Re: QCX tuning

Alan de G1FXB

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's strange the number of QSX PA failures,
yet Hans undertook rigorous testing and never encountered a failure?
A recent comment was

2/.    What version PCB have you and any modifications made?

3/.    Are all the BS170's that failed the ones originally supplied or have you had reason to replace one or more before?


On 01/09/2018 18:04, Matthias Zwoch wrote:
I used my 20m QCX until yet on my station antenna without any problems for numerous QSOs among them one to PY1AX with over 9900 km. Yesterday I had to prepare the QCX for a fieldday next week. I erected my outdoor inverted-V in my garden and hat a look at it with the antenna-analyzer. Yes, at 14030 SWR was 4,9 but a 1,1 minimum was 300 kHz nearby. No problem for my tiny elecraft T1 tuner. But after few seconds of tuning the display got dark. The fuse was blown and the finals including MPS751 were gone. The loss of some parts and the fix is not a big problem. But my question is -how to tune the QCX if it cannot resist few seconds of automatic tuning?

73  DD7NT

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