Winlink VaraFM VaraHF Project

Hello Operators

I recently started work on a long overdue Winlink project. The project is a gateway serving the Northern Gulf of Bothnia coastal region between Sweden and Finland.

Project plan

This document serves are a guide or reminder of the goals of the project. In the simplest terms, the project is designed to provide Winlink email access for amateur radio operators in the Northern Ostrobothnia (Gulf of Bothnia) coastal region. Gateway and radio-only access for emergency comunications and preparedness, in the event of a grid down infrastructure failure. The system will also (eventually) serve as a remotely deployed, self-contained fill-in Winlink email system operating on HF & VHF.


The first phase of the project is testing hardware compatibility and performance between the old but reliable Kenwood TMD700, Digirig audio and cat control interface and VaraFM Wide. If/when performance is sorted out, this hardware will be used to fill-in the VHF Winlink gaps between FIN Oulu (my QTH), Hailuoto island, Raahe, Kemi, Tornio & SWE Kalix, Luleå, Piteå, Skellefteå with Winlink VaraFM Wide. These towns are all over-the-horizon but salt water shots from my own QTH. Umeå, Kalajoki, Kokkola might be too ambitious, but we’ll give it a try.

Although both HF and VHF are the end goal, starting with VHF was chosen for a couple of reasons. Firstly, the equipment is already here! Secondly, I’ve recently come to the conclusion that our Winlink strategies must incorporate both VHF & HF for increased accessibility, throughput and security. VHF (50 or 144Mhz) as it provides local access at higher speed, using modest equipment (portable Operators perspective). HF as it has no infrastructure requirements, provides wider regional communications range and acts as a bridge between regions well beyond VHF coverage.

Pre-Testing – Repeaters in towns around the Northern Gulf of Bothnia region can already be accessed using the Kenwood TMD700 and tower mounted GP. APRS connections can also be made throughout the region. The antenna is at best “OK”, but will get the job done for now. There are two SSB electronics preamps in the system. One tower mounted, the other in the radio room. These preamplifiers make up for long coax losses, giving the humble D700 exceptionally good RX on VHF. This is a good starting point!

Most of my operations from home take place on HF or 6 meters. V/UHF weak signal work was a passion at one time. Today there is very little practical activity on 2 meters, so my local and regional comms requirements are met with NVIS on 160, 80, 60 & 40 meters, leaving the VHF/UHF equipment, mostly unused. Repurposing the for emcomm and preparedness scenarios seems like a pragmatic use of the gear. 

Audio interfaces

There are two sides of the RMS. The first is VHF, while the second is HF. These will be connected via RMS Relay, but more on that later.

Kenwood TM-D700
The VHF radio is the Kenwood TM-D700 which is a full duplex dual-band radio. It can transmit and receive simultaneously on any combination of VHF/UHF, UHF/UHF, VHF/VHF. It is also possible to have a voice or data QSO on the other VFO, while actively in a Winlink session on the Winlink VFO of the radio. This is literally two radios inside a single enclosure.

The Kenwood TM-D700 can use either the Masters Communications DRA-50 audio interface or the DigiRig Mobile revision 1.9 for Vara FM Wide.

In the video above, the VaraFM Wide was tested with the Masters Comms DRA-50, Kenwood TM-D700E and a 1/4w dual band GP at 12m/40ft.Throughut was absolutely brilliant, but I expect it to get better when some distance is put between the testing stations.

The Masters Communications DRA-50 has been a pleasure to test. High throughput, integrated PTT, simple jumper configurations, excellent documentation. The DRA-50 is overkill for most projects, but it is proven. I ordered it during my Digirig testing, thinking the Digirig was having a bandwidth limitation issue.

Vara FM Wide on the Icom IC-705 with Microsoft Surface Go2.

DigiRig Update 15 September 2020
Testing the Digirig with Vara FM Wide. there were some issues I couldn’t handle on my own. Denis K0TX at guided me through troubleshooting, to sort out the problem. Ultimately, I wasn’t paying close attention to the Digirig revision being used. For this project, Digirig revision 1.9 is required. There are also a set of cables required for 9k6 with rigs having individual 1k2 & 9k6 audio lines, like the TM- D700. Attentuation was also a problem during testing. The revision 1.9 of the Digirig will also solve that problem. Seems like Denis is on top of things. Denis is sending over the latest Digirig revision and matching cables for the TM-D700. Please show him some love.
When theDigirig and cables arrive, testing with Digirig will start again. Either way, the Digirig will run both HF & VHF, or just HF. We’ll know after the testing. Huge thanks to Denis for supporting this project.

On the HF side, VaraHF will use a Digirig mobile and perhaps the unused Yaesu FT-817ND with PA500 60-watt amplifier (@ 20-30w) sitting on the bench. The Vertex VX-1210 is still an option although it doesn’t have CAT control. It is an incredibly energy efficient radio, but would limit HF to a single frequency. Perhaps 60 meters!? 60m would give us dat time and night time NVIS capabilities without changing frequencies.

Regarding a QRP rig and PA500. There is an upcoming PA500 firmware release allowing auto resume functionality after a power loss. This functionality will allow the amp to be remotely deployed or tower mounted, without the need to “turn it on” again manually after a power loss. Why the PA500? Keep in mind it has an autonomous antenna tuner built-in, requiring no user interaction for antenna tuning or band switching. It also has excellent filtering and a rediculously low current consumption. A bias T could provide the power from the shack. Alternatively, a tower mounted solar gen could be built, providing power on the tower itself.

Station power

Primary power comes from a 24ah LiFePO4 battery graciously supplied by Gigaparts. You can order this battery here . This isn’t the largest capacity battery one could deploy, but it is a great starting point. With such a small capacity battery, keeping current consumption to a minimum is critical. For this reason, I may start off using the second Icom IC-705 or Vertex VX-1210. instead of the 817ND. The 705 uses less than half the current draw of the 817ND on RX. The VX-1210 uses even less. Could using a 705 in this way could be a waste!? Perhaps one of the bare bones QRP rigs recently released. Anyway, it is not todays problem.

Charge controller could be a Genasun GV-8B Boost or Genasun GV10L controller or some other controller supporting both wind and solar. If a dual power source controller can be sourced, I’ll add a second wind turbine to the tower. If not, the Genasun with a couple of hundred watts of solar panels. Another option is the Victron 75/15 MPPT I’ve been testing. It has a bluetooth interface built-in making power/usage tracking much simpler.

Current consumption I know you’ve all heard it before. Rigs drawing more the a couple of hundred milliamps of current on RX are a complete no-go for an off-grid powered emcomm system. The Yaesu FT-891 or Icom IC-7300 would both have been good if not for the high current consumption on RX and low efficiency on TX. These losses make similar rigs impractical for applications where sipping energy rather gulping it down is required. It saddens me to say, there are no current QRO rigs with good enough efficiency, that they could be used for emcomm or preparedness!

The wind turbine supplied by Ham Radio Prep last year, will help supply supplemental and backup power for the Gateway/BBS. 


For computing, a Larkbox Pro or Intel NUK mini computer to run the Winlink RMS software. I have good experience powering the Larkbox Pro from a solar gen. You can read about it here:
Although there is a USB-C connector for power, the Larkbox Pro actually runs off of ~12-14.x volts. Don’t be fooled by the connector!

Some mods for the Larkbox: Pro

  • Add a couple of resistors in series with the fan to slow it down. This reduces noise.
  • Drill the fan ventilation holes larger for better air flow. Then add a layer of porous cloth as a dust filter.
  • Remove the heatsink and add thermal paste, then replace the heat sink.
  • Disable Windows updates. Do them manually when/if you like.
  • Use your multimeter to find the plus/minus leads on the fake USB-C cable, then add appropriate connectors for battery power.


Once a reliable VHF system is up and running, a second radio (HF radio) will be added to the system. The HF radio will add Winlink access 60 & 30 meters. 60m for its day/night regional NVIS capabilities, 30m as it is usually open during day & night. 60m will be limited to 500hz connections, allowing operators to make use of the narrow filters in their rigs, for more reliable weak signal connections.
Antenna For fixed station the antenna could be something as simple of a horizontal dipole or off-center fed dipole for 60/30 meters or random wire endfed like the Chameleon EMCOMM2 QRP just in for testing. For extended field work, a full wave loop for 60 or 40 meters could be employed. The built-in antenna tuner on the PA500 makes these broadband options excellent rapid deployment combinations.

Field deployment

Once the entire system is up and running, it would be an added bonus to make this a self-contained, field deployable system. We have all read about the aftermaths of natural disasters wiping out critical infrastructure. Well Imagine a Winlink RMS with Starlink Portability service for internet access. Such a system could be deployed anywhere on the planet, where Starlink service is available. Emergency responders could be deployed strategically in key locations. They then connect over HF/VHF for email communications, weather forecasts, … within and/or out of the region.

Portable Power

For field deployment, there are already two PowerFilm FM16-6000 100 watt panels and a 20ah LiFePO4 base solar generator, dedicated for this purpose. These can be seem in the image above.
This is more of a concept atm. It is documented here to keep the idea fresh.

More about the concept

Operators deployed in urban areas don’t always have the luxury of big and efficient HF antennas for local or regional comms. We support these operators by making HF & VHF connections available. Imagine a handheld radio with whip antenna and a microsoft surface for fast winlink with VaraFM. Imagine using the radio-only functionality as a sort of cross band email gateway regardless of your modest backpack portable station. Primary function is supporting the portable or deployed operators who can’t carry a ton of extra comms gear.

Missing equipment

As always, these projects are dependent upon equipment. If you would like to donate some equipment, these are the major component still missing:

  • Solar panels (fixed station)
  • Charge controller
  • Mini Computer or lightweight energy-efficient laptop

Support the blog and channel by shopping on ebay, at battery hookups or GigaParts. For GigaParts and Battery Hookup, use my callsign for a small discount.

If you’re a business looking to sponsor the project in part or in its entirety, please reach out.

This post is always a work in progress.

Julian oh8stn

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  1. Julian. This is wonderful. My local ARES group (West Santa Barbara ARES) have been getting all the members up to speed on this awesome was to communicate. Keep up the great work. Love the videos

    • Thanks John.
      The computer arrived. Battery and charge controller arrived. I ended up ordering a Masters communications DRA-50 to support VaraFM Wide with the Kenwood TM-D700. The 12VDC powered 4k LED screen arrived. Once everything is here, I’ll need a build an enclosure to mount everything inside.
      The build will be published don’t eh channel like the battery projects.
      Julian oh8stn

  2. Great stuff, Julian. The vision is outstanding; of course, we test to see the gaps between the vision and reality. Good luck. As for VHF, if you have two 705s, and one is not being used (other than as backup), I don’t see how it is a waste to use it. I love the 817/818 but, as you rightly keep repeating, power consumption is key. The 705 does what the 817/818 does, band-wise, but easier and more efficiently. Use it. As for support, I would think that local business and government offices, as well as NGOs, would have an interest, for just the reasons you outlined in your introduction. Good luck! 73

  3. Hi Julian,

    Another great essay and a very ambitious project, thank you! (BTW, does your IC-705 support 60m?)

    I fully understand your choice of Vara, even though it’s Windows-only and closed-source. I agree that ARDOP is not very robust (I haven’t been able to find or create a build on modern 64-bit Linux that actually works), and therefore not an option. There’s of course the OFDM variant of it, supposedly a lot closer to Vara in performance than the standard version, but, again, no luck running it on a standard Linux.

    More recently, people have been talking about freedata based on codec2, with the apparent goal of creating a real competitor to Vara. What do you think of that? I think that your input on it could be very useful to the development team, and that your attention could give the project extra momentum.



    • Honestly, I’m very disappointed that VaraHF hasn’t been ported to Linux. I understand the reasons why though! It’s the Chicken and the Egg. PAT Winlink is what it is. Difficult to configure, no install shield like WSJT-X or JS8Call, no graphical config, and generally terrible GUI. Still, it is a great start and better than nothing. Until there’s a better winlink client for Linux,( a real executable not a web page) I imagine the developer of Vara sees no point in doing the work for what is essentially a moving target. PAT is open source. If one were going to start anywhere, it should be with a greatly improved version of PAT. Something as easy to install and configure as winlink express on windows. Something with a allowing third party plugins to add functionality. Then an alternative to VaraHF would be pure awesomeness!
      Chicken and the egg.
      Julian oh8stn

  4. Another great video Julian! One thing I am not clear on. How are you connecting the D700 to the DigiRig? Is it the DB9 to Digi Rig? I would love to to work on a 440, 9600 baud node. As well as my HF node. Thank you!

    • The Digirig has 2 ports. One for audio, the other for CAT control. The audio port connects to the mini-din 9k6 port of the D700. The CAT control port connects to the DB9 port. It works flawlessly.
      Julian oh8stn

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