Many thanks Wolfgang.
Your reasoning and accompanying scope traces make very good sense. They much appreciated. I would like to know what scope you use. It produces excellent traces.
I decided to try out your modifications the the 17 Metre board first. I added a 470R resistor in parallel with R41. I also changed C22 to 0.1uF electrolytic to sort out the audio key click problem.
Positive outcomes:
The audio clicks have gone completely.
The CW waveform is much sharper in rise and fall times producing a much better cleaner waveform overall.
Using full break-in there is no sign of ringing between the dit and dah character formations. This works very well.
The output transistors only get a little warm when keying for more than a minute or two continuously.?
Issues to resolve:
I still have issues with a "ringing" CW tone when using semi break-in!
There is still a persistent albeit low level trace shown on the scope between the individual character formations when using semi break-in.
The lack of clean switching results in a slight "ringing" CW tone when monitored on a receiver.
Strangely the 20Metre board does not display ANY of these characteristics and Q6 in this board has a lower measured DC gain than the one in the 17Metre board which exhibits all of the problems you mention. Any more thoughts on solving the semi break-in issue would be most welcome Wolfgang.? Your time and effort is much appreciated. I can supply some spectrum scope graphs if required.
73 Derek G4VWI. HNY.
