FT-891 Home Brew Separation kit

Discussion in 'Ham Radio Discussions' started by WE1K, Mar 15, 2018.

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  1. WE1K

    WE1K Ham Member QRZ Page

    I'm getting ready to order a Yaesu Ft-891 for the mobile and am looking for some info on the Yaesu YSK-891 separation kit interconnects. I'd like to avoid buying it as I dont need the mounting bracket, speaker extension or mic extension. Can anyone tell me what the connector is for the control head and how many conductors it has? On my Ft-857 it looks like a 6 conductor telephone style connector.

    Can anyone confirm that this is the same on the FT-891?
  2. AC2FB

    AC2FB Premium Subscriber QRZ Page

    The control head connector is an RJ12. The factory extension kit utilizes 26ga, 6 wire. The mic connector is RJ11, using 8 wires. Both cables utilize "straight through" wiring. I can't recommend paying full price for the factory extension kit, that's absurd. Check Monoprice for the parts you want, you can even get cable in different colors. I did just that and made my own custom length extension kit.

    However - You may get an increased noise floor - hiss - on the headset port, as well as amplified clicking noise when operating any portion of the radio. See my other post about noise on the 891. Amplified, as in some people can hear a noise with a headset or external speaker, this can get worse/louder when the control head is extended. You may have different results, I would be highly interested if you do.

    Best of luck to you.
  3. WE1K

    WE1K Ham Member QRZ Page

    Well I went ahead and installed the 891 in the mobile. I used a 4 foot, 6 conductor RJ12 for the control head and a 4 foot, CAT5 cable for the mic (maybe CAT6...its the shielded version). I havent noticed any additional noise or increased noise floor. Im using an external Yaesu speaker. Seems to work good.

    My next challenge is to change the factory supplied power wiring to a larger gauge. The voltage drop is enough that the radio restarts during starting the car. My Ft-857D never did this in this vehicle. Specs in the manuals both call for 13.8V +-15%.
  4. K4PDM

    K4PDM Ham Member QRZ Page

    I have always read that you should not have a radio turned on when starting your vehicle due to voltage spikes/transients when the starter is cranking.

    I'm not saying I've never done it...but I don't do it very often!
    ND6M likes this.
  5. WE1K

    WE1K Ham Member QRZ Page

    I agree on the potential problems during start up. Im just trying to find a happy medium with respect to starting the vehicle and the radios being on as Im in and out of the vehicle often during the course of my work day. Perhaps I turn the HF rig on/off as I get in/out of the car...I wonder if that causes undue stress/wear on the radio. Still strikes me as odd that the 857 never restarted during starting the car...same set-up and all. My 2m rig and 440 DMR dont seem bothered by voltage fluctuations during startup.

    Someone had mentioned a capacitor inline as a way to minimize voltage drops.
  6. N5NXZ

    N5NXZ Ham Member QRZ Page

    None of my other radios restart during startup either, only my 891. I just turn it off.
  7. WE1K

    WE1K Ham Member QRZ Page

    Interesting. I’m glad to know it’s not just me. I wonder if there’s a minimum voltage shut off hidden in the menus somewhere. Probably a long shot tho.
  8. AC2FB

    AC2FB Premium Subscriber QRZ Page

    Yes, the radio shuts off with low voltage, but that's not adjustable in any menu. It sounds like a voltage sensing relay, you can hear it come on when using a variable power supply and turning up from zero, when the radio is off. It's a self protection method so it doesn't have a little radio heart attack and die. Just turn it off each time. Much less wear and tear than under-volting. The voltage drop is likely at the battery, changing the wire may not help. Can you test at the battery during startup?

    For an upgraded power wire, I used 10AWG wire and double fused near the battery connection. You can get a new 4 plug connector through eBay, or through Powerwerx:


    I used their crimp in line fuse holders as well:


    Crimped everything and heat shrink, only small bit of solder at the radio plug. Heat shrink over the connections, then a larger 3-1 shrink over the end of the fuse holder to the wire.

    To note, the factory uses 12awg wire to near the plug, then splits to two wires, so the radio has 2 positive and two negative connections. I went from 10awg to two 12awg for about 1 1/2 inches as 10awg does not fit the 4 pole connector. Use a bit of the factory wire, or just splice in the connector before the split.

    I have not measured a pull of more than 18A, even though Yaesu states 22A max. Happy wiring.
  9. WE1K

    WE1K Ham Member QRZ Page

    Well, I replaced the factory 12AWG with 10AWG. No difference, was hoping that a lessened voltage drop would make the difference needed, even though its about 1/3 of a volt.

    I have heard the relay, and if its what you think it is, its probably ok to start the car with the radio on as it probably only contacts when the radio sees the proper voltage. That said, Ill probably just do the on/off thing.
  10. 4Z1ZV

    4Z1ZV Ham Member QRZ Page

    Consider adding a boot (step up) DC-DC inverter to 13.6V.

    This will keep your radio running during startup and have full power output when the engine is off and battery voltage is even below 12V.

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