Manufactured in 1989.
The Racal-Dana microwave counter Model 2101 is a microprocessor controlled instrument offering high accuracy measurements of frequency from 10 Hz up to 20 GHz. The counter has three inputs.

Frequency range: 10 Hz to 20 GHz in 3 subranges:
Input A: 10 Hz to 100 MHz, impedance 1 Mohms/35pF
Input B: 40 MHz to 1.3 GHz, impedance 50 ohms
Input C: 500 MHz to 20 GHz, impedance 50 ohms
Resolution of 0.1 Hz at frequencies up to 1 MHz
Gate 1 ms to 10 s
Automatic and manual operation as well as tracking and offset
Internal timebase 10 MHz
LED display with 13 digits