Return to VK3YE projects
|
Superregenerative receivers for VHF and UHF
Superregenerative (or 'superregen') receivers have been used since the early days of radio as a simple and cheap way of receiving VHF and UHF signals. Unlike regenerative sets (which are common
homebrew projects for medium and high frequencies), superregens have very broad selectivity. They can normally only be used for receiving AM and wide band FM signals. Consequently they can pick
up FM broadcast band signals. They are somewhat contankerous and hissy. Nevertheless for the small number of parts involved they work well and sensitivity is such that an antenna is hardly required.
The secret behind the incredible gain achieveable from a single transistor is the oscillating detector. This oscillating is a radiated signal that can be picked up on other nearby receivers. This is why
though superregens will tune the VHF aircraft band it's unwise to use them there because of interference risks. I've had success with FETs such as the MPF102 in simple superregens. Keep wires short for
best results. Once you have oscillation and can tune stations in try experimenting with changed component values. There may be a little distortion on received transmissions due to the 'slope detection'
superregen receivers employ. That is you tune off to one side of a signal for best recovered audio. If you find you don't get oscillation or reception across the whole FM broadcast band vary
component values as an experiment. Even moving parts slightly closer or away from each other can help.
The superregen experience is available to you even if you'd rather buy than build. UHF superregen receiver modules are available cheaply and make a good basis for various radio experiments.
Superregen receivers are also used for short range remote control and data transmission applications. Frequencies
most commonly used are just above 300 MHz and around 434 MHz. Demonstrations of these are below:
Items were chosen for likely usefulness and a satisfaction rating of 4/5 or better.
|
Books by VK3YE
Ham Radio Get Started (USA)Australian Ham Radio Handbook (Aust) More Hand-carried QRP Antennas 99 things you can do with Amateur Radio Getting back into Amateur Radio Illustrated International Ham Radio Dictionary Make your Passion Pay (ebook writing)
All material on this site |