Trying to run a 2x8 on sideband an they say it sounds like I

[bigdoglbc]

I'm running a 2950 and 2x8 and my match on antenna is 1.0 and the match on 2x8 is 1.0 and that's with a antenna analyzer. So I have this issue just on ssb not on am, I thought it was the coax and made new ones and tested them with a meter solder was good. I even changed radio and no still the same. I do have to tell you that I'm running my rig on a rig 18 wheeler and I am running 4 batteries and my alternator is a 145amp. If there is any suggestions out there I'm willing to hear them.

[zygoma]

Since you changed radios already without noticeable effect, there's one more thing to check: Do you know how the radio(s) sound barefoot on SSB? If they're OK, then the only thing left is the amplifier.
That was actually already my first guess, as most amplifiers made for the CB market are horribly non-linear. And "linear" is what you need for your rapidly changing, narrowband AM signal (SSB) to not be squashed into mostly just one constant RF output level. Even with AM only, a typical CB amp isn't able to accurately change levels in concert with the input. What happens is that the input changes from maximum to minimum get averaged towards one level instead of tracking with the input, and the result sounds muddy because most of the accurate modulation has been sacrificed.
It doesn't matter if an amp has an AM/SSB switch in it; all they typically do is engage a delay so that the changeover relays in the amp don't drop out in between syllables, when the drive RF from the radio drops off.
Sadly, most inexpensive RF amps run in Class C, which is really only usable with FM. If you look at how much a ham amplifier for equivalent output as your 2x8 costs, and compare it with what you paid, you'll probably see a large disparity. Ham amps have to be able to handle AM, SSB, and CW and keep the output looking like just a larger version of the input (on a scope), and that kind of circuitry doesn't come cheap.

My suggestion is to just run barefoot when using SSB, and save the rockcrusher for AM.

Probably not what you wanted to hear, but sometimes physics is not our friend.

73

[MDYoungblood]

That is what it sounds like, the amp is not biased for SSB. You didn't say the brand amp you have and if it is brand new , call the manufacturer and get a repair form, mail it to them to have it fixed (biased) and you shouldn't have a problem anymore.

3's

Greg

[bigdoglbc]

Since you changed radios already without noticeable effect, there's one more thing to check: Do you know how the radio(s) sound barefoot on SSB? If they're OK, then the only thing left is the amplifier.
That was actually already my first guess, as most amplifiers made for the CB market are horribly non-linear. And "linear" is what you need for your rapidly changing, narrowband AM signal (SSB) to not be squashed into mostly just one constant RF output level. Even with AM only, a typical CB amp isn't able to accurately change levels in concert with the input. What happens is that the input changes from maximum to minimum get averaged towards one level instead of tracking with the input, and the result sounds muddy because most of the accurate modulation has been sacrificed.
It doesn't matter if an amp has an AM/SSB switch in it; all they typically do is engage a delay so that the changeover relays in the amp don't drop out in between syllables, when the drive RF from the radio drops off.
Sadly, most inexpensive RF amps run in Class C, which is really only usable with FM. If you look at how much a ham amplifier for equivalent output as your 2x8 costs, and compare it with what you paid, you'll probably see a large disparity. Ham amps have to be able to handle AM, SSB, and CW and keep the output looking like just a larger version of the input (on a scope), and that kind of circuitry doesn't come cheap.

My suggestion is to just run barefoot when using SSB, and save the rockcrusher for AM.

Probably not what you wanted to hear, but sometimes physics is not our friend.

73

Well I didn't mention was this amp is home made from somebody here in the LA area, but the thing is that I took it back to him and he put it back on the bench and he started transmitting with somebody and he was getting reports that it sounded great and it was load and all that good stuff. That why I mentioned the alternator maybe if it was to small or something else that it could be. I do appreciate all the in site and input.

[Night Crawler]

I took it back to him and he put it back on the bench and he started transmitting with somebody and he was getting reports that it sounded great.

Why don't you take it back again and let him put it on the bench this time you listen to it on another radio maybe it won't sound as great as he said.

[str8stroke]

I think I missed something here. Not sure.

['Doc]

He puts it on his bench and it sounds great? Try the same sort of test while in your vehicle instead of his bench. If it doesn't sound 'great' then you can safely make the bet that the problem is in your 'system'. Then the 'trick' is to find that problem and 'cure' it.
The most common cause of not sounding 'great' is because something is being 'over done'. The two most common 'over done' things are input power levels and audio levels. There's big differences between big power numbers and sounding 'great'...
- 'Doc

[bigdoglbc]

He puts it on his bench and it sounds great? Try the same sort of test while in your vehicle instead of his bench. If it doesn't sound 'great' then you can safely make the bet that the problem is in your 'system'. Then the 'trick' is to find that problem and 'cure' it.
The most common cause of not sounding 'great' is because something is being 'over done'. The two most common 'over done' things are input power levels and audio levels. There's big differences between big power numbers and sounding 'great'...
- 'Doc

Yea I now it's in my system that why I've taken it back to him and he's checked it and it transmits and he gets good reports while I'm there listening to these reports shaking my head. That's why I'm still pushing towards the alternator because it seems that I've done everything and changed everything to try and resolve this issue. The thing is that I don't want to make a big purchase like that because its a work truck not mine unless I know that's what it is. Another thing that I've even tried is going low on drive from my radio and going as high, went from 2.5 watts up to 8 watts drive and no change from the reports I got from a friend of mine in a near by city.

[Night Crawler]

I've taken it back to him and he's checked it and it transmits and he gets good reports while I'm there listening to these reports shaking my head.

Instead of listening to the reports from someone else telling him it sounds good why don't get out in your mobile about 5 or 10 miles from him have a conversation with him and see what it actually sounds like for yourself.

[jessejamesdallas]

He puts it on his bench and it sounds great? Try the same sort of test while in your vehicle instead of his bench. If it doesn't sound 'great' then you can safely make the bet that the problem is in your 'system'. Then the 'trick' is to find that problem and 'cure' it.
The most common cause of not sounding 'great' is because something is being 'over done'. The two most common 'over done' things are input power levels and audio levels. There's big differences between big power numbers and sounding 'great'...
- 'Doc

Yea I now it's in my system that why I've taken it back to him and he's checked it and it transmits and he gets good reports while I'm there listening to these reports shaking my head. That's why I'm still pushing towards the alternator because it seems that I've done everything and changed everything to try and resolve this issue. The thing is that I don't want to make a big purchase like that because its a work truck not mine unless I know that's what it is. Another thing that I've even tried is going low on drive from my radio and going as high, went from 2.5 watts up to 8 watts drive and no change from the reports I got from a friend of mine in a near by city.

First off...A 145 amp alternator even with 4 battery's, on a Big Rig is going to be pushing it to run a 2x8...

Since you said this is not your truck, instead of replacing the alternator with a bigger one, why not just get a Motor Maul? You could use the battery's you already have, and not have to up-grade the alternator...Plus, if you change trucks, you can take the Maul with you!

Now since you say the Amp sounds good on AM, just not good on SSB, I would say that's typical for most C Class Amps...Like pointed out earlier "the amp is not biased for SSB"...

You didn't say what kind of watts this 2x8 is doing, but on a Peak meter it should be doing at least 1500w's to 1800w. If not, then you probably just don't have enough juice to run it properly.

Another thing it could be is the radio...Either you don't have the SSB channels tuned in good when transmitting, or the radio needs to be tuned to frequency...May try a different radio with your set-up on SSB and see how it sounds.

[bigdoglbc]

Since you said this is not your truck, instead of replacing the alternator with a bigger one, why not just get a Motor Maul? You could use the battery's you already have, and not have to up-grade the alternator...Plus, if you change trucks, you can take the Maul with you!

Now since you say the Amp sounds good on AM, just not good on SSB, I would say that's typical for most C Class Amps...Like pointed out earlier "the amp is not biased for SSB"...

You didn't say what kind of watts this 2x8 is doing, but on a Peak meter it should be doing at least 1500w's to 1800w. If not, then you probably just don't have enough juice to run it properly.

Another thing it could be is the radio...Either you don't have the SSB channels tuned in good when transmitting, or the radio needs to be tuned to frequency...May try a different radio with your set-up on SSB and see how it sounds.[/quote]
What does a non bias amp mean? I do have a bird hooked up and on am it will dead key about 800 watts and it will swing backward about another 600. I've switched out with another 2950 and a cobra 148 and with both radios got the same results

[jessejamesdallas]

I do have a bird hooked up and on am it will dead key about 800 watts and it will swing backward about another 600. I've switched out with another 2950 and a cobra 148 and with both radios got the same results

There's your problem! Your radio's DK is set too high. You should be keying 200-250w's and swinging to 600-650 on a Bird...Lower your radios DK to 1 1/2 to 2w's and let it swing from there...IF the radios by itself swings more than 12-15w's your going to be sounding over modulated on SSB...

I know guys will run 40w radios with the same set-up, and sound just fine...ON AM! I have done the same thing too, and sound just fine on AM. But SSB is a different critter.

9 times out of 10, when you see a backward swing, it's because the DK on the radio is too high, and 800w DK on a Bird with that Amp is borderline disastrous...I'm surprised you haven't burned it up yet.

On my 16 pill, I only DK 600-800w's, and it's twice the Amp as what you have...I'm also assuming your running a stock 12v system (charging to 14v) If your volting the amp to over 16v's, your also looking for a melt-down in the near future...Amps with built-n driver stages don't like to be volted...The correct way to volt a Amp would be to have the driver Amp separate from the main Amp, then just volt the main Amp, and not the driver...Can't do that with a combo.

[bigdoglbc]

I do have a bird hooked up and on am it will dead key about 800 watts and it will swing backward about another 600. I've switched out with another 2950 and a cobra 148 and with both radios got the same results

There's your problem! Your radio's DK is set too high. You should be keying 200-250w's and swinging to 600-650 on a Bird...Lower your radios DK to 1 1/2 to 2w's and let it swing from there...IF the radios by itself swings more than 12-15w's your going to be sounding over modulated on SSB...

I know guys will run 40w radios with the same set-up, and sound just fine...ON AM! I have done the same thing too, and sound just fine on AM. But SSB is a different critter.

9 times out of 10, when you see a backward swing, it's because the DK on the radio is too high, and 800w DK on a Bird with that Amp is borderline disastrous...I'm surprised you haven't burned it up yet.

On my 16 pill, I only DK 600-800w's, and it's twice the Amp as what you have...I'm also assuming your running a stock 12v system (charging to 14v) If your volting the amp to over 16v's, your also looking for a melt-down in the near future...Amps with built-n driver stages don't like to be volted...The correct way to volt a Amp would be to have the driver Amp separate from the main Amp, then just volt the main Amp, and not the driver...Can't do that with a combo.

Ok so if I lower the radio dead key down even lower you say that might do the trick cause I'm dead keying 2.5 watts rite now? And if I do that what will it do to my AM side will I be dropping my watts that I'm putting out by dropping my radio to a 1.5 dead key. Yea standard charging system 14 volt

[jessejamesdallas]

Lowering the DK to 1w, or 1 1/2 will lower your DK with the Amp ON to 200-250w's with a forward swing to 600-650w's on the Bird...Which is normal output for a 2x8 @ 14v...Right now your driving the snot out of it!

One other thing, some radios you can't lower the DK to 1w or 1 1/2 because of their driver stage, if that's the case with your radio, you may need to find something like a stock Cobra 148, or Galaxy 959 or 979.

[bigdoglbc]

Lowering the DK to 1w, or 1 1/2 will lower your DK with the Amp ON to 200-250w's with a forward swing to 600-650w's on the Bird...Which is normal output for a 2x8 @ 14v...Right now your driving the snot out of it!

One other thing, some radios you can't lower the DK to 1w or 1 1/2 because of their driver stage, if that's the case with your radio, you may need to find something like a stock Cobra 148, or Galaxy 959 or 979.

Ok I have a cobra that I can try first and see what it does by dropping the drive to 1 or 1.5 drive I'll try that and ill keep you guys informed I do appreciate all you help 73"s

[jessejamesdallas]

Lowering the DK to 1w, or 1 1/2 will lower your DK with the Amp ON to 200-250w's with a forward swing to 600-650w's on the Bird...Which is normal output for a 2x8 @ 14v...Right now your driving the snot out of it!

One other thing, some radios you can't lower the DK to 1w or 1 1/2 because of their driver stage, if that's the case with your radio, you may need to find something like a stock Cobra 148, or Galaxy 959 or 979.

Ok I have a cobra that I can try first and see what it does by dropping the drive to 1 or 1.5 drive I'll try that and ill keep you guys informed I do appreciate all you help 73"s

Drop your DK on the radio to 1w or 1 1/2w...When you key the Mic, your meter should read just 1w or 1 1/2w's with the Amp turned OFF...Maybe hard to read on your Bird Meter that low, so if you have a peak meter you can use, it maybe easier to read...Don't trust the radios meter to give you a accurate DK...I know on some of my radios I have set at 2w's, the radios meter would say it was set at 3w's or higher, but my Dosy or Radio Shack meters would say 2w's...(or vice-versa)

[bigdoglbc]

Lowering the DK to 1w, or 1 1/2 will lower your DK with the Amp ON to 200-250w's with a forward swing to 600-650w's on the Bird...Which is normal output for a 2x8 @ 14v...Right now your driving the snot out of it!

One other thing, some radios you can't lower the DK to 1w or 1 1/2 because of their driver stage, if that's the case with your radio, you may need to find something like a stock Cobra 148, or Galaxy 959 or 979.

Ok I have a cobra that I can try first and see what it does by dropping the drive to 1 or 1.5 drive I'll try that and ill keep you guys informed I do appreciate all you help 73"s

Drop your DK on the radio to 1w or 1 1/2w...When you key the Mic, your meter should read just 1w or 1 1/2w's with the Amp turned OFF...Maybe hard to read on your Bird Meter that low, so if you have a peak meter you can use, it maybe easier to read...Don't trust the radios meter to give you a accurate DK...I know on some of my radios I have set at 2w's, the radios meter would say it was set at 3w's or higher, but my Dosy or Radio Shack meters would say 2w's...(or vice-versa)

Ill have the radio tuned down plus I have 5 watt slug that I shouldn't have any issue seeing it

[jessejamesdallas]

Lowering the DK to 1w, or 1 1/2 will lower your DK with the Amp ON to 200-250w's with a forward swing to 600-650w's on the Bird...Which is normal output for a 2x8 @ 14v...Right now your driving the snot out of it!

One other thing, some radios you can't lower the DK to 1w or 1 1/2 because of their driver stage, if that's the case with your radio, you may need to find something like a stock Cobra 148, or Galaxy 959 or 979.

Ok I have a cobra that I can try first and see what it does by dropping the drive to 1 or 1.5 drive I'll try that and ill keep you guys informed I do appreciate all you help 73"s

Drop your DK on the radio to 1w or 1 1/2w...When you key the Mic, your meter should read just 1w or 1 1/2w's with the Amp turned OFF...Maybe hard to read on your Bird Meter that low, so if you have a peak meter you can use, it maybe easier to read...Don't trust the radios meter to give you a accurate DK...I know on some of my radios I have set at 2w's, the radios meter would say it was set at 3w's or higher, but my Dosy or Radio Shack meters would say 2w's...(or vice-versa)

Ill have the radio tuned down plus I have 5 watt slug that I shouldn't have any issue seeing it

That'll work!

[Ohio_359]

You should be keying 200-250w's and swinging to 600-650 on a Bird

WOW, can you say HUGE over modulation?

That'll sound pinched on a peak reading Bird, but way over modulated on an average reading Bird.

[jessejamesdallas]

You should be keying 200-250w's and swinging to 600-650 on a Bird/quote]
WOW, can you say HUGE over modulation?

That'll sound pinched on a peak reading Bird, but way over modulated on an average reading Bird.

With the 2x8 turned ON, if his radio's DK is under 2w's, he should see 200-250w dk when the amp is ON whether it's a Bird meter or a peak meter...It should swing 600-650 on the Bird or 1500-1800 on a peak meter...But it also depends on the Amp. I have no idea what brand or how his 2x8 is built, so my numbers could be off...I'm going by my own results with Amps I've had in the past...200-250w DK could be high for his 2x8, but he said with a 2.5w DK from the radio, he was seeing a 800w DK with the Amp ON, and swinging backwards on the Bird 600w's!

So you want to talk about being "overmodulated?"

[Ohio_359]

All I'm saying is, 200 peaking 1800 is over modulated, but it's yours, run it like you like!

[Deleted User 14541]

"Trying to run a 2x8 on ssb and they say I sound like I ....." what? I may be missing it or maybe I just can't see the full thread title on my phone. What does it sound like?

Everyone has their own way but I deadkey a 4 pill @ 200 watts. I ran my 8 with a 400-500 watt carrier. If the amp is built right it should still swing foreword on an average (bird) meter....any way I thought we were talking ssb.

[bigdoglbc]

"Trying to run a 2x8 on ssb and they say I sound like I ....." what? I may be missing it or maybe I just can't see the full thread title on my phone. What does it sound like?

Everyone has their own way but I deadkey a 4 pill @ 200 watts. I ran my 8 with a 400-500 watt carrier. If the amp is built right it should still swing foreword on an average (bird) meter....any way I thought we were talking ssb.

Yea It got cut off I didn't know there was a limit but last part says (and they say I sound like I need power) like if you we're to be talking with you car turned of and you start to kill the battery that's what I sound like. But I sound like that with the truck on. And yea when I'm on sideband it does swing forward and it will show about over a 1000w on my bird with a 1000w slug. It when I'm on AM that I get the backward swing after the dead key when I start talking.

[bigdoglbc]

All I'm saying is, 200 peaking 1800 is over modulated, but it's yours, run it like you like!

We're would you run this rig if it was your I'm just trying to find a setting an this rig that I can talk on and it easy to see that what I've done has not worked cause I can't talk on this rig. So every word is greatly appreciated 73's

[Deleted User 14541]

"Trying to run a 2x8 on ssb and they say I sound like I ....." what? I may be missing it or maybe I just can't see the full thread title on my phone. What does it sound like?

Everyone has their own way but I deadkey a 4 pill @ 200 watts. I ran my 8 with a 400-500 watt carrier. If the amp is built right it should still swing foreword on an average (bird) meter....any way I thought we were talking ssb.

Yea It got cut off I didn't know there was a limit but last part says (and they say I sound like I need power) like if you we're to be talking with you car turned of and you start to kill the battery that's what I sound like. But I sound like that with the truck on. And yea when I'm on sideband it does swing forward and it will show about over a 1000w on my bird with a 1000w slug. It when I'm on AM that I get the backward swing after the dead key when I start talking.

Do you mean the audio is too quiet? Is there distortion or noise? I feel like I'm missing something. People have already diagnosed the problem before I knew the full complaint.

800 watts deadkey is excessive. Around 400 watts deadkey will be safe if the builder knew what he was doing. I've been using 50 watts per 2987 as a rule of thumb for max deadkey...opinions will vary. At that point you should have some foreword swing on the bird. If not make sure your radio isn't back swinging and causing it.

Originally you asked about ssb. The amp needs a ssb delay. The delay keeps the relay in the amp from chattering while you transmit on ssb.

Someone mentioned biasing. If you have the typical class c (no biasing) competition style amp you probably sound choppy on ssb. You can get away with class c on AM because the deadkey will turn on the pills. Since ssb has no deadkey you need some kind of bias circuit. It supplies current to the base of the transistors to keep them turned on as long as the amp is keyed.