[Amps] caps across rectifier diodes

[Bill Fuqua]

   This buzz is common. Often you can hear it in your shack but it is not 
going out to the antenna.
It is most irritating when using direct conversion receivers. The BFO of 
the receiver finds its way to the
power supply where the rectifier diodes modulate it at 120Hz rate as they 
switch on and off and then it
gets reradiated and picked up by the receiver again. Capacitors across the 
diodes usually cure that problem as
well.
73
Bill wa4lav


At 11:52 AM 3/3/2009 -0500, ToddRoberts2001 at aol.com wrote:
>Back when I first started building some low power transmitters
>I always seemed to notice a slight hum or buzz superimposed on the
>carrier until I bypassed the power supply diodes with .01 caps across
>each diode. I also seemed to notice RF getting into the AC house
>wiring that was also cured by adding .01 caps across each rectifier.
>
>Likewise I have run across some solid state and tube receivers that had a
>buzz
>superimposed on reception especially at lower frequencies. The buzz  was
>cured when .01 caps were added across the power supply diodes.
>
>73 Todd WD4NGG
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