Portable frequency counter PFM1300

• alternative name: Thandar Electronics || TTI

The TTi PFM1300 is a portable battery-operated frequency counter with a range of 5 Hz to 1.3 GHz that uses a reciprocal counting technique to achieve 7 significant digits of frequency or period answer per second of measuring time.
The timebase has a 10 MHz crystal oscillator with an initial adjustment tolerance of +-2 ppm. The temperature coefficient is typically less than +-0.3 ppm per degree C, and the ageing rate is less than +-5 ppm per year.
A user-accessible trimmer on the rear of the case allows recalibration without dismantling.
8-digit LCD display.
Trig indicator.
User-selectable 50 kHz low pass filter.
Hold function.
BNC input sockets. 

Input A
5 Hz to 25 MHz.
1 Mohm/25 pF, AC coupled.
Resolution 0.0001 mHz to 10 Hz.
Accuracy +-(1 digit + timebase accuracy).
Sensitivity sinewave 15 mV rms, 10 Hz to 20 MHz.
Maximum input 30v rms, reducing to 1v rms above 1 MHz.
Period measurement available, measurement time 0.1, 1, or 10 seconds.

Input B
20 MHz to 1.3 GHz.
50 ohms nominal.
Resolution 1 Hz to 1 kHz.
Accuracy +-(1 digit + timebase accuracy).
Sensitivity 10 mV rms 20 MHz to 700 MHz, 50 mV rms to 1.3 GHz. 
Maximum input 30v rms, reducing to 1v rms above 20 MHz.

Powered by a 9v PP3 alkaline battery, with a life of about 12 hours.
'Bat' display indicates that 10% of battery life remains.
Push-to-measure function extends battery life by switching off the instrument after 15 seconds.

The PFM1300 was superseded by the model PFM3000 offering frequency measurement up to 3 GHz.

Here you find 18 models, 14 with images and 9 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from Thurlby Thandar Instruments