Solar Powered RMS Gateway

Chris Mattia – W6AH

We setup a Solar Powered RMS Gateway special event station at the 2022 Baker2Vegas race. The project turned into a huge success in terms of lessons learned.

At the IBEX repeater site for the Medical Radio Network (MRN), WaveTalkers set up a solar powered, portable Radio Message Server (RMS) Gateway using VARA HF to pass Winlink messages via NVIS (80m, 40m) and Skywave (20m, 17m) traffic. The NVIS frequencies covered the entire race course and the Skywave frequencies encouraged global participation in the event. Stations were encouraged to send a Winlink Check-In form to the tactical call sign WAVETALKERS either directly through the portable gateway or via any other supported winlink message mode.

We approached the design of the gateway as if it were any other piece of critical infrastructure for the race. We had a primary and backup component for every aspect of the station and practiced swapping out gear to test the viability of our back up systems. For example, we reached out to Icom America who loaned us an IC 7300 transceiver to backup our primary HF station and an IC 9700 to back up our 2m station. Swapping radios, antennas, and other components proved fast and often only required minor configuration changes to the RMS gateway software.

The gateway was powered entirely by solar energy from the moment the gateway went on the air Wednesday evening until we struck the station Sunday morning. Solar energy was collected using a single 120W PowerFilm Solar panel the first day. With a solid first day of real world data, we then increased the power output of the station and added a 2m VARA FM gateway to the station. To handle this additional power load, we added a 2nd linked 120W solar panel to compensate for the additional power requirements.

By 4pm local time each day, the station’s 80Ah Bioenno Power LiFePO4 battery and backup 60Ah battery were fully charged. We would thus fold in the panels for a few hours to reduce the need of the solar charge controller to dissapate the extra energy as heat. Once a few Amp Hours of power had been pulled out of the battery, we would open the panels back up to be ready to catch the first rays of sunlight the next morning.

BuddiPole supplied us with a PowerMiniPLUS solar charge controller that managed primary battery charging using the power collected by the solar panels and handed that power off to a PowerPLUS which acted as a UPS with the backup battery and established the two power circuits we used to power all of the equipment. The IC 7300 was connected to the A Circuit on the PowerPLUS and the Alinco DR-135, and the BeeLink microPC was connected to the B Circuit. The 13 inch flat panel display was powered through one of the USB ports on the PowerPLUS.

The IC 7300 was placed in Emergency Mode which opened up the internal tuner to handle a wider range of SWR mismatching allowing us to operate safely without the need of an external tuner. This did limit our station to only 50W of power output, but with VARA HF, and the antennas we deployed, that was more than sufficient.

At the advice of the Winlink Development team, we used a short piece of RG-213 coax connected from the back of the IC 7300 to an MFJ 915 RF Isolator to cut down on any common mode current. We then had 2x 100 ft runs of RG-213 coax to allow us to easily rig and swap out multiple antennas. This flexibility proved to be critical when an unexpected wind storm suddenly blew in and we had to quickly drop the taller masts. Having the second run of coax, allowed us to quickly change back to the CHA TDL antenna and keep the station on the air even in heavy weather conditions.

For antennas we used 4 different antennas for the station. Upon arrival, late Wedneday evening, we deployed a Chameleon Tactical Delta Loop (CHA TDL) to quickly get the station on the air and operate across all 4 of our targeted HF bands. The TDL proved to be an ideal first choice due to the rapid deployment (less than 5 minutes to set up), and effective radiation pattern covering both NVIS and Skywave propagation. The TDL requires a tuner, which the internal tuner on the IC 7300 handled nicely and has limited power output in digital modes of 50W which corresponded to the Emergency Mode of the IC 7300. To establish baseline power requirements, we reduced the transmit power to 25W for the first night.

In the early morning hours of Thursday morning, we deployed our primary HF antennas. We began by setting up the main support structure of the 10m Mastwerks. The ground in Death Valley at our location was extremly rocky so to better anchor the guy system we deployed 5/8 inch by 18 inch long rebar spikes. To help get these into the ground, we used a cordless hammer drill with a 5/8 inch by 12 inches long masonry bit to drill into the desert floor. Once the rebar was pounded in, we capped each spike with a tennis ball for safety. All guylines were also flagged with orange surveyors tape to increase visibility and reduce trip hazards.

With the Mast secured, we constructed the BuddiHex which would be our primary skywave antenna for the 20m and 17m band. Construction of the BuddiHex took about 25 minutes to complete and we used the smaller 7m Mastwerks tripod with the Setup Stick installed to bring the BuddiHex down to a more managable working height for construction. With the coax attached to the 20m feedpoint, we lifted the 10 lb structure onto the 10m Mastwerks and began rigging a halyard to the mast.

A simple turning block was cable tied to Mast at a deployed height of approximately 20 ft. The halyard line was light weight dynema for strength with minimal stretch. Once the BuddiHex was raised to the final deployed height, the Chameleon EmComm III Portable that would serve as the station's primary NVIS antenna on the 80m and 40m and was attached to the halyard at the feedpoint and hoisted aloft to the full height of the halyard. The halyard was secured at the base of the tripod.

The counterpoise wire for the EmComm III Portable was lead back to the front of the RV and secured with light cordage to electrically isolate it from the vehicle. The active element was then lead down slope on a bearing of 110 degrees ensuring the entire race course would be broadside to the antenna. To secure the active element, the 7m Mastwerks was deployed and fully guyed as previously described. A short length of cordage was used secure the bitter end of the active element, again electrically isolating the antenna from the mast. Adjustments were made to reduce the sag in the active element in order to maintain an approximately 20 ft of elevation above ground for the entire length of the antenna.

Both antenas were connected with 100 ft lengths of RG-213 coax that was fed back to the station inside of the RV. Additional lengths of coax were left neatly coiled on the ground outside of the RV. The EmComm III Portable was then connected to the MFJ 915 UnUn and then connected to the IC 7300. At this point the station was fully deployed and our focus had to shift over to the deployment and testing of the MRN for the remainder of the day. Thus all day Thursday we operated on all HF bands using the EmComm III portable with a 14 second rotation cycle needed by the gateway to rotate through all 4 HF bands.

Thursday evening, we checked the power systemed and noted that we had generated approximately 37 Ah of power throughout the day using the single 120W PowerFilm Solar Panel. The PowerMiniPLUS indicated that our batteries were fully topped off and operating at FLOAT. The additional power from the solar panels was being dissapated as heat by the PowerMiniPLUS so to protech the equipment, we folded the panels up at approximately 1600 local time. The panels remained closed until about 1800 local time.

On Friday morning at 0900 local time, we swapped the coax over to the BuddiHex and changed the configuration of the gateway to only operate on 20m and 17m. We also increased the station transmit power to 50W and deployed the second 120W PowerFilm Solar Panel using the Daisy Chain wire assembly. Since the BuddiHex is resonant across all bands (6m, 10m, 12m, 15m, 17m, and 20m), we considered taking the IC 7300 out of Emergency Mode and allowing the station to run at an even higher output power level for the day. However, with the higher duty cycle of digital operation we decided to error on the side of caution and left the maximum power output at 50W and the radio remained in Emergency Mode.

Additionally, we deployed the 2m gateway as well. We had previously deployed the 12m Spiderbeam Fiberglass mast with a N9TAX roll up Slim Jim cut for 2m and 70cm. That antenna was fed back to the RV using a 75 ft run of RG-8X coax we had on-hand. Enabling the 2m gateway was simply a matter of ensuring the transciever was properly connected to the B circuit of the PowerPLUS and then launching the RMS Packet Software.

At this point we were operating as a full Hybrid Gateway. On the Software side, RMS Packet was handing the 2m traffic and was linked to RMS Relay. RMS Relay was thus connected to Tri-MODE which was handling the HF traffic. For an internet connection, the gateway was configured to Hold Mail when no internet connection was avilable. We were then able to periodically teather my FirstNet enabled iPhone to the system or once available, leverage the Verizon Crisis Response hotspot deployed for the MRN. This allowed us to test various connection scenarios and operate with a negligalbe impact on the race. Most of the time, we simply used my FirstNet connection for the gateway to communicate with other RMS Gateways.

We monitored the power production and use througout the day. With the linked 120W panels, we once again achived FLOAT of our batteries at around 1600 Local time and thus folded the panels up again. At that point, we had generated well over 80Ah of power with our solar array. This indicated that our solar array and batteries were properly sized for our deployment.

We had the capacity to swap our our 240W of linked solar pannels out for an even larger linked array capable of 480W of power generation using up to 8x 60W Light Weight Solar Panels by Bioenno Power and higher capacity MPPT Solar Charge Controllers, all wired in parallel using a custom wiring harness we created. That larager array should have once again doubled our solar production capacity. However, this proved to not be necessary so the larger solar array was split up in to 3 smaller arrays, with 4 panels deployed to one stage, a single panel deployed to a second stage, and another panel deployed to keep the MRN Ham Station charged throughout the day.

Having solar system with a flexible design proved to allow us to easily adapt to the changing conditions and needs for the station and the race. Ultimately, the 240W of solar capcity by the 2 PowerFilm Solar panels proved sufficient for our needs with the activity we were getting through the gateway. At 1700 local time we swapped the coax back to the EmComm III Portable, reprogrammed the gateway to resume operationg on all 4 HF bands and let it run for the night. The 80Ah and 60Ah battery bank by Bioenno Power easily handled the load over night and was once again fully recharged by the end of the next afternoon.

Saturday was race day, and aside from the normal 0900 antenna change back to the BuddiHex, the station operated with minimal interactions for much of the day. However, at approximately 1600 local time, a fresh breeze developed and was showing signs of continuing to build. After securing the antenna array for the MRN, we quickly made the decision to strike the two masts with our primary antennas. We needed additional hands to support the guys during the rapid drop of the 10m Mastwerks. Once at a safe heigh, we swapped the main coax for the EmComm III portable back over to the TDL and allowed the station to continue operating through the night.

Striking the BuddiHex and EmComm III Portable became a periodic task for much of the rest of the evening as we could spare a few minutes here and there. We also had to strike the 12m Spiderbeam and thus the 2m gateway was taken off the air for the night. The winds continued to build into a full gale, making visibility and working conditions in the blowing sand quite challenging. It took until late into the evening to get the entire site secured due to the heavy weather we were experiencing. Our focus constantly had to remain first and foremost on the MRN and the overall safety of the race. The gateway and all of the exposed equipment had to weather the wind storm on its own for hours at a time.

The winds howled all night with gusts well above 50 mph. The quick decision to strike the taller masts and antennas turned out to be the right choice. Even in the lee of the RV, it is unlikely either mast or antenna system would have survived the night. We did sustain significant damage to the overall IBEX site, but the crew was able to handle all of the issues with minimal impacts.

The Chameleon TDL proved to be an extremely resiliant and effective antenna system. By using the hammer drill with masonry bit trick to set the spike on the TDL in our initial deployment, the spike had just enough room to allow the TDL to freely turn enough to allow the antenna to naturally find its own orientation to the wind that offered the least resistance. This reminded me of a sailboat in the heavy weather of an angry sea, heave to and thus offering a relatively calm ride through the storm for her crew.

At dawn as the winds continued to rage, the TDL was happily bending in the breeze while still passing traffic across all 4 of our targed HF bands.

Solar Powered RMS Gateway: Equipment List

Many operators have asked for a complete list of the equipment we used for the project. Here you go! We have tried to be as complete as possible with this list of products we used for the project.

Power System:
Antenna System:
Gateway System:
Testing System:
Tools, Supplies, and Accessories:

This is a complete list of the gear we used for this project. All equipment, supplies, and tools were procured through funds from WaveTalkers Supporters, on loan from vendors, or through peronsal funds.

Manufactuer links are provided for your convience and do not represesent an endorsement of the manufactuer or products.

Links to specific products do not indicate an endorsement by WaveTalkers; they are provided simply as a courtesy to you to help you find and learn more about the products we used in our deployment. You are encouraged to do your own product research for your own station.