The Dreaded Wall Wart


It seems that the ARRL has made it official ... well, maybe not, but at least Ed Hare, W1RFI has. In a recent interview on the HamRadioNow webcast, Hare said that he believed that switching-mode power supplies are a more common source of QRN than noisy power lines ... and I believe him. I have heard countless horror stories of amateurs having to go QRT for good (at least on HF) because of issues with neighbourhood switching supplies. It's one thing to be able to hunt these things down and remediate the problem within your own home but when it comes to the whole neighbourhood, it's an awfully large challenge. And it's not as if there's just the odd one around, here and there ... they are everywhere.

In Ed's own words:

 “The old days of those iron transformers are gone,” Hare said. “Every single one of these is a switcher. We’re also seeing noise from pulse-width control motors.” Hare said the big culprits are “little wall warts,” not switching supplies designed to power Amateur Radio gear. “Every TV you own has a built-in switcher, almost every device has a wall-wart, and a lot of these are imported, not necessarily meeting the FCC rules, so we’re seeing more reports involving those.”

I've never personally had a problem with a wall wart, other than a cheap charger for my I-Pad, but that's not to say I haven't run into switchers. The charger emitted a low-level hash that I could hear only on a very quiet 6m band, not much of a real problem considering that I could unplug it at any time. A couple of problems here in the neighbourhood were eventually traced to the poorly designed or faulty switchers inside some CFL bulbs. These were emitting signals via the powerlines and being picked up by my antennas almost two blocks away. This was a problem only on LF however, where the powerlines make pretty efficient antennas.

Hare went on to say that some of the new LED-type lightbulbs have proven to be noisy as well. Not hard to understand when each one has its own low voltage switching power supply. What is hard to understand is why these device are even allowed on the market without having to undergo some type of noise-testing for approval. Another 'growing' threat are the lights used by neighbourhood grow-ops, legal or otherwise.

Hare also indicated that the ARRL lab can work with manufacturers to correct problems but that they need to know specific model numbers and information about the problems you are experiencing with the device.

Apparently, according to Hare, many issues can be resolved without involving enforcement from the FCC, the last step, should issues not be resolved by other methods.

You may be able to help by sending the needed information to the ARRL Laboratory for this and other types of RFI. Both Ed Hare and ARRL EMC Specialist Mike Gruber, should be contacted if you can supply information or have an unresolved problem.

The excellent 11-minute interview (Episode 196 'W1RFI's Tall Tales from the ARRL Lab') can be watched here, with thanks to HamRadioNow TV and to Gary Pearce, KN4AQ of HamRadioNow.

Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

QRPTTF – 2015

It seems for me at least, that these event hardly ever go as I envision them. In my mind, I get onsite early, with plenty of time to set up, which goes like a hot knife through butter. I have plenty of time to spend on the air, and just make scads of QSOs, then break down and come home, tired but triumphant.

As Mr. Lennon wrote, "Life is what happens when you're busy making other plans."

I had planned to get to Washington Rock State Park around Noon. The park, which is on the first ridge of the Watchung (Wach Unc in Lene Lanape) moutnains, meets the  QRPTTF theme requirement for being a place somehow related to Native Americans. What actually happened was that my daughter was invited to a sleepover/birthday party, and I had to have her at her friend's house at 2:00 PM. So much for the early start.



Set up did go like the knife through hot butter, after I made it to the park. The new Joplin ARC antenna launcher got my antenna hoist line up over a 40 foot high tree branch on the first shot.  The EARCHI was up, literally in minutes.

I got on the air at about 1830 UTC and I spent about 15 minutes calling CQ QRP on 15 Meters with no takers.  I had a feeling that 15 Meters was going to be good today. It wasn't, at least for me. So I meandered over to 20 Meters and was answered by Craig N8KMY at 1855 for my first QRPTTF QSO.

It didn't start out as a QRPTTF QSO. He called me because in his words, he couldn't believe that I was QRP.  He is located in northern MI and told me that I was one of the loudest signals on the band for him. He repeatedly asked me to confirm that I was only running 5 Watts.

He was as loud to me as I was to him, so that's where the fun began.  First he lowered his power from 40 Watts to 20 Watts, when I told him there was no difference in his signal, he continued to lower his power down to 10 Watts, and then, eventually 5 Watts.  He was astounded when I told him (quite honestly) that there was no difference between his signal at 40 Watts or 5 Watts.  A new QRP convert? I certainly hope so! Craig seemed enthusiastic enough.

Getting him down to 5 Watts qualified as a QRPTTF contact. We had a nice ragchew for about 25 minutes. A bit longer than I had intended, but it's never a bad thing to promote QRP, and bring a new soul into the fold, right? So it was worth it.

Besides, as it turned out, the bands weren't exactly rip-roaring with QRPTTF activity. I ended up making only 8 QSOs. Six on 20 Meters and two on 40 Meters.



I worked, in addition to N8KMY, NK9G, WQ8RP, K7RE, K4UPG (Kelly, my fellow QRP Polar Bear - Grrrrrrrr), WB3T, KS8M and AA5TB.

What made the day, was when my fellow SPARC members, Marv K2VHW (my official QRPTTF 2015 photographer) and Drew W2OU came for a visit.  They kept me company in between QSOs and also stayed with me until I packed up for the return trip home. Around 5:00 PM, it started getting chilly again and QRPTTF signals were becoming about as scarce as hen's teeth. So only though I put in only 2 & 1/2 hours behind the key, I decided to call it an event and head home.

The important thing was that I had fun and enjoyed my time playing radio today. It feels like I don't get to do this anywhere near enough.

72 de Larry W2LJ
QRP - When you care to send the very least!

Larry Makoski, W2LJ, is a regular contributor to AmateurRadio.com and writes from New Jersey, USA. Contact him at [email protected].

Explaining Standing Waves

When we teach the Technician License Class, we provide a simple explanation of Standing Wave Ratio (SWR) that emphasizes the concept of impedance matching. An SWR of 1:1 is a perfect match; anything higher is less than perfect.

SWR is an important amateur radio concept, one that is not that easy to explain so I am always on the lookout for training materials. HamRadioNow just republished this video of excellent standing wave demonstration by Bill Hays, AE4QL. Bill actually goes well beyond just standing waves and shows some antenna and transmission line theory as well.

If you just want to learn about standing waves and basic antenna radiation, view the first 35 minutes. After that, it starts to get a little deep.

Grab a cup of your favorite beverage, settle in and get ready to learn from this video.

73, Bob K0NR

The post Explaining Standing Waves appeared first on The KØNR Radio Site.


Bob Witte, KØNR, is a regular contributor to AmateurRadio.com and writes from Colorado, USA. Contact him at [email protected].

Amateur Radio Weekly – Issue 58

The hidden FM radio inside your pocket, and why you can’t use it
You may not know it but most of today’s smartphones have FM radios inside of them. But the FM chip is not activated on two-thirds of devices. That’s because mobile makers have the FM capability switched off.
NPR

Google Shakeup & Amateur Radio Clubs
We take a quick look at how these changes may impact amateur radio websites, and how without action, some of our amateur radio club websites may be even harder to find after this change by Google.
Essex Ham

Rookie Roundup roundup
The South Plainfield Amateur Radio Club ran a station for the ARRL Rookie Roundup.
W2LJ

ITTY: Internet Teletype
With today’s streaming audio over the Internet, George, W7TTY has come up with a scheme that allows him to broadcast teletype news over the Internet 24 hours per day, 7 days per week.
rtty.com

Tinkering with the Credit Card Crystal Radio
All that is required is connecting the high-impedance earphone, earth/ground and aerial/antenna to the board. Since all of these components can be connected with the supplied alligator clip cables, getting it on the air took all of 20 seconds.
SWLing Post

ISS 2395 MHz Digital Amateur TV blank transmission test
Please monitor the 2395 MHz at 2.0 Ms/s frequency and tell everyone as soon as you observe it.
AMSAT UK

How to

Turning a wireless router into an SDR
OpenWRT is a special custom Linux based firmware designed to create a fully functional Linux system on a internet router by replacing the stock firmware. Since OpenWRT is Linux based, it is possible to install the RTL-SDR software and run it on the router itself.
rtl-sdr.com

Video

Ham Radio Mobile in 1984
The late Don Wallace, W6AM, was interviewed in 1984 by Wayne Overbeck, N6NB, for the PBS series, “Radio Collector.”
California Historical Radio Society

D-STAR and the Icom RS-MS1A Android App
Our latest video about D-STAR features Don Turner (G4TKR) who is being interviewed by Bob McCreadie (G0FGX) of TX Films.
Icom

Arduino comparison guide
Thinking about getting started with Arduino but not sure where to start? Look no further! We’ve put together this handy guide to help you pick the right microcontroller for your project.
SparkFun Electronics

Homebrew D-STAR repeater
YouTube


Amateur Radio Weekly is curated by Cale Mooth KK4HSX. Sign up free to receive ham radio's most relevant news, projects, technology and events by e-mail each week at http://www.hamweekly.com.

Amateur Radio Newsline Report 1962 April 24 2015

  • Australian ham radio floater balloon makes a trip around the world
  • FCC proposes new privacy rules for amateur radio operators past information
  • 2014 CQ World Wide SSB contest disqualifies some hams and warns others
  • Palmyra Atoll DX operation announced for early 2016
  • Barbados warns CBers and hams not to use excessive power
  • Possibly the greatest selfie is taken by a ham radio operator on the ISS

THIS WEEK'S NEWSCAST
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Audio 


Bill Pasternak, WA6ITF, is the co-founder and producer of Amateur Radio Newsline. Contact him at [email protected].

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