Fred's Blog about Ham Radio, Python, Unix and more...
Just a quick note for anyone who needs to convert between QRA (Maidenhead) locators and geographic coordinates. We've set up a simple, no-frills web tool at bsdworld.org/QRA-Locator . It's a lightweight page that does exactly what it says in the title: Earth Enter a QRA locator (like CM87VL ) See …
The objective of a choke balun is to reduce RF current flowing on the outside of the coaxial cable, thereby improving the symmetry of the radiation pattern and suppressing radio-frequency interference (RFI).
This letter was written by Frank (F4AJQ), and sent to members of the French club F6KOP. The text was originally in French. I translated and posted it here as a reminder of what Ham Radio is about.
Stop Guessing and Start Whispering! I recently moved to a new house and had to rebuild my antenna setup from scratch. Like most people, I checked the SWR to make sure my radio was working well, but a good SWR only tells part of the story. It doesn’t show …
Introduction VHF and UHF 1 bands form an essential part of the radio spectrum, supporting everything from amateur radio communications to public safety networks. These frequencies offer reliable local coverage and occasional opportunities for impressive distance work when conditions are favorable. The right antenna can make a dramatic difference in …
Unlocking the Power of Repeater Networks Amateur radio operators understand the excitement of connecting with others, and repeater networks incredibly enhance that connectivity. I want to share my experiences with several repeater networks: CARLA, N6ICW, WB6ECE, and the WIN System. Each of these networks provides excellent coverage, but they also …
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 …
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 …
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 …
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 …
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…
Heliax Coaxial Cable 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 …
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 …
In previous years, amateur radio enthusiasts heavily relied on dip meters as an indispensable tool for circuit testing. These meters are also known as grid dip meters. However, as of 2024, dip meters have become increasingly scarce …
It's important to keep an eye on space weather for effective communication, especially for a ham radio operator. Solar activity can have a significant impact on how radio waves travel. I'll share some essential graphs to monitor from my website: http://bsdworld.org/ . Note The graphs provided on this page …
Club members construct a Delta Loop antenna for the 40m band, using calculations and hands-on methods for installation and tuning. Through collaborative effort and practical experimentation, they achieve resonance and manage impedance, showcasing the educational value of experiential learning in amateur radio construction.
We've decided to tackle an HF 40-meter to 10-meter Delta Loop antenna for our next meetup. We picked this one because it's a multi-band antenna, which adds a challenge compared to a simple dipole.
On repeaters, in Ham Meetings, or when people talk about electricity in general, I hear the sentence, "It's not the voltage that will kill you, but the current." The idea that "current, not voltage, kills you" oversimplifies electrocution.
The Hustler 4BTV antenna is a vertical HF antenna known for its efficiency, durability, and versatility across multiple bands. However, if you want to use that antenna to tap into the 17-meter band, you'll need to modify it by adding a dedicated wire. This blog post describes how to include …
The San Mateo Radio Club is organizing a ham radio scavenger hunt. A radio scavenger hunt can be a fun and engaging way to encourage amateur radio operators to explore their skills and connect with other club members. The hunters gather clues to find the final meeting location …
A ground-plane antenna, also called a quarter-wave or a monopole antenna, is widely used in radio communication systems. It is relatively simple in design and consists of a vertical conductor, typically a metal rod or wire, mounted above a conducting surface known as the ground-plane. The ground-plane acts as a …
Ham radio repeaters play a crucial role in extending the range and enhancing the clarity of your amateur radio transmissions. They act as relay stations, receiving signals on one frequency and retransmitting them on another, allowing for broader coverage and improved reception. Whether you're a seasoned ham radio enthusiast or …
Often, ham radio operators who just got their general license are confused about which band to use. Here's an explanation of each HF band's typical usage and characteristics.
I wanted to see how long it would take to contact 100 countries using automated software and only 10 watts. For that challenge, I wrote a plugin that replies to any call from any country I haven't worked at least 4 times.
A radiosonde or weather balloon is an instrument with a series of sensors to measure the atmosphere parameter from ground level to an altitude of up to 35,000 meters (100.000 feet).
A couple of weekends ago, I took my trapped vertical antenna apart to clean it up , ensure every component was in good working condition, and fine-tune it. While working on the antenna, I noticed that the Common Mode Current choke box had a crack due to the hot California summer …
The Hustler 4BTV For most of my HF traffic, I use a Hustler 4BTV antenna. The antenna is a vertical trap antenna capable of working the 40, 30, 20, 15, and 10-meter bands without using a tuner. I installed this antenna five years ago, and it has always worked fine …
Telegram is an instant messaging application like iMessage, Google Chat, or WhatsApp focusing on security and privacy. I have used Telegram for this bot because Telegram provides a very extensive API allowing ...
Leslie Moxon, G6XN, invented a two-element in the 1950es, named after him. Less Moxon published an article in a QST magazine from 1952 titled Two-Element Driven Arrays describing his antenna.
A Double Bazooka Antenna is a broad-banded half-wave Antenna. This antenna can operate efficiently across an entire band without needing an antenna tuner. In the 1940es, the MIT staff designed and developed this antenna as a radar antenna for the military. Like a dipole, the Double Bazooka is a balanced …
It is often helpful to run tests and take measurements without connecting an antenna. Ham radio operators or anyone who builds or experiments with radio transmitters should have a good dummy load. Since I didn't have such a device, I decided to make one. Dummy Load In radio, a dummy …
In my last article , I showed how to measure an inductor using a known capacitor. This method could be used to measure a capacitor using a known inductor. This post will demonstrate a better and more accurate way to measure a capacitor using an oscilloscope. Usually, a capacitor's value is …
Resistors, inductors, and capacitors are passive components used in every electronic circuit. Usually, the value is marked on the resistor or capacitor, either as a color code or a number. Often, inductors have no markings, especially those with a ferrite core or an air core. To measure their value, professionals …
People think that all wires are the same and that any cable should be OK to power their rig. This is far from true, especially when you want to power your radio using a battery. This article focuses on installing a mobile radio or installing a battery backup for your …
I gave a presentation on antenna modeling software to a couple of clubs in California and Oregon. From the physical antenna design to the matching network, we designed the antenna live with the participants. Here is a little more about the talk: During the first part of the talk, we …
A year ago, I installed a system based on a Raspberry Pi Zero to manage my backyard lights . Since the system is installed outside in a weatherproof box, I have decided to install a DS1820 temperature sensor , send the data to APRS 1 , and use the APRS infrastructure to monitor …
Every Thursday, the Portland Amateur Radio Club ( PARC ) organizes a series of conferences called Beginning Ham Radio . These conferences aim to teach new hams all the aspects that ham radio has to offer. This week, the club invited me to talk about the latest and popular Digital Voice modes. The …
When we re-did our house plumbing, we asked our contractor to install a water recirculation pump. A water re-circulating pump is used to circulate hot water so that any faucet or shower will provide hot water instantly upon demand. What is a recirculation pump? A typical home can hold between …
The Wordsworth method After watching George Allison's (K1IG) talk on QSO-Today describing his methodology to "head copy" Morse code, I have decided to give another shot to learning Morse code, often called CW in the ham radio word. According to George, high-speed operators who copy in their heads at speeds …
The 2021 Field Day was the first time member of the San Mateo Radio Club met in person since the pandemic. It was nice to see friends again after so long, but the most enjoyable part was to be in a group of people working toward the same goal …
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.
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 …
Is Resonance required? Important This is an extract from the ARRL Antenna book 1 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 …
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 …
Many ham radio operators are interested in EMERCOM 1 . It can be useful to have a reliable source of weather information during an emergency. Some radios come with the NOAA 2 frequencies already programmed in the memory. Hams have also programmed the following channels in their radios: NOAA weather channels …
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 WSPR 1 activity. A few days ago, I sent an email to Philip Gladstone, from the PSK Reporter 's …
Before you can use it, the SA818 radio module needs to be programmed. This is a guide to program the SA818 radio module.
Over the years, I have made several Allstar, Echolink, and APRS nodes 1 . A few months ago, my friend JC (W6IPA) told me he wanted to build an Allstar node. I gave him this piece of advice: if I had to make a new Allstar node, I would create a …
Over the last few months, I have participated in an increasing number of discussions, either on local repeaters or in zoom meetings, about newly licensed hams interested in operating in the HF bands. Two main questions kept coming back: what radio to buy and what antenna to use. It is …
A few months ago, I installed a new 40 and 80-meter dipole . My shack and my antennae are on opposite sides of the house. My feed line goes through narrow spots inside the house and runs underground from the house to the antenna. Installing a new feed line for this …