Luckily the times when DIY projects in the GHz range have been the final frontier that’s rarely been crossed are over. Monolithic Microwave Integrated Circuits (short MMIC) are making the design of microwave (pre-)amplifiers a piece of cake. Mini-Circuits GVA-84+ is a perfect candidate for a simple 7 GHz preamplifier. The datasheet [1] of the … [Read more…]
The Sudden Storm receiver from QRPme is a simple direct conversion receiver. The circuit is nothing new: A NE602 mixer with crystal oscillator for downconversion and a LM386 as audio amplifier. What is new though is the enclosure. The parts for the sudden storm kit are being delivered in a tuna can. But the tuna … [Read more…]
Working low earth orbit (LEO) satellites is fairly easy and a great exercise for amateur radio operators of all classes. A simple HT for both 2m and 70cm (440 MHz) and a directional antenna is all that is needed for first experiments. There’s an 2m / 70 cm Antenna from Arrow that is highly recommended … [Read more…]
For homebrew crystal filters such as Cohn-Type or Ladder-Type filters it is often necessary to select crystals within 10 – 50 Hz of the target frequency. To make the selection process a little bit more pleasant, I designed this little test circuit. It is basically just a very simple oscillator utilizing a hand full of … [Read more…]
A little tool for various calculations revolving around PSK and QAM modulation schemes commonly found in ENG, SNG, and BAS applications. Useful for bandwidth calculations in satellite (VSAT) and terrestrial broadcast applications. The calculator takes factors such as Forward Error Correction (FEC) and roll-off values into account. It’s also extremely useful for amateur radio operators … [Read more…]
Probably any person interested in RF knows the basic concept of frequency (FM) and phase modulation (PM) as the terms are pretty much self self-explanatory. Yet when it comes to the practical implementation, I frequently notice how little the properties of both modulation techniques are actually understood. From my experience, a vast majority falsely believes … [Read more…]