[Amps] plate bypass caps

Steve Flood kk7uv at bresnan.net
Sun Jan 11 20:38:04 EST 2009


I have an Ameritron plate choke mounted in my amp project.  It is 225uH.  With 2700 plate volts, this is 2544 ohms at 1.8 MHz and thus 1.06 amps.  I am now assuming the plate bypass capacitor at the base of the choke must be very low reactance on 1.8 Mhz which tells me .01 or .02 uF at maybe 5kv rating.  Am I thinking about this correctly?  If so, such capacitors seem quite rare - the usual internet sources only carry .001 or .002 which would seem ineffective at bypassing at 1.8 MHz.  Yet, there are many 160m amp designs that use .001 for bypass.  Perhaps they are using much much larger plate chokes?

Steve, KK7UV


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