Also FB group Building Transistor Radios
When I was a teenager, my high school friend and I worked for a guy who had acquired many thousands of dollars worth of test equipment. We used equipment with famous names such as Hewlett Packard, General Radio, Boonton, Fluke and many others. In the army, it was the same thing, only more specialized, for Radars. After that I assembled several Heathkits – that was all I could afford.
Heathkit is long gone, but there are several kits on the market that will help the electronic experimenter. Some of the kits are:
DMM Digital Multimeters – For years an inexpensive DMM has been available online and from Harbor Freight Tools. One brand is Cen-Tech and costs 5 dollars US or less. Better ones are available, with prices up to hundreds of dollars. Better ones have auto ranging and more functions. The latest ones have an oscilloscope built-in.
Transistor Tester – actually a component tester and identifier. Resistors, capacitors, inductors, diodes, and some combinations.
Oscilloscopes such as the DSO138 kit. Low bandwidth but okay for audio. Single channel, and inexpensive. Not an easy kit to assemble.
Frequency Counters – some are made for checking RF transmitters in the VHF and UHF bands. Gooit is not a kit but is inexpensive. Some DMMs come with a frequency counter. Make sure the one you buy will cover the frequency range you are going to test.
Frequency Generators – Some frequency counters have a simple generator. There are different types. One is a function generator, which puts out Sine, square and triangle waves. Another is an audio frequency generator. And another is an RF (radio frequency) generator.
Signal Tracer – Basically a high impedance, high gain audio amplifier with a probe. They also have a detector to change an amplitude modulated RF to audio. Some can also inject a signal.
Power Supply – There are many different kinds, and many different prices. For working on transistor projects, a 0 to 20 volt, up to 1 amp regulated power supply will take care of most requirements.