Off the grid and portable HF radio communication including camp site, POTA and SOTA operations. Under development

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My current version of Off-Grid Radio Communications

Exploring remote locations, including off-the-grid camping, has been and still is one of my greatest joys, and when a bit of radio communications is part of the adventure, well, it can’t get much better than that.

A camping trip, a Parks On The Air (POTA) activation, or being prepared for an emergency - reliable and straightforward off-grid radio communication is the key. A modest but well-chosen set-up that can handle voice and data modes even when no mains power or infrastructure is available is, in my mind, the minimum requirement.

From fun voice chats with fellow hams to sending digital messages or emergency check-ins, the system needs to be reliable and adaptable to band conditions, and while VHF, UHF, and repeaters have their place, here we’re talking about a standalone, long-distance HF radio communications system.

For a campsite, a park activation, or putting together an emergency communications kit, having the right gear makes all the difference.

Photo 1 Back of the 4WD set-up with the HP laptop, PC to radio Interface, Kenwood TS50 and Yaesu FC-700 manual tuner. The laptop screen shows a successful Winlink email connection in progress. Possibly emailing Mark - VK3PI of what I'm up to.
 

Using traditional SSB (or FM) voice remains one of the most immediate and intuitive ways to communicate. It’s ideal for coordinating with other stations, local nets, or emergency traffic. However, beyond voice - when band conditions are poor and signals are weak - digital modes provide longer-range, resilient communications with low power, often less bandwidth, and more flexibility. Keyboard-to-keyboard digital modes offer a clear printed message record with no ambiguities or confusion, that can sometimes occur with voice traffic. While I will always be keen to experiment with the vast array of available digital modes, I have a small selection that has proven both reliable and popular, each serving particular needs. 

Winlink - Enables emails to be sent over HF within a standard SSB voice channel. The email is sent to one of the various Winlink gateway stations (also known as an RMS - Radio Message Server) located around Australia and the world, and from the gateway the message is automatically forwarded via standard internet infrastructure to almost any email address. Email traffic works both ways, and the recipients do not need to be licensed radio amateurs - very useful.

Olivia 8/250 - A robust, narrowband HF mode for challenging conditions when propagation is marginal. Olivia is a basic point-to-point text communication mode with few extra features; however, unlike JS8Call for example, Olivia doesn’t require time syncing and is therefore suitable for extended off-grid communications, where a standalone laptop’s clock can drift over time and render some digital modes inoperable. While Olivia has many sub-modes, my experience is that the 8/250 sub-mode is almost the universal standard for operations on all bands these days, with the most popular bands being 20m (14.0715 MHz) and 40m (7.0715 MHz).

JS8Call - A modern weak-signal mode derived from FT8/FT4, that allows a conversational style texting on HF with very low power. JS8Call is feature-rich, with an email style message inbox, message forwarding, or simple keyboard-to-keyboard communication. It has an exceptionally good signal-to-noise ratio and, in my experience, is the most resilient weak-signal keyboard-to-keyboard mode available at this time. It is also quite popular, with strong activity in the afternoon on 20m (14.078 MHz) and in the early evening on 40m (7.078 MHz). The trade-off for weak-signal resilience is a relatively slow baud rate; however, when there is  good signal, JS8Call can be switched to a fast baud rate known as Fast, or even faster baud rate known as Turbo - and Turbo is much faster than I can comfortably type. Importantly, JS8Call will attempt to decode irrespective of the other station’s selected speed.

Photo 2 JS8Call screen shot. 80m band contact with VK5CZ.

All three of the above modes give you options when you’re off-grid and want reliable communications that are less demanding on your power budget and antenna perfection. The digital mode applications are pre-loaded with templates for Winlink messages, as well as various shortcut macros for JS8Call and Olivia to help facilitate efficient communications.

The HF transceiver I'm using for portable work is a Kenwood TS 50, a compact basic radio that, while lacking many features is suitable for QRP or full 100W SSB transmission.

The Kenwood TS-50 transceiver is well suited for portable operation, especially when used with the AT-50 automatic antenna tuner. However, it lacks a VOX (voice-operated transmit) function, and while there are various ways to activate the PTT (push-to-talk) when operating digital modes, some modes - such as Winlink - require either advanced radio interfacing or rely on the radio’s VOX feature to key the transmitter. Due to limitations in both the TS-50 and certain software, a radio-to-computer interface in this set-up must include a built-in VOX circuit. Obviously, with a radio that has a VOX feature, the interface circuit is greatly simplified.

The radio-to-computer interface that I designed and constructed includes a VOX feature for all digital-mode PTT triggering, along with isolation transformers in the audio paths between the radio and laptop to prevent noise transfer between equipment.

The interface successfully operates all digital modes such as Winlink, JS8Call, WSPR, and Olivia, and should be compatible with most similar modes.

Keeping the laptop or tablet in a suitable location to minimise RF interference, using ferrite line suppression, keeping cables separated, and installing an earth with the shortest possible cable to the HF radio are all necessary steps in preventing RF feedback and ensuring a clean, reliable signal.

None of this works without an antenna, and I’m currently using two antenna configurations successfully; however, I’m always experimenting to create the ultimate portable antenna - an elusive pursuit for sure.

A portable linked-section ground-plane antenna for rapid campsite deployment, with a small footprint, allows relatively quick set-up and is suitable for use with a fibreglass squid-pole mast, without requiring any existing supports such as trees. As it’s currently designed, this antenna is limited to the upper HF bands from 14 MHz to 28 MHz.

Fig 1 The multi-band ground plane antenna link arrangement. Note that only two of the ground plane radials are shown for simplicity, however it is intended that there normally be 3 radials.

A multi-band dipole antenna provides broader HF band coverage from 3.5 MHz to 30 MHz when time allows. The multi-band dipole requires a bit more space but offers excellent flexibility across all HF bands. It can be worth taking the time to orient this antenna for the best take-off on the higher bands due to the often complex multi-lobed radiation pattern on the upper HF bands, as shown in Fig. 1.

Photo 3 The centre support of the multi-band dipole for broader HF band coverage from 3.5 MHz to 30 MHz. The total length of the dipole is 30m.

Photo 4 The on the ground radio equipment with balun connection to the open wire transmission line in the foreground. Worked David - VK4OF with SSB on 10m during this test run.

Fig 1 MMANA-GAL antenna model prediction: The antenna at 10m with a very complex multi-lobed pattern

In remote areas, or when the grid fails, reliable 12 V battery systems, solar charging, and efficient equipment form the fundamental basis for a communication system - and even for survival.

For extended periods of off-grid camping the power system needs to be well constructed to avoid intermittent faults, possible fires and equipment damage. The system needs a sufficiently large capacity battery and in my case I have chosen a 97Ah lead acid battery of the same type as that used in my four wheel drive, so that if the vehicle battery was to fail I have a replacement to drop in. 

As important as battery storage is, you still need a reliable way to generate power - and for off-grid set-ups, solar is king. It’s quiet, efficient, and requires no fuel. My system uses a 160-watt fold-out portable solar panel, which provides more than enough capacity for extended camping trips.

Reliability is dependent on a well design distribution board or system that has circuit fuse or circuit-breaker protection and quality standardised  connectors, such as Anderson connectors. 

I like to know what is happening on the power system at a glace and have included a digital power monitoring meter that displays; battery voltage, system load and energy (Wh or kWh) consumption. The camping trailers also includes metering for generation, so that for long duration stays I can know that I'm generating enough power to cover the average load for the stay.  

Photo 5 Camping trailer DC distribution board and water pump. The right side metering shows generation data, such as current, power and most importantly energy in Wh, the left meter presents data for the system load.

For shorter duration radio operations a small more compact version of camping trailer’s 12V systems is used.

Photo 6 Compact power box containing the battery, fuse protection, metering and Anderson connectors. Also not clearly shown are USB outputs phone charging etc.

Standardisation of all connectors to allow for simplicity and flexibility in set-ups with 50A Anderson connectors for major loads such as12/230V inverters, 30A Anderson for all other loads including transceivers. All RF connectors are standardised with the old reliable PL259 and SO239 connections that cheap and well suitable for HF frequencies.  

Where possible, it’s very useful to have all required equipment in one or two go-boxes. I learned this from bitter and embarrassing experience - that after a day’s drive to a remote location, only to find that a critical bit of kit had been forgotten. I’ve now got the basic kit down to two boxes, plus the pre-packed gear in the camping trailer. To back up the trailer and the equipment boxes, there is a fairly comprehensive checklist to ensure there will be an operational station at the destination. Just think Thunderbird 2.

Finally, a basic station that includes a reliable power supply, an efficient antenna system, and the ability to handle both voice and digital modes means you’re not locked into one style of communication and can pivot to whichever mode best suits propagation, power budget, or other operational requirements. For example: a POTA activation using the multi-band dipole for full HF coverage, Winlink to send activation data, and switching to OLIVIA when conditions deteriorate.

Off-grid radio communication is far more than just turning on the radio - it’s about designing and deploying a system that is self-sufficient, flexible, and robust. With correct gear, experiences, repair-capability and the use of both voice + digital modes, this is a winning combination. Whether it’s a relaxed weekend's activation or a serious emergency role, there is the tools and mindset to deliver reliable communications and maybe be the Last Voice Standing.

References:

Kenwood TS-50S compact HF transceiver https://vk6ysf.com/ts-50_20250624.htm

Mult-band HF portable linked section ground plane antenna - 14 MHz to 28MHz https://vk6ysf.com/hf_portable_linked_section_ground_plane_antenna-20251023.htm

Portable HF Doublet Antenna for a frequency range of 3.5MHz - 30MHz https://vk6ysf.com/hf_multi-band_dipole-20250825.html 

Kenwood TS-50 radio - laptop interface with internal USB soundcard and VOX circuit.   https://vk6ysf.com/radio_soundcard_interface_20250415.htm 

12V distribution for managing solar off-grid camping  https://vk6ysf.com/dc_distribution_off_grid_20250219.htm 

Olivia band-planhttps://vk6ysf.com/olivia_freq.htm 

JS8Call overview and international band-planhttps://vk6ysf.com/JS8Call_20241005.html 

Article about the reliance on modern communication infrastructure and where amateur radio can fit in.  https://vk6ysf.com/last_voice_standing-20250709.htm 

Winlink Global Radio Email https://winlink.org/ 

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Page initiated 10 November, 2025 

Page last revised 26 November, 2025