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Ssb audio distorted when using amplifier

Discussion in 'CB and Export Equipment and Accessories' started by Damo666, Feb 13, 2009.

  1. Damo666

    Damo666 Member

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    Hi guys. I am having some problems. When i use my radio with no amp in use on ssb my audio is a good q5 according to everyone i request reports from. However, when i attach my amplifier everybody says the audio is very scratchy and darlicky and generally crap. I've altered the gain on my mic and even lowered the drive power, but people say it sounds terrible. Can anybody assist please? I'd be very grateful for any feedback.


     
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  2. EDUK8TR

    EDUK8TR Administrator

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    With the amp on or Off?

    If on, is the amp biased for SSB (Class B or AB) or is it a Class C amp?
     
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  3. Moleculo

    Moleculo Administrator Staff Member

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    What amp and what radio. And what Eduk8tr said...we need a few more details.
     
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  4. park

    park Active Member

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    RF ??
     
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  5. TonyV225

    TonyV225 Supporting Member

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    Could be RF feeding back into audio section dirty amplifer but more info would help class of amp A/B biased?
     
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  6. Damo666

    Damo666 Member

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    Thanks for the numerous responses. The amp is a zetagi b47. I don't know what class it is, but there's a schematic on the cb tricks website. The audio is perfect when the amp is off, but awful when switched on. By the way, there's a ssb/am switch. I've tried it switched both ways. Cheers.
     
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  7. hookedon6

    hookedon6 W9WDX Amateur Radio Club Member

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    i think you're gona get smacked real hard on that "other " forum:eek::eek:

    zetagi burner:confused:
     
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  8. Moleculo

    Moleculo Administrator Staff Member

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    what radio?
     
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  9. EDUK8TR

    EDUK8TR Administrator

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    Ok. If the amp has a SSB switch it is probably biased for that mode. I'm kinda with Tony up to this point. Sounds like an RF feedback issue which could be remedied with some proper grounding and a check on how good a ground you have on the antenna install. I had the same issue once in a previous mobile install and the extra grounding took care of the issue.
     
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  10. Damo666

    Damo666 Member

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    the audio is perfect on fm and am with the amp, and it's also good on ssb without the amp switched on. I use a 1/2 wave basic vertical. Suggestions as to grounding my system would be appreciated. Would joining a wire from the bracket of my antenna into the garden help do you think? I'm willing to give anything a try to eliminate this problem. Cheers again.
     
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  11. Moleculo

    Moleculo Administrator Staff Member

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    First, let me preface this by saying that I'm not that great at reading schematics...

    ...but I just looked at the schematic for that amp and it looks like a class C amp to me. It's using FETs and I'm not very familiar with amplifier design with them. Perhaps someone else can look at the schematic who is better than me. The SSB switch on the schematic is clearly just switching a capacitor inline with the relay to keep the relay from chattering in SSB mode.

    If it's a class C amp, you're going to have this problem on ssb. You still didn't say what radio you're using.
     
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  12. Damo666

    Damo666 Member

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    cheers for the reply. I also noticed that all the ssb switch does is switch in a cap. I'm using a Superstar 3900 turned down to 4 watts on fm/4 watts pep on ssb. Can anybody else confirm that this amp is unsuitable by viewing the schematic please? Cheers.
     
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  13. 9C1Driver

    9C1Driver Well-Known Member

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    Is this a base or mobile? How are both units being powered? Running both on too small a power supply or the amp on small feed wire and a week battery can cause what you are seeing.
     
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  14. Damo666

    Damo666 Member

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    I'm base. I'm running the radio and burner from the same battery. And the power cable is rated at 10 amps. I'm beginning to think that the amp circuitry isn't designed for ssb, even though a ssb switch is on the unit. Have you had a look at the schematic?
     
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  15. 9C1Driver

    9C1Driver Well-Known Member

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    I think you are drawing too much from the battery when the amp is in-line and turned on. If you starve an amplifier it will sound like crap. Buy a decent power supply and go that route. My money says thats your problem. I did a google search on your zetig amplifier, it has a SSB delay so it will work on SSB.
     
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