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speech compression on ssb

Discussion in 'CB and Export Equipment and Accessories' started by Lil'Yeshua, Dec 10, 2012.

  1. Lil'Yeshua

    Lil'Yeshua The Great Link Poster

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    Hey guys! While my Galaxy DX-959 is due to be at DTB Radios soon for a tune up and align/mods,I still have my K40 Speech Processor Mic that I bought new 28 years ago and still functions and has been in storage twenty-five years. I've been thinking that instead of using my RF Limited 2018 mic on ssb,I'm thinking about using my K40 mic instead. My thoughts about the Top Gun Compressor circuit and the K40 compressor circuit would work in similar ways. The K40 is not as loud as the 2018. So guys,what are your thoughts about compressing the audio on ssb?:pop:


     
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  2. Captain Kilowatt

    Captain Kilowatt Professional Amateur Staff Member

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    A little compression on SSB works great. Cranking compression and mic gain settings up too far results in crap. It is NOT a case where if a little is good then a lot is better. I almost always use a little compression on SSB on the HF ham bands.
     
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  3. Lil'Yeshua

    Lil'Yeshua The Great Link Poster

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    a little compression

    I can see that. I've noticed on my Galaxy DX-959 that you have to keep the radio's mic gain up full in order to have sufficient power to transmsit a good signal. My radio is on the way to DTB to get tuned and aligned with transmit,receive mods as well as a Viagra board install and open the clarifier. Before this I had the ssb alc turned to the 7:30 position('O' on top of pot knob side facing me)per Galaxy Tech's instructions. How ever,that setting along with a amc pot turned all the way up made the meter light dim greatly on full modulation. I will have to familiarise myself with just how much modulation to use when doing ssb. I trust that when I get the radio back from DTB,he will have it set properly. Note:I'm not getting a swing mod done to this radio. Still,compressing the audio signal will keep it from overmodulating (y)
     
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  4. Lil'Yeshua

    Lil'Yeshua The Great Link Poster

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    a little compression

    :pop:
    SSB Compression
     
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  5. Captain Kilowatt

    Captain Kilowatt Professional Amateur Staff Member

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    Not necessarily. Compressing the audio simply lowers the peak to average ratio thus boosting the overall audio level as perceived by the listener and raises the average power output as observed on a meter or oscilloscope. It does not guarantee that the radio will not be over modulated. In fact if audio levels are set too high and a lot of compression is used severe flat-topping and carrier cut off can occur due to the radio's RF amp not being able to produce what it is being asked to do and the result is splatter. In the broadcast biz we ran several Db of compression on the AM transmitters and set the mod levels using an oscilloscope. It was easy to overdrive the transmitter to far beyond 100% negative modulation.
     
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  6. Lil'Yeshua

    Lil'Yeshua The Great Link Poster

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    clipping

    So,that leads me to believe that if you keep the modulation near 100% and maybe having a swing mod,that will keep it from distorting? Does. The swing mod work on ssb as well? I'm new to these formulas but am a fast learner. (y)
     
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  7. Robb

    Robb Yup

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    That 959 doesn't need a swing mod - IMO.
    Just peaking the TX coils is more than enough to make it a solid talker on AM.

    When compression is used on AM with/at 100% modulation, it will give a higher average power output. Anything done to a radio that makes it go past the design specs is going to be hard to control and runs the risk to make the radio sound crappy. DTB will do anything for your radio that you ask him. But if you asked him what he would recommend, I'll bet the swing mod isn't on that list.

    No; a swing mod only works on AM.
    Bad medicine/juju . . .
    Adding a Top Gun compressor could be done though - works on both AM and SSB.
     
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  8. Lil'Yeshua

    Lil'Yeshua The Great Link Poster

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    compression

    DTB is doing the transmit upgrade mod and the receive mod as well as opening the clarifier,installing a Viagra board,and tune,alignment. I want him to make it a perfectly functioning radio as far as a Galaxy can be made to perform. And no,I'm not having a swing mod done. I'm thinking about using my K40 Speech Processor mic mainly on ssb. W4NEQ SSB audio
    :pop:
     
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  9. Lil'Yeshua

    Lil'Yeshua The Great Link Poster

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    alc+Compression

    I'm thinking that the CR577 mic along with a compression circuit along with a properly set ssb alc will allow you the best results. HamRadioAndVision - How To Use An ALC Meter (y)
     
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  10. Lil'Yeshua

    Lil'Yeshua The Great Link Poster

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  11. Robb

    Robb Yup

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    TGT Modulation Control

    About ~$15 and easy to install.

    The same compressor that is used/installed in many Magnum radios.
     
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  12. Lil'Yeshua

    Lil'Yeshua The Great Link Poster

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  13. Lil'Yeshua

    Lil'Yeshua The Great Link Poster

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    Thanks! Would that mess up DTB's work done to my radio?
     
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  14. Robb

    Robb Yup

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    Nope.
    Ask him about putting the Top Gun Compressor (affects AM & SSB) and Top Gun Modulator (affects AM) in your radio if you want to go that far with your radio . . .
     
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  15. Lil'Yeshua

    Lil'Yeshua The Great Link Poster

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    lions and tigers and bears,oh my!

    I'll check into that. I'll have to rename my 959 as KING KONG:eek:
     
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