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

A Look at HF Digital Modes in Ham Radio

Voice communication methods such as SSB, AM, and FM are fundamental to the hobby. Digital modes present a captivating and often more efficient way to communicate, particularly when signals are weak or there is interference. These digital modes convert your text or voice into digital signals that can be transmitted …


Link pi-star to reflectors using systemd

Most people managing a repeater or using a Pi-Star open-spot at home want to automate the connection to a specific reflector to ensure they don't miss a net. To automate that task, they look online, and the internet tells them to insert a line in the file /etc/crontab to …


Alternatives to HWEF Antenna

If you've experimented with HF antennas, you've probably encountered the Half-Wave End-Fed (HWEF) antenna. It's popular for its simplicity, ease of deployment, and ability to resonate on multiple bands. In my previous post, I outlined several significant drawbacks of HWEF antennas, including their inefficiency, susceptibility to noise, and the persistent …


HWEF Antenna: Pros & Cons and Why I'm Not a Fan

Half-wave end-fed (HWEF) antennas have gained popularity among amateur radio operators for their simplicity, versatility, and ease of installation. While they have a few notable benefits, they also have many problems that make them less than ideal. Here's why I'm not totally sold on HWEF antennas. The Benefits of HWEF …


Cable comparison tool

In my previous article, I've been exploring the details of total losses in transmission lines and the extra losses caused by SWR. I've created a loss calculator to help users effectively determine their cable losses. This project required meticulous data collection from various cable manufacturers…


Coax Cable Loss and the Impact of Bad SWR

The coaxial cable is critical when setting up a radio communication system. This cable transmits RF signals from the radio to the antenna. We use coax cables because they have a conductive shield surrounding the inner conductor. This shielding minimizes electromagnetic interference (EMI) and radio frequency interference (RFI) when correctly …


Measure Resonance using a NanoVNA

In my last article, I explained how to measure the resonant frequency of an LC circuit by simulating a grid dip meter using an antenna analyzer or a NanoVNA. This method is convenient when you only have an antenna analyzer. However, a NanoVNA has two ports, and you can use …


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