Hope your shots are up to date, had a friend whose husband came back and expired from an Amazon jungle fever (no kidding).
Some distortion measurements with my Shibasoku 725. These are all at 10V, 2400 Hz.
First are from a Fluke 510 AC standard (tweaked). The second 2 are the Shibasoku 590AR. They are scope pictures of the display from a Wavetek FFT, which has the internal corrections for bandwidth. These are from the monitor out at -90 dB (= 1V).
Scaling is pretty straightforward. 1V = -90 db from the signal (10V or + 20dBV) so for example first picture the -32 dB is -122 dB from the fundamental Second picture, the displayed noise is -67 dBV/rtHz so scaling 67 dB + 90 dB to the signal -20 dB to get to 1V yields -137 dB/rtHz noise density. Its -157 db from 10 V. I'm not sure that noise is the source or internally limited.
On this model the AGC starts at the input amp. That means, unless the noise is pretty high in the source, it will probably change with level as the input gain changes. What I have noticed is that the distortion and noise do change with level. The 590AR uses a passive 600 Ohm attenuator on the output for all levels. As a source it will never have less than 3 nV/rtHz.
I tried different levels with the 590AR and the distortion remains the same until the front end gain changes and then it all changes a lot with the harmonics shifting in levels significantly. All below -120 db so it meet spec.
Looking at the block diagram the meter gets its input in different ways but not directly from the monitor output. It looks at the ratio of input to output but the agc's are not that fine grained so it may have +/- 2 dB variation from level to level or more? Lots of moving parts in this thing.
Fluke 510 distortion w/ marker at distortion
Fluke 510 distortion w/ marker at noise in noise density mode
Shibasoku 590AR distortion w/ marker at distortion
Shibasoku 590AR distortion w/ marker at noise in noise density mode
First are from a Fluke 510 AC standard (tweaked). The second 2 are the Shibasoku 590AR. They are scope pictures of the display from a Wavetek FFT, which has the internal corrections for bandwidth. These are from the monitor out at -90 dB (= 1V).
Scaling is pretty straightforward. 1V = -90 db from the signal (10V or + 20dBV) so for example first picture the -32 dB is -122 dB from the fundamental Second picture, the displayed noise is -67 dBV/rtHz so scaling 67 dB + 90 dB to the signal -20 dB to get to 1V yields -137 dB/rtHz noise density. Its -157 db from 10 V. I'm not sure that noise is the source or internally limited.
On this model the AGC starts at the input amp. That means, unless the noise is pretty high in the source, it will probably change with level as the input gain changes. What I have noticed is that the distortion and noise do change with level. The 590AR uses a passive 600 Ohm attenuator on the output for all levels. As a source it will never have less than 3 nV/rtHz.
I tried different levels with the 590AR and the distortion remains the same until the front end gain changes and then it all changes a lot with the harmonics shifting in levels significantly. All below -120 db so it meet spec.
Looking at the block diagram the meter gets its input in different ways but not directly from the monitor output. It looks at the ratio of input to output but the agc's are not that fine grained so it may have +/- 2 dB variation from level to level or more? Lots of moving parts in this thing.
Fluke 510 distortion w/ marker at distortion
Fluke 510 distortion w/ marker at noise in noise density mode
Shibasoku 590AR distortion w/ marker at distortion
Shibasoku 590AR distortion w/ marker at noise in noise density mode
yes, Nasty bugs and malaria .... I think my shots are still good from time I went to Nepal right after earth quake... had to leave because of spreading cholera. Cant get enough shots for everything.
Another lawless area with no 911, no hospitals nor help. But hey... they have real heavy-duty Shamans. So it cant be all bad.
Actually it is mostly bad but worth the torturous experience seeing the tribal people and villages along the many streams and rivers which form to make up the mighty Amazon. The anaconda, the pirana, constrictors, Jaguars, crocodiles, army ants etal. As long as i bring gifts and a machete, I'm OK. Going with guide who has a home in there somewhere. years ago, he had a shoot out with local area robbers in his house... they had shot guns... he had 45. He lost 2 fingers and a big hole in his side but with his wife reloading for him, he killed both of them. In the middle of the night his wife stuffed his side with cloths... gave him a loaded weapon and ran a long way to a village, they came back and carried him out to another village where a small plane could land and get him to hospital. Its that kind of area. -Richard
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And just to get more data here are measurements of the same two sources using a passive (B&K 1604) notch filter. The harmonics are not corrected.
First the Shibasoku 590AR same as above.
Then the Fluke 510
The noise pickup on the 510 measurement is frustrating but typical when going directly into a PC sound card, even differentially.
Use the upper correction curve to correct for the harmonic levels to compare. Using the "distortion" setting introduces too much loss.
First the Shibasoku 590AR same as above.
Then the Fluke 510
The noise pickup on the 510 measurement is frustrating but typical when going directly into a PC sound card, even differentially.
Use the upper correction curve to correct for the harmonic levels to compare. Using the "distortion" setting introduces too much loss.
yes. Pulsed high energy is Always dangerous. Everything about it. The 3rd world stuff isn't.... more of an annoyance.
Did I tell you the time I ate at the dictators house in northern Laos? Later.
-Richard
Yes you did, I would not sneak into North Korea without a visa. BTW Xian and several Chinese cities are 72hr. visa free zones now to accommodate tourists and their money.
I ran into a volunteer archaeologist in Belize and got his attention by asking some questions about Mayan hieroglyphics he took the 4 of us out of the tour for some private showings of recent finds. I gather this is the kind of thing you like. Nothing like showing genuine interest in local culture/history to get just about anyone to put themselves out a little for your benefit.
This notch (B&K 1607) is completely passive. No mods. The EMU clips at around 7V (10V peak). I used the -20 dB attenuators on the 1607 to calibrate the input. The notched output is around -60 dB. I duplicated everything again today and got essentially the same results.
and the trip to Xian? No visa at all. Custom toured with the chief of police's daughter. yes, the best places to go are not where the "main" attractions are and best to see what is what is by the locals. Adlib.... once we saw an island far off shore.... no one goes there and nothing built on it. We asked around and was set up with a local fisherman to take us there for cheap. He dropped us off at a small beach and left... came back when the sun was going down. We had the whole place to ourselves... and found fantastic shells on the beach undisturbed and the water was clear, clean and warm. Those are the things that stick in the mind. No camera needed.
I make it a point to do at least one adventure per year... Two if I can.
-Richard
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Now you need to truly experience the culture by doing the funky food. Stinking tofu, snake wine, chicken uterus, sea "cucumber", the fat behind the fish eye is the special treat.
Ah yes. Nothing like 3rd world food. Now, I am getting hungry. Need some monkey knuckles to chew on.
-R
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I hope you're not using 3rd world as a pejorative, the food is not just from necessity I seek it out and prefer it to many alternatives. Pig stomach with peppers wonderful Chinese dish at the source.
Attachments
Many times, once in Japan I was served my own huge portion after expressing my liking for it. I bought some live sea urchins a few weeks ago just to sample the local ones. Lots of folks in Japan have a disdain for them but there are far worse things such as squid gonads.
One of the things you have to understand is that there is an aphrodisiacal folklore around many of these "specialities" and there is no real liking of them.
Honestly that pig stomach and peppers really was wonderful, Cal knows some of these dishes too. To me Chinese mac and cheese for comfort value.
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Oh. I thought you meant 3rd world food. I really mean third world. Jungle food. Caught and prepped as is done with minimum fan fare. You know, the ones who never used a spoon or fork? never seen a stove?
-RM
Summary of the mods to the HP 339a
Folks, this has been a fascinating thread and very thought provoking.
I am about halfway through the posts and am thinking of getting a HP 339A test set and modifying as RNMarsh has done. So, is there a summay/list of the mods and a pointer to the schematics. Or have I missed a thread about this subject?. Any suggestions most welcome
Thanks and regards,
Mike
Folks, this has been a fascinating thread and very thought provoking.
I am about halfway through the posts and am thinking of getting a HP 339A test set and modifying as RNMarsh has done. So, is there a summay/list of the mods and a pointer to the schematics. Or have I missed a thread about this subject?. Any suggestions most welcome
Thanks and regards,
Mike
Hi Sync. I just plug the monitor port straight into ARTA. I wouldn't want a sound card getting in the way.
I have an EMU0204. I use the un-mod'd factory original left channel input.
In level mode I input 1Vrms into the 725D and plug the EMU0204 into the 725D monitor output then cal ARTA for 0dBV.