If you run SSB stay away from the class c comp boxes.
73
Jeff
73
Jeff
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Amplifier recommendations.
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Any builder worth his salt can bias a class C amp. Most just copy and paste a poor unregulated bias circuit. It's no worse than the Texas Star though.
Comp amps work good enough on SSB. Xforce makes a special amp TNT for SSB class AB I think? People say that class C sounds bad on SSB but how bad? I can't understand a quarter of the guys on AM as it is. Hell I can't understand many people when they talk to me face to face.
This argument has been going on forever.
If you listen to a amp that is biased class c while working SSB and then listen to a amp with proper bias you can tell the difference.
I can, I know others that can.
It has to do with the threshold of the transistors turning on and off.
In class c the transistor is basically turned off.
This is not so bad on carrier modes like AM or FM, but on SSB it can cause a problem.
Back in the day my little brother could tell if I was using my Modulator as soon as I spoke a few words.
One time on 10 meters I was playing with a Boomer 400 style amp that had the bias hooked up but it was still not quite right, and other guys could tell that just by listening to my voice on SSB.
Once you do a side by side comparison on the air you will recognise the sound...almost crunchy sounding.
It also adds to IMD products.
There is a difference.
And I agree that the set up that Texas Star is not the best, but it is better than nothing, or even worse class c.
I have seen some amps that have the parts for a crude bias installed, and it has been grounded out because the builder did not have the skill to make it work right and it caused problems.
XForce( back when Carl was building them) had a half decent bias set up on some of there amps but it still lacked thermal tracking if I remember right.
There were some amps built by Palamar, the TX series and the Magnum series that had fully adjustable regulated electronic bias built in.
Some of the best I have ever seen in CB style Amps, but that was years ago.
73
Jeff
If you listen to a amp that is biased class c while working SSB and then listen to a amp with proper bias you can tell the difference.
I can, I know others that can.
It has to do with the threshold of the transistors turning on and off.
In class c the transistor is basically turned off.
This is not so bad on carrier modes like AM or FM, but on SSB it can cause a problem.
Back in the day my little brother could tell if I was using my Modulator as soon as I spoke a few words.
One time on 10 meters I was playing with a Boomer 400 style amp that had the bias hooked up but it was still not quite right, and other guys could tell that just by listening to my voice on SSB.
Once you do a side by side comparison on the air you will recognise the sound...almost crunchy sounding.
It also adds to IMD products.
There is a difference.
And I agree that the set up that Texas Star is not the best, but it is better than nothing, or even worse class c.
I have seen some amps that have the parts for a crude bias installed, and it has been grounded out because the builder did not have the skill to make it work right and it caused problems.
XForce( back when Carl was building them) had a half decent bias set up on some of there amps but it still lacked thermal tracking if I remember right.
There were some amps built by Palamar, the TX series and the Magnum series that had fully adjustable regulated electronic bias built in.
Some of the best I have ever seen in CB style Amps, but that was years ago.
73
Jeff
Yes the facts were confirmed many years ago that class c does not sound as good as ab. But class C guys still insert delays for "$50" extra. Don't the Texas Stars sound pretty good on SSB?
I have never had a compliant with any of my Texas Star amps in 30+ years.
Yes, TS amps work well on SSB.
They could do it better, but for what it is they work fine as long as people don't drive the snot out of them and are realistic about the output numbers.
Yes there are guys that run class c comp amps on SSB, they sound crunchy as hell, but they do it anyway.
Kind of like guys that run radios with overmodulated signals on AM......what ya gonna do?
I just recomend if you plan to work SSB, use a amp that has some Bias on the transistors.
73
Jeff
They could do it better, but for what it is they work fine as long as people don't drive the snot out of them and are realistic about the output numbers.
Yes there are guys that run class c comp amps on SSB, they sound crunchy as hell, but they do it anyway.
Kind of like guys that run radios with overmodulated signals on AM......what ya gonna do?
I just recomend if you plan to work SSB, use a amp that has some Bias on the transistors.
73
Jeff
Maybe I should start a new thread, but how would I add AB bias to a class C amp? Basically put a little positive voltage on the RF signal going into the transistors? Or am I totally wrong?
Just remember this ........
The more power transistors in the amplifier, the bigger the power supply has to be.
Be it for base operation, or more battery power and definitely more alternator amperage capability.
A 4-transistor amplifier for mobile use in your car or truck is a very good fit without having to increase alternator and battery output.
Just saying .........
I'll keep it short and simple to begin with. BJt's require a low impedance, temperature tracking current source. MOSFET's and LDMOS require a temperature tracking voltage source. I won't get into linear transfer curves created by "predistortion" and drive compensating gain networks, makes my head hurt.
https://www.worldwidedx.com/threads/pill-factory.230557/#post-628379 Been done did this once
https://www.qsl.net/va3iul/Bias/Bias_Circuits_for_RF_Devices.pdf is a fairly broad description of BJT and FET bias possibilities.
http://www.seboldt.net/k0jd/mot-an762.pdf is a very good reference.
Not at all. You just touched on a fundamental that is anything but simple. You have a bit of reading to do.
In the absence of a specific how-to or extensive test equipment play follow the leader. Much of this work is well documented. Helge O Granberg and Tom Rauch are the most readable. There are others that delve into esoteric math that accomplishes the same thing.
In the end what we are striving for is a "linear" transfer curve. What we generally end up with is a compromise.
Also see the sticky thread I just bumped up at the top of the forum.
Quick and dirty bias mod.
73
Jeff
Quick and dirty bias mod.
73
Jeff
The quick and dirty bias mod is a good place to start. You can build on that and make a very good bias circuit. Just don't be so scientific about the whole process that you talk yourself out of doing it. Perfection only exist on the internet.
I have never had anybody say anything except i sounded crystal clear on SSB with my 667V and more recent dying 400/500. Had the 667V for sbout 9 years and sold it and the recent 400/500 for 5 years.
Thats what i was using but i have a 300 amp alt and wired already because of my 1000 watt stereo. Looking to get the sweet 16 for a long time actually. Now I have an excuse lol. Was just asking for some opinions as I have read things about builders who I thought were good. As I previously posted probably going to start the search for where to by the TS. Still open for recommendations and opinions.
Big Rig CB has them for $810. I'd call to check stock..
GIJoes says $819 and has cart button. I'd call to check stock there also
CustomCBradios is $774 says 1 in stock.
GIJoes says $819 and has cart button. I'd call to check stock there also
CustomCBradios is $774 says 1 in stock.
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