Build a simple 160 metre receiver

Related wiki pages: Apparatus, Receivers, Electronic Theory

A POOR MAN'S 160 METRE RECEIVER
If you are of very limited financial means (i.e., poor) and you would like to eavesdrop on one of the amateur bands, then read below.

Most starting out with receiving amateur radio transmissions might purchase a receiver, such as the Yaesu FRG-7 or the Kenwood R-1000. But did you know that you can receive the 160 Mx band with just a common AM transistor radio?

When you prise the back off the transistor radio, you will notice a square plastic object which is the radio's tuning capacitor. Notice that there are two adjustment screws on the back of the tuning capacitor. These are the antenna and oscillator trimmers.

To make the radio tune to 160 Mx, the trick is to find which trimmer is the oscillator trimmer. By turning this trimmer so that its tuning plates are "out of mesh," you will be increasing the radio's maximum local oscillator frequency, which will allow the radio to tune to any frequency in the 160 Mx band.

When you receive an actual amateur radio transmission, adjust the other trimmer, the antenna trimmer, for maximum signal strength. If you place the modified transistor on top of a large metal object, such as a refrigerator, this will enhance the received signal. If you string up about twelve feet of wire around your room and wind one end onto the radio's "ferrite rod" antenna, you will further enhance reception, but be careful as this could also cause the radio to pick up too much interference from "birdies."

But that modification is fine for a 160 Mx amateur station transmitting AM. What if they are transmitting on lower sideband or CW instead?

Just place another domestic AM radio near your modified radio and tune this second radio to somewhere between 1,200 and 1,400 KHz. The signal from the second radio's local oscillator will act like a BFO signal, to allow you to listen to both lower sideband and CW.

Submitted by John L WICKHAM VK3ZK Cranbourne, Victoria, Australia.