[Amps] Tank circuit Q

[Gary Schafer]

Thanks for the help on capacitor current.  I think I have that figured out
now but I am still not sure what happens to tank Q.

 

When designing a tank circuit we first find what the load impedance should
be, then decide what Q we want then do the math to find the proper value of
plate tune C and tank L.

 

Knowing the value of plate tune C we find the reactance that it presents and
then find the plate voltage swing  and  find the rms voltage that is applied
across the plate tune C and find the current that pass thru it. The same
current passes thru the coil.

 

I see that things just happen to work out that using plate current times
tank Q also gives the approximate current thru the plate tune C. But I
understand that Q is not needed if plate voltage is used to determine
current thru the tune capacitor.

 

Xc can also be found by dividing load impedance by Q.

 

In setting up what values to use for plate tune C and L, that gets
determined by what Q we want for a given load impedance. 

If I then change the coil to one with more loss (higher resistance) but the
same amount of inductance as before and keep the same plate tune C then does
the overall Q still remain the same even though the coil may have much more
loss? 

 

Thanks

 

Gary  K4FMX