YAESU FTM-400DR EXTERNAL SPEAKER THUMP

Discussion in 'General Technical Questions and Answers' started by KE9OL, Aug 16, 2018.

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  1. KE9OL

    KE9OL Premium Subscriber QRZ Page

    DOES ANYONE ELSE'S DR HAVE THIS PROBLEM?

    IS THERE A KNOWN FIX? HELP!

    MY DR HAS, SINCE NEW, HAD A SPEAKER THUMP WHEN THE SQUELCH CLOSES EVEN WITH THE VOLUME ALL THE WAY DOWN. IT ONLY HAPPENS WITH THE EXTERNAL SPEAKER CONNECTED - THE INTERNAL SPEAKER DOES NOT DO IT AT ALL BUT I EXPECT IT DOES NOT HAVE AS GOOD LO FREQ RESPONSE.

    I HAVE USED AFTERMARKET SPEAKERS AS WELL AS THE YAESU OPTIONAL ONE FOR THIS RADIO WHICH I AM READY TO SELL IF I CAN'T CURE THIS. I TRIED A HI VALUE CAP ACROSS THE SPEAKER WIRES WHICH HAD DECENT SUCCESS BUT DEGRADED THE AUDIO AND COULD POSSIBLY DAMAGE THE OUTPUT AMP?

    ANY COMMENTS/SUGGESTIONS WOULD BE HELPFUL PLEASE.

    TNX,

    TED.....................
    73
     
  2. KD4MOJ

    KD4MOJ Premium Subscriber QRZ Page

    Ted:
    Did you use the enclosed adapter for the external speaker? If not, the speaker might perform just as you described.

    ...DOUG
    KD4MOJ
     
  3. KG7FIU

    KG7FIU Ham Member QRZ Page

    Think you're already "on the right track" in noting that the internal speaker doesn't thump because it doesn't have a good low-freq response.

    Think all you would need to add in is a simple "hi-pass" audio filter circuit, with the cutoff freq. determined by experiment. Enough to get rid of the thump, but not too much to take away from the intelligibility of the audio.

    Perhaps there's an inexpensive commercial solution available -- perhaps you could even place an inline unit in-between the radio and the speaker.
     
    Last edited: Aug 16, 2018
  4. KD4MOJ

    KD4MOJ Premium Subscriber QRZ Page

    From the 400XDR manual, Page 167:

    upload_2018-8-16_13-55-10.png



    ...DOUG
    KD4MOJ
     
  5. KE9OL

    KE9OL Premium Subscriber QRZ Page

    THANKS DOUG,

    I FORGOT TO MENTION IN THE POST THAT I HAVE USED THE INCLUDED ADAPTER WITH MY MONO EXT SPEAKERS. I USED A PAIR OF UN-AMPLIFIED COMPUTER SPEAKERS WITH A STEREO PLUG (OBVIOUSLY) WITHOUT THE ADAPTER AND THE PROBLEM GOT A LOT BETTER. (NEARLY IMPERCEPTIBLE) BASED ON THIS I (FOOLISHLY) BOUGHT THE YAESU OPTIONAL EXT SPEAKER FOR THIS RADIO ONLY TO FIND MYSELF RIGHT BACK WHERE I STARTED. I ASSUME THE CHEAP COMPUTER SPEAKERS HAVE POOR LO FREQ RESPONSE AS WELL. I MIGHT GO BACK TO USING THEM AFTER I CHECK THEM OUT FOR A WHILE AND THEY DON'T HAVE THEIR OWN PROBLEMS.

    NOW I'M REALLY UPSET, I CAN'T BELIEVE YAESU WOULD LET SUCH A DESIGN FLAW AS THIS OUT. UNLESS, OF COURSE, IT'S ONLY MY RADIO WITH A SPECIFIC FAILURE. IF THAT'S NOT THE CASE I MIGHT SELL THE RADIO BECAUSE I'M SO UPSET. I CAN'T USE THE INTERNAL SPEAKER BECAUSE I HAVE THE RADIO MOUNTED UNDER MY BENCH, AND I SURE DON'T WANT TO PUT THE GIANT CAP BACK ON THE EXT SPKR.

    REGARDS,

    TED..............
    73
     
  6. KE9OL

    KE9OL Premium Subscriber QRZ Page

    THANKS JOHN,

    THAT'S WHY I WAS HOPING IT IS A KNOWN PROBLEM WITH FIX...SO I DON'T HAVE TO DO THE WORK OF DESIGNING SOMETHING. ;)

    REGARDS,

    TED......................
    73
     
  7. KA9JLM

    KA9JLM Ham Member QRZ Page

    Add a speaker level to line level attenuator.

    The amplified speakers do not want speaker level in.
     
  8. KE9OL

    KE9OL Premium Subscriber QRZ Page

    I DON'T UNDERSTAND...NONE OF THE EXT SPEAKERS I'VE TRIED ARE AMPLIFIED. :confused:
     
  9. KA9JLM

    KA9JLM Ham Member QRZ Page

    OK. My mistake. Your ALL CAPS MADE ME READ IT WRONG.

    You want a cap in series to get rid of the DC pop.
     
    Last edited: Aug 17, 2018
  10. KE9OL

    KE9OL Premium Subscriber QRZ Page

    the thump in question is low in frequency...but i don't think that low. o_O
     

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