Anyway, when time permits, I'd like to give your notch filter a try.
I have a batch of a brand new version of the Hall Notch filter boards heading back my way via DHL right now. 😀 I'll post the results when I get them built up. 3/4" linear trimmers this time that access through the front panel, to get it boxed up in the metal B2-080 case, along with some other new stuff. 🙂
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Hi agdr,
Sounds interesting. How touchy do you think the adjustment will be? (how much range on the trimmer pot)
-Chris
Sounds interesting. How touchy do you think the adjustment will be? (how much range on the trimmer pot)
-Chris
The amount of rotation around the notch bottom should be around 1/2 this time. The 3/4" linear trimmers are 15 turn vs. the previous 25 turn 3/8" square trimmers. With the 3/8" I had about 1/2 turn in either direction around the notch bottom, so now probably +/- 1/4 turn.
But - I'm going to improve that.🙂 In the EDN Hall Notch article he has a resistor in series with either side of the frequency pot to limit the range. I think he did the math for a 750Hz to 1.5KHz range as I recall. I want to go back through the numbers and tighten that up to 900Hz to 1.1KHz. Should just be a BOM change, no layout changes. I'll probably build them up first though with the original 0.75 - 1.5KHz.
But - I'm going to improve that.🙂 In the EDN Hall Notch article he has a resistor in series with either side of the frequency pot to limit the range. I think he did the math for a 750Hz to 1.5KHz range as I recall. I want to go back through the numbers and tighten that up to 900Hz to 1.1KHz. Should just be a BOM change, no layout changes. I'll probably build them up first though with the original 0.75 - 1.5KHz.
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Did you have a measurement loop at 20kHz for QA401 ? At 192khz sample rate ? Before to buying a QA401, I would like to see the 20khz THD measurement, device capability at the superior limit of the audio-band.
Here you go, from some stuff now buried further back in the thread:
Post 1976 has 1KHz tones on the left and right channel at 192Ksps. Those tests turned up an issue: the left channel had more harmonics (small amount) than the right.
Post 1981 is a confirmation of the above issue from QA (emailed them). It is a known thing. But for my purposes at least it was a non-issue since the right channel (red) is very clean. I can just use that at 192Ksps. QA also confirmed this issue is why they didn't implement sampling above 192K, which they had originally intended. It doesn't show up at all at 48Ksps. I think I recall, but could be wrong, discussion that QA felt the issue was actually in the ADC.
Post 1984 is closer to what you are looking for, a 19KHz tone at 192Ksps. Everything here is done with the right (red) channel due to the above issue.
Post 1985 was a good suggestion from Bob to try 18KHz and 19KHz tones for CCIF IMD. All at 192Ksps on the right channel again.
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Quant Asylum out of business? And V1.50 QA401 update
Well this is not good. Something has happened to QuantAsylum. Their website
https://quantasylum.com
now says:
QuantAsylum coming soon
QuantAsylum is moving. We'll be back with more products in late February. Files can still be downloaded from this location: http://quantasylum.web707.discountasp.net/content/Support/Downloads.aspx
Be the first to know when we launch
Not entirely unexpected. I nearly posted a month ago that almost all of their products were listed as discontinued, save for the QA401 and a digital scope.
The link they give works and goes to the old website. There a new V1.50 (January 2017) of the QA401 software is listed in the downloads section with many bug fixes:
- Manual updated (See Help->Launch Help for PDF)
- Added ability to tweak DC offsets in output stage
- Fixed bug where constant tone generation left outputs in indeterminate state
- Added ability to mirror QA401 DAC output on PC DAC to permit testing of PC DACs
- Added ability to change burst duration to account for DUTs with increased processing latency
- Fixed bug where API calls were not seeing the state of the attenuator
Hopefully they will be back as a re-formed company of some sort, which kinda sounds like what they are hinting at.
Well this is not good. Something has happened to QuantAsylum. Their website
https://quantasylum.com
now says:
QuantAsylum coming soon
QuantAsylum is moving. We'll be back with more products in late February. Files can still be downloaded from this location: http://quantasylum.web707.discountasp.net/content/Support/Downloads.aspx
Be the first to know when we launch
Not entirely unexpected. I nearly posted a month ago that almost all of their products were listed as discontinued, save for the QA401 and a digital scope.
The link they give works and goes to the old website. There a new V1.50 (January 2017) of the QA401 software is listed in the downloads section with many bug fixes:
- Manual updated (See Help->Launch Help for PDF)
- Added ability to tweak DC offsets in output stage
- Fixed bug where constant tone generation left outputs in indeterminate state
- Added ability to mirror QA401 DAC output on PC DAC to permit testing of PC DACs
- Added ability to change burst duration to account for DUTs with increased processing latency
- Fixed bug where API calls were not seeing the state of the attenuator
Hopefully they will be back as a re-formed company of some sort, which kinda sounds like what they are hinting at.
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This is very strange. If they indeed are still in OK condition, they are handling this very poorly, and understandably spooking their customers. This is indeed a WTF moment, and hopefully we will get the real story very soon.
No cheers this time,
Bob
In my experience, companies moving really don't plan the even very well at all. This from years of commercial telephone system work. It costs a lot of money to move a business along with a ton of small details. Phones always seem to be the forgotten element for the move and may not be addressed until the very day of the move. If not that day, too close to the date for many telcos to redirect their line. Often, companies elect to direct incoming calls to a cell phone which tends to go dead mid-day.
-Chris
-Chris
Matt mentioned he was changing subcontractors to US ones a few months ago. I suspect this has become quite the challenge to redo the business without his China guys. I have seen this now with several other US companies dependent on Chia partners. It tends to get messy. I hope he gets it back up and running. I would guess its really a one man show.
This is the kind of move that Trump like's to see, out of China, into the US, with the factory.
Yikes.... I better check and download the latest and greatest software asap...... while still there.
Nice product, too.
-Richard
Nice product, too.
-Richard
In the mid 90s Magic Parts tried to set up a tube manufacturing plant in China. 1 1/2 years later he threw the towel in. Too much bureaucracy.
Hmm ...
The QuantAsylum page says "Will be back in late February with new products". You don't get any later than today. I hope this isn't bad news. The players in this market are disappearing much too quickly for my comfort.
The QuantAsylum page says "Will be back in late February with new products". You don't get any later than today. I hope this isn't bad news. The players in this market are disappearing much too quickly for my comfort.
They are still around a little bit as they are answer emails albeit a little slowly. They seem to have stock of some items as well.
Sent from my iPad using Tapatalk Pro
Sent from my iPad using Tapatalk Pro
New features in that January V1.50 QA401 SW release!
Ah - "moving" meant "moving to a new website" then. I took it literally to mean loading up the moving van and moving the business somewhere else, maybe to do something else!
Well that is good news. QA might still be around for awhile.
Also - poking around the new site I found a description of some cool new features in that January 2017 V1.50 software release!
https://quantasylum.com/blogs/news/qa401-update-1-50
The first one I'm glad to see, the abilty to plot frequency response directly without having to dump a csv and export to Excel.
The 4th one is important too, DC output offset trim. I was wondering where that 1 - 2mV was coming from. Apparently it is the DAC. As this recent QA support forum comment mentions that small DC output can get "gained up" to something a lot larger if testing a high gain stage:
QA401 dangerous bug! - Forum
The poster also apparently found a tone-generator mode in the menu system that would put 1.2Vdc on the output. Sounds like that bug got squashed in V1.5, from the fix listing.
Ah - "moving" meant "moving to a new website" then. I took it literally to mean loading up the moving van and moving the business somewhere else, maybe to do something else!
Well that is good news. QA might still be around for awhile.
Also - poking around the new site I found a description of some cool new features in that January 2017 V1.50 software release!
https://quantasylum.com/blogs/news/qa401-update-1-50
The first one I'm glad to see, the abilty to plot frequency response directly without having to dump a csv and export to Excel.
The 4th one is important too, DC output offset trim. I was wondering where that 1 - 2mV was coming from. Apparently it is the DAC. As this recent QA support forum comment mentions that small DC output can get "gained up" to something a lot larger if testing a high gain stage:
QA401 dangerous bug! - Forum
The poster also apparently found a tone-generator mode in the menu system that would put 1.2Vdc on the output. Sounds like that bug got squashed in V1.5, from the fix listing.
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Has anybody got the sweep-display stuff in V1.5 to work? There seems to be now menu-entry for this....
A new blog post has shown up about how noise on the USB power can get into the measurements:
https://quantasylum.com/blogs/news/qa401-and-usb-noise
Interesting - it uses isolated DC-DC converters running at 400KHz.
https://quantasylum.com/blogs/news/qa401-and-usb-noise
Interesting - it uses isolated DC-DC converters running at 400KHz.