Tag Archives: Top Band

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N2YCH’s Top Band POTA Activation Field Report

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Many thanks to Conrad (N2YCH) who shares the following field report:

Top Band POTA Activation Field Report

By: Conrad Trautmann (N2YCH)

November 15, 2023

In February 2023, Brian, K3ES, wrote here on QRPer.com about designing and building his own QRP portable random wire antenna he called the VK160 to work on 160 meters to make parks on the air contacts. This was in order to achieve his goal of getting the James F. LaPorta N1CC award where activating on 10 bands at 10 parks is needed. It’s not as easy as it sounds. As an avid parks on the air activator myself wanting to try activating on 160 meters, I built my own antenna based on Brian’s design and used it to get my first contacts ever at a park on the “Top Band.”

The Antenna

Brian used a 9:1 unun that he built himself in his design. Rather than build my own from scratch, I took a short cut and bought a QRPGuys 40m-10m UnUnTenna to use as the starting point for my VK160. Even though it says 40m-10m, it works on 160 meters, as you’ll see.

With shipping, it cost $36.00. It comes with all of the parts you need to assemble the antenna except for the wire. The main thing I liked about the QRPguys design was that the circuit board also doubles as a wire winder, so it’s all self-contained.

I sourced the wire from Davis RF and ordered 200’ of “POLY STEALTH – 26 AWG, 19 0.22000 44.00 STRAND COPPER CLAD STEEL, BLACK PE JACKET.” It cost $50 including shipping. The polyethylene insulation prevents the wire from knotting up. I measured out 144’ for the radiator based on Brian’s design and used the remaining wire as the counterpoise.

The completed antenna

I did a back yard test once it was all assembled and it worked great. For $86, I had created my own VK160. I encourage you to read Brian’s detailed design/build report here.

The POTA Activation – November 14, 2023

Now that I had completed building and testing the antenna, the next challenge was how to actually put it to use at a park. 160 meters doesn’t really come to life until dusk or after dark. In Connecticut, most state parks close at dusk. The park rangers clear the parks to close them at the best time to activate the band. However, there is one park nearby my QTH, the Stuart B. McKinney National Wildlife Refuge, K-0228, that has an annex called the Great Meadows Unit in Stratford with a nice parking lot that is not gated and has no posted hours. I arrived and set up at sunset, around 4:30 pm ET and operated from 5 pm until 6 pm. It gets dark here early in the Northeast US in November.

Another challenge is how to manage and string up 144’ of wire. Brian suggested an inverted V over a tree branch in his write up. There were no trees nearby, so instead I used a Spiderbeam fiberglass pole secured to my Jeep to get the feed point up in the air about 25 feet. I used RG58 cable from the feed point to the radio.

Spiderbeam fiberglass pole supporting VK160

Finally, I used one of my $3.00 Home Depot electric fence posts to secure the far end to keep it tight and up in the air and set up the antenna as a sloper. I laid out the counterpoise on the ground under the sloping wire.

By the time I had all of this set up, it was getting dark. I connected my Elecraft KX3 to the other end of the RG58 cable and to my surprise and delight, I was already receiving stations.

My KX3 has a built-in ATU and one tap of that ATU button and it tuned to 1.0:1. I started the activation right at 5 pm local time and in about 15 minutes, I had six QSO’s on 160 meters.

The PSK Reporter map showed me being received by stations on the dark side of the gray line in the Northeast. It was pretty much what I expected for QRP power on the low frequency. Then, the next ten minutes things were quiet. It appeared I had gotten everyone who could hear me.

Since this is a random wire antenna, it should work on all bands so I decided to test it on 80 meters. Again, the KX3 tuned right up and I got six more QSO’s. I was surprised to see Del, N2NWK from Washington, DC pop up on JT Alert. I have a an alert set for stations calling CQ POTA. Del was also at a park. I called and he answered and we ended up with a park to park. Anyone who knows Del knows that when you hunt him, he’s usually activating at a two-fer, at least. When I checked my hunter log afterwards, I saw four parks listed from him (a four-fer?).

At this point in the activation, I had gotten the ten QSO’s that I needed to call the park activated. I thought, let me try the VK160 on 60 meters. I re-tuned the KX3 and got five more fast QSO’s. The antenna worked great.

Before I packed up, I decided that I really wanted at least ten contacts on 160 meters, which was my original goal. I went back to 160 meters, now close to an hour later than when I began the activation, and easily added five more new QSO’s to the log. Maybe propagation had changed the later/darker it got or some new hams were on the band who weren’t on earlier, but I was satisfied to have gotten more than 10 on the top band.

The Results

Here’s how I did. Green pins are QSO’s on 160 meters, blue pins are 80 meters and the pink ones are 60 meters (click image to enlarge).

Equipment List

Conclusion

The “Top Band” activation was a success! The VK160 worked flawlessly, thank you Brian, K3ES for posting your design and providing the inspiration to activate on 160 meters.

My POTA “My Stats” page now shows 11 digital QSOs on 160 meters that I didn’t have before. I love conquering new challenges and given the challenge of going mobile with an antenna that will actually work and tune up on that low of a frequency at a park that won’t make you leave at sunset, well… that was quite an accomplishment!

Thank you to the 22 hunters (11 on 160 meters) who helped make it a success, including my friend Del, N2NWK in Washington, DC.

Conrad, N2YCH and Del, N2NWK
Antennas, Articles, Guest Posts, How To, News, Portable, POTA, QRP

In Pursuit of the Top Band: Brian describes how he built and tested a field-portable 160 meter EFRW antenna

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Many thanks to Brian (K3ES) who shares the following guest post:

The VK160 Antenna packed on its Winder/Feedpoint for storage, transport, and deployment.

Building and Testing the VK160 Antenna

by Brian (K3ES)

The ability to set and achieve long- and short-term goals keeps me interested and active in the Parks on the Air (POTA) program.  Often these goals are associated with POTA awards.  Currently, I am working slowly to complete the activator version of the James F. LaPorta N1CC award, which requires an activator to make QSOs on 10 amateur bands from 10 different parks.  With my operating style, I have found it achievable to make QSOs on the 9 available HF bands (80m, 60m, 40m, 30m, 20m, 17m, 15m, 12m, and 10m), and this has become easier with the rising solar cycle.  I have completed QSOs on non-HF bands using 2m and 70cm simplex.  The other options to pick up 10th band QSOs include the 6m band and the 160m band.

I have found it difficult to make unscheduled POTA contacts on 2m and 70cm, and scheduled contacts can be difficult to arrange in parks that are remote from population centers.  I have built a 6m antenna, but contacts are seasonal (and for me very elusive).  So I started looking for a way to add 160m capability to my portable station.  Ultimately that resulted in homebrewing a new antenna that I now call the VK160, and here is its story.

Objective

I needed a field-deployable 160m antenna.  My operating style requires that the antenna system be both light and compact.  QRP power levels are sufficient for my purposes.  I am very comfortable deploying wire antennas in the Pennsylvania woods, and QRP wire antennas can be both light and compact.  I have found that end-fed antennas are simpler to deploy in the field, because they can be configured as an inverted V or as a sloper, using only one point of support.

An end-fed half wave (EFHW) antenna would be naturally resonant, but would need to be over 250 ft (76m) long.  A wire antenna of that length would be challenging to deploy, even in more open areas.  So, I decided to pursue a 9:1 unun-based end-fed “random wire” (EFRW) antenna.  In fact, I have two commercial EFRW antennas available, but have never been successful in tuning them for 160m using the ZM-2 tuner in my field kit.  So, I concluded (probably incorrectly, but more on that later) that I needed to build a 9:1 random wire antenna with a longer radiating element than the 71 ft wire built into my largest existing EFRW.  I also wanted to build this antenna myself, using available components, so that it would be both inexpensive and customized to my needs.

I broke the task into four parts:

First, I needed to build a 9:1 unun suitable for use at QRP power levels.  The 9:1 unun is an autotransformer that reduces antenna feedpoint impedance by a factor of 9, hopefully a level that a wide-range tuner can match to the 50 ohm transceiver impedance.

Second, I had to design and build mechanical elements of the antenna system, incorporating the electrical components needed for the feedpoint.

Third, I needed to select a suitable non-resonant wire length for the radiator.

Finally, I needed to deploy and test the finished antenna on the air.  If successful, testing would culminate in completing an on-air QSO with the antenna being driven at 5 watts or less.

Building the 9:1 Unun

While I have built successful 49:1 ununs as the basis for EFHW antennas, I had no experience building 9:1 ununs.  Accordingly, I started with the ARRL Antenna Book, then a web search.  VK6YSF’s excellent web page provided very detailed instructions for 9:1 unun construction. His 9:1 Unun design was based on a FT140-43 toroid wrapped with heavy gauge magnet wire, with design power rating around 100 watts.  My application was focused on 10 watts maximum, and I wanted a lighter-weight solution to the unun design.

Looking at the components I had available, I found FT50-43 toroids and 24 AWG magnet wire in my inventory.  I had used those during construction of successful 49:1 EFHW antennas.  The VK6YSF design, built with the smaller toroids and lighter magnet wire, seemed to be a good (and cheap) starting point.

The “50” portion of the FT50-43 toroid designation specifies its 0.50 inch (1.27 cm) outside diameter.  The “43” portion designates nickel/zinc composition that is suitable for high frequency inductive applications.

The next problem that presented itself was a problem with translating the winding technique to smaller wire and a smaller toroid.  Put simply, my fingers do not have the dexterity to wrap three parallel 24 AWG wires around a ½ inch OD toroid without getting them crossed, twisted, or worse.  So, why not twist the three conductors from the start, and wrap the toroid with “trifilar” windings?  It would be simple enough to identify the mating wire ends after wrapping, just with a set of continuity tests.  That would facilitate proper connection of the wires to yield the final auto-transformer configuration.

FT50-43 toroid with three-10 inch (25.4 cm) segments of 24 AWG enameled magnet wire staged for construction of the 9:1 unun.

I posed the “trifilar” winding question to my friends over on the QRPer.net discussion board.  Nobody identified a significant flaw with the proposed method, but neither did anyone have experience that would assure success.  So, I decided to use the “trifilar” winding technique to construct my 9:1 unun, with the full recognition that its success would be uncertain, and only proven by testing the finished product. Continue reading In Pursuit of the Top Band: Brian describes how he built and tested a field-portable 160 meter EFRW antenna →