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LOC:JO51PL   ;CQ-Zone:14

Zero Beat

When tuning the VFO to a desired receive signal, the CW signal should have the same pitch as its own sidetone, e.g. 700Hz, have. Otherwise, if one lies next to the receiving frequency of the partner, e.g. 100Hz or 200Hz. A Zero Beat indicator with LED helps.

Circuit and construction


Description (Excerpt from FUNKAMATEUR - Bauekementeinformation)

The LM567 is a tone decoder with a phase locked loop. Via the two external components R1 and C1 you can set the center frequency fo of the detector area. The capacitor C2 sets out the detection door width fixed, the max. 14%. With C3 is adjustable how fast the reaction to a detected Signal is to take place. The vote is made on the highest brightness of the LED.

The circuit had to be set up so flat that it fits under the board of the QCX (max.1cm). For this I used a small strip PCB.

The sound decoder performs well and helps a lot in tuning. With advancing age leaves the ear now and then the small circuit helps. All in all, it was worth it!
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