0 °C to 55 °C and a humidity level of 10% to 90% (non-condensing). It also withstands operational shock ratings of 30 g peak, half-sine, with an 11 ms pulse duration. The PXI-5691 is constructed in accordance with IEC 61010-1 and EN 61010-1 safety standards, ensuring reliable and safe operation in industrial environments.