There have been some upgrades to the power supply boards to make them more robust over time (higher wattage zener, higher voltage tantalum capacitor). So depending which Rev QMX pcb yours was built from, and when purchased, the best course of action may be to purchase a new power supply board set from QRP-Labs.?
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My first Rev 1 QMX had a similar fate.?
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73
de Roy - KI0ER
Littleton, Colorado USA
