On Sun, 4 Nov 2007 12:20:37 -0000, "Andrew Holme"
wrote:

I'm playing with super-regenerative oscillators in LTSpice.

My question concerns the 230XP valve VHF super-regenerative oscillator in
this figure 8.9:

http://www.holmea.demon.co.uk/temp/duplex.jpg

Here's figure 8.11 from the same book:

http://www.holmea.demon.co.uk/temp/iff.jpg

The text reads: "the super-regenerative oscillator in figure 8.11 is a
triode valve connected in a commonly used high-frequency circuit of the
Hartley type which relies on the internal capacities of the valve for its
operation." Why is it a Hartley when the tap is fed through an RFC?

Does the 230XP oscillator in figure 8.9 also rely on internal valve
capacities? How do these oscillators work? What is special about tuning
capacitor C in figure 8.11? What is the role of the cathode chokes?

I've been playing with JFET oscillator circuits in LTSpice and I can't get
them to oscillate unless the LC network between drain and gate creates a
phase inversion. How do these valve circuits make 0 (or 360 degrees) of
phase shift around the loop?

What is the nearest semiconductor equivalent of the above valve circuits?
Below is a JFET oscillator with feedback from drain to gate; but no reliance
on parasitic capacities, although I'm sure they affect the frequency. Is
this an LC Pierce?

Aha, that came form the unique (and now quite rare) book "Super-Regen
receivers" by JR Whitehead.

Without knowing what the RFC value is, it's hard to say what type of
oscillator it is.

There were thousands of super-regens built in the 1960's and 70's
using transistors, often OC170 and OC171, for radio control, door
openers, alarms, early CB sets and the like. I have a lot of
schematics somewhere.

There has been some more recent work done on super-regen receivers,
One was in QEX Sept-Oct 2000.

Barry