05-01-2017, 05:17 PM
I did do some experiments with tuned circuits a few years ago.
For a random selection of crystals you need a circuit that can work with both parallel or series crystals. You need a circuit with two places to plug the crystal in.
A series tuned crystal can simply be added in parallel with an emitter resistor and the gain stage can then be adjusted to get a clean output.
A parallel tuned crystal will need to be in series with the resistive feedback loop and again the gain stage adjusted for a clean output.
Manually tuned circuits can then be added in the two crystal positions according to the type of crystal found in the first test to see what harmonics can be tuned.
A bit of bespoke test equipment needs to be made for this task.
For a random selection of crystals you need a circuit that can work with both parallel or series crystals. You need a circuit with two places to plug the crystal in.
A series tuned crystal can simply be added in parallel with an emitter resistor and the gain stage can then be adjusted to get a clean output.
A parallel tuned crystal will need to be in series with the resistive feedback loop and again the gain stage adjusted for a clean output.
Manually tuned circuits can then be added in the two crystal positions according to the type of crystal found in the first test to see what harmonics can be tuned.
A bit of bespoke test equipment needs to be made for this task.
