Here at the VHF station, we’re exploring the exciting world of Very High Frequency radio, specifically operating on the 6-meter band (around 50 MHz) during Field Day.
VHF encompasses frequencies from 30 to 300 MHz. This range is home to many familiar signals, including your favorite broadcast FM radio stations, as well as several popular amateur radio bands: 6 meters, 2 meters, and 70 centimeters.
The Magic of VHF Propagation
Generally, VHF signals travel by line-of-sight. Think of it like seeing a distant object – if there’s a hill in the way, you can’t see it. The same principle applies to radio waves. However, the lower VHF bands, like 6 meters, can experience a fascinating phenomenon called sporadic E propagation. This is when patches of unusually ionized atmosphere in the E-layer of the ionosphere can reflect VHF signals far beyond their usual line-of-sight range, sometimes allowing for contacts hundreds or even thousands of miles away!
The Ever-Popular 2-Meter Band
While we’re on 6 meters today, the 2-meter band is by far the most popular VHF amateur radio band. Why? It’s a combination of readily available and inexpensive equipment, along with a strong “network effect” – meaning there are a lot of hams on 2 meters, making it easy to find someone to talk to! Most of the 2-meter band is dedicated to repeaters, which we’ll discuss more in a moment. The most common mode you’ll hear on these channels is FM (Frequency Modulation), typically with a deviation of ±5 kHz for clear voice communication.
Your First Ham Radio: Portable Power
Many new ham radio operators begin their journey with a portable radio, often called an HT (Handheld Transceiver). These compact devices are perfect for local communication. While an HT typically transmits with 5 watts of power, upgrading the antenna on your HT is one of the best first steps a new ham can take to significantly improve their range and signal clarity.
Mobile VHF: On the Go Communication
VHF radios are incredibly popular for mobile use, and you’ll find them in countless vehicles. The ease of mounting a modest antenna on a car, combined with the ability to reach local repeaters, makes VHF ideal for staying connected while on the road. Many hams use these radios for everything from checking in with local nets to communicating with other hams during commutes or road trips.
Building Your Own Antenna: A Simple Project
One of the great things about the 2-meter band is how easy it is to build your own antenna! Simple designs, like a “J-pole” or a “ground plane” antenna, can be constructed with readily available materials and provide excellent performance for local communications. This hands-on experience is a rewarding part of the amateur radio hobby.
Repeaters: Extending Your Reach and Building Community
Since VHF signals are largely line-of-sight, how do hams talk to each other across greater distances or over obstacles like buildings and hills? The answer is repeaters!
A repeater is essentially an automated relay station, usually located on a high vantage point like a mountain or a tall building. When you transmit to a repeater, you transmit on one frequency (the “input” frequency), and the repeater simultaneously re-transmits your signal on a different frequency (the “output” frequency). This allows your relatively low-power signal to be re-broadcast with much more power from a better location, extending your effective communication range significantly.
How Repeaters Work (and how to set up your radio):
- Two Frequencies: Repeaters always use two frequencies: one for you to transmit to the repeater (the input frequency) and one for the repeater to transmit to you (the output frequency).
- Offset: The difference between these two frequencies is called the “offset.” For most 2-meter repeaters, the offset is ±600 kHz. This means if the output frequency is 147.060 MHz, the input frequency will be 147.060 MHz + 0.600 MHz = 147.660 MHz.
- Tone (CTCSS/PL): Many repeaters also require a specific “tone” (often called a CTCSS or PL tone) to activate them. This helps prevent interference from other signals. You’ll configure this tone in your radio.
Configuring Your Radio for a Repeater:
You’ll typically enter the repeater’s output frequency, the correct offset (e.g., +600 kHz or -600 kHz), and the required tone into your radio’s memory channels. Once set, your radio automatically handles the transmit and receive frequencies when you select that repeater channel.
NFARL Repeaters: Your Local Hubs
The North Fulton Amateur Radio League maintains several repeaters to serve our local community. These repeaters are a fantastic resource for local communication, emergency preparedness, and staying connected with fellow hams.
- 145.470 MHz (Output) with a -600 kHz offset and 100 Hz tone
- 147.060 MHz (Output) with a +600 kHz offset and 100 Hz tone
- 444.475 MHz (Output) with a +5 MHz offset and 100 Hz tone (This is on the 70cm band, another popular VHF/UHF amateur band!)
Your VHF Journey Starts Here!
VHF is often the first band a new licensed radio operator explores, and for good reason! It’s fantastic for local communications, and the equipment is generally accessible. If you’re a new ham, the two most impactful things you can do to enhance your VHF experience are:
- Upgrade the antenna on your HT.
- Configure and learn to use your local repeaters.
We hope you’ve enjoyed learning about the exciting world of VHF radio! Feel free to ask our Station Captain, Robert Achtenberg (AJ4RJ@nfarl.org), any questions you may have.
