Altek Model 40A Frequency Source provides 40 precise frequencies from 0.5 to 60,000 Hertz. Output is a square wave of 15 volt peak-to-peak amplitude which can be set to any lower value with a built-in attenuator. A switch selects zero based or zero center outputs for standard or zero crossing inputs.

The Model 40A checks and calibrates the electronics of turbine meters, vortex shedding meters, positive displacement meters, oscilloscopes, electronic counters, tachometers and many other frequency input devices. LED flashes to calibrate optical and fiber optic devices.

Frequency accuracy is ±8 parts per million. Long term stability is ±3 parts per million per year.

Instant turn-on allows long life from the two 9 volt alkaline batteries (200 hours continuous). Frequency is adjusted with the 8 position frequency selector switch and a 5 position range multiplier switch.

The low cost Model 40A is a complete, compact source for checkout and calibration of all frequency instruments in the field, shop, lab and control room.