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speech compression on ssb

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Old 12-09-2012, 05:34 PM
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Question speech compression on ssb


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?

Last edited by Lil'Yeshua; 12-09-2012 at 05:36 PM. Reason: spell check


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Old 12-09-2012, 05:57 PM
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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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Old 12-09-2012, 06:41 PM
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Cool 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

Last edited by Lil'Yeshua; 12-09-2012 at 06:44 PM. Reason: spell check

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Old 12-09-2012, 07:02 PM
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Thumbs up a little compression

Quote:
Originally Posted by Captain Kilowatt View Post
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.
SSB Compression

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Old 12-09-2012, 07:20 PM
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Quote:
Originally Posted by Lil'Yeshua View Post
Still,compressing the audio signal will keep it from overmodulating
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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Old 12-09-2012, 07:28 PM
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Thumbs up 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.

Last edited by Lil'Yeshua; 12-09-2012 at 07:36 PM. Reason: spell correction

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Old 12-09-2012, 07:40 PM
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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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Old 12-09-2012, 08:11 PM
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Thumbs up compression

Quote:
Originally Posted by Robb View Post
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.
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

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