Hi Ed,
Thank you for sending me the schematic of the Dit Dah Keyer by
David Efison, N6GKC. I built one for the ham in Okalahoma City
and delivered it this past Saturday. I worked just great!!! I had to
make the following changes to the basic circuit to keep it from
oscillating and to give it better response:
Change the gain of the second op amp (amplifier/clipper)
from 100 to 50 (replace the 100K feedback resistor with
at 51K) --- This helped the circuit not to ring/oscillate.
Change the .1 mfd caps in the detector circuit to .01mfd
this change gives the unit better high speed response.
I used an cheapie headphone speaker as the microphone
element. It worked great with the above changes. I removed
on of the speaker pads from the headset and used the band
to hold the mic against the mouth. This frees up the hands
and works very well. Several hams tried the unit at the
Okalahoma City QRP club meeting and they were amazed
at how well it worked. The ham with Parkinson's desease was
overwhelmed.... can't wait to work him on voice cw.
Thanks again for your help.
73's
Jerry Henshaw
KR5L / QRP
jerryh@webzone.net
ARCI 9165, QRP-L 847, NORCAL 1999
49er, ARK 20, Wilderness Sierra, 38 Special
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