As a cautionary tale to others, here is how I wasted an hour this
afternoon.
I had just unbent my antenna after the recent high winds, and was
tuning it up with some RF. At the end of my transmission, I sent my
callsign at about 20WPM as a courtesy. It was then that I noticed the
CW was distorted and rather clipped, especially the dots. I also had
bad key clicks. After checking all sorts of things, I found that the
distortion applied only to mid-range speeds, so that it did not
affect below about 10WPM or above 30WPM. This was an important clue
but I ignored it.
I then took numerous measurements, assuming that RF was getting into
the keying circuitry or even the PSU, finally dismantling the Tx and
looking for poor connections or flash-overs. After double-checking
that I had not introduced any problems when working on the antenna, I
stopped to have a think. Not a moment too soon.
It then dawned on me that I had switched on both of the noise
blankers in my TS-850 to reduce the Loran noise by some 3dB.
Switching these off solved the keying problem. Of course, I didn't
have a keying problem at all - I had a receiver which had tried its
hardest to suppress my CW dots, and had mostly succeeded!
Moral. Have a cup of tea and a think first, before stripping the
station down.
Mike, G3XDV
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PS: Excellent signal from IK5ZPV this morning.
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