Older style test eqpt?
 

Who, (apart from CB0TEY who admits to being a lecher
of underage jail bait) uses Lecher Lines now that
the boundaries of frequncies for off-the-shelf technologies
are now up to the several GHz?

Although not used these days, somewhere in the depths
of the shack is the cavity wavemeter I made up for
2m from baked bean tins and a brass stir rod.

Hint for M3OSN : Consume the beans, open tin at both ends
(except for the bottom and top tins) and solder all together.

Use the remains of the spindle from a volume control
or capacitor as the bush for entry of the brass rod.

Calibrate reasonably accurately (for fundamental and
harmonic analysis) with a ruler.