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Education needed: RF power meter

Discussion in 'FPV (First Person View)' started by Buk, Sep 30, 2014.

  1. Buk

    Buk

    Joined:
    Feb 28, 2013
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    Location:
    Iowa, United States
    After reading so many negative comments about having a ImmersionRC 60mW video transmitter with a 32 frequency Black Pearl, combined with my own dissatisfaction with not having a consistent video image, I swapped out the Immersion for a 32 frequency Flysight transmitter. Again not thrilled with what I was seeing on the Pearl, I purchased an ImmersionRC RF Power Meter to determine the best antenna combination of the antenna I have.

    The Power Meter is connected to the provided 30db attenuator, and to the provided extension cable and then the video transmitter (in the menu of the Power Meter, 30db attenuation is also set). The video transmitter is powered by a Phantom 2. The Phantom is 20 feet from the Power Meter with a clear line of sight. The transmitter is powered for 15 minutes in this configuration to get it warmed up and nearly to the point of what I would describe as hot. At that point, the transmitter is cycled through all of the available 32 frequencies and the mW readings of the each frequency is written down. The power of each frequency is within what I expected, above and below the 400mW rating of the transmitter.

    I performed the test again, but added an additional right angle adapter and extension cable to the chain of cable, attenuator and transmitter. This was just for my own interest, in case I want to use that extra cable length to get the antenna below the quad in actual flight. I cycled through all the frequencies on the video transmitter again and recorded the mW readings. They had decreased, but still, perhaps, useable mW power.

    Next I put an antenna on the transmitter and a matching antenna on the the Power Meter (no attenuator and in the menu of the Power Meter set to 0db). Turn on the Phantom, powers up the video transmitter and no mW readings show up on the Power Meter, no matter which band letter or channel number, i.e. A1,A2...B1, B2..E..F. All 32 frequencies.

    Turn on the Black Pearl with ducky antenna and picture shows up fine (with an intermittent poor picture).

    So no readings on the Power Meter, yet Black Pearl is receiving some signal.

    I have three sets of antennas (ducky, mushroom, clover leaf) and I switched them all around and no combination gives me a reading on the Power Meter. At least not until I program in a 55db attenuation into the Power Meter and then the readings go all over the place. And yes, for the last test I hooked the video transmitter up to the attenuator and extension cable and all was good from the transmitter.

    Please, what am I doing wrong?

    Thanks, forgive the long request.