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  1. ohmrun

    Proper setting of Resolution Band Width

    "It's worthwhile to connect an antenna to a spectrum analyzer, and explore the effect of the various settings while viewing (for example) the FM Broadcast band." I never thought of that VE1BLL. Thanks for the advice.
  2. ohmrun

    Proper setting of Resolution Band Width

    I'll buy that MacGyverS2000. I gather from these post that you narrow the RBW to detect frequencies within the bandwidth. So the sweep should be as wide as the bandwith?
  3. ohmrun

    Proper setting of Resolution Band Width

    What is the proper setting of the Resolution Band Width of a Spectrum Analyzer relative to the Band Width of an amplifier? Should it be greater, equal, or narrower than the amplifier's Band Width?
  4. ohmrun

    Styrofoam coil form

    I can't really find a bobbin of the size I need. 1.2 x 4 inches. Styrofoam is light weight, easily formed and low cost. I need the induction field from it to induce a signal into a wire. A 2 x 4 works, but I was afraid that it would absorb moisture. I did notice the styrofoam compressing at...
  5. ohmrun

    Styrofoam coil form

    I have wound a coil on a styrofoam form. Does anyone know of any issues with a styrofoam form? I plan to use it in a device that is used outdoors. It's Q will be 100 and low inductance. It will also be part of a resonant circuit with circuit Q about 50.
  6. ohmrun

    Miniature IF Transformers

    Thanks for all of the info VE1BLL and logbook. The amp would operate at a single frequency, hence the narrow band circuit. Currently, the operating frequency is 480 kHz. The high Q is for both selectivity and noise suppression. I have to worry about close proximity of output to input and...
  7. ohmrun

    Miniature IF Transformers

    Thanks. I have considered down converting. I will look at that and the xtal and saw filter methods.
  8. ohmrun

    Miniature IF Transformers

    A very good idea, nbucska. But my fault for leaving an incomplete subject. I would like to design a narrow band circuit with out transformers and still maintain Q > 100 and gain of about 100 dB. I am researching the alternatives. Does anyone have any ideas?
  9. ohmrun

    Miniature IF Transformers

    Many AM (amplitude modulation) radios utilize 455 kHz IF (intermediate frequency)transformers. My company uses a similar circuit to amplify a single CW (continuous wave) signal in the 100 kHz to 500 kHz band. However, it appears that the IF transformers are becoming harder to acquire. At...
  10. ohmrun

    Faraday shield material

    I would like to make a Faraday shield and place it around an inductor. The purpose of the inductor is to detect ac magnetic fields. Will the conductive plastic (similar to the static shielding bags) function as a shield? If so, how would one make a connection to it? Is the resistance of the...
  11. ohmrun

    Lead Temperature due to Soldering?

    The reason for asking the question is that if I use a soldering iron with a 700 F or 800 F (370 C or 425 C) tip, for about 2 seconds, what happens? Will I exceed the equivalent of 260 C for 10 seconds?
  12. ohmrun

    Lead Temperature due to Soldering?

    The absolute maximum ratings for an integrated circuit states that the lead temperature should not exceed 260 C. And in parenthesis it states "Soldering, 10 seconds". Does this mean that the lead can be at 260 C for 10 seconds? Does it imply that it can be soldered with a higher...
  13. ohmrun

    Inductor selection criteria

    Any suggestions?
  14. ohmrun

    Inductor selection criteria

    I wanted to use a 4.7 mH coil Toko 181LY-472J. The test frequency is 50 kHz with Q minimum of 100. The rated DC current is 40 mA. The appealing characteristics of this coil is that it is magnetically shielded and it is small, 10.5 mm od and 14 mm tall.
  15. ohmrun

    Inductor selection criteria

    I need to select an inductor to be used in a 10 kHz circuit. It will be used in a series resonant circuit where the A.C. current can be as high as 200 mA. I notice that most of the inductors of the type I would like to use have a D.C. current rating. There will be no D.C. current flowing in...
  16. ohmrun

    Battery Contact Corrosion

    I am having problems with AA batteries and the contacts to the battery terminal in a battery pack. The battery pack will hold 6 batteries. It appears that a green patina forms on the contacts in the holder. It does not look like the batteries are leaking. Is this a unique phenomena or should...
  17. ohmrun

    Lossy Transmission Line Component Calculation

    Tracing pipe by injecting a signal and tracing the resulting magnetic field. I am attempting to detemine the how different frequencies respond.
  18. ohmrun

    Lossy Transmission Line Component Calculation

    This is not an ordinary transmission line. It is actually an insulated pipe in the earth of unknown length. The particular line that I am testing is about 250 feet long before it makes a connection to the main line; it then continues several miles.
  19. ohmrun

    Lossy Transmission Line Component Calculation

    I need to determine the R, L, C, and G of a lossy transmission line at various frequencies below 1 MHz. I have only one access point at an end. Any suggestions would be appreciated. My first attempt was to determine the input impedance and set it equal to sqrt{(R+jwL)/(G+jwC)} and solve...
  20. ohmrun

    Soldering Iron tip temperature

    A 12 watt soldering iron has a tip that weighs about 2 grams. I need some help in determining how hot does the tip get? The Formula Q=M x Cp x dT seems to produce a dT of 85,370 when Cp is .109BTU/(lb x F)(assuming nickel steel material). This seems way out in left field. Any help is...

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