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Welcome to the chaotic, thrilling world of the HF pileup. When a rare station or a Parks On The Air (POTA) activator goes on the air, dozens or even hundreds of operators might try to make contact at the exact same time. Working a pileup is an art that takes time to master. Whether you are the one calling CQ from a park in Nebraska or the one hunting a rare DX station, success relies on rhythm, frequency management, and a deep understanding of human behavior.

Here is a proper look at how a pileup appears on a modern display, followed by a complete guide on how to survive it.

A “pileup” on shortwave amateur radio frequencies. The main station is at the low frequency, and stays put. The hunters spread out, above, and call on a single frequency somewhere in the calling window of frequencies (I.e., up five to ten).

Over my decades of working Morse code (CW on amateur radio), I have learned a few critical things about how to navigate the chaotic, thrilling world of the HF pileup. When a rare station or a Parks On The Air (POTA) activator goes on the air, dozens or even hundreds of operators might try to make contact at the exact same time. Working a pileup is an art that takes time to master. Whether you are the one calling CQ from a park in Nebraska or the one hunting a rare DX station, success relies on rhythm, frequency management, and a deep understanding of human behavior.

One of the most important strategies is to determine the operating style of the DX station, specifically discerning how that operator scans the pileup for the next station to work. With modern waterfall displays, that process is MUCH easier. As an example, I worked the Temotu DXpedition (H40RH) that had just started a few hours prior to my attempt. I broke through with only five calls into the pileup, and it took me a mere 60 seconds to call and get an answer. Of course, I first listened and watched the waterfall for about five minutes to get a hang of the operating style of H40RH. This was on 10 Meters where 28.026 MHz was the DX frequency. We callers spread out five to 15 kHz UP in frequency from the DX station because we never want to cover up the DX station with our own signals. Even with a long carrier of intentional interference visible on the waterfall, the visual aid of the SDR made the catch possible. Temotu was a new country for my DXCC, so I am incredibly pleased to have made the contact!

Here is a proper look at how a pileup appears on a modern display, followed by a complete guide on how to survive it.

When You Are the Hunted (The Activator)

When you are the station that everyone wants in their logbook, you are the conductor of the orchestra. If the pileup senses hesitation, chaos ensues. You must dictate the pace, for both CW and SSB operations.

Controlling the Pileup on CW

Establish a Predictable Rhythm: Your CQ, your exchange, and your QRZ should follow a strict pattern. Consistency allows hunters to time their calls perfectly. If you change your cadence, the pileup gets messy.

Run Split for Large Piles: If the pileup merges into a single continuous drone, go split immediately. You might send “UP 1” to tell callers to transmit one kilohertz above your listening frequency. This spreads the callers out. Send your “UP” frequently enough that the self-appointed pileup police do not take over your transmit frequency. I suggest sending “UP” after each successful logged contact (QSO).

Own the Partials: If you only pull “NW7” out of the noise, send “NW7?”. Do not send “QRZ?” immediately. Stick to that partial call until that specific station finishes the exchange. If they fade out, clearly send “QRZ?” to reset the pile.

Adjust Speed to Control Volume: A slight speed increase (bumping up 3 to 5 WPM) will naturally thin the pileup down to the more experienced operators. Dropping your speed will invite the newer operators back in.

Receiver Management: Back off your RF gain and use a wider filter than you might expect (around 400 to 500 Hz). A filter that is too narrow will cause you to miss the operators who are smartly calling slightly off-frequency.

Controlling the Pileup on SSB

Command with Your Voice: Speak clearly and maintain a steady, authoritative tone. Avoid shouting. Just like in CW, a predictable rhythm helps callers know exactly when to key their microphones.

Use Standard Phonetics: Stick strictly to the standard NATO phonetic alphabet (Alpha, Bravo, Charlie). Cute or custom phonetics confuse operators who do not speak English as their first language.

Acknowledge and Isolate: When multiple voices blur together, listen for the last phonetic letter you can understand. If you hear “Sierra,” say “The station ending in Sierra, go ahead.” Ignore everyone else until that station completes the contact.

My POTA / Portable HF station (a low-power, or, QRP, station).

When You Are the Hunter (The Chaser)

When you are trying to break through a massive wall of sound, raw output power is secondary to timing and sharp observation.

Breaking the Pileup on CW

Listen First, Key Second: Before touching the paddle, listen to three or four complete exchanges. If the activator is working split, figure out their pattern. Are they tuning from the bottom up? Top down? Find where they listened last, and place your transmit frequency just above it.

Use XIT (The Golden Rule): Never perfectly zero-beat the DX station if others are calling. To the activator, three zero-beat stations merge into a single tone. Use your Transmitter Incremental Tuning (XIT) to shift your transmit frequency by 30 to 50 Hz. This slight difference in pitch makes your signal pop out of the receiver passband.

Time the Tail-End: Wait for the massive wall of sound to begin fading, and send your call exactly as the main group finishes. A perfectly timed tail-end call lets your suffix ring out in the clear.

Send Once: When the DX sends “QRZ?”, send your callsign exactly once and listen. Sending your call multiple times just causes interference and slows down the entire operation.

Follow Instructions: If the DX sends “NW7?”, and that is not you, keep your hand off the key. Transmitting over the station they are trying to work only prolongs the pileup for everyone.

Breaking the Pileup on SSB

Study the Cadence: Just like with Morse code, listen to the activator to find the rhythm. Wait for the exact moment the activator stops speaking before you key up.

Drop Your Call and Wait: Say your full callsign once using standard phonetics, then unkey and listen. If you are tail-ending, you might just drop the last two letters of your callsign precisely as the noise floor drops.

Adjust Your Pitch: If you have equalization controls on your radio, boost the mid-to-high frequencies on your microphone audio. A slightly punchy and higher-pitched voice will cut through the bass-heavy rumble of a dozen other stations calling at once.

Working a pileup tests your patience and your ear. Whether you are tapping out Morse code or speaking into a microphone, the operator who listens more than they transmit almost always makes the contact first.

Propagation and the Pile-Up

As many of you know, I was the space weather and radio propagation columnist in CQ Amateur Radio Magazine from 2001 through its demise. I strongly advocate for all HF radio operators to understand the basics of radio wave propagation on shortwave frequencies. There are a lot of myths and frankly, horrific theories on how radio waves propagate.

Understanding how the ionosphere refracts radio waves is a crucial tactical advantage. The behavior of a pile-up changes dramatically based on the frequency band you choose and the current mood of our sun.

The Sun Dictates the Rules

The ionosphere is charged by solar radiation. When solar activity is high, higher frequencies become usable for long distances.

Solar Flux Index: The SFI is a great indicator of overall ionization. A higher SFI means better conditions for the higher HF bands. When the SFI climbs, bands like 15, 12, and 10 meters open up globally.

Geomagnetic Storms: Measured by the K-index, these storms can disrupt communications entirely. A high K-index often absorbs signals crossing the polar regions. This can suddenly mute a massive European pile-up for North American operators.

Fading: The ionosphere is always shifting. Signals will constantly rise and fall in strength, which is known as QSB. A smart chaser listens for the rhythm of this fade and throws their callsign into the pile-up exactly when the band peaks for their specific location.

How Bands Shape the Pile-Up

Every amateur radio band has its own personality. The pile-ups you encounter will reflect these differences perfectly.

10, 12, and 15 Meters: These high bands are daytime frequencies that thrive on high solar activity. When 10 meters opens up, signals can be astonishingly loud with very low atmospheric noise. Pile-ups here can ignite suddenly and stretch very wide across the frequency spectrum.

20 Meters: This is the traditional workhorse band for global communication. Pile-ups on 20 meters are massive, sustained, and densely packed. You will often compete with high-power stations and massive beam antennas on this frequency day or night.

40 and 80 Meters: These low bands come alive at night. They are heavily affected by atmospheric noise and static crashes. Breaking a pile-up here requires an exceptionally well-tuned ear and the ability to pull faint CW tones or muffled voices out of a very high noise floor.

The Skip Zone Effect

The propagation of radio waves.

One of the most confusing aspects of a pile-up for a new operator is the skip zone. Radio waves bounce off the ionosphere and return to earth far away, which means they skip right over the geographic areas in between. You might hear the DX station perfectly, but you might not hear the hundreds of other operators calling them because those callers are inside your skip zone. This phenomenon is exactly why you must rely on the DX station’s cadence rather than waiting to hear the pile-up clear.

While raw power is often cited as the key to breaking a pile-up, your antenna system plays a far more decisive role in your overall effectiveness. A directional antenna, like a Yagi or a hexbeam, not only focuses your transmitted energy directly toward the DX station but also actively rejects interfering signals from other directions. However, do not be discouraged if you are running a simple wire antenna. A well-placed dipole or end-fed half-wave can still break monumental pile-ups if you leverage good timing, exploit the skip zone, and listen closely to the DX operator. Ultimately, the best antenna in the world cannot compensate for poor operating habits.

Over to You

Working a pile-up is one of the most rewarding challenges in amateur radio. It tests your patience, refines your ear, and forces you to understand both the science of radio wave propagation and the psychology of your fellow operators. Every massive wall of sound is a puzzle waiting to be solved.

Now, I would love to hear from you. What was your most memorable pile-up experience? Do you have a specific tactic that consistently helps you break through the noise, or perhaps a frustrating moment that taught you a valuable lesson? Drop your stories and questions in the comments below, and let us keep the conversation going.

From my shack to yours, 73 de NW7US.

I started in the ham radio and shortwave listening hobby in 1972. By 1975, this was my first real receiver. It heard very well, and ignited my lifelong passion for radio.

The R-366/TRR-5 military receiver.

This old radio, the R-366/TRR-5, which is clearly identified on the faceplate in this picture of the military rig, had great ears. It was what I used to hone my Morse code copying skills and to get the hang of how amateur radio operators conducted communications with each other, with CW, AM, or SSB. I hope someday to own one once again.

The R-366

The R-366/TRR-5 is a significant piece of military history manufactured for the Navy Department Bureau of Ships by the Espey Manufacturing Company. Built during an era when the United States Navy required absolute reliability for ship to shore and ship to ship communications, the unit is a testament to the rugged industrial design of the mid-twentieth century. Often referred to as part of the TRR-5 receiving set, this equipment frequently incorporated high quality components and precision engineering including the gold standard Collins Radio Company designs of that period. These internal components were vital in providing the remarkable stability and selectivity needed to pull weak signals out of the dense electronic noise environment found on a crowded naval vessel. It did have heterodyne squeals on a select few frequencies, which any old tube receiver was prone to have, but those did not detract from the excellent capability of the radio.

The Service

For the sailors and radio operators serving aboard ships in the 1950s and 1960s these receivers were far more than just tools for duty. In the often cramped and isolated conditions of life at sea these radios served as a critical psychological anchor. Access to the bands meant hearing the familiar sounds of home or tuning into MARS stations where amateur radio operators facilitated phone patches that reconnected sailors with their families. This bridge to the outside world was essential for maintaining morale and supporting the mental health of military personnel who were otherwise cut off from the rhythms of civilian life for months at a time. Sitting in the radio shack and slowly tuning that large central dial while listening to the crackle of the ionosphere was a meditative escape from the constant hum of shipboard operations. Many ships would pipe ball games and news shows, or music programs, over the ships intercomms, providing health and morale to the personnel.

Operating the Radio

The tactile experience of operating this specific receiver remains vivid in my memory. The layout with its distinct knobs for selectivity phasing and BFO control was designed for the hands of a professional radio operator who needed to manipulate the signal in real time. It required a disciplined ear and a steady hand to copy Morse code through heavy atmospheric conditions but that struggle made every successful reception feel deeply rewarding. It taught me the patience and technical appreciation that have defined my amateur radio hobby for decades. Owning and using a piece of history like this represented a connection to the generations of operators who stood the watch before me.

Traveling the World…

With this historic military receiver, I discovered an entire world as a child in the mid 1970s. I spent countless nights in the quiet darkness of my room with only the warm orange and yellow glow from the vacuum tubes leaking out of the back and top grills and slots of the radio enclosure, as those hot tubes cast soft light on the ceiling and walls. That radio allowed me to travel the globe from my listening position often sitting cross-legged on the floor in front of this big rig. Those late night listening sessions, when I should have been sleeping, ignited a lifelong passion for understanding the vast and interconnected world of shortwave radio as well as medium-wave DXing. I heard International Shortwave Broadcast stations as well as AM broadcast stations from Europe, Asia, the South Pacific, the Atlantic regions, South America, Central America, and North America–all over the world! I listened to amateur radio operators on Morse code, SSB, and AM modes. Ships at sea, aircraft doing transoceanic flights, fishing vessels comms where fishing captains would chat with other boat captains, and even military communications were all at my fingertips on the dial of the radio as I listened to these exotic places by headphones. I even picked up a station from Peru, South America late one night, on the mediumwave broadcast band. That is how great that receiver could hear. Of course, I had a very excellent outdoor dipole antenna that was cut for 160 meters.

What Receiver Was Your First?

What was your first major receiver? Was it just a receiver, or was it a transceiver? When was that? What did you hear that captured your imagination? Do you still have that radio?
I hope to someday have this R-366/TRR-5, once again.

~ Happy DX!
NW7US

This livestream recording is from September 1, 2024 – the NW7US Radio Communications Channel Livestream.  We do this livestream every Sunday at 21:15 UTC.  Here is the link to the livestream from this past Sunday:

The livestream list is here:

https://www.youtube.com/@nw7us/streams

I hope to see you in our livestream live chat, during the next session on Sunday, at 21:15 UTC.  See you there!

From the RAIN HamCast episode #57, 2021-XII-25 (used with permission):

RAIN’s Hap Holly/KC9RP spoke with Tomas recently about Solar Cycle 25. This is the second and final excerpt from their discussion.

From the introduction to The RAIN HamCast, Episode #57:

In this episode, we continue our discussion with Tomas Hood/NW7US, the author of many writings about space weather and effects of solar activity the past 20-plus years.

(Part 1 of 2 can be found here: Episode #56, https://www.youtube.com/watch?v=HnuSOXhFELQ)

Tomas has been a short wave enthusiast since 1973, a ham operator since 1990, and is a United States Army Signal Corps veteran today. He launched the first civilian space weather propagation website, HFRadio.org, in the mid 90’s; HFradio later spawned SunSpotWatch.com; at press time Sunspotwatch.com is being revamped for the new Solar Cycle 25.

Tomas has contributed to the Space Weather Propagation column in CQ magazine for over 20 years, and for The Spectrum Monitor magazine since 2014. A product of the Pacific northwest, Tomas resides now in Fayetteville, Ohio.

RAIN’s Hap Holly/KC9RP spoke with Tomas recently about Solar Cycle 25. This is the second and final excerpt from their discussion.​

Here is the second part of the two-part interview:

If you missed part one of this conversation, you’ll find it as RAIN Hamcast #56 both on therainreport.com and on the RAIN Hamcast page on YouTube, as well as here: Episode #56, https://www.youtube.com/watch?v=HnuSOXhFELQ.

RAIN Hamcast #58 will post January 8, 2022. Hap Holly/KC9RP edits and produces this biweekly ham radio podcast. It is copyright 1985-2021 , RAIN, all rights reserved. RAIN programming is made available under a Creative Commons license ; you are encouraged to download, share, post and transmit the RAIN Hamcast in its entirety via Amateur Radio. Your support and feedback are welcome on therainreport.com. Thanks for YouTube Technical Assistance from Tom Shimizu/N9JDI. I’m Will Rogers/K5WLR bidding you very 73 and 44 from the Radio Amateur Information Network.

KEEP ON HAMMING!

Footnote: Yes, NW7US misspoke about the time it takes sunlight to travel from the Sun to the Earth. He meant that it takes sunlight and radio waves just over 8 minutes to make that trip…

It might not take as much antenna as you may think would be necessary to make two-way contacts on shortwave radio (as an amateur radio operator putting an HF transceiver on the air). However, often, makeshift antennae are effective enough to be viable–just look at all the contacts many amateur radio operators make with their low-power (QRP) rigs (transceivers) using short, helically-wound, mobile antenna sticks. If they can work magic with such inefficient antenna setups, surely your effort at an antenna would pay off to some degree. Right?

[embedyt] https://www.youtube.com/watch?v=-k5Su–ez2Y[/embedyt]

Of course, I want to make a proper dipole out of this example antenna. But, while I wait for the rest of the parts I need to complete this antenna project (pulleys and a ladder, and maybe a potato launcher), I’ve put this makeshift antenna on the air, with it just high enough so that I can enjoy some time on the shortwave bands.

With this antenna, I’ve made successful two-way voice and Morse code contacts (QSOs) with stations in Europe and across North America. I am able to tune it on the 60-, 40-, 30-, 20-, 15-, 17-, 12-, and 10-Meter bands. Reverse beacon detection picks up my Morse-code CW signals, especially on 40 meters (the band on which it is tuned physically).

The bottom line: just get something up in the air and start communicating. Improve things over time. You’ll have much fun that way.

73 de NW7US dit dit

In the 1990s while living in eastern Montana, I had the amazing experience of reuniting two soldiers that served in the Devil’s Brigade. They both trained near Helena, Montana.

One day, I was operating on the amateur radio shortwave Ten-Meter band, and a gentleman answered my, “CQ, CQ, CQ, this is N7PMS in Montana, Over”. I took notes of our conversation.

The next day, when again I called for any station to answer my call for a conversation, another fellow, from Canada, answered me. I learned something amazing: Both of these two men mentioned that, during World War Two, they both were in the same special forces unit, training near Helena, Montana.

One of these Veterans served in the Canadian Armed Forces, and the other in the American Armed Forces. Listen to my story, for the full details of this amazing experience I had as an amateur radio operator.

Jump to 3:22 if you wish to skip my introduction to the story, during which I give some background on when and so on:
https://youtu.be/YFMplHjxy6s?t=3m22s

This certainly was one of the most memorable moments in my amateur radio hobby experience! The joy of reuniting friends is good.

From https://en.wikipedia.org/wiki/First_Special_Service_Force:

The 1st Special Service Force (also called The Devil’s Brigade, The Black Devils, The Black Devils’ Brigade, and Freddie’s Freighters), was an elite American-Canadian commando unit in World War II, under command of the United States Fifth Army. The unit was organized in 1942 and trained at Fort William Henry Harrison near Helena, Montana in the United States. The Force served in the Aleutian Islands, and fought in Italy, and southern France before being disbanded in December 1944.

The modern American and Canadian special operations forces trace their heritage to this unit. In 2013, the United States Congress passed a bill to award the 1st Special Service Force the Congressional Gold Medal.

Thank you for watching, and sharing. Comments are welcome: do you have a memorable moment in your radio hobby experience on the air?

73 de NW7US

In this video, I expound on another point of view regarding the ARRL petition to the FCC. The petition requests an expansion of operating privileges of Technician-class operators in the USA. The ARRL believes that giving broader shortwave access, using digital communications, to Technicians, will better entice the Techs to upgrade to General or Amateur Extra. In this video, I discuss this a bit.

If you are wondering why I’ve made a few videos about this topic, when the topic has been the hot item on many forums already, I believe that the drama will not cease until well after the FCC makes a decision, because this is a relevant topic, and one that has a significant impact on the amateur radio community at large. It is not a trivial conversation about which type of coax is best suited for Arctic field activity.

After some replies came from various viewers, I clarify my point. I stand corrected.

I failed to mention that there are a limited few slices of VOICE (SSB) spectrum on HF that the petition seeks for the Tech licensee. The ARRL states, “ARRL has asked the FCC to expand HF privileges for Technician licensees to include limited phone privileges on 75, 40, and 15 meters, plus RTTY and digital mode privileges on 80, 40, 15, and 10 meters.”

More specifically, “ARRL proposes to provide Technician licensees, present and future, with phone privileges at 3.900 to 4.000 MHz, 7.225 to 7.300 MHz, and 21.350 to 21.450 MHz, plus RTTY and digital privileges in current Technician allocations on 80, 40, 15, and 10 meters. The ARRL petition points out the explosion in popularity of various digital modes over the past 2 decades. Under the ARRL plan, the maximum HF power level for Technician operators would remain at 200 W PEP. The few remaining Novice licensees would gain no new privileges under the League’s proposal.” Reference: http://www.arrl.org/news/arrl-requests-expanded-hf-privileges-for-technician-licensees

My point holds: give some reason to desire to upgrade to a higher class. Do this by granting HF operations on lower bands (lower in frequency than 10 Meters), with more than a CW-only privilege.

If a tech can only use CW on 80m, but doesn’t know CW, then it is likely she won’t ever try making contacts on 80m. Hence, no exposure to the magic of 80-meter DX. If, however, the Tech can dabble with digital or limited SSB, on 80m, then she gets a real, practical exposure to the magic, and may well upgrade. Why do you think a General, who has limits, would ever upgrade? What am I missing here?

The following video expands this idea:
[embedyt] https://www.youtube.com/watch?v=83I3EEQxfZA[/embedyt]

The truth is, I see a strong argument for just ONE license, permanent. Or a temporary entry-level training ticket, then the permanent. But, that would make us like some other countries. That can’t be good.

The original video to which this new video continues is here:
[embedyt]https://www.youtube.com/watch?v=BWSAvDWE3Js[/embedyt]

Some viewers are asking me why I am making a video while driving. They try to convince me that talking while driving is too distracting. My answer is here:
[embedyt]https://www.youtube.com/watch?v=pyNHKViyCGE[/embedyt]

73 de NW7US