[TenTec] Questions on Corsair II

[Steve Hunt]

Steve,

Just taken a look inside my Corsair II. The Speed Pot on the front panel measures 8 KOhm across the ends.
At 12 wpm it measures 1 KOhm from slider to right hand pot terminal (seen from above)
At 30 wpm it measures 6 KOhm from slider to right hand pot terminal

>From that you might be able to work out some series / parallel resistor values around the pot to make it less sensitive.

For interest I also checked the frequency of the CW clock oscillator feeding the processor (pin 15 of the Audio processor board): 12 wpm = 16.6 KHz and 30 wpm = 23.8 KHz. So you could play around with resistors to give that range of clock speeds. No idea why the clock frequency doesn't scale linearly to wpm, but I checked it several times and those figures are right. It may be because the clock is not 1:1 mark/space and the processor may only be looking at one half of the waveform?

73,
Steve G3TXQ




>Another thing is the silly keyer speed control pot's usable range is
>crammed into about 15 degrees? What's up with that? Plus the manual
>does not include the keyer schematic. Although it's referenced in the
>block diagram as the "logic board" no. 81246. Someone have the
>schmatic for this?