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Why is my SWR different on different SWR meters

Mike-VA3MW
Mike-VA3MW Administrator, FlexRadio Employee, Community Manager, Super Elmer, Moderator admin
in Peripherals & Station Integration

AKA - The SWR Meter on my Radio is wrong

This is a common question I see a lot. And, it is a good one.

The SWR / Power Meter is an actual standalone device in the radio and calibrated to bench standards. However, there are times that your SWR meter in SmartSDR will show something different than your external SWR / Power meter.

It is best explained in this article by the ARRL. They do a great job at it.

https://www.arrl.org/files/file/Technology/tis/info/pdf/q1106037.pdf

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Comments

  • Brock
    Brock Member ✭✭
    This is easily the best (i.e., understandable) explanation of SWR I've seen, so thanks for posting. The Smith Chart on my NanoVNA is now less theoretical and more practical too.
  • tomhank
    tomhank Member, Unconfirmed ✭
    edited October 2023
    Standing Wave Ratio is a shortened form of SWR. A gadget that measures the broadcast signal from a radio is an SWR meter, to put it simply. In order to have the best signal possible and to improve the antenna, this is crucial. By doing this, you can ensure the highest possible quality while avoiding radio damage.
    You can find more infor here: https://windupradio.com/swr-meters/
  • JohnT
    JohnT Member ✭
    A Flex Radio should NOT show any swr deflection when a 50ohm load is placed right at the antenna connection on the back of the rig and the rig is in transmit (period).
  • Gord-VA7GP
    Gord-VA7GP Member ✭✭✭
    edited June 13

    <sigh>

    With various gears (TunerGenius XL, 6400, LP-700) I get different (sometimes wildly different!) SWR and power readings when I use an awesome Bird 2500-watt dummy with new '213 co-ax jumpers. I check with nanoVNA, and my entire systems is a flat 50-ohms in this situation, yet the various gears do all show quite different results.

    Dead-flat 50-ohms, return-loss in excess of -40dB (typ. -45dB) yet hundreds of watts different between the detectors (when using amp). I have 0.00 watts reflected power in all circumstances, yet often showing 0.2 VSWR variations. Using Bird 8890 as swept here:

    http://tigerfire.ca/radio/dummyloads.html

    I view SWR and watt-meter readings as being like Politicians 🤣😂🤣😂 ☹️

  • Geoff AB6BT
    Geoff AB6BT Member ✭✭✭

    Hey John…Have you measured the actual impedance of the load?

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