Activating on the Road:  Stealth Activating with the AX1 Antenna System

by Brian (K3ES)

As I prepared my radio gear to do Parks on the Air (POTA) activations across the states of the American West (Six Weeks and 7300 Miles:  Activating on the Road), I knew that I would need to operate in a wide variety of different park environments.  This need was primarily connected with differences in topography, vegetation, population, and regulatory environments.

A selection of wire antennas, a throw line kit, and some collapsible mast options would serve many of my needs well.  However, I also expected that our travel schedule might require me to activate quickly or unobtrusively, from less-optimal locations.  Since I do not have an HF rig or antenna system installed in my truck, any vehicle-based operations would need to use equipment from my portable POTA kit.

For these occasions, I intended to use either a wire antenna supported by a telescoping mast attached to back of the truck, or my diminutive Elecraft AX1 base-loaded vertical antenna system.  During the trip, I found that I could use the AX1 to complete rapid, and extremely stealthy, activations.

I had ordered the AX1 antenna system from Elecraft early in 2024, and took delivery in March.  I used it in a variety of configurations, gaining experience and confidence in its ability to make contacts (K3ES Travels: Ten Days of QRP with Compromised Antennas).

In early May, I also ordered an AM1-2 clamp-on antenna mount from ProAudio Engineering, and it had proved its versatility in deploying the AX1.  All of this equipment and more found its way into a Maxpedition Fatty pouch, to become part of the stealth antenna kit packed for our trip across the country.

I Wonder if this Will Work…

Badlands National Park (US-0005) was one of the most spectacular parks that we visited on our cross-country adventure.  I plan a future report with full coverage of the park and the activation, but the conditions in the park led me to make my first attempt at a truck-based activation.  Shade was almost non-existent, the sky was cloudless, the air temperature was over 90°F, and the ground was too hot for POTA Dog Molly’s paws.

We pulled into a parking space at a roadside overlook, so that Becky could take some pictures, and I decided to try for a quick activation from the truck.  After I set out a bowl of water in the back of the truck for Molly to drink, I pulled out my radio gear, and looked over my antenna options.  I could have put up a mast and used a wire antenna, but I did not want to block access for other visitors, so my thoughts turned to the AX1 system.

The small size of the parking lot made it important to keep my operating footprint within the confines of my own parking space, both to avoid inconveniencing others, and to minimize the risk of damage to my antenna components.  I decided to try attaching the AM1-2 clamp to the cylindrical base of my 2m/70cm mobile antenna, which is mounted on the front fender of the truck.  The AM1-2 clamped on securely, and provided firm support for the the AX1 coil and whip.  I also attached a counterpoise wire to the ground screw of the AM1-2, then tossed the wire under the truck to keep it on the ground, hidden, and out of the way.

That left two questions:  could I get the antenna to tune, and would it radiate well enough to get contacts?  I connected my feedline to the AX1, ran it in through the open driver’s window to the KX2, and quickly got answers to both questions:  yes and yes.

The KX2 tuned up immediately on the 20m band, and in 14 minutes, I was able to complete the activation, logging 11 contacts.

Results

In the course of the activation, I made contacts from MN to TX, and NJ to NM.  Signal reports ranged from a single 229 RST to 559 RSTs for most of the rest.  I was pleased enough with the antenna performance that I used this configuration six more times during the trip.  In all cases I was able to complete activations without inconveniencing (and generally without even being noticed by) other park visitors, despite crowded conditions.

Table:  AX1 Stealth Activations

Park	Park ID	State	QSOs	On Air Time	QSO Rate (#/min)
Badlands NP	US-0005	SD	11	00:14	0.79
Mount Rushmore NM	US-0786	SD	11	00:23	0.48
Mount Rushmore NM	US-0786	SD	49	01:05	0.75
Devils Tower NM	US-0920	WY	15	00:34	0.44
Yellowstone, NP	US-0070	WY	11	00:46	0.24*
Point Reyes NS	US-0651	CA	11	01:50	0.10**
Grand Canyon NP	US-0030	AZ	33	01:12	0.46

*  This activation was completed after a large RV pulled into the next parking space.  (See K3ES’ Unplanned activation of Yellowstone National Park.)

** Completing this activation required both park-to-park hunting and operating on three HF bands, to obtain a sufficient number of contacts.

During QRP CW POTA activations using wire antennas, I find that my fastest contact rate is about 1 QSO per minute.  This is not to say contacts cannot be made more quickly, but this is about my upper limit.  For a compromised antenna like the AX1, with its base-loaded 4 ft whip, to routinely pull in 0.4 to 0.8 contacts per minute was just fine with me.  In fact, the performance amazed me, because the whip was mounted parallel to the 2m/70cm antenna, with only about 2 inches of separation, and the counterpoise wire was largely covered by the truck.

With this configuration, I had only two challenging activations:  at Yellowstone National Park (K3ES’ Unplanned activation of Yellowstone National Park), a large Recreational Vehicle pulled into the parking space beside me, with its large, metal sidewall only about 3 ft from the AX1 whip; and at Point Reyes National Seashore, where propagation conditions were extremely difficult.

The difficulty at Point Reyes was unexpected, because the activation was completed during the Autumn 2024 Support Your Parks Event, when there are plenty of hunters on the air.  To complete the activation, I operated on all three immediately available bands (20m, 17m, and 15m), and I hunted park-to-park contacts from other activators.

Park-to-park hunting slowed my contact rate, but made it possible to succeed in the activation.  I do believe I could have completed the Point Reyes activation more easily and more quickly with a wire antenna.  I will confidently make use of this stealth AX1 antenna configuration again, when I need to operate from my truck with the smallest available footprint.

QSO Maps

Figures below have QSO maps from each of the AX1 stealth activations listed in the Table.  Click on the image to enlarge.

Gear

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• Elecraft KX2
• SideKX end-panels and cover for the KX2
• Bioenno 3 Ah LiFePO4 battery
• Elecraft AX1 antenna with 13 ft counterpoise
• ProAudio Engineering AM1-2 clamp-on antenna mount
• Maxpedition Fatty organizer pouch
• 15 ft RG316 feedline with BNC male connectors at each end
• Homebrew VK3IL-designed, pressure paddles
• Generic earbuds
• Rite in the Rain No. 946 notepads
• Pentel Twist-Erase mechanical pencil in 0.9mm
• US M7 Army Light Weight Service Mask pouch:  WWII vintage, canvas construction

Conclusion

The AX1 antenna performed above and beyond my expectations for completing truck-based stealth activations.

There were some circumstances where it took longer to complete an activation, but even so, performance was satisfactory.  Recognize that these activations were made near the peak of the solar cycle, with generally good propagation.  This time period was not affected by solar flares or significant solar storms.

The AX1 should not be your first choice for poor propagation conditions, and higher gain antennas may yield longer-distance contacts and better signal reports.  Nevertheless, the AX1, like any compromised antenna, is first and foremost, an antenna.  It performed better than expected, despite my using it in a sub-optimal configuration.  I needed and valued this stealth option.

I will note that my kit included the Elecraft AXE1 extension coil, with companion 33 ft counterpoise wire.  The extension coil permits the AX1 to be used on the 30m and 40m bands.  I have used this lower-band capability successfully in the past.  I did not use the AX1/AXE1 for the lower bands on this trip, because my high band activations were successful, and because the the longer counterpoise wire requires more space.