Converting the HP ESP120 Power Supply

Quick notes on converting the HP ES120 2950-watt blade server power supply to run “48-volt” amateur radio amplifiers.  The power supply I have has a slightly different in configuration from the one described by W8ZN on the K8GP site.

hp_001

I picked up the power supply on good terms at Dayton some years ago and finally managed to get around to hooking it up after I put two 240-volt, 20-amp circuits in my shack this spring/summer.  I used a molded air conditioner extension cord with the female end cut off to attach it to the wall.  Hot-ground-hot is the wiring on the AC input side.  On the output, there is a jumper block and two pairs of blade connectors, with one pair being positive and the other negative, strapped together.  In the middle of the output there is a jumper block.

hp_002

Here is where the steps differ from the W8ZN steps:  instead of shorting two pairs of pins together, this power supply requires three in a line to be shorted together.  It’s visible in the photo below, I think.  The center row.

hp_003

I’m getting 51.4 volts unloaded.  Load will be described in the future as it comes to be…

Ethan Miller, K8GU, is a regular contributor to AmateurRadio.com and writes from Maryland, USA. Contact him at [email protected].

5 Responses to “Converting the HP ESP120 Power Supply”

  • kc6swr:

    i have this power supply and configured same as reccomended but when dc current pulls over 20 amps HP esp tripps over current and i must recycle the switch that connects 3 pins together.

  • kc6swr:

    Turns out device was triping due to RF being senced by power supply. No longer tripps ,i placed ferrite chokes to a/c power cord and unit no longer shuts down.

  • kc6swr:

    WELL FORGET ABOUT MY FIRST TWO POSTS. LOOKS LIKE I WAS PREMATURE ABOUT SHUT DOWN PROBLEM FIX. CAME TO RADIO ROOM AFTER I GOT BACK FROM SHORT TRIP AND WENT TO RADIO ROOM AND MY SHUT DOWN PROBLEM HAS RETURNED. AT THIS TIME I CANNOT USE MY LDMOS AMP UNTIL I FIGURE OUT WHATS GOING ON. ANY ONE GOT ANY IDEAS?

  • David KD4E:

    What is the location of your antennas relative to the amp cabling?

    Have you checked the quality of your grounding system?

  • Bruce W8HW:

    Where can I find service information (Manual) for the HP ESP120 power supply?

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