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PS-125 Power Supply – Using it with Flex 6300

ps-125 power supply

My new FlexRadio needs power. With a few modifications, I can use my old ICOM PS-125 power supply. Here’s how. 

The FlexRadio 6300 needs 13.8 volts DC at 25 amps. That’s just what my old ICOM PS-125 power supply provides. Unfortunately, rather than terminals, this power supply uses a “Molex-type” plug, shown above. I put quotes around “Molex-type” because it is not really a Molex connector. It is proprietary and is no longer made.

I want to use the PS-125 because it works great and is really quiet. By quiet, I mean both audio and RF. Many new high current power supplies use a fan, which can be quite noisy. They can also produce RF interference if they are switching power supplies. The ICOM PS-125 does not have a fan. And, since it is a linear supply, no RFI.

Some people would just cut off the plug and wire in a new connector. I prefer to keep the unit in original condition, so that means making a power cable adapter.

Making a PS-125 Power Supply Adapter Cable

The Flex 6300 provides a power cable with with ring connectors. What I need is a way to attach the rings to the “Molex-type” plug on the power supply. My solution was really simple and completely non-destructive.

ps-125 power supply

First, I removed the mating female power jack from the back of my old ICOM 756 Pro II. This proved to be quite easy. Just remove the top of the case, and unscrew two small ring connectors from the radio’s power board. The jack just pops out by squeezing the tabs on its sides. (See above left.)

Second, I connected the small rings from the jack to a terminal connector. Since the Flex cable rings were too large diameter to fit into the terminal block, I soldered some one inch lengths of #14 wire to matching ring lugs. See lower left.

Third, I used some brass hardware (quarter inch screws, nuts and washers) to mate to the Flex power cable. The final assembly is shown on the right.

Finally, the exposed connections were wrapped with electrical tape. When all was said and done, everything worked fine. Plus, I saved a few bucks along the way.

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