I purchased a Yaesu FT-7900R mobile radio and Diamond NR770HB antenna and installed both for mobile operation in a Jeep Wrangler that I had when I was new to the world of amateur radio in 2014. Some years later, having traded in the Jeep for a sedan, the radio and antenna called the hall closet home. That is until 2022 when I realized my amateur radio license was nearing its renewal date and I hadn’t been active on the air in several years.
I did not want to install the radio and antenna in my car, so I looked for other options. The FT-7900R was the only radio I owned other than a handheld radio. There are plenty of repeaters around my home and the FT-7900R was in great shape given its age. No reason not to put it to use, right?
I started searching online for instructions on how to power this radio by battery since I’d seen many amateurs on Youtube operating portable from parks and other locations using battery power. I wanted to do that also!
I came across one Youtube channel that catered to the “prepper” crowd that happened to discuss some options for setting up mobile radios for battery powered portable operation. One such video on the channel referenced a mobile radio similar in size to the FT-7900R and two molle style pouches. One pouch would hold the radio and the other pouch would hold the battery. A bracket called a pack frame would hold the radio body in a way so that it would be protected slightly while contained within the pouch.
This kit sounded like it would be just what I was looking for, so I bought the following items.
- Helikon-Tex E & E pouch (Amazon)
- 5.11 Tactical 6″ x 6″ tech pouch (Amazon)
- TPA-7879 pack frame for Yaesu FT-7800/7900 (Armoloq.com)
- Bioenno 12V 6Ah LiFePO4 battery (Amazon)
- Bioenno 14.6V 2A AC-to-DC charger (Amazon)
- Anderson Powerpole 30A connectors (15A ones were too small for the Yaesu power wires) (Amazon)
- 12 inch MPD Digital RG-8X BNC male to BNC male antenna jumper (Amazon)
- PL-259 to BNC female right angle connector (Amazon)
- BNC male to PL-259 female straight connector (Amazon)
The BNC to PL-259 connectors I bought are for making the connections from the radio to the antenna. The Armoloq antenna relocation kit includes a mounting bracket and BNC male to BNC male straight through adapter. The FT-7900 has the standard SO-239 antenna connection. I used the right angle PL-259 to BNC female connector to connect the radio to the MPD patch cable. The patch cable then connected to the Armoloq antenna relocation kit adapter. The PL-259 to BNC male connector was used to allow my Diamond NR770 antenna to connect to the BNC connector of the relocation kit. The Diamond NR770 is a mobile antenna and is perhaps a bit too large for this kit, but it’s all I had at the time.
The Armoloq pack frame is really cool. The two-piece aluminum frame comes with the correct mounting hardware for the radio it is designed for. If for whatever reason you decide to use your own mounting screws, pay mind to the length so they are not too long.
I cut the original Yaesu power wiring close to the plastic connector and terminated the wires with the Anderson Powerpole connectors to facilitate quick and easy connecting to a battery.
Here, I’ve shown the FT-7900R radio mounted in the Armoloq TPA-7879 pack frame with the antenna relocation kit installed. Also shown is the modified wiring for power.
To connect the radio to the antenna relocation kit, I installed the right angle connector to the radio and then ran the MPD patch from the connector to the relocation kit connector.
I then used the PL-259 to BNC straight connector on the Diamond NR770 antenna to allow it to be connected to the antenna relocation kit adapter.
The Bioenno battery that I chose supplies enough power to operate for a few hours depending on the duty cycle during that period of time. The 6Ah battery is small and light. Radio mic included in the photo for general size reference.
After putting the kit together and placing it all in the Helikon tech bag, I noticed the bag was too short for the pack frame by about two inches. An oversight on my part that I could have avoided by comparing physical dimensions of the kit components prior to purchase. Lesson learned.
In the end, I returned the Helikon-Tex and 5.11 bags and bought the G4Free Tactical EDC Sling pack (Amazon) whose main compartment fits the TPA-7879 pack frame perfectly and has ample storage pockets to carry the Bioenno battery and any extra connectors and wires that I might need when operating portable. Here’s a look at the bag itself and one of the kit fully assembled and packed up.
Having the antenna connector relocated and having a strap on the pack will allow me to wear the kit on my front and connect a handheld yagi antenna via a short patch cable for working out in the field also. I intend to test this use case in the near future.
All in all, I’m very satisfied with how the kit turned out. I have been using it in the evenings to check in to the Northern Virginia Traffic Net and it seems to be working pretty well. I have not put the Bioenno battery through any long rag chewing work yet, but based on the power ratings for the Yaesu FT-7900R, the 6Ah battery should provide several hours of good communication capabilities when I’m ready to do so.
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