[AMPS] SB-220 Smoke Test

[measures]

>
>
>
> .07 pf at 205 Khz. = 11 meg
> 50 uh at 205 Khz. = 64 ohms
> .002 ufd 205 Khz. = 388 ohms
>
> What is this, a math test? 

no, but you got the answers right.  

>I was just curious
>of the frequency.

In order to bring about the alleged VLF parasitic oscillation, the 
feedback path must deliver a significant signal to the cathode.  This 
seems unlikely if the feedback path has 11meg-ohms of Xc.  //   I have 
operated my SB-220 with directly grounded grids and with grids that were 
grounded through capacitors.  There was little difference at 40m or 80m.  
.    There was no indication that a VLF oscillation was taking place.  // 
  Another problem with the VLF osc. theory is that the anode to gnd path 
for 205KHz is quite low, 388-ohms minus 64-ohms.
>
later, Mark 
>
>> > If my calculation is correct, it would be about 
>> >205 Khz, assuming the choke is 1 mh.
>> >
>> Agreed /  What is the reactance of the 3-500Z's 0.07pF anode/cathode 
>> 
>> feedback capacitance at 205KHz, Mark?  At 205KHz, what is the Z of 
>> the 
>> 50uH HV-RFC and 2000pf HV bypass.?
>> >
end

-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


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