17-08-2013, 09:18 AM
Hi Al, it's not so much about the effect temperature change has on sensitivity per se, the question was more a about taking the classic stability (including temperature) measures for the tuned circuit ie: low LC ratio which you probably know can reduce the degree of drift caused by changes in capacitance (including stray) due to temperature change and also reduces the degree of drift caused by the inductor due to temperature change because of the fact that it's inductance is lower (less copper etc) because of the low LC ratio.
As I understand it the Q of a low LC ratio tuned circuit is lower than that of a tuned circuit where the LC ratio is higher, if that is the case then one would assume that the overall magnification of that circuit would be lower, on the other hand does that matter in the context of a regen as the detector is taken to the point of oscillation (for SSB/CW) which means that the stage has a very high level of gain anyways due to the feedback/oscillatory nature of it?
"""How is the degree of reaction to be controlled? By varying the degree of mutual inductance between those coils? By changing the voltage on the screen grid of a pentode? By a variable capacitor"""
That is by screen grid voltage control, feedback is cathode tapped Hartley, I have that bit working nice and smooth, no plops or ear shattering birdies.
Lawrence.
As I understand it the Q of a low LC ratio tuned circuit is lower than that of a tuned circuit where the LC ratio is higher, if that is the case then one would assume that the overall magnification of that circuit would be lower, on the other hand does that matter in the context of a regen as the detector is taken to the point of oscillation (for SSB/CW) which means that the stage has a very high level of gain anyways due to the feedback/oscillatory nature of it?
"""How is the degree of reaction to be controlled? By varying the degree of mutual inductance between those coils? By changing the voltage on the screen grid of a pentode? By a variable capacitor"""
That is by screen grid voltage control, feedback is cathode tapped Hartley, I have that bit working nice and smooth, no plops or ear shattering birdies.
Lawrence.
