Bench AF Amplifier. Schematic Diagram.
The circuit… This circuit consists of just a few discrete components and one common IC amplifier – the LM380N. It’s simple, cheap, quick to build and works well. I built mine in a steel,...
Category: DIY
5 element quad for 2m band
Boom Length – 1651 mm Distance between: Between Distance, mm R – V 432 V – D1 330 D1 – D2 406 D2 – D3 483 Dimenson of elements: Side, mm Diagonal, mm Perimeter,...
QRP Dummy Antenna
I needed a small dummy antenna for testing my Elecraft K2. It was to be small and capable of being used into the VHF range. It had to have a BNC connector, and it...
Hi-Z Microphone Preamplifier. Schematic Diagram.
This preamplifier for a high impedance microphone was built into a Harris limiter/compressor which needed a line-level input. Its response is essentially flat from 20Hz-30KHz. The 10uF capacitors are 25v Tantalums, the .01uF capacitors...
Power Supply 12.6V 25A from old Microwave Oven Transformer
Dig out that old microwave oven transformer you’ve been saving and take a look in your junk box. It’s time to build that battery eliminator you need for the mobile rigs. Although the transformer...
Variable Power Supply Unit. DIY.
This little circuit is a copy of a design which was built around twenty years ago. The heart of the unit is based around a 723 regulator chip. It has variable voltage and current...
6m to 10m converter
This circuit is based around mixer/oscillator IC2. A 50mHz signal is fed to pin1 input of IC2 and mixed with the local oscillator injected at pin7. The resultant output is the antenna frequency minus...
Simple modification of the HM-36 Microphone from ICOM
The Icom HM-36 microphone is a simple electret mic. But many owners notice that some microphones sounds bad. What reason? There are two different types of ICOM microphone HM-36 (exclude chinese fake): First type...
A 40′ Tilt-Tower for VHF Beams
This is the first tower I built. After moving here, the idea occurred to me that trees can save a lot of money and work when it comes to towers. Trees are already firmly...
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