HP 5315A 0.1 Hz to 100 MHz UNIVERSAL COUNTER

The HP 5315A Universal Counter measures frequency, period, time interval, ratio, and totalize functions across a 0.1 Hz to 100 MHz range, with optional C channel extension to 1 GHz. Built on advanced LSI circuitry with HP’s Multiple Register Counter (MRC) architecture, it delivers high-resolution measurements down to 10 ps for averaged time intervals. The instrument accepts both continuous wave and burst signals through dual input channels with independently selectable AC or DC coupling, variable trigger levels (±2.5 V DC), and adjustable sensitivity. Channel A includes a switchable low-pass filter at 100 kHz nominal and selectable X1 or X20 attenuation. The optional C channel operates from 50 MHz to 1000 MHz with 50 Ω impedance and AC coupling only. Period measurements span 10 ns to 10 seconds. Single-shot time interval resolution reaches 100 ns minimum; averaged mode extends to 0 ns with 10 ps resolution. A programmable delay (hold-off) function provides variable timing from approximately 500 µs to 20 ms between start and stop triggers. Ratio measurements compare Channels A and B up to 100 MHz. The 10 MHz time base offers three stability options: standard aging at <3 parts in 10⁷/month, Option 001 TCXO at <1 part in 10⁷/month, or Option 004 Oven Oscillator at <3 parts in 10⁸/month after 30 days operation. Trigger slope selection (positive or negative) is independent per channel. Channel A and B operate ±2.5 V DC signal range with 1 MΩ input impedance; Channel C supports ±5 V DC with fuse protection at ±8 V damage level. Input sensitivity ranges from 10 mV rms at lower frequencies to 75 mV peak-to-peak pulses (5 ns minimum width). Totalize mode supports manual or electrically gated operation via Channel B control.