Many new ham radio operators spend hours researching antennas and transceivers but give very little thought to the coax cable connecting them together. That can be an expensive mistake. Your feed line affects both transmit and receive performance, and the wrong cable can waste valuable RF power before it ever reaches your antenna.
The good news is that choosing the right coax isn’t as complicated as it first appears. The best cable depends on your operating bands, the length of your feed line, your power level, and whether you’re building an HF station, a VHF/UHF station, or both.
In this guide, I’ll explain how coaxial cable works, compare the most popular ham radio coax types—including RG-8X, RG-213, and LMR-400—and help you choose the right feed line for your station. I’ll also cover connectors, installation tips, weatherproofing, and common myths that continue to confuse many amateur radio operators.
In this guide, I’ll explain how coaxial cable works, why signal loss matters, and how to choose the right feed line for both HF and VHF/UHF stations. I’ll also cover connectors, installation tips, weatherproofing, and several common myths that continue to confuse new operators.
Basic Recommendation-
If you… | Recommended Coax |
|---|---|
Have an HF station under 50 ft | RG-8X or RG-213 |
Have an HF station over 100 ft | LMR-400 |
Operate 2 meters | RG-213, LMR-240, or LMR-400 |
Operate 70 cm | LMR-400 preferred |
Operate portable (POTA/SOTA) | RG-8X |
Need maximum performance | LMR-400 |
What Is Coaxial Cable?
Coaxial cable, usually called coax, is a specially designed transmission line that carries radio frequency (RF) energy between your transceiver and antenna. Unlike ordinary electrical wire, coax is engineered to contain the RF signal inside the cable while shielding it from outside electrical noise.
The name “coaxial” comes from its construction. The center conductor and the outer shield share the same axis, creating a balanced structure that provides predictable electrical characteristics and excellent shielding.
Although there are dozens of coax types available, most amateur radio feed lines share the same basic construction.
The Five Layers of Coax
A typical coax cable consists of five parts:
- A center conductor that carries the RF signal.
- A dielectric insulator that keeps the conductor centered.
- A metallic shield that provides the RF return path and blocks interference.
- An optional second shield for improved performance.
- An outer jacket that protects the cable from moisture, sunlight, and physical damage.
Each layer contributes to the cable’s overall performance. Better materials generally reduce signal loss, improve shielding, and increase durability, but they also increase cost.
Why Amateur Radio Uses 50-Ohm Coax
Most amateur radio equipment is designed around 50-ohm impedance, which provides an effective balance between power handling and signal loss. Radios, antenna tuners, SWR meters, dummy loads, and most antennas all expect a 50-ohm feed line.
You may also encounter 75-ohm cable, such as RG-6, which is commonly used for television and satellite installations. Although 75-ohm cable has lower attenuation than some 50-ohm cables, the impedance mismatch makes it less suitable for general transmitting applications unless a specific system is designed to use it.
For nearly every amateur radio installation, sticking with quality 50-ohm coax is the simplest and most reliable choice.
Understanding Coax Loss
No coaxial cable is perfect. Every foot of cable absorbs a small amount of RF energy before it reaches the antenna. This reduction in signal strength is called attenuation, or more commonly, feed line loss.
Several factors determine how much signal is lost.
Frequency Matters
The single biggest factor affecting coax loss is operating frequency.
On the HF bands, coax losses are usually modest, even with relatively inexpensive cable. Once you move into VHF and especially UHF, attenuation increases rapidly. A cable that performs well on 40 meters may waste a surprising amount of power on the 70-centimeter band.
For example, a 100-foot run of RG-8X may lose only a small percentage of your signal on 40 meters, but that same cable can lose several decibels at 440 MHz. In practical terms, that means noticeably less power reaches the antenna, and weak received signals become harder to hear.
This is one reason experienced VHF and UHF operators often invest in lower-loss cables such as LMR-400 or similar premium feed lines.
Cable Length Matters
Every additional foot of coax adds a little more attenuation. A 25-foot feed line may have negligible losses, while a 150-foot run can become a significant part of your station’s performance.
That doesn’t mean every station needs the shortest cable possible. Instead, the goal is to use only as much coax as necessary while avoiding unnecessary loops or excess cable coiled behind the operating desk.
If your antenna is only 40 feet away, there is little benefit in installing a 75-foot feed line simply because that’s what was available. Shorter runs almost always produce lower losses.
Not All Coax Is Equal
The size and construction of the cable also influence attenuation.
Larger coax generally has lower loss because its conductors have lower resistance and the dielectric materials are optimized for RF transmission. Premium cables often use foam dielectric materials and high-coverage shielding to further reduce losses.
The trade-off is that larger cables are heavier, less flexible, and more expensive. Choosing the best cable is therefore a balance between performance, installation requirements, and budget.
Typical Characteristics of Popular Coax Types
Cable Type | Flexibility | Relative Loss | Typical Use |
|---|---|---|---|
RG-58 | Excellent | High | Short portable runs, QRP, test leads |
RG-8X | Very Good | Moderate | HF base stations, portable operation, mobile installations |
RG-213 | Good | Low | Permanent HF stations, higher power operation |
LMR-240 | Good | Low | VHF/UHF base and mobile stations where flexibility is important |
LMR-400 | Fair | Very Low | Long base station runs, VHF, UHF, repeaters |
Rather than asking which coax is “best,” it’s more useful to ask which coax is best for your station. A modest HF station with a 40-foot feed line has different requirements than a VHF contest station feeding a tower-mounted antenna 100 feet away.
Choosing the Right Coax for HF Operation
One of the biggest mistakes I see new amateur radio operators make is assuming they need the biggest and most expensive coax they can afford. While premium feed lines certainly have their place, HF stations are generally much more forgiving than VHF and UHF installations.
On the HF bands, frequencies range from 1.8 MHz on 160 meters up to 30 MHz on the 10-meter band. At these frequencies, feed line losses are relatively low compared to VHF and UHF, especially when cable runs are kept to reasonable lengths. That means many operators can achieve excellent performance without investing in premium low-loss coax.
Instead of asking, “What’s the best coax?” it’s better to ask, “What is the most appropriate coax for my station?”
Short HF Feed Lines
If your antenna is only 30 to 50 feet from the shack, you have considerable flexibility.
For a typical 100-watt transceiver feeding a dipole, end-fed half-wave, or vertical antenna, cables such as RG-8X or RG-213 usually provide excellent performance. The signal loss over these relatively short distances is small enough that you’ll rarely notice any difference on the air.
For many home stations, spending significantly more on premium coax for a short feed line offers only marginal improvements. That money is often better invested in a higher antenna, better grounding, or an antenna analyzer.
Medium-Length Runs
As feed lines approach 75 to 100 feet, cable selection becomes more important.
Although HF losses are still modest, choosing a lower-loss cable begins to make sense, particularly if you spend a lot of time operating on 10 or 12 meters where attenuation is slightly higher than on the lower bands.
For many permanent home installations, RG-213 represents an excellent compromise. It offers lower attenuation than RG-8X, handles higher power comfortably, and has an excellent reputation for durability. If you’re installing coax once and expect it to remain in place for many years, it’s a cable that’s hard to criticize.
LMR-400 also becomes attractive at these lengths, especially if you expect your station to grow into VHF and UHF operation later. Although it costs more and is less flexible, its lower losses make it a worthwhile investment for operators planning a long-term station.
Long HF Feed Lines
Once feed lines exceed roughly 100 feet, attenuation becomes much more noticeable, even on HF.
If your antenna is at the far end of your property or mounted on a distant tower, using lower-loss coax can preserve more of your transmitted power while improving weak-signal reception.
For these installations, I would seriously consider cables such as LMR-400 or an equivalent low-loss feed line. The additional upfront cost is often justified because replacing buried or tower-mounted coax later can be far more expensive than choosing better cable from the beginning.
Portable Operations
Portable operating introduces a different set of priorities.
When activating parks, participating in Field Day, or operating from temporary locations, flexibility and weight become just as important as electrical performance. Carrying 100 feet of heavy coax through the woods quickly becomes tiresome.
RG-8X has become one of the most popular choices for portable HF operation because it strikes a good balance between performance, flexibility, and weight. It coils easily, packs well, and is durable enough for repeated deployment.
Some operators use even smaller cables to reduce pack weight further, particularly during Summits on the Air (SOTA) activations where every gram matters. While these lightweight cables introduce slightly higher losses, the convenience often outweighs the small performance penalty during portable operation.
Higher Power Operation
Most modern transceivers produce around 100 watts, and nearly all common amateur coax types can handle that power level without difficulty when properly installed.
If you plan to use a legal-limit amplifier, however, power handling becomes a more significant consideration. Larger cables such as RG-213 and LMR-400 generally dissipate heat more effectively and offer greater safety margins than smaller-diameter feed lines.
It’s also important to remember that connectors become part of the equation. Poorly installed or low-quality connectors can overheat long before the coax itself reaches its limits.
My HF Recommendations
For most amateur radio operators, I would recommend the following general guidelines:
Station Type | Recommended Coax |
|---|---|
Home HF station (under 50 ft) | RG-8X or RG-213 |
Home HF station (50–100 ft) | RG-213 or LMR-400 |
Long feed line (100+ ft) | LMR-400 or equivalent low-loss coax |
Portable / POTA / Field Day | RG-8X |
QRP portable | RG-8X or lightweight portable coax |
High-power HF station | RG-213, LMR-400, or equivalent |
These aren’t hard rules, and there are certainly other excellent cables available. However, for the majority of amateur stations, these recommendations provide an effective balance between cost, performance, durability, and ease of installation.
The key takeaway is that HF is relatively forgiving. Keeping feed lines reasonably short and selecting a quality cable appropriate for your installation will usually have a greater impact than chasing the lowest possible attenuation figures.
Choosing the Right Coax for VHF and UHF Operation
If HF is forgiving, VHF and UHF are not.
One of the biggest surprises for new operators is how quickly feed line losses increase as operating frequency rises. A coax cable that performs perfectly well on 40 meters can become a significant source of signal loss on 2 meters, and by the time you reach the 70-centimeter band, cable selection can have a noticeable impact on both transmit and receive performance.
This doesn’t mean every VHF station requires expensive coax, but it does mean that feed line choice deserves much more attention than it typically receives.
Why Loss Increases with Frequency
RF energy doesn’t travel through coax in exactly the same way at every frequency. As frequency increases, electrical losses within both the conductors and the dielectric material also increase. The result is higher attenuation over the same length of cable.
A simple example illustrates the point.
Imagine transmitting 50 watts into a 100-foot feed line. On an HF band, only a small percentage of that power may be lost before reaching the antenna. On 440 MHz, however, the same cable could waste a much larger portion of your transmitted signal as heat.
The reverse is equally important for receiving. Every decibel of feed line loss weakens incoming signals before they reach your receiver. If you’re trying to hear a distant repeater, work satellites, or copy weak simplex stations, excessive coax loss can make the difference between solid copy and no copy at all.
Feed Line Length Becomes More Important
Many VHF and UHF antennas are mounted much higher than HF antennas.
A vertical antenna may sit on a rooftop, a tower, or the top of a mast, which often means feed line lengths of 75 to 150 feet. Those additional feet increase attenuation, making cable selection even more critical.
If your antenna is only mounted on a short mast outside the shack, the difference between cable types may not be dramatic. Once you begin running 75 feet or more, however, lower-loss coax quickly becomes a worthwhile investment.
Comparing Common Coax Types
Several cable types are commonly used by amateur operators, each with its own strengths and weaknesses.
RG-58
RG-58 is inexpensive, lightweight, and very flexible, making it popular for short jumper cables and portable equipment.
For permanent VHF or UHF installations, however, it is rarely my first choice. Its relatively high attenuation means performance drops quickly as cable length increases.
I generally reserve RG-58 for:
- Short patch cables
- Test equipment
- Mobile jumpers
- Portable operations with very short feed lines
RG-8X
RG-8X is a noticeable improvement over RG-58 while remaining easy to handle.
Many operators successfully use RG-8X for mobile installations and shorter base station runs on 2 meters. If the antenna is only 25 to 40 feet away, it often performs very well.
Once feed lines become much longer, however, its higher attenuation begins to make lower-loss alternatives more attractive.
RG-213
RG-213 has been a favorite among amateur operators for decades.
It offers good durability, handles higher power comfortably, and provides lower losses than RG-8X. It is particularly well suited for operators who use both HF and VHF and want one versatile cable throughout the station.
Although newer low-loss cables outperform it at UHF frequencies, RG-213 remains an excellent all-around choice for many installations.
LMR-240
LMR-240 occupies an interesting middle ground.
It provides noticeably lower attenuation than RG-8X while remaining smaller and more flexible than LMR-400. This makes it an excellent option where routing larger cable would be difficult.
It’s particularly useful for:
- Mobile installations
- Short VHF base stations
- Scanner installations
- SDR receivers
LMR-400
If someone asked me to recommend one cable for a permanent VHF/UHF base station, LMR-400 would probably be my first suggestion.
Its low attenuation makes it especially attractive for longer feed lines, where preserving every decibel becomes increasingly important. Although it costs more than traditional coax and is less flexible, it is widely regarded as one of the best values for serious amateur radio installations.
For operators installing a rooftop antenna or tower that they expect to use for many years, LMR-400 is often money well spent.
Choosing Based on Your Station
Rather than focusing on a single “best” cable, consider how your station will actually be used.
For a mobile installation, flexibility is usually more important than achieving the absolute lowest attenuation. Feed lines are relatively short, so cables like RG-8X or LMR-240 often make excellent choices.
For a home base station with a rooftop antenna 30 or 40 feet away, RG-213 or LMR-240 provides a good balance between performance and cost. If the budget allows, LMR-400 offers additional performance and room for future expansion.
For taller towers or long cable runs, I would strongly lean toward LMR-400 or another high-quality low-loss feed line. Replacing coax after it has been routed through conduit, secured to a tower, or buried underground is a job most operators only want to do once.
Typical Recommendations
Station Type | Recommended Coax |
|---|---|
Mobile 2-meter station | RG-8X or LMR-240 |
Home VHF base station | RG-213, LMR-240, or LMR-400 |
Home UHF base station | LMR-400 preferred |
Long tower installation | LMR-400 or equivalent low-loss coax |
SDR receiver | LMR-240 or LMR-400, depending on cable length |
Scanner installation | RG-8X for short runs, LMR-240 or LMR-400 for longer runs |
It’s worth remembering that receive performance matters just as much as transmit performance. Every decibel lost in the feed line weakens incoming signals before they ever reach your receiver. While you can always increase transmitter power within legal limits, there’s no amplifier that can recover signal strength lost in a poor-quality or excessively long feed line.
For that reason, investing in good coax is often one of the simplest and most cost-effective upgrades you can make to a VHF or UHF station.
Choosing the Right Connector
Even the best coax cable is only as good as the connectors attached to it. A poorly installed connector can introduce signal loss, create intermittent faults, allow moisture into the cable, and cause frustrating SWR problems that are difficult to diagnose.
Fortunately, choosing the right connector is much simpler than choosing the right coax. In most amateur stations, you’ll encounter only a handful of connector types, each designed for a particular purpose.
Choosing the Right Connector
The connector at each end of your coax cable is just as important as the cable itself. Even the highest-quality feed line can perform poorly if the connectors are incorrectly installed or poorly matched to the application.
Most amateur radio operators will encounter only four connector types on a regular basis. Each has its strengths, and choosing the right one depends largely on the equipment you’re connecting and the frequencies you use.
PL-259 and SO-239
The PL-259 plug and its matching SO-239 socket have been the standard connector for amateur radio for decades. If you’ve owned an HF transceiver, antenna tuner, SWR meter, or dummy load, you’ve almost certainly used them.
One reason they’re so popular is their ruggedness. They are relatively inexpensive, easy to install with the proper tools, and capable of handling the power levels used by most amateur stations.
Although the PL-259 works well on HF and 6 meters, opinions become more divided as frequencies increase. Many operators continue using them successfully on 2 meters and even 70 centimeters, especially for short cable runs. However, because they were not originally designed as a constant 50-ohm connector, they become less desirable for higher-frequency or precision applications.
For everyday HF operating, they remain an excellent choice.
Type N Connectors
If your station operates extensively on VHF or UHF, you’ll probably encounter Type N connectors.
Unlike the PL-259, the Type N connector is designed to maintain a consistent 50-ohm impedance throughout the connection. This results in lower losses and better performance at higher frequencies.
Another advantage is weather resistance. Many Type N connectors include gaskets that provide a much better seal against moisture, making them popular for antennas, repeaters, and permanent outdoor installations.
If I were installing a new VHF or UHF antenna today, particularly one on a tower, I’d choose Type N connectors whenever the equipment supports them.
BNC Connectors
BNC connectors are common on handheld radios, test equipment, scanners, and many SDR receivers.
Their biggest advantage is convenience. The bayonet locking mechanism allows them to be connected and disconnected quickly without tools, making them ideal for equipment that’s frequently moved or reconfigured.
While BNC connectors perform very well at VHF and UHF frequencies, they are generally intended for lower-power applications. You won’t often find them on high-power HF amplifiers or large base station antennas.
SMA Connectors
Modern handheld transceivers and many SDR devices use SMA connectors because they’re compact and perform well at higher frequencies.
The downside is that they are relatively delicate. Repeatedly attaching heavy coax directly to an SMA connector can place considerable stress on the radio.
For handheld radios, I prefer using a short flexible adapter rather than allowing the weight of a larger coax cable to hang directly from the connector. It’s an inexpensive way to reduce strain and potentially extend the life of the radio.
Installing Connectors Properly
Many coax problems can be traced to connector installation rather than the cable itself.
A connector may look perfectly acceptable from the outside while hiding poor solder joints, loose braid connections, or tiny strands of shielding that create intermittent shorts.
When installing connectors, take your time and follow the manufacturer’s instructions carefully.
A few good practices include:
- Use a quality coax stripping tool whenever possible.
- Trim the dielectric cleanly without nicking the center conductor.
- Ensure the braid makes good electrical contact.
- Avoid overheating the dielectric while soldering.
- Check for shorts with a multimeter before connecting the cable to your radio.
A few extra minutes during installation can save hours of troubleshooting later.
Weatherproofing Outdoor Connections
Water is one of the biggest enemies of coaxial cable.
Moisture entering through a connector can travel surprisingly far inside the cable. As it contaminates the dielectric and shield, attenuation increases and performance gradually deteriorates. In cold climates, repeated freeze-thaw cycles can make the problem even worse.
Whenever a coax connection is exposed to the weather, it should be properly sealed.
A common approach is to wrap the connector with self-amalgamating (self-fusing) rubber tape, stretching it as it’s applied so it bonds into a continuous waterproof layer. A layer of high-quality UV-resistant electrical tape over the rubber tape helps protect it from sunlight and mechanical damage.
Heat-shrink tubing can also provide additional protection, although it shouldn’t be relied upon as the only waterproofing method for exposed outdoor connections.
It’s worth inspecting outdoor connectors every year or two. Replacing a few dollars’ worth of sealing tape is far easier than replacing an entire feed line damaged by water intrusion.
Installing Coax Correctly
How the cable is routed is almost as important as the cable itself.
Avoid pulling coax around sharp corners or bending it tighter than the manufacturer’s recommended minimum bend radius. Tight bends can deform the dielectric and alter the cable’s electrical characteristics, increasing losses and, in severe cases, causing permanent damage.
Support long vertical runs so the connectors are not carrying the cable’s weight. On towers or masts, use UV-resistant cable ties or purpose-made clamps rather than relying on electrical tape.
It’s also good practice to keep coax separated from household AC wiring whenever possible. While quality coax provides excellent shielding, avoiding long parallel runs with power cables helps reduce the possibility of unwanted noise coupling into your station.
If the cable enters the shack from outdoors, install a proper feed-through panel or entry point that allows the coax to be grounded and sealed against the weather. A drip loop just before the cable enters the building will encourage rainwater to fall away from the entry point instead of following the cable indoors.
Finally, avoid leaving large coils of excess coax behind the operating desk. Purchase or make a feed line that’s close to the length you actually need. While a few extra feet won’t hurt anything, unnecessary loops create clutter and make future maintenance more difficult.
Common Coax Myths
If you’ve spent any time reading amateur radio forums or watching videos online, you’ve probably come across conflicting advice about coaxial cable. Some of these ideas have been repeated for decades, while others are based on misunderstandings of how transmission lines actually work.
Let’s separate a few common myths from reality.
Myth: Coax Must Be a Certain Length
One of the oldest myths in amateur radio is that your coax should always be a specific length, with 18 feet often mentioned as the “correct” choice.
For most amateur stations, this simply isn’t true.
A properly matched antenna system does not require the coax to be any magical length. If your antenna presents a good 50-ohm load, your radio doesn’t care whether the feed line is 18 feet, 37 feet, or 62 feet long.
So where did the myth come from?
Certain antenna systems, matching networks, and impedance transformers can make feed line length appear to improve SWR readings. In those cases, the coax is becoming part of the matching system rather than simply carrying RF to the antenna. While there are legitimate situations where transmission line length matters, they are the exception rather than the rule.
For most dipoles, verticals, beams, and commercially manufactured antennas, use the length needed to comfortably reach your radio without unnecessary excess.
Myth: Longer Coax Improves SWR
Another misconception is that adding extra coax can “fix” a poor SWR.
Sometimes changing the feed line length changes the SWR reading seen at the radio, but that doesn’t mean the antenna has suddenly become better. The underlying mismatch still exists.
Adding coax simply changes how that mismatch is transformed along the transmission line. The radio may see a different number, but the antenna has not become more efficient.
If your SWR is high, the correct solution is to identify and fix the cause. Common issues include an improperly tuned antenna, poor connections, damaged coax, or water intrusion.
Myth: Expensive Coax Always Performs Better
Premium coax certainly has advantages, but that doesn’t automatically mean it’s the best choice for every station.
Suppose you have a 35-foot feed line to an HF dipole operating on 40 and 80 meters. Replacing perfectly good RG-8X with expensive low-loss coax may produce only a tiny improvement that’s impossible to notice during normal operation.
Now imagine a 120-foot feed line feeding a 70-centimeter antenna. In that situation, upgrading to LMR-400 or a similar cable can make a measurable and worthwhile difference.
The best coax is the one that fits your installation. Spending more than necessary doesn’t always improve performance, but buying cable that’s too small for the application can certainly reduce it.
Myth: Thicker Coax Is Always Better
Larger-diameter coax generally has lower attenuation, but it also has disadvantages.
Heavy cables cost more, are harder to route through walls and conduit, require larger connectors, and place more strain on antenna mounts and equipment.
For portable operating, many hams intentionally choose smaller coax because flexibility and weight matter more than squeezing out every fraction of a decibel.
Choose the cable that matches your operating style rather than assuming bigger is always better.
Myth: All PL-259 Connectors Are the Same
Connector quality varies considerably.
A well-machined connector with quality plating and proper strain relief is far more likely to provide years of reliable service than a bargain connector made from thin materials with poor tolerances.
The difference becomes especially noticeable outdoors, where moisture, temperature changes, and corrosion quickly expose weaknesses in lower-quality connectors.
Considering how much your station depends on just a few connectors, it’s worth spending a little more for good-quality components.
Finally…
If someone asked me for one piece of advice about choosing coax, it would be this: buy for the station you have today, but keep one eye on the station you want tomorrow.
For a typical HF station with a reasonably short feed line, RG-8X or RG-213 will meet the needs of most operators without breaking the budget. Both have earned their reputation through decades of reliable service and remain excellent choices for everyday amateur radio.
If your primary interest is VHF or UHF, especially with longer cable runs to a rooftop or tower-mounted antenna, investing in lower-loss coax such as LMR-400 is money well spent. Every decibel you save in the feed line benefits both your transmitted signal and your ability to hear weak stations.
Regardless of which cable you choose, pay equal attention to the connectors, installation, and weatherproofing. A quality feed line that’s properly installed can provide reliable service for many years, while poor connectors or water intrusion can undo the benefits of even the best coax.
Finally, don’t get caught up chasing myths or marketing claims. Amateur radio is full of opinions, but the fundamentals remain the same. Use quality materials, keep feed lines only as long as necessary, install everything carefully, and match your cable to the frequencies you operate.
Do that, and your coax will quietly do its job—delivering as much of your signal as possible to the antenna and bringing weak signals back to your receiver with minimal loss. That’s exactly what a good feed line is supposed to do.
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