February 27, 2011 The Noise Blanker: A must have for VHF home made Transceivers!
Yesterday I made a noise blanker. The only one I’ve made.
You may find that very few homebrew transceiver designs have this option, an option that may be of much more importance than the AGC for example.
My NB PCB is about 30×20 mm (click to enlarge)
From my new location, where I use just a vertical “balcony” antenna at the moment, I was very surprised of the amount of noise (just above 59!!! on my S’Meter) on 28, 50 or 144MHz that apears every day, at random hours, without regard of season. I never realised that I could get rid of this electrical noise that mask completely even very good CW or SSB signals.
And another picture, the noise blanker and the PCB for a little varicap controlled VFO that I’ve “painted” also yesterday (click to enlarge)
At least! The Mizuho style noise blanker did it! Only three transistors some fast Schottky or Germanium small signal diodes in this simple and efficient design!
And it is driven with 10,7MHz IF (in Yaesu designs, you need another two stages: a mixer and a local oscillator for converting the IF to 455KHz).