[Thomas Scherrer] likes to tear down old test equipment, and often, we remember the devices he opens up or — at least — we’ve heard of them. However, this time, he’s got a Hung Chang HC-F100 multifunction counter, which is a vintage 1986 instrument that can reach 100 MHz.

Inside, the product is clearly a child of its time period. There’s a transformer for the linear supply, through-hole components, and an Intersil frequency counter on a chip. Everything is easy to get to and large enough to see.

Powering it up, the display lit up readily. The counter seemed to work with no difficulties, which was a bit of a surprise.

The oscillator inside has a temperature regulator so that once warmed up, it should be more or less stable. Touching it disturbs it, but you really shouldn’t be making real measurements with the top off while you are poking around on the inside.

This would pair well with a period function generator. Compare it to a modern version.