50MHz Frequency Counter FC50

50MHz Frequency Counter, Model FC50  is a six-digit readout instrument with automatic location of the decimal point.
The effective resolution can be increased, in some instances up to eleven digits, by under ranging.
The ranges are 0.1 Hz to 50 MHz and 1 µs to 105 seconds, with a count facility to 999,999.
Start and stop can be manual or electrical (or a mixture of the two) and facilities are provided for inhibit, gating, storage and varying the updating rate. Clock signals are available for external use and there is an option of B.C.D. outputs from the six number tubes.
The display can be switched to show a ‘non-blink' series of completed counts of the run as it proceeds.
Acceptable input levels range from 20 mV (r.m.s.) to 100 V, and provision is made for correctly terminating 50 Ω or 75Ω lines

Here you find 32 models, 31 with images and 15 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from Wayne Kerr; New Malden, England