My love of the FT-891 is waning...

Discussion in 'General Technical Questions and Answers' started by N5NXZ, Jul 19, 2017.

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  1. N5NXZ

    N5NXZ Ham Member QRZ Page

    So I am experiencing a new issue with my FT-891. I have noticed over the last week that the noise floor is terrible. It is sitting anywhere from s8 to s9+. I live in the middle of no where and usually have nearly zero noise. I had attributed this to the solar flare or whatever but I noticed that if I key the mic, even for a second, the noise level drops back down to normal. More than that, if i'm running digital I see nothing but noise on my water fall and then I either call CQ or just bump the PTT button and the noise disappears and the waterfall is full of signals again. Please tell me I have messed up a setting or something. I have tried changing the AGC to slow/mid/fast/auto, I have tried turning the AGC off because i've read it should be off when running digital. I see this behavior no matter what setting I have the AGC set to. All AGC delay settings are set to factory default. After I bump the PTT and everything is normal it will receive fine for about 20 or 30 minutes and then the noise creeps up until I key it again. I really don't know if its been like this since day one or if I have just noticed it because i've been watching my station receive remotely from work and don't transmit much from work (because i'm working, in case anybody asks :) ). I tried a full reset, Upgraded to firmware V1.06 because I had V1.02. No change. Is anyone else seeing this behavior in the FT-891?

     
  2. AF6LJ

    AF6LJ Ham Member QRZ Page

    What is the noise level with the antenna disconnected??
     
  3. K8ERV

    K8ERV Ham Member QRZ Page

    Antenna?

    TOM K8ERV Montrose Colo
     
  4. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    Sounds like it "could" be static charge building up over time, and when you bump the TX on even for a second, that shorts out the charge and relieves the noise until it builds up again.

    To check this theory (and that's all it is!), try using a coaxial "T" adapter with one connection to your antenna, one connection to the rig, and one connection to a PL-259 having a 10K Ohm, 2 Watt carbon film resistor soldered inside, from center pin to ground (body of connector), thus placing a 10K resistor directly across your feedline at all times.

    If it's static charge, that should disspate it and your noise level will drop.

    An RF choke like a 1 mH or so in lieu of the resistor should do the same thing.

    A "DC shorted" antenna like a closed loop (and many other designs) often solves a static buildup problem, if that's what it is.
     
    AF6LJ likes this.
  5. K8ERV

    K8ERV Ham Member QRZ Page

    Now you are being helpful. I didn't know that was allowed-----

    TOM K8ERV Montrose Colo
     
    KF5RRF, KD4MOJ and AF6LJ like this.
  6. AF6LJ

    AF6LJ Ham Member QRZ Page

    That is a good suggestion.
    If you don't or can't do the above get a coaxial T fitting and use a screw driver or a pair of needle nose pliers to temperately short the center conductor to the outer shell and see of the noise goes away and builds back up.
    If that is the case then you need to change the antenna you are using to one that presents a DC short to the transmission line.
     
  7. N5NXZ

    N5NXZ Ham Member QRZ Page

    I am running a center fed dipole. I'll test the noise with the antenna disconnected. I will also try to find a T connector (not many ham radio stores close by, though i think the truck stop near by has some with the 11 meter things...) I'll report back.
     
    AF6LJ likes this.
  8. AD0MI

    AD0MI Ham Member QRZ Page

    it might also be worth factory defaulting your radio if you aren't sure you have settings set back the way they should be.
     
  9. N5NXZ

    N5NXZ Ham Member QRZ Page

    Thanks for the suggestion, I started with a factory reset and then another reset after I flashed it to the latest firmware.
     
  10. AD0MI

    AD0MI Ham Member QRZ Page

    you're right, I missed that in your first post, my bad! Hope you get it resolved, I think the others have you on the right track.
     

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