Re: Digest for sark110@googlegroups.com - 10 updates in 2 topics

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Edward Mccann

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Apr 28, 2020, 11:28:21 AM4/28/20
to sar...@googlegroups.com
My experience with noisy signals has in every case ended up with a connector failure, Coax issue , or poor connection to ground. Nothing has led to the Sark-110.

Run those items thru the mill and see what happens.

Ed McCann
AG6CX

Sent from my iPhone

On Apr 28, 2020, at 1:56 AM, sar...@googlegroups.com wrote:

k3gau Dave <k3g...@gmail.com>: Apr 27 09:25AM -0700

GM,
 
I had noticed what seemed to be "a noisy input" problem even before I had
Steve repair my SARK 110. So his repair had NOTHING to do with the
problem.
 
It doesn't seem to act right then it is looking at an the open circuit. It
does seem to read a short, 50 ohm, 100 ohm and 200 ohm loads across its
bandwidth just fine. But looking at an open, it sometimes reads out some
negative resistances, etc. when measuring 'RS' and plots them on the screen
as well. The problem seems worse at the higher end of the spectrum when
scanning the full 230 MHz range. As I recall, when I first got my unit,
open circuit 'RS' was always full scale, a high value (in the kOhms) and
never a negative. I have gone through the detector check and calibration
procedures. They seemed to be about normal.
 
Any idea what could be causing the problem? Bad component, bad solder
joint?
 
Dave
<melchor...@gmail.com>: Apr 27 06:33PM +0200

Hello Dave,
 

 
Could you please save a scan for the open circuit condition (connecting the same open load as the used for calibration) and send to me for analysis? Also, it will be helpful if you send me the calibration files.
 

 
Thanks,
 
Melchor EA4FRB
 

 
De: sar...@googlegroups.com <sar...@googlegroups.com> En nombre de k3gau Dave
Enviado el: lunes, 27 de abril de 2020 18:25
Para: sark110 <sar...@googlegroups.com>
Asunto: Noisy Input Problem
 

 
GM,
 

 
I had noticed what seemed to be "a noisy input" problem even before I had Steve repair my SARK 110. So his repair had NOTHING to do with the problem.
 

 
It doesn't seem to act right then it is looking at an the open circuit. It does seem to read a short, 50 ohm, 100 ohm and 200 ohm loads across its bandwidth just fine. But looking at an open, it sometimes reads out some negative resistances, etc. when measuring 'RS' and plots them on the screen as well. The problem seems worse at the higher end of the spectrum when scanning the full 230 MHz range. As I recall, when I first got my unit, open circuit 'RS' was always full scale, a high value (in the kOhms) and never a negative. I have gone through the detector check and calibration procedures. They seemed to be about normal.
 

 
Any idea what could be causing the problem? Bad component, bad solder joint?
 

 
Dave
 
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k3gau Dave <k3g...@gmail.com>: Apr 27 10:24AM -0700

Melcor,
What files are looking for? (name)
Dave
 
On Monday, April 27, 2020 at 12:33:41 PM UTC-4, EA4FRB wrote:
<melchor...@gmail.com>: Apr 27 07:29PM +0200

The calibration .dat files, e.g. detcalib.dat, oslcalib.dat, oslprof1.dat; and a saved .csv file for the sweep scan with the open load (select <File> <Save Data File> after completing the scan).
 

 
Thanks,
 
Melchor
 

 
De: sar...@googlegroups.com <sar...@googlegroups.com> En nombre de k3gau Dave
Enviado el: lunes, 27 de abril de 2020 19:25
Para: sark110 <sar...@googlegroups.com>
Asunto: Re: Noisy Input Problem
 

 
Melcor,
 
What files are looking for? (name)
 
Dave
 
On Monday, April 27, 2020 at 12:33:41 PM UTC-4, EA4FRB wrote:
 
Hello Dave,
 

 
Could you please save a scan for the open circuit condition (connecting the same open load as the used for calibration) and send to me for analysis? Also, it will be helpful if you send me the calibration files.
 

 
Thanks,
 
Melchor EA4FRB
 

 
De: sar...@googlegroups.com <javascript:> <sar...@googlegroups.com <javascript:> > En nombre de k3gau Dave
Enviado el: lunes, 27 de abril de 2020 18:25
Para: sark110 <sar...@googlegroups.com <javascript:> >
Asunto: Noisy Input Problem
 

 
GM,
 

 
I had noticed what seemed to be "a noisy input" problem even before I had Steve repair my SARK 110. So his repair had NOTHING to do with the problem.
 

 
It doesn't seem to act right then it is looking at an the open circuit. It does seem to read a short, 50 ohm, 100 ohm and 200 ohm loads across its bandwidth just fine. But looking at an open, it sometimes reads out some negative resistances, etc. when measuring 'RS' and plots them on the screen as well. The problem seems worse at the higher end of the spectrum when scanning the full 230 MHz range. As I recall, when I first got my unit, open circuit 'RS' was always full scale, a high value (in the kOhms) and never a negative. I have gone through the detector check and calibration procedures. They seemed to be about normal.
 

 
Any idea what could be causing the problem? Bad component, bad solder joint?
 

 
Dave
 
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k3gau Dave <k3g...@gmail.com>: Apr 27 10:35AM -0700

On Monday, April 27, 2020 at 12:33:41 PM UTC-4, EA4FRB wrote:
k3gau Dave <k3g...@gmail.com>: Apr 27 10:40AM -0700

Melchor,
 
I think I sent all files you ask for and probably a couple you don't need.
SARK 1, SARK 2 and SARK 3 are three different shots of my screen taken
within a few minutes.
 
Dave
 
On Monday, April 27, 2020 at 12:25:06 PM UTC-4, k3gau Dave wrote:
<melchor...@gmail.com>: Apr 27 09:44PM +0200

Thank you for the files. I don’t see a problem with these readings and the cal files. When there is no load connected, it is possible to get negative Rs readings influenced by noise because the error is high when the load is close to the infinity. Also, there is the influence of the used open load for the OSL calibration.
 

 
Best regards,
 
Melchor EA4FRB
 

 
De: sar...@googlegroups.com <sar...@googlegroups.com> En nombre de k3gau Dave
Enviado el: lunes, 27 de abril de 2020 19:40
Para: sark110 <sar...@googlegroups.com>
Asunto: Re: Noisy Input Problem
 

 
Melchor,
 

 
I think I sent all files you ask for and probably a couple you don't need. SARK 1, SARK 2 and SARK 3 are three different shots of my screen taken within a few minutes.
 

 
Dave
 
On Monday, April 27, 2020 at 12:25:06 PM UTC-4, k3gau Dave wrote:
 
GM,
 

 
I had noticed what seemed to be "a noisy input" problem even before I had Steve repair my SARK 110. So his repair had NOTHING to do with the problem.
 

 
It doesn't seem to act right then it is looking at an the open circuit. It does seem to read a short, 50 ohm, 100 ohm and 200 ohm loads across its bandwidth just fine. But looking at an open, it sometimes reads out some negative resistances, etc. when measuring 'RS' and plots them on the screen as well. The problem seems worse at the higher end of the spectrum when scanning the full 230 MHz range. As I recall, when I first got my unit, open circuit 'RS' was always full scale, a high value (in the kOhms) and never a negative. I have gone through the detector check and calibration procedures. They seemed to be about normal.
 

 
Any idea what could be causing the problem? Bad component, bad solder joint?
 

 
Dave
 
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k3gau Dave <k3g...@gmail.com>: Apr 27 04:16PM -0700

GE Melchor,
 
Have you plotted those Sark files? I would like to send you a picture of
the SARK screen but my cellphone is not working. Maybe I can use my other
camera. I can save a file with the 'open' removed and just the open
connector on the input.
 
In any case, I don't remember my screen looking that when it was new.
 
I got them with my other camera. Does that look normal for an 'OPEN'
condition?
 
Dave K3GAU
 
On Monday, April 27, 2020 at 3:45:04 PM UTC-4, EA4FRB wrote:
<melchor...@gmail.com>: Apr 28 08:13AM +0200

Hello Dave,
 

 
Yes, I have plotted those files. Note that the ripples are more or less visible depending on the selected scale: fixed or automatic; or logarithmic (default) or linear. Please find below some pics for comparing.
 

 
The fact is that for the open condition it is possible to get negative readings of Rs due to the increased error close to infinity and influenced by the noise. This effect can be reduced by using averaging and/or double sampling, and calibrating w/o a computer connected.
 

 
 
 
Figure 1, sark__01.csv, logarithmic scale, auto-scale
 

 
 
 
Figure 2, sark__01.csv, linear scale, auto-scale
 

 
 
 
Figure 3, sark__01.csv, linear scale, auto-scale (SARK_Plots)
 
 
 
Figure 4, sark__01.csv, smith chart
 
Best regards,
 
Melchor EA4FRB
 

 
De: sar...@googlegroups.com <sar...@googlegroups.com> En nombre de k3gau Dave
Enviado el: martes, 28 de abril de 2020 1:17
Para: sark110 <sar...@googlegroups.com>
Asunto: Re: Noisy Input Problem
 

 
GE Melchor,
 

 
Have you plotted those Sark files? I would like to send you a picture of the SARK screen but my cellphone is not working. Maybe I can use my other camera. I can save a file with the 'open' removed and just the open connector on the input.
 

 
In any case, I don't remember my screen looking that when it was new.
 

 
I got them with my other camera. Does that look normal for an 'OPEN' condition?
 

 
Dave K3GAU
 
 
On Monday, April 27, 2020 at 3:45:04 PM UTC-4, EA4FRB wrote:
 
Thank you for the files. I don’t see a problem with these readings and the cal files. When there is no load connected, it is possible to get negative Rs readings influenced by noise because the error is high when the load is close to the infinity. Also, there is the influence of the used open load for the OSL calibration.
 

 
Best regards,
 
Melchor EA4FRB
 

 
De: sar...@googlegroups.com <javascript:> <sar...@googlegroups.com <javascript:> > En nombre de k3gau Dave
Enviado el: lunes, 27 de abril de 2020 19:40
Para: sark110 <sar...@googlegroups.com <javascript:> >
Asunto: Re: Noisy Input Problem
 

 
Melchor,
 

 
I think I sent all files you ask for and probably a couple you don't need. SARK 1, SARK 2 and SARK 3 are three different shots of my screen taken within a few minutes.
 

 
Dave
 
On Monday, April 27, 2020 at 12:25:06 PM UTC-4, k3gau Dave wrote:
 
GM,
 

 
I had noticed what seemed to be "a noisy input" problem even before I had Steve repair my SARK 110. So his repair had NOTHING to do with the problem.
 

 
It doesn't seem to act right then it is looking at an the open circuit. It does seem to read a short, 50 ohm, 100 ohm and 200 ohm loads across its bandwidth just fine. But looking at an open, it sometimes reads out some negative resistances, etc. when measuring 'RS' and plots them on the screen as well. The problem seems worse at the higher end of the spectrum when scanning the full 230 MHz range. As I recall, when I first got my unit, open circuit 'RS' was always full scale, a high value (in the kOhms) and never a negative. I have gone through the detector check and calibration procedures. They seemed to be about normal.
 

 
Any idea what could be causing the problem? Bad component, bad solder joint?
 

 
Dave
 
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Steven Andros <andro...@gmail.com>: Apr 27 02:10PM -0700

Hello everyone,
 
Since I seem to have a bit more free time available than I usually do, I've
decided to experiment with low pass filter circuits for use with my home
brew water cooled LDMOS amp. Since the SARK-110 can measure L and C values
at a specified frequency, it seems like a better instrument to use that my
trusty L/C Meter 2B from Almost All Digital Electronics.
 
I have a MCX to Type N female cable. With adapters to temporary convert it
to BNC, I performed an OSL calibration, then tested the SARK-110 using a
1000pF cap I had on hand. With the unit set to test at 7 MHZ. It read as
expected.
 
Next, I tried a torroid inductor I had wound. The AADE meter read what I
expected - about .48uH, but to my surprise the SARK-110 read almost twice
that (.802uH). Given the success with the cap, I was quite surprised at the
results with the inductor.
 
I also need to construct a fixture that will allow convenient testing of
not only torroids, but SMD caps. Anyone have a setup they've made that
works to their satisfaction? If so, how did you facilitate OSL calibration?
 
All the best from Bradenton Fl,
 
Steve KG4LJB
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