Powering an LDMOS amp using a Server PS

Discussion in 'Homebrew and Kit Projects' started by K7JOE, Jul 26, 2018.

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  1. K7JOE

    K7JOE Ham Member QRZ Page

    HI, I have a power supply that I'd like to use to power an LDMOS amp for experimentation. The power supply comes from a server. LDMOS amps require approx 50V DC.

    The PS offers

    +5V at 20A
    +12V at 20A
    -50V at 40A

    I would like to use the -50V setting (but am suddenly concerned that it's -50V versus +50V). To use this, is it as simple as reversing polarity of the positive and ground connections ? Or is there more to it?

    The power supply interested me due to price and multiple voltages (use 12V to power the radio, use the -50V to power the LDMOS amp)...all for $100 or less.

    Please advise how I might use this?

  2. W9GB

    W9GB Ham Member QRZ Page

    Please provide Manufacturer and Model Number of your Surplus Computer Server SMPS.

    The Internet is filled with Conversions of Surplus Server SMPS ... demand was largely driven by CyberCurrency Mining (BitCoin). Some models are easier (trouble-free models, few failures, etc.). Conversion kits with Breakout boards from proprietary SMPS connector were common.
    Last edited: Jul 26, 2018
  3. KA9JLM

    KA9JLM Ham Member QRZ Page

    It needs to have the ground isolated or smoke will appear with great smells.

    Good Luck.
  4. K7JOE

    K7JOE Ham Member QRZ Page

    how is that done conceptually ?
  5. G0GSR

    G0GSR Ham Member QRZ Page

    Hi Joe.
    I think what we need to know is, are the 0v rails of the three supplies connected together within the PSU.
    If they are, then its going to be difficult to use the -50v supply unless you can make an LDMOS amp with positive earth supply.


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