Could the fact that the original tube reproduction had a metal case, either providing some unintentional shielding, or perhaps, the metal tube being close to the regen coil detuning in some way? Just a thought..,
There is a simple way to create really good looking overlays of these badly oxidized silver plate dials. Let me know if you want a .pdf of the process.
It looks like a regenerative circuit. en.wikipedia.org/wiki/Regenerative_circuit It seems a puzzle at first glance why this would result in a detected audio signal. I'd deduce that it is from the nonlinear characteristics of the triode. There is no explicit diode detector circuit here. The tickler adjustment, when the radio is not tuned to a station or the antenna is not connected, should be able to produce oscillations, something that would be visible on an oscilloscope. A more efficient design might be to parallel two of the 5676's, averting waste of filament power and the need for a series or shunt resistor.
Very interesting and thanks for sharing!
Could the fact that the original tube reproduction had a metal case, either providing some unintentional shielding, or perhaps, the metal tube being close to the regen coil detuning in some way? Just a thought..,
A little Barkeeper's Friend Cooktop Cleaner should clean that brass right up!
There is a simple way to create really good looking overlays of these badly oxidized silver plate dials. Let me know if you want a .pdf of the process.
It looks like a regenerative circuit.
en.wikipedia.org/wiki/Regenerative_circuit
It seems a puzzle at first glance why this would result in a detected audio signal. I'd deduce that it is from the nonlinear characteristics of the triode. There is no explicit diode detector circuit here. The tickler adjustment, when the radio is not tuned to a station or the antenna is not connected, should be able to produce oscillations, something that would be visible on an oscilloscope.
A more efficient design might be to parallel two of the 5676's, averting waste of filament power and the need for a series or shunt resistor.
I'm using a ux299 tube that i mounted on a wd11 tube base. Sadly the wd11 got smashed. Said a couple of bad words when that happened. :)