Am 01.09.2018 um 19:40 schrieb Alan de G1FXB via Groups.Io:
Hi Matthias,
Sad to hear of the failure,
1/.??? out of interest what supply voltage and fuse value & was it (fast blow or time lag type) did you have?
It was a 1A fuse fast type. Supply voltage was at 15V via stepup converter fed from a 12V Pb akku.
It's strange the number of QSX PA failures,
yet Hans undertook rigorous testing and never encountered a failure?
A recent comment was? /g/QRPLabs/message/26421
2/.??? What version PCB have you and any modifications made?
I assume its a PCB 3, it came already with the MPS751. Not much modified. Just the modifications from Hans' website and I set the display separately in the case. Have a stepup regulator for the PA and an extra 5V regulator for display and backlight.
3/.??? Are all the BS170's that failed the ones originally supplied or have you had reason to replace one or more before?
All part are originally supplied. No reason to change something until yet...
73 Matthias, DD7NT
