All posts in the 'RF projects' Category
Posted on 06 Jul 2008
This small, light weight digital SWR and power meter uses an Atmel AVR “Butterfly” demo board and a “Stockton” type directional coupler. It is built into a “Whitmans Sampler” candy tin. The display board is mounted to the lid of the tin, so the cover can be closed to protect the display when the unit is not in use or is in transport. This makes it an idea meter to use when traveling or in the field. [more]
Posted on 06 Jul 2008
The Pixie is about the simplest rig ever devised, using just 2 transistors and a LM386 audio amp. The circuit starts with a standard Collpits crystal oscillator. In order to provide a 600 Hz frequency shift, a trimmer cap and 2N7000 FET is added in series with the crystal. During transmit, the 2N7000 is turned on, effectively shorting out the trimmer cap and lowering the oscillator frequency. [more]
Posted on 06 Jul 2008
It is a 40 meter rig with SSB (voice) and CW (Morse code) operating modes. This is a low power (QRP) rig with up to 6 watts CW or PEP (peak envelope power) output. This rig was designed for the ARRL Homebrew Challenge, the goal of which was to come up with a functional CW/SSB rig design which could be reproduced for under $50.00 using common hand tools and a minimum of test equipment. [more]
Posted on 06 Jul 2008
The circuit presented here is a method of using the standard PSK audio modulation from a PC sound card to transmit a PSK signal without the need for a SSB transmitter. Since the RF Power Amp runs in Class C mode, it is much more efficient than a linear amplifier normally used with PSK transmission. [more]
Posted on 17 Jun 2008
LCD SWR Meter presented here meet many simple task using a micro controller, especially, dear to all of us, a PIC!!. This time its PIC16F88. The very basic purpose to make this project is to encourage radio amateurs to build their own High Quality LCD SWR Meter at low price, instead of buying expensive ready made units. [more]
