class A push - pull amplifier ?

[VenomBallistics]

Class AB transistor amplifiers are always biased to the mid point otherwise they would not work correctly. Class A transistor amps are just class B (or AB) biased to have a large current flowing in the output stage in the quiescent state. A class AB would have the same output stage topology but would be biased so that the output stage passes just a couple of mA in the quiescent state.

Class A push pull is mid biased ... as one transistor swings toward saturation, the other swings toward cutoff.
Class B is by nature, push pull as they are biased exactly at cutoff as one transistor swings toward saturation, the other simply remains in off state while waiting it's turn.
Class AB is the same as class B, only it is biased slightly above cutoff in a bid to eliminate the need for meticulous bias generator adjustment.
Beyond this region of overlap, they run class B ... a transistor swings toward saturation, the other waits it's turn in off state. If it didn't, it's just be a class A.

 

[WHONOES]

Class B has no quiescent current flowing in the output stage and leads to crossover distortion. The small current in class AB output stage ensures that crossover distortion is kept to a minimum.
Class A as previously mentioned has a large current flowing in the output stage proving superior linearity whilst producing a substantial amount of heat. Also class A is the least efficient of all the topologies.
As also mentioned all the mentioned topologies are biased to half supply.

 

[Audioguru]

Anne, the very old book you found shows high radio frequency power amplifiers for a radio transmitter that must be designed properly to avoid interference with other communications and you must have a license to use it. I thought you wanted an audio power amplifier to drive a speaker. Audio amplifiers have not used transformers for the audio since many years ago.

 

[anne ranch]

Now the question is - which direction to wind the load torroids?

 

[VenomBallistics]

Is it for a Spice simulator run like you said?
Then there's no need to wind any transformers at all
If class doesn't matter, neither do our answers

 

[Audioguru]

Maybe that very old high radio frequency amplifier used little ferrite transformers in it.

 

[Harald Kapp]

it might answer some of them, but it does not show you heat

But it can show power dissipation, e.g. in LTSPICE using ALT + left mouse click.

I am not that concerned what is the class

Anyway, using the correct terms is extremely helpful to gain a common understanding.

 

[bertus]

Hello,

What are your intentions with the 14 MHz transmitter?
14 MHz is a licensed radio amateur band.
https://en.wikipedia.org/wiki/Amateur_radio_frequency_allocations
Do you have a license?
Also it is close to the 13.56 MHz of the RFID frequency:
https://en.wikipedia.org/wiki/Radio-frequency_identification
When you want to make a RFID jammer, you are on the wrong adress.

Bertus

 

[anne ranch]

Hello,

What are your intentions with the 14 MHz transmitter?
14 MHz is a licensed radio amateur band.
https://en.wikipedia.org/wiki/Amateur_radio_frequency_allocations
Do you have a license?
Also it is close to the 13.56 MHz of the RFID frequency:
https://en.wikipedia.org/wiki/Radio-frequency_identification
When you want to make a RFID jammer, you are on the wrong adress.

Bertus

...actually it is none of your business
thanks tor contributing to resolution of the subject

 

[anne ranch]

Now the question is - which direction to wind the load torroids?
Help would be appreciated

 

[Harald Kapp]

...actually it is none of your business

Actually it is. It is our forum policy not to support potentially illegal actions.

Now the question is - which direction to wind the load torroids?

Why should that matter? As long as the result is a single inductor, not a transformer, direction doesn't matter at all.

 

[bertus]

Hello,

Did you have a good look at your posted page:
http://www.sm0vpo.altervista.org/tx/rf_pa_cct_00.htm#trans

BTW the amplifiers will be broadband, as there are no tuned circuits in it.

Bertus

 

[anne ranch]

Hello,

Did you have a good look at your posted page:
http://www.sm0vpo.altervista.org/tx/rf_pa_cct_00.htm#trans

BTW the amplifiers will be broadband, as there are no tuned circuits in it.

Bertus

,,,did you ?
and did you see any hit how to orient the primary winding of the torroid ?
I did not - that is why I posted here. ( I not interested in discussing anything else )

BTW the amplifiers will be broadband,
And that is what I asked.

Please do not sidetrack the discussion , is has been already done once , please stay on the subject

 

[bertus]

If you keep up the attitude you show, you will be in problems.
The other moderators are also notified.

 

[anne ranch]

If you keep up the attitude you show, you will be in problems.
The other moderators are also notified.

Please note that last post encroached on my privacy and you blame it on me as being a problem ?
You members should stay with technical issues and leave their
opinions at home.

If that is the norm on this forum , you have been notified .

IBTL

 

[anne ranch]

Actually it is. It is our forum policy not to support potentially illegal actions.

Why should that matter? As long as the result is a single inductor, not a transformer, direction doesn't matter at all.

Perhaps I need to repeat - it is a push-pull amp - each collector connected to torroid transformer with power applied to the common center tap. Since only 1/2 of the transformer is working - on opposite polarity of the sine wave - should the primary winding be opposite hence the secondary would have always same wave - positive ?

I guess this will became academic argument - I can probably model the winding in spice - when I get it stable.

 

[WHONOES]

No more interest in post due to posters attitude.

 

[(*steve*)]

you have been notified

ROFL, I see you have a sense of humour.

The questions I've seen you refuse to answer call into 2 categories.

1. Questions asking you what this is for. These are asked because it can actually make a difference between good and bad advice.
   
2. Questions if legality. It is our policy not to assist with things that are illegal. You don't have to like this.

When you start asking questions or making statements that indicate a lack of experience, answers to these questions become more important.

On the other hand, if you want to indicate that you're not interested in good advice, we can ignore questions of type (1) above...

 

[anne ranch]

ROFL, I see you have a sense of humour.

The questions I've seen you refuse to answer call into 2 categories.

1. Questions asking you what this is for. These are asked because it can actually make a difference between good and bad advice.
   
2. Questions if legality. It is our policy not to assist with things that are illegal. You don't have to like this.

When you start asking questions or making statements that indicate a lack of experience, answers to these questions become more important.

On the other hand, if you want to indicate that you're not interested in good advice, we can ignore questions of type (1) above...

AS i said - I am not interested getting involved with somebody who automatically assumed that I am doing something illegal - it is none of his business. And being told that I may become "a problem" obviously will lead to getting kicked out if I continue in this matter.
It has been an experience that administrator have no interest resoling stuff like this and prefer to ban "the offender". Starting with accusations /suspicion is no way to inquire if I have a ham license - it is none of his business.

I posted technical question and get a sermon....
Yes, I have added more description , hopefully it will lead to TECHNICAL solution.
Here is a hint

73 es 88

... -.- ..

 

[anne ranch]

Sorry , there was a typo

BTW the amplifiers will be broadband,
And that is NOT what I asked.