On Tue, Aug 10, 2021 at 10:24 AM, Björn (SM0SBL) wrote:
The QCX uses the Hipermite narrow CW filter which I think is set to 750Hz
I also use my external SotaBeams Laserbeam CW filter which has an LED that lights when tuned to the 750Hz cw tone.
It goes between QCX and headphones.
Im sure there was a circuit publishedin a qrp mag with a simple led zero beat circuit.
Could help you ?
Cheers Mark G0NMY