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Fred's Blog about Ham Radio, Python, Unix and more...

80/75/40-meter antenna for Field Day

This year for Field Day, our club decided to build a new multi-band antenna for 80 and 40 meters. The antenna had to have enough bandwidth to use the entire band without using an antenna tuner.


Reflected Power and VSWR

Our main goal as Amateur Radio Operators is to make sure that as much of the power coming out of the radio as possible is radiated by the antenna. The maximum power transfer occurs when the power source, the radio in our case, and the load or the antenna are …


Random-Wire Antenna

Is Resonance required? This is an extract from the ARRL Antenna book1 Please recognize that an antenna need not to be resonant to be an effective radiator. There is in fact nothing magic about having a resonant antenna, provided of course that you can devise some efficient means to …


Using DUDE-Star for digital contacts

DUDE-Star is a software developed by Douglas McLain (AD8DP) that connects to D-STAR, Fusion, NXDN, P25, Allstar, and even to the new digital mode designed by and for ham radio operators: M17. DUDE-Star includes a software IMBE and AMBE vocoder for encoding and decoding, but it can also use any …


NAVTEX for Emergency Communication

Many ham radio operators are interested in EMERCOM1. It can be useful to have a reliable source of weather information during an emergency. Some radios come with the NOAA2 frequencies already programmed in the memory. Hams have also programmed the following channels in their radios: NOAA weather channels …


Followup on: where are all the hams?

A few months ago, I wrote a blog post asking the question "Where are all the hams?". For that blog post, I generated heat maps of regions of the world showing WSPR1 activity. A few days ago, I sent an email to Philip Gladstone, from the PSK Reporter's …


Programming the radio module SA818

Before you can use it, the SA818 radio module needs to be programmed. This is a guide to program the SA818 radio module.


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