Yaesu 857D Receiver is Intermittent

Discussion in 'General Technical Questions and Answers' started by N0BAA, Apr 5, 2021.

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  1. N0BAA

    N0BAA Ham Member QRZ Page

    Hopefully this isn't in the wrong place I don't know how to use these forums. My 857 receiver doesn't seem to work. Maybe I have something wrong in the settings. After power on it doesn't receive and then after maybe 5 to 10 seconds it comes on but is very choppy. It eventually comes on fully and is fine (I think) for a little bit but is still rarely intermittent. After transmit is will lose rx for the same period of time that the startup caused. Any thoughts on what I should do? I know something is gonna need to be fixed or replaced so I need to learn how to do it myself because I don't think Yaesu will fix it and If they do I think its gonna really cost me. Oh I should say I dont use it often and when I do its portable. Thanks for the help.
     
  2. W1NB

    W1NB XML Subscriber QRZ Page

    Benjamin,
    When the receive cuts out are you still seeing signal indication on the S meter?
     
  3. N2PQW

    N2PQW Ham Member QRZ Page

    When trying to solve a problem like this, there is SOOO much more information that is needed to make an informed judgement. You are the only one at the controls, so please don't be insulted if you get suggestions that seem overly simplistic. We can't tell what you know, or what steps you have already taken.

    That's my disclaimer.

    Here's the things I would suggest that you look at first, before you ship the radio back to Yaesu.

    Is your power supply providing full power to the radio? The voltage should be displayed on the screen:
    FT-857 Panel Supply Voltage.png
    Generally, if it is less than 11.5V, you should do what's necessary to make sure it's at least 12.0V
    (from the manual: Supply Voltage: Normal: 13.8 VDC ±15 % [11.7V to 15.8V] )

    The next thing to check, and what I believe is the root cause here, is the setting of the SQUELCH.
    FT-857 Manual pg 38 Squelch Operation.png
    Honestly, what you described sounds to me like the SQUELCH is partially engaged, and the signal level is not always strong enough to overcome the SQUELCH setting level. Just make sure that the SQUELCH is set fully Counter-Clockwise, or turned to the LEFT, and see if the receiver is now wide open.
    Note this comment from the manual:
    "In the FM and Packet modes, with “RF Gain” selected, the FT-857D goes into an “Auto Squelch” mode, with the Squelch level being preset at the factory."

    Best of luck, let us know what you find out.

    Cheers,
    David / N2PQW
     
    Last edited: Apr 5, 2021
  4. N0BAA

    N0BAA Ham Member QRZ Page

    No. My noise floor here is about s7 on the scale and when it cuts out it goes to nothing and to hear static I need to crank the volume up to about 75-90% to get it audible again.
     
  5. N0BAA

    N0BAA Ham Member QRZ Page

    Thanks for the reply David. It is not a squelch problem. The receiver just seems to die. I have the knob set to RF gain. There is still audio (static) when the receiver cuts out its just extremely faint. If anyone wants me to I can record a video of what is happening. I dont know where I would post it though. Oh and my radio is getting a good voltage. About 13.5v
     
    N2PQW likes this.
  6. WR3V

    WR3V Ham Member QRZ Page

    External speaker jack wonky?
     
  7. N0BAA

    N0BAA Ham Member QRZ Page

    Oh one very important thing I completely forgot to mention is I think the receiver is fine on air band, 2m, and 70cm. It doesn't seem to have problems. This is entirely on HF and 6m. The FM broadcast band I think is also affected. I can hear the stations but there extremely weak so Im gonna say the problem is there too. Its too bad my signal generator is broken it would make this much easier lol.
     
  8. N0BAA

    N0BAA Ham Member QRZ Page

    I am using the internal speaker. It works fine like if I tune to air band the S meter moves and I can hear stations nice and clear.
     
  9. N2PQW

    N2PQW Ham Member QRZ Page

    Well, if it weren't for the FM Broadcast band problem, I'd say the issue could most likely be an antenna connection that is intermittent. I say this because of the separation between the antenna ports of the radio. HF/6m having trouble, but VHF/UHF works as it should.
    Are you certain about FM Broadcast being intermittent, also?

    Another combination of questions usually asked during diagnosis:
    • Was it working ok before, or did you just receive this radio with this problem? (I know, you wrote that you have used it as a portable setup, but it's part of the usual questions.)
    • When did it start to malfunction?
    • What event has happened or situation has changed since it was last known to be working well?
    Cheers,
    David / N2PQW
     
  10. SM0GLD

    SM0GLD Ham Member QRZ Page

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