Set capacitor in hf tuner

Discussion in 'General Technical Questions and Answers' started by N2GQ, Jan 14, 2020.

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  1. N2GQ

    N2GQ Ham Member QRZ Page

    How can I set the capacitors in a hf tuner. I installed veniers and want to set indicator.
    In an atr15 tuner. Not sure if it is full mesh or not.
    Jay n2gq
  2. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Are you asking which end of the dial should be full meshed and where the pointer should point for a fully open capacitor? In a T- network tuner like the ATR-15 the fully CCW position of the pointer generally corresponds to a fully meshed capacitor and the far CW position corresponds to a fully open capacitor.

    And as a general rule of thumb with such tuners you should avoid tuning solutions that require one or both capacitors to be fully open or nearly fully open especially at higher power as that's the condition that leads to arcing capacitors.
    N2GQ likes this.
  3. N2GQ

    N2GQ Ham Member QRZ Page

    Okay yes I installed veniers and I'm setting the dial. I will set them to the way you explain. Will make it easier to save tuner setting. I have the small red indicators that will be installed. Thank you for the response.
    Jay n2gq
  4. AA5MT

    AA5MT Ham Member QRZ Page

    On a different model, I made a capacitance scale so that I could use it with tuning formulas. I disconnected the wiring and connected it directly to my capacitor meter. I decided how many marks I wanted on my scale. I then measured the capacitance at each mark, and marked the scale. I also did this with the inductor; values in uF. So, once I tuned an antenna, I could use the L and C values in formulas to find the antenna + feedline impedance for whatever I was testing.

  5. N2GQ

    N2GQ Ham Member QRZ Page

    Sounds cool. Just tested the vernier today and it works great. Went back to the setting I copied and quick tune.
    Might try to apply same to my amp. There is a kit out there by a n6 station that I would like to apply to my al-82 amp.
  6. N2GQ

    N2GQ Ham Member QRZ Page

    Does anyone know the size screw that is used to hold the knob pointer on vernier from mfj.
  7. K8JD

    K8JD Ham Member QRZ Page

    I would think a vernier gear would make retuning take forever !~!! I just made a chart with the tuner settings for each band on the CW area I use and referred to it when i change bands. Actually had to make two charts , one for dry WX and the other for rain and snow on my twinlead feedline :D
  8. K7TRF

    K7TRF Premium Subscriber QRZ Page

    The Ameritron ATR-20 and ATR-30 tuners use 6:1 verniers on their capacitor tuning knobs and they don't take forever to tune...
    N2GQ likes this.
  9. N2GQ

    N2GQ Ham Member QRZ Page

    Does not take long to tune and my atr15 tuner used turn on its own. You guys should look at this he added a mod to amplifiers for rapid tune. Quite slick. I like it for next project.
  10. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Well, no; they have Reduction Drives, but not Vernier Scales/controls.

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