Category Archives: Portable

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

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

KX2/AX1: Second quick activation of the day at Lake James State Park!

As I mentioned in my previous field report, on Saturday, January 21, 2023, I had just enough time to activate two parks in short order on the way back to my QTH

I thought it might be fun to perform both of these activations with the Elecraft KX2 and AX1 combo because they’re so speedy to deploy.

Once again, I wanted to show the whole KX2/AX1 set-up and pack-up process in my activation video.

Lake James State Park (K-2739)

As I pulled into the Lake James Catawba River access, I discovered that there were few other guests there that day. I was expecting more people on a Saturday especially since the weather was so pleasant and South Mountains had been so busy earlier that morning.

Then again, the Catawba River access always has less visitors than the Paddy’s Creek area (which is really the main public access point for Lake James).

I pulled into a parking space, found one of the closest picnic tables, and set up the station in short order.

At South Mountains State Park, an hour earlier, I performed the entire activation on 20 meters. To shake things up a bit, I decided to perform the one at Lake James on 17 meters (note here that the AX1 only works on 20 and 17 meters unless you have the coil which adds 40 meters). Continue reading KX2/AX1: Second quick activation of the day at Lake James State Park!

ES80 padded cases on sale at Elecraft

Many thanks to Marshall (W4MKH) who writes:

Hi Thomas,

I thought you or your readers might like to know that Elecraft has a limited number of the ES80 cases on sale at half price. They have a slightly crooked logo but I doubt it will be noticeable when the case is stuffed full of gear.

I bought one for my IC-705 and USPS says it is out for delivery today (Wednesday). Just ordered it on Sunday.

https://elecraft.com/products/es80-i
73

Marshall (W4MKH)

Thank you for the tip, Marshall! You’ll have to share some pics with your gear loaded in the ES80!

Elecraft AX1 and AX2 packages with free shipping in February Specials

This month, I’ll be posting a number of field reports using the Elecraft AX1 on a wide variety of radios.

Serendipitously, Elecraft is offering up AX1 and AX2 package deals for February 2023. Many thanks to Mark (KM3P) for the tip!

The AX1 Package ($151.85 US) includes an:

  • AX1 Multi-Band Whip Antenna
  • AXB1 Whip BiPod
  • and AXT1 Tripod Adapter

Note that this does not include the 40M coil extension. That would need to be purchased separately.

The AX2 Package ($101.94 US) includes an:

  • AX2 Minature 20-Meter Whip Antenna
  • and AXB1 Whip BiPod for AX-Line Whips

Ironically–and a testament to my terrible timing–I purchased the equivalent of the AX2 package on Jan 30 (yes, two days before the Feb sale started) and I paid $130.51 shipped. I can confirm that $101.94 shipped is a great price!

I decided to purchase a second AX1 package yesterday, basically to have a dedicated AX1 system for my Elecraft KX2 field kit.

Click here to checkout the full February 2023 specials at Elecraft.com.

Note that Elecraft is not a sponsor of QRPer.com (though they really should be, shouldn’t they–? Please put in a good word for us!) and I have no affiliation with them other than buying, using, and evaluating their products.

Brian puts a new antenna to the test during Winter Field Day!

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


A shelter for Winter Field Day operations in a field

Field Report:  Winter Field Day with a New Antenna

Winter Field Day (WFD) 2022 found me operating indoors, despite my best intentions to get out in the field.  I was recovering from a bad cold, and did not want to risk having complications arise from sitting out in the cold and damp.  So for WFD 2023, outdoor time with my radio was a must.  I wanted to operate a 1-Oscar station, and to do that I had to set up more than 500 feet from my home QTH.  So a site next to the pond in our back field, about 800 feet from the house, became my WFD shack.

I started planning and collecting kit for the operation in mid-January, with the long term forecast hinting at near-freezing temperatures with the potential for rain or snow.  Let me introduce you to my WFD station.

Shelter

A shelter was needed to keep out rain and snow, and to provide a barrier against the winds whipping across the adjacent field.  A few poles lashed together, and steadied by stakes, provided the frame to support the shelter.  With a poly tarp secured to this frame, the resulting a-frame shelter, while not completely enclosed, did provide effective weather protection for both operator and equipment.  There was about 3 inches of snow on the ground when I set up the shelter, and I was able to pile some of it along the bottom edge of the tarp to keep the wind from getting under it.

A-frame shelter constructed of a poly tarp stretched over a frame of poles

Antenna

I know that when setting up a station, the antenna is not generally the first thought, but I had recently finished building a homebrew 9:1 random wire antenna with a 144 ft radiating wire, and I wanted to test it out.  There are better ways to put a new antenna on the air, but the opportunity was a good one.  Besides, I had backup antennas that could be quickly substituted if the need arose.  In the event, things worked well, and the antenna proved agile and capable on all activated bands.  I particularly wanted to see if it would tune on the 160m band.  More on that later.

The feedpoint of the 9:1 random wire antenna is built into a wire winder to support transport, deployment, and recovery for field use.  The RF functional components include a female BNC connector, a 9:1 unun, and miniature banana jacks for connecting the radiator and counterpoise wires.  There is no wire on the winder, because a corner was broken off during WFD deployment, and a mechanical repair is needed. (Click to enlarge)
The 9:1 unun is mounted near the BNC connector, and is electrically connected to a one miniature banana jack for the radiator and another for the counterpoise.  The unun and wiring are covered with hot melt glue to provide mechanical integrity and protection from the weather.

Radio

The goal of trying the antenna on 160m left me with only one choice for a radio.  I would use the Lab599 TX-500 Discovery, because it is the only transceiver among my field rigs that is capable of operating on the 160m band.  Since a tuner is required, I paired it with an LDG Z-11Pro II, a wide-range autotuner.  I also included a Monitor Sensors Power and SWR Meter in the feed line to help assure that I was legitimately running less than 5 watts to qualify for the QRP power multiplier. Continue reading Brian puts a new antenna to the test during Winter Field Day!

A quick two park KX2/AX1 POTA run starting at South Mountains State Park!

You might have noticed that I’ve been taking the Elecraft AX1 antenna out quite a lot recently. At time of posting, I’ve almost used it for a month’s worth of activations.

In December, I thought it might be fun to only use the AX1 for one 2023 calendar month–say, the month of March–but since I evaluate and review radios and antennas, it’s just not realistic to make that kind of commitment.

That said, I did decide to simply start using the AX1 as my primary field antenna for roughly a 30-ish day period and, so far, that’s working out very nicely. I thought it might give some real-world context and usage for those who still believe I’ve just been lucky the days I use the AX1 in the field. No better way to test that theory than to just do it!

Mini rove!

It’s been a while since I’ve had time to do a proper park rove. I hope to do a five park rove within the next month or so, if I can clear out space in the schedule. I find roves so much fun and a nice change of pace.

On Saturday, January 21, 2023, on the way back to my QTH in the mountains of WNC, I had just enough time to activate two parks in short order. Having just been challenged by a short activation window at the Vance Birthplace (which, turned into a normal length activation due to a schedule change in my favor) I thought it might be fun to once again, show the whole KX2/AX1 set-up and pack-up process in my activation video.

South Mountains State Park (K-2753)

I chose South Mountains State Park as my first stop.

South Mountains has a number of public access points. I decided to drive to the main park entrance and set up at the equestrian picnic area. Choosing the main park entrance added about 15 minutes to my overall driving time; the Clear Creek access would have been quicker, but I’d been there only recently. Continue reading A quick two park KX2/AX1 POTA run starting at South Mountains State Park!

Alan’s window-mounted Elecraft AX1 POTA activation!

Many thanks to Alan (W2AEW) who shares the following guest post:


New AX1 POTA Activation

by Alan (W2AEW)

I have to admit, I have been bitten “hard” by the POTA bug!  (I blame Thomas!) It started for me in August 2022 while I was on vacation at the Jersey shore.  Since that time, I have completed 48 activations at 19 different parks.  All of these have been QRP, and almost exclusively on CW. This story is about one of my recent activations, which was unique for a couple of reasons.  Read on…

The Park

My job puts me on the road, covering a large portion of the northeastern United States.  When my schedule permits, I’ll hit the road earlier than needed in order to potentially stop for a quick activation along the way (usually giving up a lunch-on-the-road stop in favor of a bit of QRP CW operation at a park).

This particular park was not your typical state park.  It wasn’t a nature preserve, or a mountain lake, or a hiking or picnic paradise.  No, this park is decidedly urban, occupying 2 blocks in the city of Holyoke, MA.  This is K-2439, Holyoke Heritage State Park. According to the state park website, this park celebrates the rich industrial heritage of the city of Holyoke.  The park also includes a Children’s Museum, a Volleyball Hall of Fame and a restored antique Merry-Go-Round.

The park is situated along a canal that once powered some of the mills that were located on the property.

It certainly is not like any other state park that I’ve been to!

One of the reasons I chose to stop at this park is that it had only been activated 4 times in the past.  In retrospect, I suppose this could’ve been because of the city/industrial setting.  Was it going to be noisy? Maybe this was a bad idea.. Thankfully, it wasn’t… Another thing that appealed to me is that it had not been activated on CW before.  So, my activation would be a CW ATNO (All Time New One) for this park, which is kind of cool.

A New Antenna

Largely due to Thomas extolling the virtues of the Elecraft AX1 compact vertical antenna, I “had to” purchase one for myself.  This activation would be its maiden deployment. Continue reading Alan’s window-mounted Elecraft AX1 POTA activation!

POTA Field Report: The Elecraft AX1’s secret power? Speed of deployment.

I believe I mentioned in the past that when I first purchased my Elecraft AX1, I assumed it would be a bit if a toy or novelty item. I thought it was a fun concept–and that’s why I bought it–but I remember the first time I took it out to the field on an activation, I thought I’d be demonstrating that a compromised antenna delivers compromised performance.

In short? I was wrong.

The AX1 has instead become one of the most valuable tools in my antenna arsenal.

When you are the DX–activating a park or summit–the AX1 is more than capable as long as you live in an area with a reasonable amount of hunters/chasers within your normal propagation footprint.

Speed

The AX1’s secret power, as I mention in the title, is speed of deployment.

Although I can launch a line into a tree and deploy an end-fed half-wave pretty quickly–I’ve literally done this hundreds of times–I can deploy the AX1 even more quickly without breaking a sweat.

Case in Point: Zebulon B. Vance Birthplace (K-6856)

On Tuesday, January 17, 2023, I had a day full of errands and projects in town, but needed to pick up my daughters at a school function around 15:00 local. There were too many variables to accurately predict where I would be at what time, so I didn’t schedule an activation that morning.

As the day progressed, though, I realized I had a very short window and K-6856 was practically en route to the pickup point. After I finished my last errand in south Asheville, I made my way north and based on Google Maps, I had no more than a 25 minute window to fit in a full activation from deployment to pack up.

I stopped in a parking lot en route, pulled out my iPhone, and scheduled an activation at K-6856 on POTA.app.

Keep in mind that my activations are typically short, but 25 minutes for set-up, on-the-air time, and pack-up leaves very little margin for error.

The AX1 is perfect for this type of activation.

A little time math

It takes me two easy minutes to set up the AX1 and maybe one minute to pack it up.  If I wanted to, I could speed that up a bit (I take much longer on camera talking my way through the process). So that’s roughly three minutes to both deploy and pack-up the AX1.

My speaker wire antenna, on the other hand, is also very quick to deploy. With my arborist throw line, I can easily prepare that antenna in four minutes and pack it up in three minutes. Thus, I need to allow roughly 7 minutes to both deploy and pack-up the speaker wire antenna (we have to assume it might take 2 launches of the throw line to snag a branch).

Since it has a built-in ATU and battery the Elecraft KX2 takes maybe 20 seconds to set up. Seriously: pull it out of the pack, connect a key, turn it on. Continue reading POTA Field Report: The Elecraft AX1’s secret power? Speed of deployment.

Michael builds a Pacific Antenna Mini SWR Indicator for his Penntek TR-35 field kit

Many thanks to Michael (N7CCD) who writes:

Hi Thomas!

I just watched your last activation video (very fun by the way!) using the TR-35 and thought I’d share really quickly my solution to the lack of an SWR indicator.

It was a cheap (and fun) $5 for the kit, build project I did with my brother, N7BHP, while visiting him in Mexico. It was actually the first little precursor project to building the TR-35 while on that same trip.

We picked up three (one for me and two for my brother) Pacific Antenna Mini SWR Indicator kits, and some cheap cases off of Amazon that just fit the meter. Of course, we had to add the BNC connectors also.

The kit is a 50ohm dummy load, and the LED lights up if the SWR is above 2:1. I’ve actually used this to tune my AlexLoop with the TR-35. When the light goes out, you’ve hit 1:1. I’ve found the LED on this kit to be more sensitive than the AlexTune light on the antenna.

I modified my kit to eliminate the switch. The way they have you build it is to leave it inline with your antenna, and just flip the switch from ‘forward’ to ‘reverse’. To save space and fit into the little plastic case, we jumpered where the switch would be so it stays in the ‘engaged’ position. I then just put it in at the very beginning of my setup to ensure the SWR is good on my antenna, then take it out of the circuit completely when using the radio.

It’s small enough to just live with my TR-35 at all times.

Hope all is well!
Michael -N7CCD

I love this, Michael. I think I might have to build one as well. Looks like a fun, inexpensive build that’s actually quite practical! Thank you for sharing!

André’s All-Season Yaesu FT-891 Go-Box

Many thanks to André (PY2KGB/VE2ZDX) who writes:


Hi Thomas!

I’m writing to share my idea for a cheap and easy to build go box. It’s not for a QRP rig, but the concept can be applied for the ft818, for example. Check out this YouTube video:

I’ve been operating under snow with this box, in “ninja” style.

Because if I wait for it to stop snowing here I’ll do nothing for 3 months, hehe!

Photos:

Continue reading André’s All-Season Yaesu FT-891 Go-Box