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  1. ken white

    Bias design, amplifier design, filtering etc.

    Bob, if you tell me what idle current you want, I will design an op-amp driver to connect/control a series pass transistor. Or if the idle current is low enough, a simple JFET cicruit can be added to the output stage of the existing voltage regulator circuit if the voltage can be cranked up...
  2. ken white

    Bias design, amplifier design, filtering etc.

    I can design a simple voltage controlled current source for you to test. You can also download PSPICE here: http://www.eng.auburn.edu/~troppel/91pspstu.exe and trhe tutorial here: www.ece.utah.edu/~harrison/ece3110/PSpice92Tutorial2.pdf if you want to simulate it before your build it.
  3. ken white

    Bias design, amplifier design, filtering etc.

    Good link...
  4. ken white

    Bias design, amplifier design, filtering etc.

    bob85, I am not sure what you are seeing or what type of circuit you have tested. If a constant current is supplied to the base-emitter junction by the bias circuit, and there is a coupling capacitor to block the bias voltage and to allow the AC signal to be added, Kirchhoff's current law...
  5. ken white

    Bias design, amplifier design, filtering etc.

    bob85, a constant current supply holds the current at a constant value while allowing the voltage to vary between its maximum and minimum operating space - there is no foldback. A power supply can have current limiting which will fold back the voltage when the current draw is at or above the...
  6. ken white

    Bias design, amplifier design, filtering etc.

    bob85, with a constant current source, and a series diode to control/isolate the current flow between stages, the bias should stay AB and not go to C when a signal is applied. With a constant voltage source, the currrent in the base will always change with temperature since the base-emitter...
  7. ken white

    Bias design, amplifier design, filtering etc.

    Since transistors are current controlled devices, and since the base-emitter voltage has quite a bit of variability between devices and at temperature, why don't you design a constant current regulator to control base current for the amplifier class - which I'm assuming is AB? If you want to...
  8. ken white

    maco 200 capacitor replace

    Using two 120uF capacitors connected in series will generate approximately 60 uF with a 900 WV capacity - your OEM set-up. Using two 100 uF capacitors is approximately 50 uF so you will only have 83% effective capacitance which will reduce the DC bus voltage. Using two 160 uF capacitors will...
  9. ken white

    maco 200 capacitor replace

    How are they connected, in series or parallel?
  10. ken white

    Wanna become a Ham? Check this...

    The stuff below is free and is about 90% of what you need to pass the exams, experience helps too... Also, its free and you don't need to fight the crowds...
  11. ken white

    Best CB Repair Book for Beginners?

    Did you check the links I posted here? http://www.worldwidedx.com/general-ham-radio-discussion/38353-wanna-become-ham-check.html#post166999 The NEETs series was generated by the Navy to help electronic technicians who work on radio communication and navigation electronics do their job. So...
  12. ken white

    Got my Mauldulator today, WOW

    Very entertaining... :-)
  13. ken white

    Wanna become a Ham? Check this...

    These Neets publications will help with the theory missing from just memorizing the exam question and answers: navy And this link will answer the regulation parts: 2002 CFR Title 47, Volume 5 Enjoy...
  14. ken white

    Yota's Amps

    What year did you graduate and what did you do your thesis on?
  15. ken white

    AMATEUR TESTING WENT GREAT TODAY!!

    Congratulations! If you need any help with the math associated with the Extra Class, let me know, I am sure I can help. :-)
  16. ken white

    .64 homebrew temporally finished and up with pics

    Good job. Keep us updated as you tweek it and get it dialed in... :-)
  17. ken white

    Voltage drop resistor for 5 20LF6 on 120VAC

    That cap is rated at 370V, which is why it is so big. There are other smaller solutions that are not oil filled. Your resistor solution will work too. I would go with the next standard value larger than the calculated ideal value. This will give you a slightly larger voltage drop which...
  18. ken white

    Transformer mfgs.

    Hammond Mfg - Technical Shortcut Links