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Welcome to the chaotic, thrilling world of the HF pileup. 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!

When You Are the Hunted (The Activator)

A Guide To Survive The Pileup

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

Senator Ted Cruz, in this pre-Memorial-Day message, thanks amateur (ham) radio volunteers who serve the public through emergency communications, readiness to meet public communications needs, and are ever-ready technical assets.

Senator Ted Cruz Highlights Amateur Radio Public Service (Memorial Weekend 2026)

Sen. Cruz highlights the role these amateur radio FCC-licensed volunteers have in providing essential communications when violent storms knock out communications in local and regional areas, when power is out, cellular communications limited or overwhelmed, and communications services are stressed beyond capacity. Senator Cruz notes that these ham radio operators step forward to provide first-response communications in many situations, and gives examples of such in recent years, such as the 2017 Hurricane Harvey emergency when the catastrophic flooding across Texas took so many lives, and ham radio was there providing critical emergency communications. This was again demonstrated in the horrible Camp Mystic floods. He emphasized that as the United States of America prepares for yet another Summer Season, ham radio volunteers are ready to step up and provide these essential amateur emergency communications services. His comments also reflect growing Congressional recognition of the value Amateur Radio Operators bring to communities across the country.

Senator Cruz is Chairman of the Senate Committee on Commerce, Science, and Transportation. His comments align with the ARRL’s ongoing efforts to strengthen and protect Amateur Radio’s role in emergency preparedness and public service communications. As a member of ARRL, I applaud the Senator’s acknowledgement of the service we amateur radio operators provide our communities.

I have been spending time reflecting on the history of our wonderful hobby, and this April 1946 issue of Radio News really grabbed my attention. It is such a fascinating time capsule because it highlights the exact moment when thousands of hams were finally allowed back on the air after the long, forced silence of World War II. During the war, the United States government issued a total moratorium on all amateur radio activity, fearing that transmissions could be used by enemy agents to relay information. For four and a half years, our equipment sat idle and our antennas were taken down.

Radio News, April 1946, Cover

This is Bill Shaw, W9UIG, in this photo. He was among the first back on the air, and his station setup was really something else for the time. He was running a capable 500-watt station with a 3-element beam antenna, which was quite a powerhouse back then. His receiver was the legendary Hammarlund HQ 120X, which was a dream for many operators, and it was prized for its stability and sensitivity. Because early receivers often struggled with noise and image rejection, he used an RME DB20 preselector. This unit sat between his antenna and the receiver to provide additional gain and help pull weak signals out of the background noise. He also used a Meissner Signal Shifter, which was essentially a variable frequency exciter that allowed him to shift his frequency to find an empty spot or avoid interference, rather than being stuck on one fixed crystal frequency.

I look at those glowing vacuum tubes in his equipment, and those on display on his desk, and it reminds me of why I love this craft so much… there is just something special about the warmth and the technical artistry of those older rigs, with all their high voltage requirements and intense heat. And of course, I could not help but notice the wall behind him absolutely covered in QSL cards from all over the world. That really is the heart of why we do this, is it not… that thrill of reaching out across the globe and collecting those cards as a badge of honor? He had cards from places like Australia, the United Kingdom, and New Zealand, which shows he was an active DXer who specialized in long distance communication. In 1946, there was no internet or satellite communication, so amateur radio was truly the only way for a private citizen to speak directly to someone on the other side of the planet. It really makes you appreciate the history behind the call signs we use today. Does anyone else get nostalgic looking at these old shack photos… I would love to hear your thoughts on these classic setups and the history of our craft!

Regarding the magazine: While the magazine, Radio News, had its roots as, Radio Amateur News, when Hugo Gernsback founded it in 1919, it quickly evolved into something much broader as the radio industry itself exploded. By the 1940s, Radio News was far more than just a ham radio publication, it was a comprehensive technology magazine that covered the entire spectrum of radio and emerging electronics.

During that era, these magazines played an absolutely massive role in the amateur radio hobby. They were essentially the internet, the local club meeting, and the technical manual all rolled into one. For the average ham, a monthly arrival of Radio News or its contemporaries like QST or CQ Amateur Radio Magazine, was an essential lifeline. Side note: I wrote the propagation column in CQ Amateur Radio Magazine (and in CQ VHF, Popular Communications Magazine, Monitoring Times, and The Spectrum Monitor). For CQ, I wrote every month from 2001 to its demise at the passing of its publisher, Dick Ross, K2MGA (sk).

These magazines provided the blueprints and technical schematics that allowed hams to build their own transmitters and receivers from scratch. Because commercial gear was expensive and often hard to come by, the homebrew culture was the backbone of the hobby. Magazines provided the detailed instructions for these projects, teaching a generation of radio enthusiasts how to solder, how to wind coils, and how to understand the complex circuitry of vacuum tubes.

Beyond the technical side, these magazines served as a vital community connector. In a time when the hobby was geographically isolated, they fostered a sense of belonging to an international fraternity. They published operating news, shared tips on DXing (long-distance communication), and established the behavioral expectations and operating standards that defined what it meant to be a true amateur. They taught us how to be gentlemanly, how to handle interference, and how to take pride in our operating technique.

For a young operator in the 1940s, these magazines were the doorway to the world. They documented the rapid technological shifts happening at the time, such as the transition from crystal control to VFOs, the introduction of television, and the post-war availability of surplus military equipment. They did not just tell you how to operate; they inspired you to learn more, to push your technical boundaries, and to see your shack as a part of a global, scientific endeavor. It is that spirit of constant learning and curiosity that kept us all coming back to our keys and microphones, decade after decade.

What other vintage radio publications do you remember fondly from those early days in the hobby?

Welcome to The Communicator

Amateur radio has always been a pursuit of contrasts—venerating the past while racing toward the future. This issue celebrates that duality from cover to cover.

We begin with history: Harry Melville Dowsett, the architect of practical radio, and the curious case of author Zane Grey’s on-air adventures in Tahiti. Then pivot sharply to the present—AI’s creeping influence, TETRA digital tech, California’s controversial Bill AB 1043 that may affect you, and a look at the ARRL’s struggle in the digital age. 

Our technical deep dives range from the IC-9700’s capabilities for digital modes to rebuilding the Icom IC-PW1 amplifier to building a vertical HF antenna without radials. For the space-minded, we track LEO satellites, pico balloons, and the mysterious Judica-Cordiglia recordings (fact or fallacy?). And don’t miss the Baker Street walkie-talkie heist or British Columbia’s 2026 QSO Party wrap-up,

Need something lighter? Check page 13's New You Can Lose, try using a bluetooth speaker IKEA-style, exploring POTACat, or enjoying a classic Spam fritter and mash recipe (yes, really).

Don't miss the run-up to the FIFA World Cup Special Event Stations and learn how to participate.

So power up, tune in, and turn the page—The Communicator has something for every communicator, now reaching 165+ countries.

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~ John VE7TI, Editor

Contents for this issue: 

Unpacking the FAA's Boeing 787 Transponder Directive

As SARC Communicator editor I read a lot of blogs, club websites and other sources of amateur radio news. This one particularly caught my eye.

The source

https://www.paddleyourownkanoo.com/2026/03/14/ham-radio-enthusiasts-land-u-s-airlines-with-8-million-bill-to-fix-faulty-equipment-on-boeing-787s/ 

The ‘click-bait’ headline:

Ham Radio Enthusiasts Land US Airlines With 8 Million Bill To Fix Faulty Equipment On Boeing 787s

Ham radio enthusiasts could be partly responsible for landing U.S. airlines with an $8 million bill to fix faulty equipment on Boeing 787 Dreamliner airplanes after it was discovered that simple radio signals can knock out a faulty transponder on the popular widebody plane used by American, United, and Alaska Airlines.

The issue came to light after the Federal Aviation Administration (FAA) reported “multiple instances of loss of transponder for airplanes entering airspace in the presence of CW interference.”

CW interference refers to continuous-wave radio signals like Morse code, military transmitters, and even amateur ham radio signals, which could interfere with the transponder on some Boeing 787s...

When I saw this story it didn’t seem to add up. After all, Amateurs have been sending CW for a century and there has never been an allegation such as this. Although my own and other readers’ feedback has resulted in an adjustment of the original deceptive headline, the underlying story deserved  further investigation.

The actual facts

When the FAA warns of "CW interference," hams think of Morse code. Aviation engineers think of something far more dangerous—a silent, invisible wall of noise that can blind a Dreamliner to oncoming traffic.

In the world of amateur radio, "CW" is a beloved mode—the rhythmic cadence of Morse code cutting through the static, a testament to communication's simplest form. But when the Federal Aviation Administration (FAA) uses the same two-letter abbreviation in an airworthiness directive, it is describing something far more insidious and utterly unrelated to the operator in the shack.

For an avionics engineer, "Continuous Wave (CW) interference" refers to a pure, unmodulated, single-frequency carrier signal that has no business being where it is. It is a rogue tone, a sustained note of radio energy that can overwhelm sensitive aircraft receivers. And according to a new Notice of Proposed Rulemaking (NPRM) from the FAA, this type of interference is posing a direct threat to the Boeing 787 Dreamliner's ability to see and be seen by other aircraft.

The proposed directive, https://www.federalregister.gov/documents/2025/06/13/2025-10759/airworthiness-directives-the-boeing-company-airplanes which would affect 150 U.S.-registered 787-8, -9, and -10 aircraft, mandates a costly hardware replacement to fix a vulnerability that could, quite literally, render an aircraft invisible in busy airspace. But what exactly is this interference, and why is a simple hardware swap estimated to cost U.S. operators nearly $8 million?

The Problem: A Transponder That Won't Talk Back

At the heart of the issue is the 787's Integrated Surveillance System Processor Unit (ISSPU), a critical component that manages the aircraft's transponder. The transponder's job is to listen for interrogations from Air Traffic Control radar and other aircraft's Traffic Alert and Collision Avoidance Systems (TCAS) on 1030 MHz, and reply on 1090 MHz. Note that this is far from the usual HF frequencies that Amateurs normally operate at.

According to the FAA directive (Docket No. FAA-2025-0924), multiple reports have surfaced of 787s entering airspace with active "CW interference" and suffering a specific, dangerous failure: the transponder stops meeting its Minimum Operational Performance Standards (MOPS). Instead of correctly replying to at least 90% of interrogations, the unit becomes desensitized, failing to respond.

This is not a gradual degradation. It is an "unannunciated" loss, meaning the pilots receive no warning light, no aural alert, no indication that their aircraft is no longer replying to ground radar or TCAS inquiries. The first sign of trouble could be a gap in the sky where an airliner used to be, visible to everyone except the pilots of the aircraft that just went silent.

"CW" for the Layman: Not Morse Code, But a Wall of Noise

This is where clarification for the broader technical community is essential. For the amateur radio operator, "CW" (Continuous Wave) is synonymous with Morse code—a carrier wave that is turned on and off to form characters. It is intermittent, intentional, and communicative.

The "CW interference" cited by the FAA is something else entirely. In engineering terms, a "continuous wave" simply means a steady, unmodulated carrier signal. Think of it less as a conversation and more as a sustained, single-frequency tone—a pure, unbroken note of radio energy. If a pulsed radar signal is like a strobe light, CW interference is a laser pointer held steadily on a sensor, blinding it.

For a transponder receiver trying to pick out weak interrogation pulses from the sky, a powerful CW signal on or near its operating frequency (1030 or 1090 MHz) acts as a "jammer." It raises the noise floor, drowning out the very signals it needs to hear.

The Hunt for the Source: Who Is Generating This Noise?

The FAA directive is notably silent on the source of this interference, focusing instead on fixing the aircraft's vulnerability to it. So, who or what is generating these rogue continuous wave signals? The answer is complex and points to a crowded, modern radio spectrum. While the public document does not specify frequencies, the affected systems point squarely at the 1030/1090 MHz bands. Likely culprits for high-power CW interference in or near these frequencies include:

• Ground-Based Military and Civilian Radars: Some radar systems, particularly those used for long-range surveillance or specific military applications, can produce strong continuous or quasi-continuous output that generates harmonics or spurious emissions.
  
  
• High-Power Data Links: Terrestrial microwave data links, used for point-to-point communication by telecom companies and utilities, operate in frequency bands that can, with faulty equipment, generate out-of-band emissions that bleed into the aviation surveillance bands.
  
  
• The 5G Debate, Revisited: The recent spectrum battles between aviation and 5G carriers centered on the potential for signals from powerful ground-based transmitters to cause interference with radar altimeters. While that specific fight involved different frequencies (3.7-3.98 GHz), it perfectly illustrates the principle: a powerful, continuous transmission on a nearby frequency can overwhelm aircraft receivers if filtering and shielding are insufficient.

The $7.95 Million Fix

Because the sources of interference are myriad and largely outside an airframer's control, Boeing and the FAA have chosen to harden the aircraft itself. The proposed solution is not a software tweak, but a physical replacement of the vulnerable hardware.

While then issue is a worldwide problem, the directive would require US based operators to replace the left and right ISSPU units, swapping out current part numbers (822-2120-101 and -102) with a new, presumably better-shielded or more selective unit (part number 822-2120-113) . 

The FAA estimates the parts alone will cost $52,661 per aircraft. With labor, each of the 150 affected U.S. planes will incur a $53,001 expense, bringing the total for U.S. carriers to $7,950,150 .

This is a significant investment for a problem that many in the industry suspect is not going away. As the radio spectrum grows ever more congested with diverse signals, the threat of "CW interference"—in its true engineering sense—will only increase. For the pilots of the Dreamliner, this hardware upgrade can't come soon enough. For the amateur radio operator tuning up on 40 meters, rest assured: your key is not the culprit. The real threat is coming from elsewhere in the increasingly noisy radio spectrum we all share.

73,

~John VE7TI

Hello Radio Enthusiasts!

Inside this issue:

• Historical Deep Dives: From the electrical empire of Werner von Siemens to the high-stakes drama of the Alexanderson kidnapping, and a special event station commemoration of the Titanic disaster.
• Bench Projects: Learn how to make Homebrew PCBs with a 3D printer and copper tape, or peek at the elegant KD5ZZU Z-match tuner build.
• DX & Field Ops: Travel back to the 1994 Peter I Island DXpedition or get the latest on the North Fraser Club’s 925 MHz Balloon Project.
• Radio Secrets: Unlock the hidden "superpowers" of the Icom IC-7300, 7610 and 9700 and explore the "IPS Buffet" antenna mix-and-match review.

Download the Lower Resolution Issue - 6 Mb

Read it On-line as a Magazine

Please note that there are active links for additional content when viewed on your device.

~ John VE7TI, Editor

Contents for this issue: