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TS mod v
- Thread starter dxing440
- Start date
Easy, we got that part.
OK basically, all I am saying is that the amp you have now would not be my first choice to use.
Crusher has offered some good advice, you can bias it, that will help clean it up.....
I dont think there is an easy way to make it do what you are wanting to do.
73
Jeff
OK basically, all I am saying is that the amp you have now would not be my first choice to use.
Crusher has offered some good advice, you can bias it, that will help clean it up.....
I dont think there is an easy way to make it do what you are wanting to do.
73
Jeff
The problem with class C is it's too easy to drive into RF cutoff on AM. Once you do that you have destroyed the signal quality. About the only way I would run a "modulator" is with a scope so you can set the drive and bias appropriately. It is the proper setting of drive and bias that will allow an amp that runs less than class AB to sound relatively clean on AM.
That usually does not happen when the amp is solid state and has no bias at all. When there is no bias at all, you waste too much carrier to bias the transistors on and that means any reduction in carrier during negative modulation peaks can easily hit RF cutoff. Some bias with reduced carrier from the exciter (radio) is the better approach here.
To be honest, even with adjustable carrier on the radio, a variable attenuator between the radio and amp, adjustable bias on the amp and an intact modulation limiter, it's still a handful to get something like this to run clean. Especially when you consider that it's probably going to get amplified another 10 or 20 db after that stage.
That usually does not happen when the amp is solid state and has no bias at all. When there is no bias at all, you waste too much carrier to bias the transistors on and that means any reduction in carrier during negative modulation peaks can easily hit RF cutoff. Some bias with reduced carrier from the exciter (radio) is the better approach here.
To be honest, even with adjustable carrier on the radio, a variable attenuator between the radio and amp, adjustable bias on the amp and an intact modulation limiter, it's still a handful to get something like this to run clean. Especially when you consider that it's probably going to get amplified another 10 or 20 db after that stage.
I agree with shockwave. The moment that carrier starts approaching a certain amount of downward shift on negative peaks, that transistor is going to switch off and create all kinds of mess.
Good Post Shock.
These little things are really only good for one thing.....wild swings on a wattmeter.
How do I know?
Yes back in the day I played with them too.
TnT ( not the same TNT built now by x force) used to build a small amp called a Super Mod that had 2 MRF 455 transistors in push/pull with passive bias, it worked much better than the Mod V ever did, and could be dialed back easily to drive a bigger amp.
73
Jeff
♪You Ain't got a thing♫ if you ain't got that swing ♫♪
These little things are really only good for one thing.....wild swings on a wattmeter.
How do I know?
Yes back in the day I played with them too.
TnT ( not the same TNT built now by x force) used to build a small amp called a Super Mod that had 2 MRF 455 transistors in push/pull with passive bias, it worked much better than the Mod V ever did, and could be dialed back easily to drive a bigger amp.
73
Jeff
♪You Ain't got a thing♫ if you ain't got that swing ♫♪
Actually you did get answers, just not the ones you wanted to hear.
If you got a receipt with this repair, could you share what your local tech did to fix the problem? No fancy description required, a simple list of the parts he installed / charged for is preferred and will tell us if it's all good.
Did your local tech show you on the O scope how clean your swing is?
Or did your local tech get paid to show you the swing in your thing?
Most likely he made the customer happy, that is how "Your Tech" makes his money.
Me thinks what he means is "the answers I got were either completely over my head. Furthermore, I have no interest in learning what your answers mean. So, what I did, is take it to a guy and while you people said it wouldn't work, he made it "work" by connecting up the two leads, (which I answered on how to do) and powering that sucker up and by golly--more power out. I also got a radiocheck too, and this guy a few miles away on channel 19 said it's wall to wall and tree top tall. So, thank God for local tech who didn't bother me with all of this uncomfortable nonsense, and just hooked it up and stuck to simplicity".
If I were to take a guess, I do not have a PHD, but that would be closer to the actual and also psychological nature of the actual situation. It is amazing at how some of my customers would rather pass me money, and just have me stick to simple rather than explain things. It's as almost once you break a comfort line then it gets too complicated and they get uncomfotable with you.
If I were to take a guess, I do not have a PHD, but that would be closer to the actual and also psychological nature of the actual situation. It is amazing at how some of my customers would rather pass me money, and just have me stick to simple rather than explain things. It's as almost once you break a comfort line then it gets too complicated and they get uncomfotable with you.
It is quite obvious the the OP has no desire to have a clean signal nor understands the problem with what he has. All he is interested in is making the meter swing. I just wish these people would stop trying to turn nice full carrier double sideband AM into crappy suppressed carrier double sideband AM, which is exactly what they are doing with a low carrier and LOTS of swing. If they want to watch a meter bob up and down go to SSB where it actually works right straight out of the box.