Really Expensive Stuff

 These items cost a tremendous amount of money when they were new but today they are hardly worth their weight in scrap metal. If they stop working you'd have to pay to have them carried away!

Hewlett Packard HP8551B Spectrum Analyser

 HP8551B with the 5th harmonic of a 500MHz signal displayed at 2.5GHz

The top unit is valve-less, using transistors

The bottom unit is a "plumber's delight" handling the 10MHz to 42GHz specification

I suspect the lower limit may be a lot less as the dials imply that it beats a 2GHz oscillator with a VFO, tuning down to 2GHz

My Marconi sig genny has a similar arrangement which lets you generate zero Hz (is that meaningful?) when the dial is set to "0"!

Hewlett Packard 608E VHF Oscillator

 Below, my Type 608E VHF generator, which isn't much use in a domestic repair workshop as they do not include FM. I suppose they would be more useful for overhauling aircraft equipment as they still use VHF-AM.

This monster, weighing in at around 100lbs covers 10-480MHz.

These equipments were made in the days before clever methods of frequency stabilisation had been invented and relied on mechanical ruggedness (=weight) to ensure that the output frequency was stable. Another requirement of these things, with their very accurate output attenuators (the dial on the bottom right), was not to leak any RF which might upset measurements.

Even with professional test equipment, RF leakage can pose problems. I was once servicing a marine VHF transceiver and was checking the distress frequency calibration, when the local Coast Guard popped up and complained about my test signal on his receiver. This despite the use of screened leads and a dummy load.

 
 

Voltmeter?

 And at the other end of the scale the cheapest piece of test equipment ever?

A bulb tester that came with some very early reflector bulbs


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