Yaesu FT-891 POTA/Field Kit

Now that I have my new Yaesu FT-891 mostly sorted, I’ve been putting together a POTA/field kit, roughly based on the field kit I had put together for the Xiegu G90, which is now, to use the currently fashionable phrase, deprecated.

In fact, the kit is going into the same LowePro camera bag I was using for the Xeigu G90, into which it fits pretty brilliantly.

In the kit

Contents of the kit:

Yaesu FT-891 with the horrid Molex style power connector replaced with Anderson Powerpoles.
power cable, 12 gauge and roughly .5 meter long, Powerpole to Powerpole, with fuses.
Bioenno 12v 12AH LiFePO4 battery
DigiRig DR-891 digital interface for the FT-891
USB-C .5 meter cable to connect DR-891 to Macbook
Bamatech TP-3 CW paddles & self storing 3.5mm/3.5mm cable
Heil Sound BM-17 dynamic mic headset and Yaesu RJ-45 mic adaptor
trigger switch for PTT when using handset
17’ RG-316 BNC male to BNC male coax with ferrite choke on one end.

FT-891

This is one of the most popular 100W output all mode capable radios for POTA and other field deployment.

The Powerpole conversion ditches the fragile and annoying Molex power connector for Anderson Powerpoles, the ARES/RACES standard for power connections as well as the standard I’ve settled on for all my radios in the field and in the shack.

One particular noteworthy thing about the [specific conversion][Title FT-891 Powerpole conversion.md] I’ve chosen is that the Powerpole connector itself is shielded from knocks and bumps by the 3d printed shroud that houses the powerpole.

In addition the the Powerpole conversion, the RF output SO-239 connector is fitted with an adaptor to a right angle BNC connector, because everything I use in the field is either natively BNC connectors, or is fitted with an adaptor to BNC. BNC connectors are robust, lightweight, easily capable of handling 100W RF power, and are fast to use in the field; all connecting two things together requires is plugging the male connector into the female, and rotating the locking shell past the locking detent.

Power Cable

Strictly speaking, I could just plug the battery directly into the radio, and things would work fine. It’s better, though, to have fuses in the power line, and so this short cable gives a way to get the power connection fused as well as offering a bit of length for easier arrangement of the gear on a work surface, without adding too much weight and bulk to the kit.

Given the length, I could probably get away with smaller gauge wire than 12ga, but powerpole cables are like tinkertoys, you never really know what use any specific cable might get pressed into service for, and the difference between 12ga wire and 18ga for a half meter is just too small to make it worth making a cable that might present a problem in the future.

That, plus I had some problems with voltage drop in my shack, said problems being resolved by replacing some long small gauge power cables with 10-12 gauge cables custom cut to the exact minimum length, so now I am a bit twitchy about voltage drops in power cables for QRO radios.

Bioenno 12v 12AH LiFePO4 battery

A battery smaller than 12AH would almost surely suffice for anything but my longest POTA activations (if I needed more than perhaps 6ah I’d probably arrange for my 30AH battery to be on hand) but the real issue is finding a battery that will happily source the 20+ amps the radio requires when running full-on 100W output.

The Bioenno 12AH battery happens to be a convenient shape for inclusion in the kit, being a longish bar that is 8.5 inches long and not too large in the other dimensions to fit easily into the bag. (note: my experiments show that the FT-891 pulls 14.6A on 160m, 100W output CW key down, so 9aH Bioenno BLF-1209WS would actually do the trick as well)

Digirig DR-891 sound card/cat control interface & USB-C cable

For years I was a big fan of the Masters Communications sound card interfaces for running digital modes; they’re reasonably compact, inexpensive, and work well.

But more recently I’ve become a big fan of the Digirig interfaces, which roll CAT control of the radio and a USB soundcard into one interface that requires only one cable from the computer to the interface, and then two cables (one for CAT control, and one for audio in/out) from the interface to the radio. Beyond the very small size of the Digirig module itself, this cabling approach reduces the problems caused by expansive festoons of cables running hither and yon during a field activation.

To top it all off, the Digirig interfaces are relatively inexpensive; about the only way to get the job done more cheaply is to use a USB sound card dongle for the audio, and run a serial cable for CAT control of the transciever - but now you are back to the festoon of cables problem.

Bamatech TP-3 key and self-storing 3.5mm/3.5mm cable

Obviously, I need a CW key. I like the overall feel of the TP-3 - my only complaint is I don’t like the rubber covers on the paddles, which feel squishy and imprecise to me. But the key is small, light, has great action, and I have one, so into the kit it goes.

In addition to the key, I also need a cable to connect it to the radio, so one of the handy self-coiling/self-storing cables that everyone uses goes into the kit as well.

Heil Sound BM-17 dynamic mic headset and RJ-45 adapter

I very much prefer to use a headset with a mic on a boom as opposed to using a hand mic and and either the radio’s built in speaker or headphones/earbuds. I’ve used a number of different headsets, and two of my favorites are the Heil Sound Pro 7, and the Heil BM-17. Both are available with an electret mic element or a dynamic mic element. Since the Yaesu FT-891 requires a dynamic mic, I use that version in this kit.

The Pro 7 is quite bulky and heavy - too much so for a field kit. The BM-17, however, is fairly compact and very light. That’s what I use in this field kit.

The Heil headsets use an adaptor to match the mic and audio connectors to the radio. The adaptors use a 1/4” jack for the PTT signal, and I use the Heil HS-2 hand switch in the field. The HS-2 is very comfortable and convenient but it’s also somewhat bulky and comes with a very long cord, which is inconvenient in the field. I could cut the cord down but a simpler, less expensive solution is a small DIY PTT switch made with a switch from Amazon, some silicone jacketed two conductor cable, and a 1/4” plug.