2 Meter SWR meter

Discussion in 'General Technical Questions and Answers' started by KM4BDH, Sep 18, 2018.

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  1. KM4BDH

    KM4BDH Ham Member QRZ Page

    Not really sure if i can use a 2 Meter workman vhf swr meter on 40M band any input is welcome. ( even Critical Responses are welcome.
     
    KC5AKB likes this.
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    What's the model number of the meter?
     
  3. AI3V

    AI3V Ham Member QRZ Page

    A schematic and photo of the units "guts" and we can tell.

    Rege
     
  4. K8JD

    K8JD Ham Member QRZ Page

    It's just a ratio you are interested in and probably will be close enough to see if the antenna is really working.
     
    KU3X likes this.
  5. N7EKU

    N7EKU Ham Member QRZ Page

    Hi,

    If it's the kind with a forward/reverse switch and a calibrate control, it certainly won't hurt to try it. Start with the control turned all the way down, then transmit and see if you can get the meter to the calibrate mark (or just to full scale). If it reaches, then you can use it and it should give accurate SWR readings.

    Probably though, it won't be sensitive enough. Simple kinds made for one band, usually use a stripline SWR sensor, which picks up power from the fraction of wavelength that runs through it. On 2M it will be a decent fraction of 2M, but on 40M it will detect 20x less (and probably not enough to bring it to the full-scale calibration mark).

    73,


    Mark.
     
  6. N6QIC

    N6QIC Premium Subscriber QRZ Page

    My Daiwa swr meter is for 2m and 440 only. For HF I use the swr meter built into my antenna tuner.

    MFj-945E_mobile_antenna_tuner.jpg
     
  7. KD8DEY

    KD8DEY Ham Member QRZ Page

    In the older ARRL handbooks they used to say that if you could calibrate a HF Meter on VHF,
    then it would probably be accurate...I think it may have been one of the test questions at one time
    (Doesn't it have a bit to do with the diodes being used in the meter??!!)
    I don't see why the reverse wouldnt be true....
    Give it a try, and see what happens. Don't think it will harm anything...
    Ymmv
     
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Repeat.

    It's not usually the "diodes" that make a difference, it's the coupler itself. Some VHF meters use stripline or microstrip couplers which work fine on 2m but may not work well on HF because the coupling coefficient is too low and they become much less sensitive at lower frequencies; the HF couplers mostly use a ferrite core toroid to induce current from the line to the detectors, creating more effective coupling at lower frequencies.

    No problem with "trying it" to see what happens.
     
  9. AA5MT

    AA5MT Ham Member QRZ Page

    MFJ makes one for vhf which is usable down to 21 MHz or so, but it is very inaccurate there. You can use it as a go/no go meter though.

    Tom
     
  10. W5DXP

    W5DXP Ham Member QRZ Page

    The MFJ-882 goes from 1.8 MHz to 200 MHz.
     

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