Can you repeat in simple terms what the test its exactly? I'm thoroughly confused by issues of level, current, where its being measured etc. You also mentioned measuring -160 dB distortion product. Is that ref the peak level of the two IM sources (I think that's where this started). I can measure -160 dB harmonics of a 10 KHz signal but IM is a different story. That level is very close to what seems to be achievable performance with the best technology today.
I would like to know source frequencies, levels, and impedance. Load impedance. Is there a passive prefilter to eliminate part of the HF component? Are the wires balanced or is one grounded? If the signs are promising I'll give it a try. I would start with wirewrap wire unless the silver plating will invalidate the test.
I like rg-11 with a 14gauge solid center. Wired the house with it .
Is that legal?
I can't think of how having less RF loss would improve power quality.
I also just had the weird idea that skin effect should have it's own impedance unit. Resistance and inductance have units, why not skin effect? But I guess that's a bit like sorting out different grades of vomit.
I should have specified the cable not the AC . But yes if in conduit and rated to 600v for USA . Pulling larger gauge in conduit would be cheaper. The house is cable wired with rg-11 for tv etc. Hope that clears it up .
Yes, the skin effect can be measured in Ohms at a particular frequency with an impedance meter.
There are two tests. Based on the article you posted about PIM and the bits here at the time I tried taking 10' of magnet wire twisting it and measuring it for 19/20 kHz IM on my AP source 50 ohms and whatever (10K?) for the load. This was at a level of 10 mV. using it as a balanced cable via the xlr connectors. Looking around 1K not surprisingly there was a baseline of distortion. I then over twisted the cable back and forth 5 or more times. I also wiggled it a bit. I then remeasured the cable and saw a bit more distortion.
Now I also have the device I originally showed in AX 9/11 (I think) that was originally designed to try and see solder joint distortion. I have since improved it a bit. Adding some aluminum shielding and upgrading the quality of some parts as I have learned a bit since then.
The original used a pair of transverse oscillators and these are now followed by Wein resonators feeding 600 ohm resistors that go to a 10 ohm resistor to signal reference ground. The junction feeds the cable under test. A low noise differential amplifier (Noise around 700 pv/sqrt(Hz)) provides 30 db of gain and low pass filtering. As the test signals are just above 90 kHz and the residual is 2.25 Khz it is reasonably easy to get the fundamentals below where they would be a problem for the FFT analyzer. After the analyzer output I feed a few more filters centered around 2.25 khz and this then feeds a dBx log response detector to produce a voltage for a 50 uA panel meter.
The whole unit is fed by four 12 volt batteries two for transmit and two for receive. The preamp has on board cap multipliers for each stage.
I also use at least 1024 averages to reduce the noise a bit. (As my device has decently random noise the dither effect seems to work.)
ES
Last edited:
There were vacuum transistors at least 20 years ago- one of my EE prof buddies was working on that while he was at Columbia, and it wasn't new then. It was a technology related to STM/SFM. He pulled me into it because he knew I was goofy about tubes and was interested in it for microsensor applications.
I've posted up a write up on my new line preamp here
Ovation Symphony Line Preamplifier
Yes, full of glorious Ad797's, LME49710, and so forth.
Ovation Symphony Line Preamplifier
Yes, full of glorious Ad797's, LME49710, and so forth.
link's empty for me ....I've posted up a write up on my new line preamp here
Ovation Symphony Line Preamplifier
Yes, full of glorious Ad797's, LME49710, and so forth.
Indeed, and I'm also on #3. She's my final one, and as the guys here who know her (Jan, Scott, Variac, sonidos...) will attest, she was the one I should have married the first time.
Tell me about it. She sees right through you, and STILL loves you. What are the odds for meeting someone like that? Take about infinite - I would say 1/infinite
Jan
I've posted up a write up on my new line preamp here
Ovation Symphony Line Preamplifier
Yes, full of glorious Ad797's, LME49710, and so forth.
Interesting read Andrew, a lot of good considerations.
Jan
- Status
- Not open for further replies.