Modularity in Off-Grid Field Radio

After testing a modular HF radio go kit concept last May, I wonder why we don’t see more modularity in the ham radio community.

Hello Operators
This is the second episode of the After Action report from ACOGX 2023. For this off-grid communications event, I decided on a more modular go kit design than I normally would have. Naturally there were pros and cons to this modular approach.

Before the keyboard commando start going nuts about the video, this was a field test of how pragmatic “this” modular equipment deployment would be. I’m not promoting any particular setup! I’m simply testing and reporting my findings for this kit.

Ho Kit components

  • Maxpeditiin Pouch
  • Lab599 TX500
  • N9SAB OCF 80/40/20M & OCF 60/30/15M
  • Digirig Mobile
  • DL4KA PA500 Amplifier
  • DL4KA BAT500 Battery
  • RBR Modem
  • Samsung S22 ultra Android phone

Normally, I would have operated a QRP-10 watt field radio. Wanting to get over the North Pole during grey line meant using more power than traditionally required for reliable regional off-grid comms. The modular go-kit was based on the Lab599 TX500, the DL4KA PA500, and the DL4KA BAT500 battery pack. PowerFilm Solar provided lightweight portable power, and the Digirig mobile made data communications possible.

Although there are some cons to “modularity”, this video in this post shows us how a modular go it can solve a couple of common problems with field deployment.

Efficiency

The single most challenging barrier to QRO field communications is the current consumption of our radios. Other than the Xiegu G90, there are no other QRO HF radios manufactured, with lower than 1 amp of current consumption on RX. This is why we see operators deploying a Yaesy FT-891 for example. The radio itself is fine! Add the battery storage and solar power required to keep it operational for a multiday event, and then grimlins show their faces.

Weight

The second barrier to effective man-portable field communications is size and weight. If a go kit requires a trolly to move from one place to another, it is not “man-portable”. The tested go kit for ACOGX 2023 was roughly 4 lbs or 2.1kg. This is more than half the weight of an Icom IC-7300. More than half the weight of a Yaesu FT-991A. Yes those radios follow a KISS (Keep it Simple Stupid) methodology, but at that cost of great weight, greater size, and less efficieny.

The 4 lbs or 2.1kg weight of the ACOGX 2023 set up includes Radio, Amplifier, and Battery storage!

When searching for alternatives, we must understand it isn’t just the size and weight of the radio. We must also factor in the size and weight of the battery storage required to keep the station operational, throughout the duration of the off-grid deployment. When we do so, it becomes easier to understand why leaving the commercial QRO options on the bench, in the car makes more sense. They simply arent a good technical solution to the man-portable, off-grid comms problem.

Cost versus weight and effeciency

If we really want to find some reason to shut down the modular approach, it is cost. A Yaesu FT-891 costs is under $700 USD, and weighs in at just over 4 lb. The 891 is our outlier! Its weight is excellent for output power capability. Where it fails is its RX current, ~1.1-1.2A. An Icom IC-7300 costs less than $1100 USD, but weighs in at 4.2kg; 9.26 lb. Again, this radio fails with its current consumption on RX ~1.2A. The Yaesu FT-991A can be had for $1300 USD or less. It has an RX current consumption of 1.8A on RX. Its weight comes in at 9.5 lb. So yeah, we can save money, or add weight! It is impossible to save money, be QRO, and save weight. Ironically, this isn’t the worst news. The TX current is extremely poor in commercial QRO radio. The finals of commercial QRO rigs are the other achiles heal of field communications, but no other bloggers or YouTubers are talking about it.
Ultimately, this is why many Operators have focused on low power stations running data modes, and using efficient antennas.

Have you considered how modularity could play a more meaningful role in your field radio or off-grid ham radio communications?

Some of the challenges experienced:

  • Slower deployment time
  • Wire management
  • Spare parts and redundancy
  • Field repairs
  • increased complexity

While the Lab599 offers the Operator an incredibly robust field radio depolyment package, it suffered from lots of interconnections between each module. For the data modes Operators, there are two additional connections, and an external peripheral (Digirig) required to get data modes up and running seemlessly. There is also power, amp control if vox isn’t used, power for the amp, cable I/O for the battery, speaker microphone, … Some of these cables could be eliminated if using the POGO pins on the back of the TX500 to power the radio. Also, if the TX500 had an internal audio interface and CAT control over USB, two more cables could be eliminated. Afer this expedition, I firmly believe every ham radio manufacturer should include an internal audio interface and CAT control over a single USB connection, on every SSB radio. As a community, we should not support radios not having these critical features.

Ultimately, the true struggle came from wire mangement. During the expedition, the main differences between the TX-500 hardware modularity, and the modular connectivity of the Icom IC-705 became blatenly apparent. Where the analog TX-500 can stack additional modules onto its housing, the IC-705 goes even further reducing the number of interconnections required to field the station. Peripheral connectivity and hardware modularity are equally important. Sadly, both these radios take opposing approaches to modularity, leaving Operators wanting for more, despite their chosen radio.

If you have not seen the first episode of ACOGX 2023, you can watch it below.

In upcoming episodes, we’ll discuss portable power, the antenna strategy, HF Packet, and APRS.

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1 Comment

  1. Great information. I have followed you from ft857d/PI manpack to IC-705/PA500. Your comments here are an accumulation of much of what I have learned following you. Well said. Using WFView for remote control through the IC-705 hot spot, I can operate with an antenna connection and (optionally) an exterior battery. Very clean!

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