Simple broadband noise source
A broadband noise source is useful for testing purposes. This circuit gave a reasonably flat output up to 30 MHz when checked with a general coverage receiver. The output impedance is about 50 ohms.
It's basically a zener diode used as a noise source with a broadband RF amplifier. I think the higher power zeners give more noise, which is why I used a 1W device. The zener voltage isn't critical, of course; use whatever you have around 6V.
The 4:1 transformer is 8 bifilar turns on a Siemens/EPCOS B64290P37X33 ferrite toroid. An FT37-43 could be used.
My prototype, using very ugly construction.
A PCB I've designed for it. It's single-sided, with hatched copper pour for the ground connections, intended for making at home. I put in the wire link to avoid running a track between the transistor pads.
PCB designed with Pulsonix.