Frequency Standards FS725 — Benchtop rubidium frequency standard FS725 Rubidium Frequency Standard · 10 MHz and 5 MHz outputs · 1 pps input and output for GPS synchronization · 20 year aging less than 0.005 ppm · Ultra-low phase noise (<−130 dBc/Hz at 10 Hz) · Built-in distribution amplifiers (up to 22 outputs) · RS-232 computer interface · Two status alarm relays The FS725 integrates a rubidium oscillator (SRS model PRS10), a low-noise AC power supply, and distribution amplifiers in a compact, half-width 2U chassis. It provides stable and reliable performance with an estimated 20 year aging of less than 5 × 10–9, and a demonstrated rubidium oscillator MTBF of over 200,000 hours. The FS725 is an ideal instrument for calibration and R&D laboratories, or any application requiring a precision frequency standard. There are two 10 MHz and one 5 MHz outputs with exceptionally low phase noise (–130 dBc/Hz at 10 Hz offset) and one second Allan variance (<2 × 10–11). The FS725 can be phase-locked to an external 1 pps reference (like GPS) providing Stratum 1 performance. A 1 pps output is also provided that has less than 1 ns of jitter, and may be set with 1 ns resolution. Up to three internal distribution modules can be added to the FS725. Each module has four 10 MHz outputs, one 5 MHz output, and one 1 pps output, all with the same low phase noise, harmonic distortion and jitter. An RS-232 interface allows direct communication with the rubidium oscillator. Using the provided Windows software, you can easily monitor and control 1 pps timing, and determine the instrument’s operational status. There are two alarm relays that indicate the status of the rubidium oscillator lock state and synchronization to an external 1 pps input. The relays are SPDT, providing both normally-open and normally-closed contacts. Stanford Research Systems

Output Output frequencies Amplitude 1 pps pulse amplitude Phase noise (SSB) 10 MHz sine, 5 MHz sine, 10 µs wide 1 pps pulse 0.5 Vrms, ±10 % 2.5 V into 50 Ω, 5 V into High-Z loads <–130 dBc/Hz (10 Hz) <–140 dBc/Hz (100 Hz) <–150 dBc/Hz (1 kHz) <–155 dBc/Hz (10 kHz) FS725 Single Sideband Phase Noise -100 -110 external 1 pps input is applied, lock is maintained between the 1 pps input and 1 pps output, with computer adjustable time constant from 8 minutes to 18 hours. Two 50 Ω isolated sine outputs One 50 Ω sine output One 50 Ω pulse output Each option board provides four 10 MHz, one 5 MHz, and...