Rauschsperre (Squelch, z.B. für Tuner)

There are two basic types of SSB exciter: l. Filter-type circuits: these are ex- pensive because of the filter and crystal required but have the advantage of being easy to adjust! 2. Phase-type and Weaver circuits: these are cheap but not so easy to align properly. An intermediate solution is described here, using cheap ceramic filters in a high quality SSB exciter that does not call for awkward alignment procedures. The microphone signal (crystal mike or high impedance dynamic) is ampli- fied and fed to the S042P balanced mixer. The 100 D. preset poten- tiometer between pins I O and I 2 is set for maximum carrier suppression. The local oscillator uses a BF494 (or BF194) and a ceramic filter.