Low noise amplifier (LNA)

jgreentnjgreentn
in Configuration and Operation

Any sense in adding an LNA to my setup? If so, does anyone have a recommendation? Thanks


Jerry

Comments

  • G8JNJG8JNJ

    It depends, but generally I'd say no, you will most likely only boost both the wanted and unwanted signals, so the overall Signal to Noise ratio will remain the same.

    However, you will eat away at the KiWi's available dynamic range, and most likely introduce additional unwanted IMD products. Both of which are undesirable.

    What are you hoping to achieve, and what antenna are you currently using ?

    Regards,

    Martin

  • jgreentnjgreentn

    Thanks Martin. I'm using a T2FD (folded dipole), but it's not high off the ground, maybe 2 m at most. I've heard getting the T2FD up higher improves reception.

  • smgsmg

    @jgreentn - There is a rabbit hole you are probably looking down right now. Uplifting that dipole would likely help, however, what is your noise floor like? i.e, what's the S Meter showing when not "tuned in" to any signals?

    example:

    image.png

    So for me, on 20mtrs, the noise floor is just above S3 and I live in a built up urban area. Where my Xiegu G90 connected to an EFHW gets an S5-6 noise floor.

    The difference being my KiwiSDR is using a magnetic loop

    I've tried different LNAs on passive antenna, and as Martin said, you just raise the noise floor and lose even more weak signals.

  • TremolatTremolat
    edited 8:15PM

    Hello everyone. It's a very good question whether or not to use an LNA. I use one primarily to compensate for the length of my antenna cable, which is 250 meters long. Secondly, I slightly increase the sensitivity of the KiwiSDR.

    The LNA needs to have very low internal noise. I discussed this with Martin, and his advice was very helpful. I thank him for it.

    I think the first task is to eliminate all sources of background noise, noise caused by the installation and also noise in the immediate vicinity of the antenna.

    It's not simple and we have to be very methodical.

    My antenna is currently a vertical triangular mast. It's working correctly. But I'd like to build one (or more) magnetic loops in the coming months. Loops with a diameter of 2 to 3 meters. I need to find the time to do it.

    Best regards.

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