Antenna tuner and swr/wattmeter in series

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KP4ASD, Oct 23, 2010.

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  1. KP4ASD

    KP4ASD Ham Member QRZ Page

    Hello guys I just have a quick question about what is the proper way to connect my antenna tuner and a swr/power meter in series so I can make everything work properly, 73's :D
  2. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

  3. KP4ASD

    KP4ASD Ham Member QRZ Page

    Thank you everything is working great ;)
  4. WC5P

    WC5P Premium Subscriber QRZ Page

    Your homework assignment is to explain WHY they must be in that order... :D

    Seriously... This is a great learning opportunity.
  5. W5DXP

    W5DXP Ham Member QRZ Page

    A lot of antenna tuners have built in SWR meters and that is how they do it. If someone doesn't know the answers to the following questions, he will learn something important by figuring out the answers.


    What does the SWR1 reading tell us? What does the SWR2 reading tell us? What if we replace the 50 ohm coax with 450 ohm ladder-line?
  6. VA3CQC

    VA3CQC Ham Member QRZ Page

    I have been wondering about this actually.

    What if it goes: TX -> METER -> TUNER/METER -> ANTENNA

    I have this setup (the first meter is more sensitive than the second) and occasionally the results differ. USUALLY they are in sync, one goes down the other goes down, but sometimes they act in see-saw fashion! You can't make one go down w/o raising the other one.

    Is this because one meter is riding on a "trough" and the other is riding on a "peak" of the standing wave? Or is this another way of saying I have a "magic length" coax that is just the right size to invert the wave?
  7. W5DXP

    W5DXP Ham Member QRZ Page

    What is more likely is the following (assuming that the above "TUNER/METER" is an average metered tuner):


    The meters ideally should read the same but SWR meters and system conditions are rarely ideal.

    In a system with reflections, the SWR between the TX and METER will be different from the SWR between the TUNER and ANTENNA.
  8. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    The SWR bridge/meter in an antenna tuner is always on the "transmitter" side of the tuner, and not on the "antenna" side; otherwise, no adjustment you make will show an SWR change on the meter.

    That they don't agree is pretty common; in such a case, the meter closest to the transmitter is the one you want to null.
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