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Thread: Linears and SSB

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    Linears and SSB

    I've tried using two different mobile boxes on single side band, and they both sound like absolute garbage on SSB. A fatboy and one from RM Italy both sound good on AM, but flip them to SSB and it sounds over-modulated, off frequency, and like it wants to cut out between words even though the relays aren't kicking off. I did check to make sure that they were actually set to SSB so I was not sending an SSB signal through a box set to AM. Turn the linear off altogether and the radio by itself on SSB sounds crystal clear.

    Do most linears sound bad on single side band?

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    By the way I'm referring to transmit. I can still hear just fine on SSB, but when I had my wife talk on the base and got in my truck and drove down the road to do a test, that's when I found out what it sounded like on SSB with the box on. Turn the box off, no issues whatsoever.

    I drove a quarter mile or so away to avoid issues with me being too close to the antenna.

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    What class amps are they, bias a/b, b or class c. If they are class c amps they will sound bad on ssb. You need an amp with at least that is class b at least to run ssb. Check out xforce or TNT or Davemade, heck fat boy should know how to bias the amp for ssb use. But that is what it sounds like to me. Clean in equals clean out . Add a dirty signal anywhere in between will make for a dirty amplified signal. Most likely class c amps.
    Any way to open the amps and get a couple of photos of the inside, or at least a photo of the amps in question. Again I will say this, I would not use a class c bias amp as the signal is dirty, class b is normally the minimum that works on ssb, class a/b being even better. Some of the older palomar amps had a/b stamped on them but I don't know if they were real class a/b amps. If you have and bought the fatboy amp new, send it back and ask for the amp to have the bias properly set for ssb use. I use a magnaforce 350hd 2 transistor amp that was made by xforce a while back. It's a class b bias amp. Works well for ssb use and in have been told several times it sounds like a rolling base station. Go anything below class b and they sound like garbage on ssb. Send that fat boy amp back and ask for something that will work on ssb or send the amp to a good amp builder and let him properly bias the amp for at least class b operation, a/b would even be better, you may not see the same watts as the class c amp, but the output signal is cleaner. And like I said clean in equals clean out. Hope this helps and you get everything straightened out. God bless.

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    Quote Originally Posted by 222DBFL View Post
    What class amps are they, bias a/b, b or class c. If they are class c amps they will sound bad on ssb. You need an amp with at least that is class b at least to run ssb. Check out xforce or TNT or Davemade, heck fat boy should know how to bias the amp for ssb use. But that is what it sounds like to me. Clean in equals clean out . Add a dirty signal anywhere in between will make for a dirty amplified signal. Most likely class c amps.
    Any way to open the amps and get a couple of photos of the inside, or at least a photo of the amps in question. Again I will say this, I would not use a class c bias amp as the signal is dirty, class b is normally the minimum that works on ssb, class a/b being even better. Some of the older palomar amps had a/b stamped on them but I don't know if they were real class a/b amps. If you have and bought the fatboy amp new, send it back and ask for the amp to have the bias properly set for ssb use. I use a magnaforce 350hd 2 transistor amp that was made by xforce a while back. It's a class b bias amp. Works well for ssb use and in have been told several times it sounds like a rolling base station. Go anything below class b and they sound like garbage on ssb. Send that fat boy amp back and ask for something that will work on ssb or send the amp to a good amp builder and let him properly bias the amp for at least class b operation, a/b would even be better, you may not see the same watts as the class c amp, but the output signal is cleaner. And like I said clean in equals clean out. Hope this helps and you get everything straightened out. God bless.
    I'm borrowing this one from a friend who is letting me use it, and he never uses SSB, he's just an old man who talks on AM and told me to keep it and use it until he needed it again. I will open it up however and take a picture of the guts for you to see if you can learn anything about it. I don't know much about them. Will try to get the pic up later this evening I'm about to head out the door. Thanks for getting back to me.

    I don't "know" that this is a Fatboy. He said it was, and it is in a silver box like most of the other Fatboy amps I've seen, but it doesn't say Fatboy on it, so I'm not certain.

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    If it doesn't have more than 1 switch then it probably doesn't work on ssb, normally a 2nd switch is added for ssb delay. Don't know if that helps, but I am pretty sure that ssb delay is an add on for most amps like that. More work involved. When you key up is there a delay? That's another way to tell if the amp has an ssb delay listen to it when you key up it should click or I should say you can hear the relay kicking in for ssb delay

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    Quote Originally Posted by 222DBFL View Post
    If it doesn't have more than 1 switch then it probably doesn't work on ssb, normally a 2nd switch is added for ssb delay. Don't know if that helps, but I am pretty sure that ssb delay is an add on for most amps like that. More work involved. When you key up is there a delay? That's another way to tell if the amp has an ssb delay listen to it when you key up it should click or I should say you can hear the relay kicking in for ssb delay
    There's two switches, un-labeled. One turns the unit on, the other introduces a delay in the relays kicking out when you let off the key. I figured the side with the delay is for SSB. Also if you put it in the other position and talk on SSB the relays kick in and out constantly, pop pop pop pop.

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    Okay then it does have ssb. Open it up and check for any burnt resistors. It may need to be re tuned. How many transistors does it have? There are a lot of variables, it may be being over driven or under powered, as in the size wire being used to the battery. Too many variables, take some photos of the radios used and the amp In question. This way at Least I can see what is what. Thanks and I will try to help as much as possible

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    and also a quarter mile is too close, I would drive at least 10 miles away and try it, I can't run my 2 transistor amp locally as the guys around me get blown away and it will make you seem over modulated as well.

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    FYI, there is more to making an amp sound good on SSB,more than putting in a relay switch. Internal works needs to be done to the Biasing. Alot of amp builder just put the switch and call it ready for SSB, doesn't work that way.
    RCI-2950DX, 1978 Cobra 148 GTL Taiwan, SHURE526T MIC, Tug-8 With Astatic 10 DA Head, Astatic 575M6, ASTRON 70/20 AMP POWER SUPPLIES, IMAX 2000 W GROUND PLANE KIT. TIMES MICROWAVE LMR-400 COAX, RF CHOKES. DIAMOND SWR/POWER INLINE METER. 250 of Sea Level Under Me. Recent World Radio Member.

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  12. #10
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    Believe me i know that. Didn't know if the amp had ssb from the 1st post, was trying to help him out, but there may be nothing wrong with the setup, I think he needs to get further than a 1/4 mile from the house and get an audio check with an amp on. There is a lot of work that goes into making a proper amp for use on ssb, you are indeed correct, and there are not many amp builders that can do it right.

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