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Variometer with too much inductance question

Discussion in 'General Technical Questions and Answers' started by 2E0ILY, Jun 22, 2019.

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  1. 2E0ILY

    2E0ILY Ham Member QRZ Page

    I have an ex Russian military variometer (actually I am told it's really a goliometer...), that I use in series with an LF loading coil. It's remote tunable with a geared motor drive. On MF I do not need the main loading coil to resonate the antenna, just the variometer, BUT, it has to be set to its very minimum inductance and the weather etcetera sometimes means even on minimum inductance there's too much. I don't want to try and butcher it, is there any trickery, even if there's a bit of loss, to reduce its inductance a bit and put the sweet spot within its normal adjustment range please? Thanks!
     

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  2. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Perhaps you mean "Goniometer" which measures angles. That is one application for a variometer.

    Well, you can adjust the inductance three ways:
    -Short jumper some of the turns on your loading coil
    -Add an appropriate inductor/coil in parallel with either the loading coil or variometer.
     
    NE1U likes this.
  3. 2E0ILY

    2E0ILY Ham Member QRZ Page

    OK, thanks William, I'd rather not tap the stationary variometer coil breaking into its insulation, so I'll try a parallel inductor. I believe the maths is similar to paralleled resistors, so if I wanted to reduce minimum impedance by say 10% i would need to add a parallel coil of ten times the variometer's minimum inductance? Many thanks for the reply! On MF I am not needing the main (big!) loading coil at all the variometer alone is more than sufficient to resonate the aerial.
     
  4. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    [​IMG]
     
    NE1U likes this.
  5. 2E0ILY

    2E0ILY Ham Member QRZ Page

  6. KL7AJ

    KL7AJ Ham Member QRZ Page

    Add enough series capacitance to bring your antenna resonance to somewhere near mid-rotation of the variometer
     
    W2VW likes this.
  7. N3PM

    N3PM Ham Member QRZ Page

    Final value will be less than the smallest value in the set.
    Mike N3PM

    1/(1/100)+(1/10)
    1/(.01+.1)
    1/.11
    = around 9+
     
    WB2UAQ and W0IS like this.
  8. VU2NAN

    VU2NAN Ham Member QRZ Page

  9. WB2UAQ

    WB2UAQ Ham Member QRZ Page

    At the AWA (Antique Wireless Association) in Bloomfield, NY we have a variometer that is about 4 feet in diameter that once was used by a NJ station (maybe Tuckerton?). On the nomenclature plate it states the inductance, tested at 30 kHz, to be in the mH area for both cases of series or parallel config. This is a physically small one compared to some of the ones I came across on the internet but still impressive with its ceramic coil forms and worm gear drive and wound with possibly Litz wire (~1/2 inch thick copper). Hopefully this device will to on display somewhere again in or outside the museum. Wish I could get a good picture but it is buried with other related stuff right now.
     
  10. WQ4G

    WQ4G Ham Member QRZ Page

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