Making QSOs with a Tiny Solar Panel

Last year I bought a 5 watt solar panel and a little rechargeable battery for $14. This week I made two QSOs a day for 8 days powered only by the solar panel in the window. I wanted to find out if I could really make QSOs with minimal power. I worked 9 states and 3 countries.

I used the (tr) uSDX at 4 watts. The antenna was a 136 ft OCF dipole. In the foreground is the little battery. It’s only 2500 mAh. To convert the 5 volts from the battery to 12 volts for the rig, I used a Baofeng charging dongle. Everyday after making a couple of QSOs, I’d put the panel in a window and charge up the battery.

Of course using QRP is essential. The rig draws 66 mAh on receive
and 570 mAh on transmit.

Here’s my log for the 8 days I conducted the experiment:

11 Mar-26 1507 14.060 W0ANM CW 569 559 MN
12 Mar-26 1405 7056 VE3KZE CW 579 579 ON
12 Mar-26 1407 7053 K0DOG CW 579 579 PA
13 Mar-26 1511 14.060 KA5TXN CW 339 559 TX
13 Mar-26 1921 14.027 DL8DYL CW 599 599 Germany
13 Mar-26 1923 14.0 HA3MAR CW 599 599 Hungary
14 Mar-26 1405 7054 KB3NSK CW 559 599 PA
14 Mar-26 1407 7052 K3EW CW 559 599 MD
15 Mar-26 1359 7052 K4TNE CW 449 579 NC
15 Mar-26 1406 7057 K3OP CW 529 559 PA
16 Mar-26 1611 14.044 K5OHY CW 539 559 TX
16 Mar-26 1614 14.057 AF8T CW 599 599 OH
17 Mar-26 1541 7051 WA1TOM CW 339 559 MA
17 Mar-26 1549 14.044 N4DH CW 339 549 NC
18 Mar-26 1550 14.058 KF8FCC CW 599 599 MI
18 Mar-26 1555 14.047 NS1C CW 449 559 FL

For many months, I’d been using the panel and the battery to power
my WSPR transmitter at 200 mw. I’d send out a beacon every morning
on 20 meters. I was heard all over the world. So I thought I’d try CW
with a little more power.

Tektronix 475 - The Beats Keep Coming

How to test?

The scope's fastest native setting is 10 ns/div (labeled as .01µs)

A single cycle of this signal (6.83 ns) will occupy roughly 0.68 divisions on the CRT, so less than one division, which may make it difficult to assess.  But if we engage the X10 Magnifier Switch we get an effective time division of 1 ns/div.  With the magnifier on, one full wave cycle will now stretch across 6.83 divisions (the little squares), creating a waveform that's relatively easy to measure.

I keyed the HT into a dummy load at its lowest power setting next to the oscilloscopes' probe and saw...

Note the time division at 0.1µs and the X10 magnification is pressed

 

I'd venture to say they don't make'em like they used to

Conclusions

Show Notes

Deep Dive Topic

• OpenHamClock
  • A real-time amateur radio dashboard for the modern operator.
  • OpenHamClock brings DX cluster spots, space weather, propagation predictions, POTA activations, SOTA activations, WWFF activations, WWBOTA activations, PSKReporter, satellite tracking, WSJT-X integration, direct rig control, and more into a single browser-based interface. Run it locally on a Raspberry Pi, on your desktop, or access it from anywhere via a cloud deployment.
  • 📝 License: MIT — See LICENSE
    • Installation Instructions - gotcha
    • Setup - .env, rigctld
    • Features - many
    • Thoughts - Getting through the setup was rough, payoff is pretty good.
  • Source: https://lhs.fyi/KZ (github)
  • Demo: https://lhs.fyi/L0 (openhamclock)

Related Topics

• DXChrono - https://lhs.fyi/L1 (Peter MM9SQL)

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  • Don, KB2YSI

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

AmateurLogic.TV Episode 215 is now available for download.

Cutting a 1/4 wave shorted stub. DR Mode travel prep for automatic repeater memories. ATS 20+ Firmware update improvements. Emile’s latest shack update.

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