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Discussion in 'Amateur Radio Amplifiers' started by W8JI, Dec 30, 2011.

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  1. AF6LJ

    AF6LJ Ham Member QRZ Page

    I wouldn't bring the Illuminati into this they have nothing to do with any agenda in this thread.

    It's Masonic in nature, give it a rest. ;)
     
  2. W8JI

    W8JI Ham Member QRZ Page

    Rich,

    What someone views as "specious reasoning" can be handled with simple logical facts. It does not require insults or demeaning responses.

    Going "off technical" is never required when there is a valid rebuttal to anything anyone says. Insulting people as an only contribution is not an attribute. It just kills any value of a discussion.

    73 Tom
     
  3. N3JBH

    N3JBH Ham Member QRZ Page

    I believe the topic of this thread is Threads locked And i sure can see now why it is going to be. :( So really sad...
     
  4. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    "Get the pitchforks and torches!"
     
  5. KC9TNH

    KC9TNH Ham Member QRZ Page

    I wonder if anyone else is out there, resigned to not asking their even basic question of some clearly knowledgeable & experienced folks for fear of re-igniting clash of the titans.
    (I don't know enough to take any "side" in this - I just think that personal insults, innuendo, or personally demeaning comments have no place in the arena if someone wishes to be regarded as knowing their subject; well, if they want someone to listen anyway.)

    Maybe I'm deluded in thinking this community should be better than having to even need this thread in the first place.
     
  6. G0HZU

    G0HZU QRZ Member

    If you mean the mystery black box question then here is the answer :)

    You can characterise any two port (or 1 port or n port) device using s parameters. You don't need to see inside the box.

    You can do all this with an n port vector network analyser that can export the relevant data to a computer. It just takes a minute or so.

    Most VNAs are either 1 or 2 port but 4 ports are quite common too.

    There's nothing new about this and RF engineers have been measuring 'black boxes' so they can be modelled for decades.
    There's a good intro to the technique here:

    http://www.microwaves101.com/encyclopedia/sparameters.cfm


    Once you get s parameter data for the 2 port black box you can import it into a computer and treat it as a component.

    eg if you took s parameter data for a low pass filter you could simulate the reponse on a PC and it would look just the same as it did on the VNA.

    You can then see the effect of mismatching it (watch the ripple get worse on the simulation) or you can look at the impedance or you simply cascade two of them in series to see how much the stop band improves and the passband ripple deteriorates.

    In the case of a big valve PA you could take S parameter data for the whole of the PA tank circuit (do it at lots of settings if you like and export lots of different models)

    The model data would produce simulation results that look the same as the raw data of the real measurement.
     
  7. AG6K

    AG6K QRZ Member QRZ Page

     Without several competent pot stirrers , this amplifier discussion group would be a sure cure for insomnia. ,

    • Rich, ag6k
     
  8. VK6ZGO

    VK6ZGO Ham Member QRZ Page

    With all due respect,that is not how your original posting read.
    The clear implication was that,without testing,you could simulate the circuitry inside the box.
    Now,of course,your latest posting has cleared up the misunderstanding.
    It is obvious now,that if you test the box with a VNA & export it to a PC,you can use the results of a real test as a basis for your simulation,just as you would use it for calculations on paper.

    73,VK6ZGO
     
  9. AG6K

    AG6K QRZ Member QRZ Page

     Neither way works with some people. Stupid example: someone tells me that Ohm meters can not be trusted to indicate the correct resistance of a R-supp because carbon-comp resistors are well known to change value.
    • Rich, ag6k
     
  10. W1QJ

    W1QJ Ham Member QRZ Page

    Rich, honestly, I've flipped you the bird many times but when you crack a good one it desrves mention...(running to the toilet):D
     
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