My collection of vintage lab equipment has grown again. I've added a Polish nixie digital frequency meter PFL-23. (What are nixie tubes I describe here.) It is made in 1978 by Kabid Zopan Warszawa (never heard of it). It contains 6 nixies Dolam LC-531, 6x decoder for nixie 74141, 14x TTL decade counter 7490, 3x TTL circuit 7400 and 2x TTL circuit 7472. Power is 220V 50Hz 30VA. It has an internal or external standard frequency of 10 MHz. Measures from 10 Hz to 25 MHz. Manual or automatic start. Adjustable reading time of 0.2 - 7s. Measurement time is 0.01s / 0.1s / 1s / 10s. Input sensitivity is 50mV - 50V. Input resistance min. 100k, max capacity 40pF. The accuracy of +/- 1x10-5. It is also equipped with a switchable output frequency of 1Hz / 10Hz / 100Hz / 1kHz / 10kHz / 100kHz / 1MHz / 10MHz. Dimensions are 38 x 31 x 10 cm. It weighs around 4 kg. After replacing a faulty circuit 74141 appears to be fully functional.
