FT-891 Conversion to Powerpoles

My recent purchased Yaesu FT-891 came, as do all spanking new Yaesu FT-891’s do, with a four contact Molex style power connector, the male side of the connector pair connected to a pointlessly long 12 AWG power cord fitted with fuses in both the positive and negative leads. The female half of the connector pair is set in the rear bulkhead of the radio.

I have opined in the past about how crap-tastic the Molex style connector is, but to provide a brief recap, amongst the manifold deficiencies of that connector pair are the following gripes:

• It’s made out of fragile plastic, and for a radio that’s going to be subjected to the thousand natural shocks that a field radio is heir to, it’s just a horrid choice. Many of the FT-891’s that are being converted to Powerpoles are being converted because the stock Molex style connector broke, with the usual failure being the tabs that hold the connector in a fixed position in the rear bulkhead of the radio, so that when you try to plug the power cord in, the female part in the radio just falls inside the radio. Ugh.
• The connector pair is equipped with a lock, so that when you plug the power cord into the radio, it’s locked in place until you use something pointy to depress the lock so you can remove it. Now, I understand that a power cord that can’t be accidentally pulled out seems like a great idea. For a radio in the field, however, what it means is that if something/someone snags the power cord and walks off, it will pull the radio off the work surface and make it fall to the ground, instead of the power cord just pulling out. Where I come from, we find that plugging the power back in is much easier than repairing a dropped radio in the field.
• Beyond the risk of having the radio dragged off the work surface, with the Molex style connector, for a field radio either you resign yourself to dragging the radio around with the power cord attached, constantly tangling and snagging on things, or else you resign yourself to struggling with the unergonomic lock every time you unplug the power cord.
• The Molex style connector is specified with a contact resistance of 7-10 milliohms. Anderson Powerpoles are specified with a contact resistance of 0.1 milliohm.
• the Molex style contacts are not rated for many mating cycles - typically 50-100. Tin plated Anderson Powerpole contacts are rated for 1,500 cycles, silver plated ones are rated for 10,000 cycles.
• The connector is rated for 10A per contact, so the way they get more amps into the radio is they use four contacts, two for the 12V side and two for the GND side. This means that all power cords have to have a Y yoke to connect the power to both 12V pins, and another yoke to connect both GND pins, and then inside the radio there are two more Y connections to connect the connector to the 12V and GND power terminals on the circuit board. So you get extra bulk, extra weight, and make building power cords into a needless trauma.
• Beyond the hassle of building the Y, putting a Molex style connector on the spare power cord you’re building is twice as much crimping as building a Powerpole cord.
• when you’re plugging in the power cord with Molex style connectors, there’s no obvious visible indication of which of four ways to orient the connector is correct.
• Molex style connectors are not the ARES/RACES standard for power connections. Anderson Powerpoles are the standard. So if you want interoperability on any sensible emergency deployment (or even just a casual activity with people who are involved with ARES/RACES) Anderson Powerpoles are the standard to pick.
• Many batteries (especially those from Bioenno) have Anderson Powerpoles on their pigtail, so that if your radio is fitted with Powerpoles, you can just plug the battery directly into the radio without any intervening power cord. (but beware of need for fuses if you do this!)

Anyway, powerpoles are the de jure and de facto standard for 12VDC power connections in the amateur radio world. So I wanted to take the crap-tastic Molex style connector out of my FT-891, and put Anderson Powerpole connectors in, all with a minimum of fuss, botheration, hardship.

And, it turns out, a lot of other hams have had exactly the same thought and have come up with myriad ways to get this done. I’m a believer in learning from mistakes, but I have a very strong preference for learning from other people’s mistakes rather than learn from my own, so I surveyed how other hams got this all done.

The most elegant and nicest solution was a 3-d printed Powerpole holder that fits exactly into the space used by the Molex connector, designed by Jason N0BOY. You can 3-d print your own from his design, or you can buy one from Jason/Guangxin himself. He sells complete kits with wiring all assembled, or you can buy just the 3d printed bit with the screw and nut ready to go and make your own wiring. I opted to make my own wiring, simply because delivery time was shorter and I have plenty of powerpole stuff on hand and I’m utterly comfortable with powerpole crimping &c. I ordered the stuff from Jason’s web form here. Jason sent me a paypal request for funds the same evening, and by bedtime I actually had the tracking info for the shipped adapter.

Installation

I received the kit this morning and installed it this afternoon. You can order the basic kits (3d printed parts, screw, nut) for $12, or you can order the full kit (3d printed parts, screw, nut, and preassembled wiring) for $27. Since have an abundant supply of wire, powerpoles, ring terminals &c, I ordered the basic kit.

It took me about 20 minutes to do the entire operation, start to finish. Some 10 minutes of that was hunting through my studio for the box containing ring terminals the right size. If you buy the full kit and you are reasonably handy, I’ll bet you can get it all done in 2-3 minutes.

The best part: this is all fully reversible - if you need to send the radio off for warranty repair, you just take the powerpoles out and put the molex connector back in, and no one will know.

First, you remove the eight screws holding the bottom cover on the radio, and save them in a Very Safe Place^tm.

Some photos:

The relevant bit of this view of the internals of the FT-891 is in the upper right hand corner. You’re going to unscrew the two screws holding the wires that come from the Molex connector - one is red, one is black. Save the screws in a Very Safe Place^tm.

Next, you use needle nose pliers or a Kelly clamp to gently squeeze the locking bits on the left and right side of the Molex connector from the outside of the radio, and pull the entire connector and wire assembly out.

Next, try fitting the 3d printed bits into the now vacant hole, and get an understanding of how this is all going to work. There are videos on YouTube explaining all this, go watch a couple to see.

If you bought the wiring all done from Jason, you just use that. Otherwise, make up the Powerpole and the wiring with ring terminals, all sized to fit exactly.

With that done, fit the Powerpoles into the hole, fit the 3d printed inside bit into place, put the outside 3d printed bit in position, and tighten the screw using a hex driver.

The result should look like these photos. All that remains is to screw down the ring terminals into the appropriate spot. Check continuity - the red powerpole should show 0 ohms to the positive power block on the radio and open circuit to the ground power block, the chassis of the radio, and the outside of the RF output. The black powerpole should show open circuit to the positive power block, and 0 ohms to the ground block, chassis, and outside of the RF output.

With that done, button the radio back up. You’re all done.