[Milsurplus] Cubic Receiver Issues

[Ray Fantini]

That Cubic radio is one of those things that you love or hate. Imagine people love them when they work. I have owned a couple and was no big fan, Ok it’s a great radio but the ergonomics suck. Just about as much fun as using a SDR, but that’s just me.

Getting back to your radio, first off the power supply in that radio is a solid switching power supply more along the lines of what’s in a computer. If it were me would look at the one that’s shorted first being that may be easy to fix. The incoming AC power line enters the card and goes thru a line filter to a bridge rectifier. Check that first. Also check the two big high voltage capacitors being they tend to short in switching power supplies. And last but not least the power FET that drives the transformer is a high failure rate item.

Almost no protection and minimal regulation so to that extent its not an imposable power supply to fix. About the worst thing that can happen is the switching transformer can short but I fixed tons of switching supplies and they rarely fail. The input rectifier, primary power filters and switching device fail all the time.

Important Safety Tip: The input side of the power supply is at hot ground! And in order to do anything safely with it you need to use a isolation transformer to protect you and any test equipment involved.

Couple other thoughts about the 3030. The mother board has three buses that run along the second plug for all the assemblies. Pin 1 of the plug is the +16 volt bus, Pin 2 is +8, Pin 3 is ground and Pin 13 is -16 volts. Always check to be certain that there are no dead shorts on the different DC buses before risking inserting a repaired power supply.

Good luck, let me know if there is anything I can help with.

Ray F/KA3EKH


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