Hello Ludwig,
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many thanks for that hint.?
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An L101 with an invisible short was also the reason for my issues with the 5V SMPS board reported in
/g/QRPLabs/message/129508.?
None of the static tests showed any issues and also L101 looked good, so that my QMX had been in the drawer for 8 months.
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Only now measuring the resistance of L101, showed a problem. I tried to desolder it with a USB-C heating plate, but obviously temperature was too low, so that I finally heated one side of L101 with a soldering iron and broke the inductivity on the other side from the PCB.
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As I did not have a 330uH power inductivity in my junk box, I tried a 1210 100uH SMD inductivity, which did not work.
I then used a 47uH SMD 7x7 power inductivity soldered with wires and that worked!
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I will now order a 330uH SMD 7x7 power inductivity, to be on the safe side. I could not find the unshielded type used in the QMX OOTB, but will use a shielded one, that should also fit.
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73, DB2OO -Joerg
