315

The Sonoma Instrument 315 is a high-gain, broadband preamplifier covering 10 kHz to 1 GHz (-3 dB), designed for EMI measurements, antenna signal amplification, and general-purpose low-level RF signal amplification applications where maximum gain and low noise are both required across a wide frequency range. With a gain of 51 ±1.5 dB at 100 MHz — 19 dB more than the Sonoma 310 — gain flatness of ±0.5 dB from 500 kHz to 800 MHz, and a typical noise figure of 1.8 dB from 10 to 500 MHz, it delivers exceptional sensitivity for the most demanding low-level signal measurement applications.

Key specifications include an output at 1 dB gain compression of +15 dBm, a third order intercept point of +28 dBm at 300 MHz, harmonic distortion of -55 dB at 0 dBm output and 200 MHz, and 50 dB of reverse isolation from 20 kHz to 1 GHz. Input and output return loss are both 7 dB from 300 kHz to 1 GHz. The equivalent input noise voltage is 0.55 nV/√Hz from 10 to 500 MHz and 0.59 nV/√Hz at 1 GHz, including noise contribution from a 50 Ω source. The maximum input for linear operation is -36 dBm (approximately ±5 mV) — significantly lower than the Sonoma 310 due to the higher gain stage, and the input damage level matches at -36 dBm / ±5 mV, requiring care when connecting to higher-level signal sources. The unit is AC coupled with 50 Ω impedance and uses Type N female connectors at both input and output.

Time domain performance includes a transition time of 350 psec and group delay variation of 200 psec from 10 MHz to 1 GHz. The unit is mains-powered at 100, 120, 220, or 240V AC / 50–60 Hz at 20 VA. Physical dimensions are 91 × 109 × 183 mm (H × W × D) — identical in form factor to the Sonoma 310 — with a net weight of 1.5 kg.