Low Noise VHF or UHF Preamplifier

Discussion in 'Ham Made Gear' started by AA7DJ, May 11, 2018.

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  1. AA7DJ

    AA7DJ Ham Member QRZ Page

    Custom designed low noise preamplifiers for VHF and UHF amateur bands from 50 MHz till 1296 MHz.

    Some are in form of the board 27 x 40 mm (1.063 x 1.575 inch) with SMA connectors. These boards could be used inside of the receiver or external power amplifier. Also they could be placed close to antenna in additional metal box.

    Other amplifiers are in aluminum case 28 x 50 x 25 mm (1.10 x 1.97 x 0.98 inch) with N type connector. Also it is possible the same design but with SMA connector.

    All of these low noise preamplifiers could be supplied direct thru two pins or output coaxial cable. In this case I need add one inductor to the board. For power needs DC voltage 5.5-20 V with current about 20 mA.

    To have an idea how some of my amplifiers are performing you can watch this video:

    I can build amplifiers for 50 MHz, 144 MHz, 432 MHz and 1296 MHz. Also I can try to create new one for 222 MHz or 902 MHz.

    If you are interested to know more details including a possible price for chosen option please sent me e-mail to aa7dj@arrl.net.

    Attached Files:

    Last edited: May 11, 2018
  2. KM1H

    KM1H Ham Member QRZ Page

    While I find the given specs interesting and the music annoying a bit more technical details in the video would be helpful.

    There are several similar products available for decades that have similar specs but are useless for ham use without having adequate bandwidth filtering. While this will increase the NF it gives realistic numbers.

    Also missing is the IP3 .

    I do not like having to resort to email for every question either. Consider providing a price list of the most common packaging on a sheet in your video.


  3. AA7DJ

    AA7DJ Ham Member QRZ Page

    IP3 is good value for comparison with other amplifiers. But there is no direct method to measure it. To get the value need measurements of many points and use graphical plot to find intersection level.
    Easier is to measure input and output levels for 1 dB compression. It is more practical. Because if to know the level of interfering signals in antenna it is easy to compare with value measured for the LNA.
    For example I know what is FM broadcast level in my 2 m antenna and can say that it is much lower than input level for 1 dB compression in 2 meters LNA.

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