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Audio quality of 440mhz compared to 2m on HTs

Discussion in 'Ham Equipment' started by Moleculo, Jan 31, 2010.

  1. Moleculo

    Moleculo Administrator Staff Member

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    The other night I was talking to someone on my VX-8 HT on 440 simplex. He remarked that the audio quality sounded over driven and basically sounded bad. I have never monitored myself on 440 with the HT before, only 2m. So I flipped on my Yaesu FT-897D, put some headphones on and put it on the same 440 frequency to listen. I was surprised at how different the radio sounds on 440mhz compared to 2m, which has terrific audio. On 440, as soon is key the mic it sounds like gain is jacked way up, regardless of where I actually set the mic gain on the radio. The best way I can describe it is that it sounds "splatty". Also, when you turn on a CTCSS or DCS tone, it gets even worse. I can definitely hear the DCS underneath and the CTCSS affects it also.

    I'm wondering if anyone else has ever monitored themselves on both 2m & 440 from their HT and noticed much difference in the audio quality? Perhaps mine just needs to be sent in for a good alignment? Perhaps when I get time, I'll post an MP3 of the audio so you can hear it. I don't have another HT to test with right now, so I'm looking forward to hear your results.


     
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  2. GLR

    GLR Keeping It Good Natured

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    This is a new one to me. I don't have a VX-8 to try this with as I've moved entirely to the Chinese HT's but I've never had any issues at all. Look forward to hearing the audio.
     
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  3. Captain Kilowatt

    Captain Kilowatt Professional Amateur Staff Member

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    That's a new one on me too. I use a Kenwood TH-G71A dual bander and don't see any difference between the two bands. Does that rig have two different deviation adjustments,one for each band?
     
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  4. Moleculo

    Moleculo Administrator Staff Member

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    OK, here's the test clips. The output is run from the Yaesu FT-897 into a computer. The level is down a bit to prevent over driving the mic input, so you might have to turn your speakers up.

    What's weird is that I couldn't reproduce the same thing that I heard the other night. This clip actually sounds pretty good. Perhaps a couple of full battery charges and radio resets between then and now cleared up whatever was making the 440 side sound like garbage. I sure wish I had thought to record that so you guys could hear it...strangest thing ever.

    In this recording, you CAN hear the subaudible CTCSS and DCS stuff just underneath the voice. That's pretty strange.
     

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  5. Moleculo

    Moleculo Administrator Staff Member

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    Actually, yes it does...but that was the first thing I looked at when I first heard this.
     
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  6. bob85

    bob85 Supporting Member

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    its normal to hear other peoples tone when listening on some radios, not sure about the 897, did you have the 897 on narrow rx on all the samples?,

    when you first keyed with the tone on it sounds like a slow locking vco but it goes on to sound loose, im not sure it is the tone we can hear , it sounds like its wobulating, bass and deviation increase,

    when you put dcs on, bass and deviation step up significantly and the wobble gives a strange submarine sounding quality, i was expecting a sonar ping,

    you say its much better now than it was, does the radio temperature change the audio quality,

    i hope you can fix it,

    good luck.
     
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  7. KingCobra_CDX882

    KingCobra_CDX882 W9WDX Amateur Radio Club Member

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    Myself..
    I never noticed a difference using 2 meters verses 440..
    I use T90a, IC 91AD and THF6a..
    never had those issues with any of them
     
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  8. Moleculo

    Moleculo Administrator Staff Member

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    I had the 897d on standard FM on all the samples.

    Hmm...now that's an interesting question. I had been using the radio for a while, so maybe that's the cause? Bob, you're kind've hearing it the same way I do.
     
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  9. bob85

    bob85 Supporting Member

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    i just listened again because i saw you said it was low volume and it was loud here, i realised i had my sound volume manager turned on, i turned it off and it sounds about the same,
    i find it odd that your deviation climbs and bass too when its turned on but i dont hear the wobble in sympathy with your voice,
    it could be a quirk of how the 440mhz frequencies are synthesized/upmixed,
    i could be wrong but it sounds like something is wobbling the carrier not related to your voice and not a constant ctcss tone, i cant imagine the tone wobbling like that and still work opening repeaters but again i could be wrong,
    maybe vco voltage instability, dodgy battery/charger or a very wide audio bandwidth when the tone is switched on and something you cannot hear at your end getting into the modulator, the chirp when you key sounds like slow vco lock but i cant think offhand why it would do that only with the tone turned on,
    yep temperature can have a pretty big effect on handies,
    strange.
     
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  10. C2

    C2 Well-Known Member

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    My first thought was that it sounded the same for each band. You can definately hear distortion when tones are on.

    I also wondered about heat and suspected you did the test on cold start and the had the bad report after some talk time.
     
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