Thurlby Thandar PFM1300 Hand-held Portable Frequency Counter in Superb Condition.

Features:

• 5Hz to 1300MHz frequency range
• Very high sensitivity at all frequencies
• Frequency and period measurement, 0.0001mHz resolution
• Reciprocal counting technique gives superior accuracy
• Push-to-measure function with auto power-down
• Large 8 digit display with full range of annunciators

I've owned this unit from new and I'm only selling as I no longer need the portability this offers and I have a bench top unit to replace it. See photos for example of it working connected to my RF signal generator.

I've calibrated it against my GPSDO (accurate to 10MHz +/-0.001Hz) and as you can see it is significantly better than specification (< 0.5ppm).

The PFM1300 uses a reciprocal frequency counting technique which involves multiple period measurements followed by computation of the reciprocal.

The system yields at least 7 digits of resolution per second of measurement time and can measure low frequencies to a resolution of 0.0001mHz, making it more capable than many bench top counters.

The PFM1300 can measure frequencies in the range 5Hz to 1300MHz. Unlike many counters, the sensitivity is high across the whole  frequency range with no dead spots. A low pass filter can be selected to reduce high frequency signal noise and ensure stable readings at lower frequencies.

Despite its wide frequency range the PFM1300 has a remarkably low power consumption enabling it to operate for many hours from a  PP3 size battery. A push-to-measure capability gives a virtually instantaneous reading followed by an automatic power down after 15 seconds. This provides greatly extended battery life where continuous monitoring of the signal is not required. Alternatively it can be operated from AC line via a DC adaptor.