*Summary* *Amplifier and Oscillator Design* - 0:01: Introduction to selective amplifier or oscillator with good performance. - 0:15: Unsuccessful attempts to improve performance led to degradation. - 0:30: Identified high load impedance on the drain as the issue. - 1:05: Employed inductors to transform output impedance to resistive nature. - 1:19: Implemented shotky diodes to control oscillation level. *Measurement and Noise Challenges* - 1:48: Noted that lack of UADC4 slows down measurement speed. - 2:06: Employed MTR quad for noise reduction; noise still high. - 2:52: Presented noise floor and close-to-carrier noise findings. - 3:57: Suspected unclean BNC connectors as a problem source. - 4:57: Emphasized that dirty connectors can degrade results. *Diagnostic and Future Plans* - 6:17: Plans to identify and resolve the bad connection. - 8:44: Discussion on noise at varying frequency offsets. - 9:40: Acknowledged an unidentified noise issue; will investigate. - 9:52: Replaced buffer amplifier. *Long-term Results and Hardware Limitations* - 10:20: Discussed long-term measurements, criticized SDR IP results. - 12:42: Conducted measurements with a sound card; limitations persist. - 14:25: Noted noise floor uncertainty at 300 Hz and -172 dB. - 15:50: Observed new data to be 3-4 dB worse than older measurements. *Performance Metrics* - 16:40: Evaluated performance metrics like Q and phase. - 17:36: Tested gain; measured at 11.4 dB. - 17:44: Experimented with crystal tuning; observed slight degradation. *Advanced Troubleshooting* - 25:18: Discussed oscillator frequency's dependency on load impedance. - 26:09: Noted 20dB noise difference between two channels. - 27:03: Mentioned transients when linking power supplies. *Environmental Factors and Modifications* - 29:39: Found poor performance at 1 Hz due to lid removal; foam placement helps. - 31:48: Discussed phase noise variations with foam positioning. - 33:41: Trimmer capacitor replacement yields no change. - 34:21: Removal of foam and knot impacts phase noise. - 35:21: Protective coatings and resistor additions prove ineffective. *Additional Noise Remediation Attempts* - 38:02: Plastic foil on iron powder core reduces noise. - 40:20: Foam and plastic foil placement impacts noise level. - 41:33: Balancing parallel capacitance removal has no effect. - 42:29: Circuit modifications around crystal and JFET ineffective. *Positive Learnings* 1. Employing inductors successfully transformed output impedance to a resistive nature, resolving initial issues. 2. Shy diodes effectively controlled oscillation levels, improving the overall stability of the system. 3. Identification of high load impedance as a root cause led to targeted troubleshooting. 4. Using MTR quad partially mitigated noise issues, pointing to a viable noise reduction method. 5. A thin plastic foil on top of the iron powder core significantly reduced noise, offering a low-cost noise control method. 6. The test on gain provided a solid metric (11.4 dB) to quantify amplifier performance. 7. Measurement using a sound card provided a secondary method for data collection, albeit with limitations. *Negative Learnings* 1. Neglecting connector cleanliness can have a significant negative impact on results. 2. The absence of UADC4 substantially slowed down the speed of measurement, affecting efficiency. 3. SDR IP results were deemed "useless," implying a wasted effort in employing this method. 4. Long-term data revealed a 3-4 dB degradation in noise level compared to older data. 5. Environmental factors, like foam placement, complicated the issue by introducing variables that were hard to control. 6. Efforts to improve performance often led to degradation, indicating the system's sensitivity to adjustments. 7. Replacing buffer amplifiers and making other hardware changes often did not lead to the expected improvements.
*Summary*
*Amplifier and Oscillator Design*
- 0:01: Introduction to selective amplifier or oscillator with good performance.
- 0:15: Unsuccessful attempts to improve performance led to degradation.
- 0:30: Identified high load impedance on the drain as the issue.
- 1:05: Employed inductors to transform output impedance to resistive nature.
- 1:19: Implemented shotky diodes to control oscillation level.
*Measurement and Noise Challenges*
- 1:48: Noted that lack of UADC4 slows down measurement speed.
- 2:06: Employed MTR quad for noise reduction; noise still high.
- 2:52: Presented noise floor and close-to-carrier noise findings.
- 3:57: Suspected unclean BNC connectors as a problem source.
- 4:57: Emphasized that dirty connectors can degrade results.
*Diagnostic and Future Plans*
- 6:17: Plans to identify and resolve the bad connection.
- 8:44: Discussion on noise at varying frequency offsets.
- 9:40: Acknowledged an unidentified noise issue; will investigate.
- 9:52: Replaced buffer amplifier.
*Long-term Results and Hardware Limitations*
- 10:20: Discussed long-term measurements, criticized SDR IP results.
- 12:42: Conducted measurements with a sound card; limitations persist.
- 14:25: Noted noise floor uncertainty at 300 Hz and -172 dB.
- 15:50: Observed new data to be 3-4 dB worse than older measurements.
*Performance Metrics*
- 16:40: Evaluated performance metrics like Q and phase.
- 17:36: Tested gain; measured at 11.4 dB.
- 17:44: Experimented with crystal tuning; observed slight degradation.
*Advanced Troubleshooting*
- 25:18: Discussed oscillator frequency's dependency on load impedance.
- 26:09: Noted 20dB noise difference between two channels.
- 27:03: Mentioned transients when linking power supplies.
*Environmental Factors and Modifications*
- 29:39: Found poor performance at 1 Hz due to lid removal; foam placement helps.
- 31:48: Discussed phase noise variations with foam positioning.
- 33:41: Trimmer capacitor replacement yields no change.
- 34:21: Removal of foam and knot impacts phase noise.
- 35:21: Protective coatings and resistor additions prove ineffective.
*Additional Noise Remediation Attempts*
- 38:02: Plastic foil on iron powder core reduces noise.
- 40:20: Foam and plastic foil placement impacts noise level.
- 41:33: Balancing parallel capacitance removal has no effect.
- 42:29: Circuit modifications around crystal and JFET ineffective.
*Positive Learnings*
1. Employing inductors successfully transformed output impedance to a resistive nature, resolving initial issues.
2. Shy diodes effectively controlled oscillation levels, improving the overall stability of the system.
3. Identification of high load impedance as a root cause led to targeted troubleshooting.
4. Using MTR quad partially mitigated noise issues, pointing to a viable noise reduction method.
5. A thin plastic foil on top of the iron powder core significantly reduced noise, offering a low-cost noise control method.
6. The test on gain provided a solid metric (11.4 dB) to quantify amplifier performance.
7. Measurement using a sound card provided a secondary method for data collection, albeit with limitations.
*Negative Learnings*
1. Neglecting connector cleanliness can have a significant negative impact on results.
2. The absence of UADC4 substantially slowed down the speed of measurement, affecting efficiency.
3. SDR IP results were deemed "useless," implying a wasted effort in employing this method.
4. Long-term data revealed a 3-4 dB degradation in noise level compared to older data.
5. Environmental factors, like foam placement, complicated the issue by introducing variables that were hard to control.
6. Efforts to improve performance often led to degradation, indicating the system's sensitivity to adjustments.
7. Replacing buffer amplifiers and making other hardware changes often did not lead to the expected improvements.