Inverted L antenna for Reception
Do to it’s ease of construction, the most popular antenna for short wave reception is the inverted “L” antenna. It’s often just a random length of wire strung up as high as possible. My...
HAM Radio site Blog
Velocity Factor of Coax
“The velocity factor (VF), also called wave propagation speed or velocity of propagation, of a transmission medium, is the speed at which a wavefront (of an acoustic signal, for example, or an electromagnetic signal,...
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...
Drake R8. Review of Shortwave Receivers
The Drake R8 series of shortwave receivers were introduced in 1991 until 2005 or thereabouts as R8, R8A, R8B and R8E. The latter being a version of the R8. Each of these different versions...
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...
ICOM IC-718 Modifications (SWR Protection, AGC Defeat, CI-V to RS232 Interface)
I’ve been very happy with the IC-718 that I purchased last year. I also purchased a TCXO so I could work 60m someday and a 500Hz filter for the digital modes which are my...
A Simple 40m Vertical Antenna
The 40m band is a great place for DXing! I don’t have the tall supports needed for a dipole or beam, so a vertical antenna works best for me. I do have a convienent...
Simple 10m CW Transmitter. Circuit Diagram.
The original circuit by the late Doug DeMaw W1FB, differs slightly from the one shown here. Two immediate differences are: A regulated DC supply for better frequency stability and a 2-pole low-pass filter for...
Multimeters for Beginners. Meaning. Using. Short Theory.
Multimeters measure electrical quantities, and will at the very least measure Voltage, Resistance and Current. Usually they will have an AC and DC range. A multimeter is an essential item in any hobby electronics...
Arduino. Serial Communications and Debugging
When a computer program becomes more than a few lines long, or when you need to understand a complicated statement, you need to pause the program and somehow see what it is doing. One...
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