Author Archive

Yagi-Uda the III.

No, this is not the name of another royal baby… it’s about my third attempt to build a 2m antenna for my SOTA activations. In my earlier iterations I was unable to strike the balance between size/weight and usability.

What happened so far:

Yagi - UltralightMy first attempt to build a Yagi-Uda antenna was based on a design by  Paul/KD5IVP. It worked, but had some crucial flaws for my endeavors. It was a 3-element antenna made out of piano wire and a carbon fiber arrow as a boom. Very small and  lightweight indeed but in high winds/gusts the elements were flapping like a seagull during take-off. It’s demise came on it’s second outing… the arrow broke in half while bushwhacking up a mountain and I lost some of the piano wires in the woods. To read more about it and to see it in action check out this post.

 

Yagi - TapemeasureI then moved on to a tape measure 3-element antenna based on a design by Joe/WB2HOL. It worked well and accompanied me on several activations –  even a few 14ers (Summits higher than 14’000 ft / 4267m). My main gripe with this antenna is that it is delicate to transport as well. The steel tape gets kinked easily since the antenna is strapped to the outside of my backpack. It’s rather easy to replace the director and reflector, but soldering the coax to the steel radiator is another story. It turned out that this design is also vulnerable to high winds and your arms start to feel the weight after a few minutes without support. You can see the antenna in action in this video, around 3:30 into the clip.

 

The one?
I continued my research for a suitable 2m Yagi-Uda which would fit my requirements:

  • Lightweight (but sturdy enough to withstand high winds)
  • Easy and save to transport
  • Easy to build (even for me)

I eventually stumbled onto IZ2UUF’s Website –  an Italian radio amateur who enjoys hiking and playing with radios as well. He designed an 4-element Yagi-Uda weighing only 80 grams (~2.9 ounces)!! All elements fit into the fiberglass boom (fishing rod) for easy transport with no matching network necessary. The description to build the antenna focused on the critical parts with excellent pictures to support the instructions.

Davide/IZ2UUF modeled the antenna with 4NEC2, a free antenna modeling software package. Since he shared his input file with me, I took the opportunity to download the free SW and to learn more about antenna modelling. After a few more e-mail exchanges with him I was convinced by his design and started to source all the parts.

The final productI did not have afiberglass fishing pole available and opted to use a plastic one I had lying around. Davide is using aluminum welding rods for his elements which I could not find at the desired length/diameter here in the US. I therefore ordered aluminum alloy 6061 rods instead (1/8″ x 6′ ) from a supplier in IL (for details see the resource section below). My build also differs in the connector (BNC instead SMA). All these changes resulted in a slightly heavier (194 g / 6.8 ounces) first version compared to Davide’s antenna. My boom alone is heavier than Davide’s complete antenna (96 g / 3.4 oz). However, I am planning to improve/reduce the weight in version two.

 

I had a chance to use the antenna over the week-end during the CO-14er event. All I can say so far is that it worked well and that the weight is not an issue at all… huge improvement to the tape-measure version.

 

 

Mount Evans 4339 m/14264 ft - WØ/FR-ØØ3

For more pictures, a weight comparison and resources head over to my blog.

73, Matt/KØMOS

On 40m at last… (Part I)

Using a Buddipole antenna (BP) for my SOTA activations leaves me high and dry when it comes to the 40 m band. I was never able to build an efficient BP for these frequencies and received many ‘complaints’ that I never activate on 40m, thereby leaving out the ‘local’ chasers. This is going to change now…

RG174 based double Bazzoka

Yesterday I received a package from my buddy and SOTA Mountain Goat Herbert/OE9HRV, containing a home brew double Bazooka for 7 MHz based on RG174 coax. Herbert is my go-to guy when it comes to antennas. On our joint SOTA activations in OE he always carries an  impressive assortment of home brew antennas to the summits, and due to this weight I  would NOT want to carry his backpack – seriously. To see some examples of his creations, check out his FLICKR stream and/or QRZ page.

I had not known about double Bazookas before being educated by Herbert. It’s an efficient and quiet single band antenna based on 50 ohm coax cable, with the shield split at the center and feed line attache to it.  It can be used in a flat top or inverted vee configuration – the latter more suitable for SOTA. To save on weight, Herbert made it out of RG174 with a BNC connector, and used a wire-winder to create a small and easy to manage package. The final antenna is around 310 g (~ 11 ounces) and about 25 cm x 8 cm (~ 9.5″ x 3″ ). With any luck you might hear me on 40m over the week-end.

For more pictures head over to my blog.

73, Matt/KØMOS

Solar Powered Ham Shack

Adding the panels

Finally everything fell in place… my shack is running on solar power only. An idea/project I have been pursuing for years but the circumstances were never perfect… until this July. Last fall, a hailstorm took care of the roof and I had to replace it. In July I was able to secure a large chunk of money from our City which is offering a (very) limited number of rebates for Photovoltaic (PV) installations. Together with the federal tax credits it will put the ROI within my life expectancy. Good enough for me.

PV: Panel Monitor

The complete system is a grid tied, 5.5 kW system – 22 panels organized in two arrays (one south and one west facing). Each panel has a microinverter to optimize production and to add some ‘intelligence’ to the system. Monitoring and trouble shooting is a breeze. I can literally see when a bird poops on a panel and degrades my production 🙂

Since my shack consists only of a Yaesu FT-817, I am using the excess energy in the rest of the house. It should produce over 100% of our typical electricity usage per year if everything goes according to plan – I guess time will tell.

Here a short clip of the installation:

Please add your questions and comments through Youtube.

 

 

Antenna Restrictions on Mt. Evans? The Conclusion

I finally received a letter from the Clark Creek Ranger District regarding my encounter on Mt. Evans (read the first part of the story if you are not familiar with it). It took me almost six weeks and several e-mails to get an official statement from the Ranger District. I guess an underfunded federal agency has more pressing issues to deal with.

The good news is that it was an over-eager FS employee who kicked me off the mountain.

The bad news is that, according to the letter, the Federal Code of Regulation [36 CFR 261.10(a)], which applies to communication equipment, is written with some built-in ambiguity and might be interpreted differently in other Forest Service units.

Official Response

Well, I will deal with another interpretation if and when I run into another issue. The Clear Creek Ranger District interpretation however makes sense to me – chapter closed!
I really appreciate the clarification.

Read the entire letter by clicking on the thumbnail to the right.

That’s my last post from Mt Evans but there are two more pictures I wanted to share. The first one was shot at the Summit Lake trail-head early in the morning. The trail starts on the right side of the picture, goes up the ridge to Mt. Spalding and over to Mt. Evans.

Panorama of the Mt. Evans Area

Mountain goat on Mt. Evans

The second picture is from a close encounter of the third kind… well, not quite but is was remarkable. This unflinching mountain goat approached me. The picture is shot with a 52mm lens, not a tele-photo lens. He came up to me at arms lengh… too close for my taste. I normally try to keep a save distance between wild animals and myself, but this guy was not shy at all. Since I had never heard about occurrences of rabies in mountain goats and since I received some goat combat lessons earlier in the year (courtesy of Rooster) on my trip to Mt. Herman, I took the chance to take some real close-up shots instead of retreating.

73, Matt/KØMOS

Antenna Restrictions on Mt. Evans?

I activated Mt. Evans for Summits on the Air (SOTA) on July 15th. I took the route from Summit Lake to the top early in the morning since thunderstorms were in the forecast for the afternoon. I had the peak to myself for almost half an hour which was unexpected, considering that there is a road all the way to the top. I setup my vertical Buddipole for 20m and started my activation – so far nothing out of the ordinary besides the bad band conditions due to the recent CME.

I was talking to ACØA in Kansas when I spotted a National Forest Ranger running up the path from the parking lot. I could not understand what he was saying since I was

distracted by my ongoing QSO and the lack of oxygen combined with his running up the mountain made his signal about a 22, with highly distorted audio.

He arrived at the summit breathless and stood next to me, courteous enough to let me finish my QSO (or just to catch his breath?). He then introduced himself and informed me that I have to take down the antenna immediately.

My first thoughts were that the antenna was considered some sort of a safety hazard for other visitors but NO. The reason is, he informed me, that you cannot build a structure on Nation Forest land without a permit. Sounds like a sensible rule to me…. who wants to see cabins etc. erected on public land everywhere. I argued that my antenna can hardly be considered a structure and my short survey among the few visitors on the summit (~10 people) came to the same conclusion – nobody considered my antenna a structure but he insisted. Furthermore he instructed me to drive to the Clear Creek Ranger District HQ in Idaho Springs to get a permit. Needless to say that I was not planning to make a ~60 mile round-trip to get a permit for my activities. I already had enough contacts for my Mt. Evans SOTA activation and the fact that I had planned another activation for later in the day I did not want to waste my time arguing and started to pack up. Luckily I had my tape-measure YAGI with me for my next activation and I was hoping it would pass the NOT BEING A STRUCTURE test by the National Forest (to make sure I did not ask).

I tried to follow up with the person in charge for the Clear Creek Ranger District… she is on vacation. Sure glad I did not drive all the way to Idaho Springs.

GOOGLing, I found Forest Rules You Need to Know, published by the Secretary of Agriculture. On page two, under the chapter OTHER PROHIBITED FACTS it indeed prohibits “Constructing, placing, or maintaining any kind of communication equipment without a special use authorization“. Again, that makes sense to me to avoid that every Tom, Dick and Harry sets up his own repeater on public land… it does however not make sense to me for a temporary, mobile/portable antenna as I was using.

It would certainly put a damper on SOTA activations and the upcoming 14er event. I am almost certain that on Field Day a lot of antennas go up on NF land.

I would be interested in your experience and/or opinion and I am planning to follow up with the Clear Creek Ranger District. Maybe I was just dealing with an overly eager Ranger? Stay tuned…

Matt/KØMOS


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  • Matt W1MST, Managing Editor