Weird antenna behavior – KB6NU’s Ham Radio Blog

Weird antenna behavior

november 1, 2014 by dan kb6nu leave a comment

Two years ago, I put up a 20m, end-fed half-wave antenna. It wasn’t a terrific performer, but it worked OK, and I was able to make contacts on 20m.

Basically, it’s a 33-ft. piece of wire connected to a matching network, made up of a toroid and a capacitor, as shown in the figure at below. The inductor is a toroidal inductor, and the capacitor is made from a length of RG-174 coax, as shown in the figure below.

A month or so ago, the antenna started acting funny. While transmitting, the power would fluctuate, not wildly, but noticeably. Thinking it might be the coax, I took my dummy load outside and connected it to the coax, but that checked out OK.

The next step was to check the matching unit. I had built the matching network in a waterproof box, or so I thought. When I opened the box, there was water inside it. Water had apparently gotten in around the screws holding the SO-239 to the box. I dried it out, replaced a rusty nut and bolt, and when I put it back together, sealed up the SO-239 with silicone.

That still didn’t do it, though. I was still getting the erratic behavior. Today, I practically rebuilt the entire antenna, aside from rewinding the toroid and making a new coax capacitor, but it’s still acting weird.

I guess my next step is to make a new capacitor. I suppose some water could have wicked up into the braid, compromising it. That seems kind of far-fetched though. At this point, I’m open to any other ideas you guys might have.

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via Weird antenna behavior – KB6NU’s Ham Radio Blog.


Dan is asking for your help in diagnosing the weird behavior in his end-fed half-wave antenna.  Somehow, his antenna is radiating fluctuating amounts of power, despite Dan’s efforts at replacing parts of the matching network and checking to see if his coaxial feedline was alright (it checked out fine).  The source of the problem could be a failed capacitor in his matching network, but I’m not certain of that. Perhaps the RG-174 coax he used in the capacitor has a short or some water “wicked up” inside the coax shield.  If you have a solution to Dan’s problem, drop him an e-mail.

For the latest Amateur Radio News and Events, please check out the blog sidebars. These news feeds are updated daily.

Aloha es 73 de Russ (KH6JRM).

Man was fixing ham radio tower before fatal fall – Leader-Telegram: Front Page

By Chris Vetter Chippewa Falls News Bureau

CHIPPEWA FALLS — James Linstedt was familiar with repairing ham radio towers, having worked on the structures that make receiving and sending signals possible for at least the past decade, authorities and people who knew him said.

But that experience didn’t prevent Linstedt, of Eau Claire, from falling about 95 feet to his death from a tower Tuesday in the town of Eagle Point, north of Chippewa Falls, authorities said. He was 59.

Linstedt was working on a 100-foot-tall tower at 8121 163rd St. when he fell.

Chippewa County Sheriff Jim Kowalczyk said Linstedt’s death is a sad reminder that people must use their safety equipment at all times.

“When we use it for years, we get a little lax about using the equipment,” Kowalczyk said. “It’s safety equipment for a reason. If he had used it, we wouldn’t be investigating an accidental death.”

Kowalczyk said it appears Linstedt used the over-the-shoulder harness while on the 100-foot-tall tower, but as he moved around and climbed, he may not have properly strapped himself in at all times while on the tower.

“He did strap in, but he moved 10 feet up,” Kowalczyk said. “Clearly, he was not safely strapped up.”

The Chippewa County sheriff’s office received a call at 6:08 p.m. Tuesday about Linstedt’s fall. The witness requested deputies and an ambulance be sent to the scene.

Vetter can be reached at 715-723-0303 or at

via Man was fixing ham radio tower before fatal fall – Leader-Telegram: Front Page.


A cautionary tale for all of us from the “Leader-Telegram” of Eau Claire, Wisconsin.  Comments from local police say it all, “he may not have properly strapped himself in at all times while on the tower.”  In my days in the commercial broadcast business, I climbed enough towers to last a lifetime.  I gave up that chore years ago, opting for safer and easier maintained antennas.  It’s just a matter of time before “your number is up.”

For the latest Amateur Radio News and Events, check out the blog sidebars.  These news feeds are updated daily.

Until next time,

Aloha es 73 de Russ (KH6JRM).

Ham Radio: Portable Antennas on Saddleworth Moor.

1st outing on the moor as an Intermediate licence holder, trying out a couple of different portable antennas.


Nice video from a new intermediate license holder in the UK.  He tries a variety of portable antennas on a brief trip to the moors.  Lots of valuable antenna dos and don’ts in this video.  Part of the fun in amateur radio is experimenting with antennas.  Each time we build an antenna, we learn something.  Good video.  Aloha de Russ (KH6JRM).

See on Scoop.itKH6JRM’s Amateur Radio Blog

An Arrow for the Quiver of Municipalities and Neighbors Opposing Amateur Radio Tower Antennas | Land Use and Zoning

RT @TonyVerwey: Have a neighbor applying for an outsized and excessive amateur radio tower antenna?


The antenna height issue rolls on.  Here’s a statement from a prominent law firm that is offering local governments a way of fighting amateur radio operators who “seek to install not just an antenna, but a tower antenna of 100 feet or more in height…this is cause for concern and frustration for municipalities and neighbors in higher density suburban settings.”  This law firm has found a way to use the limited FCC PRB-1 preemption rule against amateur radio operators, who erect “outsized and excessive antenna towers.”  The only people who will benefit from the continuing debate will be attorneys prosecuting amateur radio operators.  Despite some antenna tower victories in California and other states, amateur radio antennas are still the target of people who consider towers a nuisance and a detriment to local real estate values. Perhaps, it’s time to go into “stealth mode” and think of more creative ways to avoid HOAs and CC&Rs.  Aloha de Russ (KH6JRM).

See on Scoop.itKH6JRM’s Amateur Radio Blog

KH6JRM’s Amateur Radio Antenna Topics: Simple Ham Radio Antennas: Antenna Basics. Post #291

Basic Antenna Rules. (Simple Ham Radio Antennas: Antenna Basics. Post #291 #basicantennarules #dipoleantenna)


This post stemmed from an antenna discussion I had with Dean Manley (KH6B) this past Thursday over breakfast at a Hilo fast food restaurant.  Dean gave me an article from James R. Duffey (KK6MC/5) about “Some Rules of Thumb for Beginners” who want to design and construct their own antennas.  I found the article informative, often humorous, and extremely helpful in resolving some nagging antenna issues.  Aloha de Russ KH6JRM).

See on Scoop.itKH6JRM’s Amateur Radio Blog

From my Twitter feed: Antennas! – KB6NU’s Ham Radio Blog

Richard GW1JFV @gw1jfv. Mr Cebik (W4RNL sk) Top 5 backyard multi-band wire antennas via N8SDR… MW0IAN’s avatar Ian @MW0IAN The versatile endfed VK3YE …


Daniel Romanchik always has something interesting on his website. This time, Dan features three outstanding antenna designs for those amateurs who prefer to build their own antennas:


1.  L. B. Cebik’s (W4RNL…sk).  “Top 5 backyard multiband wire antennas.” (excellent article).

2.  The versatile end fed VK3YE.

3.  FMW magnetic loop antenna by M0AJJ.


Anyone of these design would make a good addition to your antenna “farm”.  Aloha de Russ (KH6JRM).

See on Scoop.itKH6JRM’s Amateur Radio Blog

Copasetic Flow: Standing Wave Ratio, or SWR, A Ham Radio Exam …

The amount of energy reflected is determined by how well the impedances of the antenna, the transmission line, and the transmitter match. The reflected rf energy can enter the transmitter and damage the final radio frequency …


A nice, compact review (with questions) of the standing wave ratio (SWR).  This brief guide will help aspiring amateur radio licensees understand the workings of SWR.  Hamilton Carter (KD0FNR) reviews SWR test questions and highlights  the correct choices.  A good, general review for those  taking the Technician Class Amateur Radio License.  Aloha de Russ (KH6JRM).

See on Scoop.itKH6JRM’s Amateur Radio Blog

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