So very interesting. Your graphing shows a lot of data. Nothing is easy , always compromises. Nice work. Can you share what you have found regarding the " No Swiss Cheese" on your PCB making?
Yeah, it actually was pretty easy. I slosh the board in and out of the etchant. I think this speeds up the acid attack on the copper and washes away the etchant products, and less time in the etchant means less penetration through the toner, so less swiss cheese effect. I also preheat the bottle of etchant by soaking it in a bucket of hot tap water for 15m before beginning.
i think since you are not measuring the fundamental power at the output, which you should, and instead measruing wideband (total) power using a power meter that can explain some of the oddities e.g. increasing gain with increasing input power is perhaps because the harmonics are growng and contributing to the measured output power more and more. Also with so much distortion I dont think you are working in class A really. Moreover, for gain compression you must only measure th epower of the fundamental not including all the harmonics unless they are negligibile (which usually they must be but they seems to be significant in your amplifier)
Very good point, I overlooked the fact that my power meter measures all components. I do have my homebuilt SA so I will redo the gain compression study and look at the magnitude change of the fundamental, along with identifying all the harmonics.
So very interesting. Your graphing shows a lot of data. Nothing is easy , always compromises. Nice work. Can you share what you have found regarding the " No Swiss Cheese" on your PCB making?
Yeah, it actually was pretty easy. I slosh the board in and out of the etchant. I think this speeds up the acid attack on the copper and washes away the etchant products, and less time in the etchant means less penetration through the toner, so less swiss cheese effect. I also preheat the bottle of etchant by soaking it in a bucket of hot tap water for 15m before beginning.
Do you have a spectrum analyzer? Would be curious to see what the output looks like and how it changes over drive level.
I agree, so I made a quick bonus episode on just that, will release it very soon.
i think since you are not measuring the fundamental power at the output, which you should, and instead measruing wideband (total) power using a power meter that can explain some of the oddities e.g. increasing gain with increasing input power is perhaps because the harmonics are growng and contributing to the measured output power more and more. Also with so much distortion I dont think you are working in class A really. Moreover, for gain compression you must only measure th epower of the fundamental not including all the harmonics unless they are negligibile (which usually they must be but they seems to be significant in your amplifier)
Very good point, I overlooked the fact that my power meter measures all components. I do have my homebuilt SA so I will redo the gain compression study and look at the magnitude change of the fundamental, along with identifying all the harmonics.