Yaesu FT-817ND/FT-818 PowerPole Adapter

Estimated reading time: 4 minutes

The Yaesu FT-817ND can be either powered by its internal battery or by a external DC power source. When supplying the radio via its rear panel DC connector mechanical stress can lead the DC connector shearing off the connected PCB. A suitable counter-measure is to install the Yaesu FT-817ND PowerPole Adapter which provides stress-relief and therefore safeguards the power connector. Note: The FT-871ND PowerPole Adapter is also suitable for the Yaesu FT-818.

Background

The Yaesu FT-817ND can either be powered by its internal NiMH battery (9.6V, 1400 mAh, YSU-FNB-85) or via external power source (~13.8V DC). When using its internal battery transmission power is limited to 2.5W. However, when power is supplied externally a transmit power of 5W can be reached. Consequently I’ve always been using an external power source during portable ham radio operation. This has been done by simply soldering battery connectors to the other end of the charging connector (don’t forget to integrate fuses).

Supplying the Yaesu FT-817ND via its external power source input on the rear panel
A flimsy wire connects a LiFePo battery pack with to Yaesu FT-817ND’s external power source input

Unfortunately this simple approach to externally powering the radio can introduce issues in the long-term. Due to the nature of portable operations mechanical stress is exerted on the connector every time the radio is setup on a remote destination. Since the receptacle of the external power source is a SMT mounted component it’s quite likely to shear off at some point in time due to mechanical forces introduced by the batter cable. Note: This is definitely not a problem in shack-based operation where the radio is hardly ever moved.

SOTABEAMS FT-817ND PowerPole Adapter

Fortunately there’s an easy solution: SOTABEAMS sells an FT-817ND PowerPole Adapter which consists of a 3D printed case which houses both the external power source plug as well as a Anderson PowerPole connector. It capitalises on the existence of a small protruding cylinder with a tapped center hole to securely fix the adapter to the radio’s rear panel. It’s worth noting that after mounting the adapter there’s still a margin for tiny movement. Nonetheless a considerable amount of mechanical stress which would otherwise directly be introduced into the radio is now relieved by the FT-817ND PowerPole Adapter.

SOTABEAMS FT-817ND PowerPole Adapter mounted on back of Yaesu FT-817ND
The SOTABEAMS FT-817ND PowerPole Adapator mounted to the back of Yaesu FT-817ND provides a strain-relief during portable operation

I’ve successfully used the FT-817ND PowerPole adapter for about a year when during a recent SOTA activation I decided to test the FT-817ND’s merits as a handheld 2m radio. As you might guess by taking a look at the picture below the experiment took a rather unexpected turn. While balancing the radio with the battery pack on top in one hand I alternately handled microphone and QSO log notebook in the other hand. While inattentive for a short second the battery fell from top of the radio and – ripping out of the PowerPole connector – destroyed the 3D printed case of the SOTABEAMS FT-817ND PowerPole adapter.

This broken SOTABEAMS FT-817ND PowerPole Adapter highlights the weakness of the 3D printed case
This SOTABEAMS FT-817ND PowerPole Adapter case broke highlighting the weakness of 3D printed cases

For now I’ve replaced the destroyed adapter with a new one. Regardless, the incident clearly demonstrated the inherent weakness of a 3D printed case. A better solution might be FT-817ND PowerPole adapter milled from aluminium. Another improvement would be the inclusion of a protruding leg to further stabilise the adaptor against rotational forces (and eliminate the spiel present in the SOTABEAMS version).




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