Sunday, June 25, 2017

24 VDC Power Supply Modifications

Original Power Supply
The T/R Relay for the EME station requires 20-28 VDC.  Since I did not have that supply voltage available, I was planning on using a Boost Regulator from W6PQL to provide the necessary power for that relay.  However, my friend Steve Gillispie, K8LZ, just happened to offer me a very nice 24/28 VDC power supply that would do the job.  He had no way of knowing I needed just the very thing that he was planning to dispose of while down-sizing his shack.  We had the "Perfect Match" - he needed to get rid of a power supply and I needed that exact power supply!  You can see a photo of the supply Steve gave me on the left.  (Click on any photo to see a larger image.)

Modified Power Supply
The power supply came from Steve in the original box with the manual so I had everything I needed to install and operate it.  It was a "bare bones" device with just a barrier strip for connections and no way to switch on (or off) the AC voltage.  Thus, I needed to make a few minor modifications to it so that it was more efficient for my needs.

I picked up a power switch and fuse holder at the Charleston hamfest for just a couple of bucks and my junk box already had a new AC power cord and an LED.  I used a couple of existing holes in the metal case to mount the AC Power Switch and the LED after drilling them out to the necessary sizes.  I then had to drill a new hole on the side for the fuse holder.  A little heat shrink, a 1.2 k ohm dropping resistor for the LED from the junk box, a strain relief for the AC cord and a couple of hours work turned this "bare bones" 24 VDC power supply into a needed shack accessory.

You can see in the photo at the right the modifications I made to Steve's power supply.  I am now ready to add this to the EME station equipment and move on to the next thing I need to build (like maybe the antennas?)


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