In message
<CANnsUMHruA-cbtCW3yswZaaKDayat7KKSm1wdPE3YZpvtmrAww@...>,
dated Mon, 23 Dec 2013, Chris Maness <chris@...> writes:
So would the change in gain due the change in B+ be the most likely
cause of f_o change for a Clapp oscillator with a valve state
amplifier?? The reason for the inquiry is at this point mostly
academic.? I love learning things as I work my way through fixing an
old radio.? If indeed that is the case, then it would be the Miller
effect indirectly.
One way to tell is to analyse the circuit in detail, or you could try to
find Clapp's original paper:
J. K. Clapp, "An inductance-capacitance oscillator of unusual frequency
stability", Proc. IRE, vol. 367, pp. 356-358, Mar. 1948.
For analysis, look at the size of the a-g1 capacitance compared with the
tuning capacitor (the 'capacitance tap' capacitors should be so much larger that their effect is negligible). The consider what internal gain
would be needed for a small change in the Cag to affect the frequency
by say 1 kHz. If that turns out to give a gain of 10 000, you can be
pretty sure that you don't have a Miller effect problem.
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
Nondum ex silvis sumus
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
