Today I got another old AC millivoltmeter, this time a Trio Kenwood VT-151.
This thing is autoranging so the classical range switch is missing. Back in the 70's and 80's lots of japanese companies produced look-alikes of the HP 400 series of millivoltmeters, Trio did that too, of course but not with this instrument, this seems to be one of their own creations.

Unusually the meter uses an N connector for the input - luckily there was a BNC adapter included.
The unique feature of this meter is the range display, that's the black rectangle on the right.
A series of bulbs light up and illuminate a two coloured display that shows the range in V and in dB.


Let's take it apart!

Ok. This doesn't look like the insides of high quality measurment equipment, looks rather like the insides of 1970's japanese A/V equipment. No FR4 boards, lots of wires and messy wiring looms, soldered wire wraps, components thrown on the boards in all orientations but not straight, lots of bodge jobs.
Now, for an instrument like this it is what you'd expect to find. Not only was it made by a radio manufacturer but these instruments were dirt cheap compared to R+S, HP or Fluke.
The really shocking part comes now: The main wiring loom between the back and the front.
They lumped mains and signal wires into one, using the same thin wires for mains and signals.


I really don't like the look of that. One expects to find unisolated main contacts on the fuse holder and voltage switch in equipment of this age.