Re: Stray Coupling Suppression
John, a couple of years ago I went on a common mode choke building and measuring kick. I wrote the procedures up and I believe you can find them in the Wiki or archives filed on this group. I wrote them up to help others make the measurements you are attempting. They do not involve any PC applications, just readings from the NANOVNAs. Dave - W?LEV On Thu, Jan 19, 2023 at 1:53 PM John Leach K0JHL <john@...> wrote: Brian,
Looks interesting but I'm not sure how to use it. I am checking the
attenuation of common mode chokes I make. It boils down to impedance.
However I am taking the S21 logmag reading. Can I apply this to that
measurement? I tried using your app to read the sp2 file I saved and it
created the sp1 file. I load it into nanovna saver and do not see any
result. Can you give me a walk through of your procedure for implementing
the stray app? Sorry to be so dense.
John K0JHL
-- *Dave - W?LEV* -- Dave - W?LEV
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Re: Stray Coupling Suppression
John, the program neglected to handle logmag data. I've upload a new version that does. I appreciate your reporting this problem! If it still doesn't seem to work, please email the .s2p file to me.
Brian
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Re: Stray Coupling Suppression
Brian,
Looks interesting but I'm not sure how to use it. I am checking the attenuation of common mode chokes I make. It boils down to impedance. However I am taking the S21 logmag reading. Can I apply this to that measurement? I tried using your app to read the sp2 file I saved and it created the sp1 file. I load it into nanovna saver and do not see any result. Can you give me a walk through of your procedure for implementing the stray app? Sorry to be so dense.
John K0JHL
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Stray Coupling Suppression
After I added a neat trick to suppress common-mode current in my ground probe calculator, I realized a general purpose utility to suppress stray coupling when measuring impedance with a VNA might be useful. I've uploaded it here: /g/nanovna-users/files/stray.zipBegin by reading README.TXT Brian
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Re: Idea: Measuring parameters at different drive levels
Take out the "Regards,Jim" and you won't get a "404"
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On 1/16/2023 10:35 PM, Jim Whartenby via groups.io wrote: DonIt seems that this thread is headed in the direction of Load Pull measurements.? Those interested can get a heads up here:,Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
-----Original Message-----
From: Donald S Brant Jr<dsbrantjr@...>
To:[email protected]
Sent: Mon, Jan 16, 2023 8:32 pm
Subject: Re: [nanovna-users] Idea: Measuring parameters at different drive levels
Some high-end commercial units can do measurements at swept power levels, but none of the nanoVNA or its relatives.
Also note that the nanoVNA stimulus is not sinusoidal but is a square wave, so active devices will not act the same as they will with a sine wave stimulus.
In general they are not suitable for characterizing active devices,
73, Don N2VGU
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Re: Has anybody measured electron tubes
On 1/17/23 10:10 AM, Manfred Mornhinweg wrote: Firstly, of course a NanoVNA can be used directly to measure some tube characteristics, such as interelectrode capacitances, without powering up the tube.
And then, I don't see why it should be impossible to use a NanoVNA to measure two-port characteristics of a tube amplifier, just like it can be used to measure them on a solid state amplifier! Appropriate tube biasing, matching, and attenuation would be required, and the measured results would be for the tube in that specific test amplifier setup, not for the bare-bones tube, but that's how such parameters are usually measured in transistors too.
My main worry would be to make sure that in the event the tube breaks into oscillation, there is enough attenuation or limiting of some sort between the tube and the NanoVNA, to avoid damage. That's no different from measuring solid state amplifiers that could develop enough power to kill the NanoVNA.
To me, the square wave test signal is the big problem with NanoVNA and wideband power amplifiers. But you know, if your application is "narrow band-ish" (< octave BW), then a band pass filter would solve the problem. (and that's something people already have to be careful about, new fancy power meters that measure "power in the signal" with a tracking filter vs "total power") And yeah, blowing up the VNA when the amplifier oscillates.. But I'd rather spend $100 on a new NanoVNA than $100k on a new Keysight <grin>
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Re: Has anybody measured electron tubes
Firstly, of course a NanoVNA can be used directly to measure some tube characteristics, such as interelectrode capacitances, without powering up the tube.
And then, I don't see why it should be impossible to use a NanoVNA to measure two-port characteristics of a tube amplifier, just like it can be used to measure them on a solid state amplifier! Appropriate tube biasing, matching, and attenuation would be required, and the measured results would be for the tube in that specific test amplifier setup, not for the bare-bones tube, but that's how such parameters are usually measured in transistors too.
My main worry would be to make sure that in the event the tube breaks into oscillation, there is enough attenuation or limiting of some sort between the tube and the NanoVNA, to avoid damage. That's no different from measuring solid state amplifiers that could develop enough power to kill the NanoVNA.
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Re: Has anybody measured electron tubes
A vacuum tube is a multi port device. it is no different than any other device that would be characterized by matrix methods, like Z, Y, ABCD and S. In fact if you search
the IEEE data base, you will find a number of recent papers on scattering parameter analysis and measurements of tubes. Most are large tubes for unique systems. For example, see the attached. So, if you really wanted to and desired to build the appropriate added testing elements, appropriate bias tees and so on, go for it!
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Re: Has anybody measured electron tubes
On 1/17/23 8:07 AM, KENT BRITAIN wrote: Hard to find a TWT that a Nano could test.
He's thinking more 12AX7!
(Been using TWT's for over 40 years, don't think I have ever seen one for under 1 GHz.)
Kent Plenty of L-band TWTs around (big honkin' things) and some Nanos go up to 1.5 GHz. But mostly in space applications, and if you're playing in that ballpark, you can probably afford suitable test equipment.. (Inmarsat uses L-band, for instance) I don't think I've seen one as a low noise preamp, though, which is more level-appropriate for a Nano. Yes, I'm sure he's thinking classic gridded power tubes. But people *do* design tube circuits these days using S-parameters.
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Re: Has anybody measured electron tubes
I learned that S Parameters came into use when devices designed for higher frequencies (UHF and Microwave) had to be characterized. Also, test equipment have to be developed which could measure S Parameters.
Here is a historical perspective:
<
Mike N2MS
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On 01/17/2023 11:07 AM KENT BRITAIN <wa5vjb@...> wrote:
Hard to find a TWT that a Nano could test.
He's thinking more 12AX7!
(Been using TWT's for over 40 years, don't think I have ever seen one for under 1 GHz.)
Kent
On Tuesday, January 17, 2023 at 09:00:25 AM CST, Zack Widup <w9sz.zack@...> wrote:
Yes, that's true. But what is the probability that the OP wants to test a
TWT?
Zack W9SZ
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Re: Has anybody measured electron tubes
Hard to find a TWT that a Nano could test.
He's thinking more 12AX7!
(Been using TWT's for over 40 years, don't think I have ever seen one for under 1 GHz.)
Kent
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On Tuesday, January 17, 2023 at 09:00:25 AM CST, Zack Widup <w9sz.zack@...> wrote: Yes, that's true. But what is the probability that the OP wants to test a TWT? Zack W9SZ On Tue, Jan 17, 2023 at 8:21 AM Jim Lux <jimlux@...> wrote: On 1/17/23 2:21 AM, Zack Widup wrote:
I have never seen any manufacturer publish s-parameters for tubes. Pretty much every manufacturer of Traveling Wave Tubes publishes
S-parameters - In particular one tends to be interested in the S12
(reverse gain) at the second harmonic of the intended frequency band.
The other thing one tends to be very interested in is the group delay
across the band of operation, which is derived from data gathered with a
VNA.
I think you're thinking of gridded tubes like tri-, tetr-, and pent-odes.
And the
design techniques are different. The parts and methods used in biasing and
matching tubes are completely different than those used for FET's and
BJT's. The frequency ranges used for most commonly-available tubes do not
require s-parameters. There are very few tube amps around that operate
above 1296 MHz. I wouldn't be surprised if there are more microwave tube amps today than
HF band tube amps.? If you want power, tubes are where it's at.
I see no reason to measure a tube on a VNA.
Zack W9SZ
On Mon, Jan 16, 2023 at 8:29 PM Leif M <leif.michaelsson@...>
wrote:
I read about first TV sets and their tubes, thats history. And began to
wonder if anyone has measured tubes with VNAs. Do you get meaningfull
results. Connecting something with 200V supply voltage to NanoVna must
be
interesting.
That's solved with just a DC block.? A bigger issue is not blowing up
the VNA with the output power.
(and for the NanoVNA, the fact that the test signal is a square wave)
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Re: Nanovna App v1.1.208 needs a driver?
Its working now white my laptop.
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Re: Cant fine Aivaible DFU Devices
Its working now, only with the laptop!
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Re: Has anybody measured electron tubes
Zack
Published S-parameters for a W-band TWT, Figure 5.
See:?
Regards,
Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
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-----Original Message----- From: Zack Widup <w9sz.zack@...> To: [email protected]Sent: Tue, Jan 17, 2023 4:21 am Subject: Re: [nanovna-users] Has anybody measured electron tubes I have never seen any manufacturer publish s-parameters for tubes. And the design techniques are different. The parts and methods used in biasing and matching tubes are completely different than those used for FET's and BJT's. The frequency ranges used for most commonly-available tubes do not require s-parameters. There are very few tube amps around that operate above 1296 MHz. I see no reason to measure a tube on a VNA. Zack W9SZ On Mon, Jan 16, 2023 at 8:29 PM Leif M <leif.michaelsson@...> wrote: I read about first TV sets and their tubes, thats history. And began to
wonder if anyone has measured tubes with VNAs. Do you get meaningfull
results. Connecting something with 200V supply voltage to NanoVna must be
interesting.
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Re: Has anybody measured electron tubes
Yes, that's true. But what is the probability that the OP wants to test a
TWT?
Zack W9SZ
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Show quoted text
On Tue, Jan 17, 2023 at 8:21 AM Jim Lux <jimlux@...> wrote: On 1/17/23 2:21 AM, Zack Widup wrote:
I have never seen any manufacturer publish s-parameters for tubes. Pretty much every manufacturer of Traveling Wave Tubes publishes
S-parameters - In particular one tends to be interested in the S12
(reverse gain) at the second harmonic of the intended frequency band.
The other thing one tends to be very interested in is the group delay
across the band of operation, which is derived from data gathered with a
VNA.
I think you're thinking of gridded tubes like tri-, tetr-, and pent-odes.
And the
design techniques are different. The parts and methods used in biasing and
matching tubes are completely different than those used for FET's and
BJT's. The frequency ranges used for most commonly-available tubes do not
require s-parameters. There are very few tube amps around that operate
above 1296 MHz. I wouldn't be surprised if there are more microwave tube amps today than
HF band tube amps. If you want power, tubes are where it's at.
I see no reason to measure a tube on a VNA.
Zack W9SZ
On Mon, Jan 16, 2023 at 8:29 PM Leif M <leif.michaelsson@...>
wrote:
I read about first TV sets and their tubes, thats history. And began to
wonder if anyone has measured tubes with VNAs. Do you get meaningfull
results. Connecting something with 200V supply voltage to NanoVna must
be
interesting.
That's solved with just a DC block. A bigger issue is not blowing up
the VNA with the output power.
(and for the NanoVNA, the fact that the test signal is a square wave)
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Re: Has anybody measured electron tubes
On 1/17/23 2:21 AM, Zack Widup wrote: I have never seen any manufacturer publish s-parameters for tubes. Pretty much every manufacturer of Traveling Wave Tubes publishes S-parameters - In particular one tends to be interested in the S12 (reverse gain) at the second harmonic of the intended frequency band. The other thing one tends to be very interested in is the group delay across the band of operation, which is derived from data gathered with a VNA. I think you're thinking of gridded tubes like tri-, tetr-, and pent-odes. And the design techniques are different. The parts and methods used in biasing and
matching tubes are completely different than those used for FET's and
BJT's. The frequency ranges used for most commonly-available tubes do not
require s-parameters. There are very few tube amps around that operate
above 1296 MHz. I wouldn't be surprised if there are more microwave tube amps today than HF band tube amps. If you want power, tubes are where it's at. I see no reason to measure a tube on a VNA.
Zack W9SZ
On Mon, Jan 16, 2023 at 8:29 PM Leif M <leif.michaelsson@...> wrote:
I read about first TV sets and their tubes, thats history. And began to
wonder if anyone has measured tubes with VNAs. Do you get meaningfull
results. Connecting something with 200V supply voltage to NanoVna must be
interesting. That's solved with just a DC block. A bigger issue is not blowing up the VNA with the output power. (and for the NanoVNA, the fact that the test signal is a square wave)
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Re: Has anybody measured electron tubes
Most likely. In the really early days, there weren't any transistors that
worked above HF. Then some VHF transistors came along. There were no
high-frequency FET's in the early days. Now we have some FET's that work up
to 40 GHz. All my microwave designs using FET's have been on microstrip
transmission line printed on somewhat exotic substrates like Duroid 5880. I
have never seen a tube design that used microstrip.
Zack W9SZ
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On Tue, Jan 17, 2023 at 6:58 AM Allasso <kevinhowjones@...> wrote: "The frequency ranges used for most commonly-available tubes do not
require s-parameters. There are very few tube amps around that operate
above 1296 MHz."
I remember back in the day, using the giant round-screen tube oscilloscope
on the rollaround cart to measure high frequencies, because transistors
weren't fast enough. How things have changed. I can't remember if that
was before FETs came on the scene.
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Re: Has anybody measured electron tubes
"The frequency ranges used for most commonly-available tubes do not
require s-parameters. There are very few tube amps around that operate
above 1296 MHz."
I remember back in the day, using the giant round-screen tube oscilloscope
on the rollaround cart to measure high frequencies, because transistors
weren't fast enough. How things have changed. I can't remember if that
was before FETs came on the scene.
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Re: Has anybody measured electron tubes
I have never seen any manufacturer publish s-parameters for tubes. And the
design techniques are different. The parts and methods used in biasing and
matching tubes are completely different than those used for FET's and
BJT's. The frequency ranges used for most commonly-available tubes do not
require s-parameters. There are very few tube amps around that operate
above 1296 MHz.
I see no reason to measure a tube on a VNA.
Zack W9SZ
toggle quoted message
Show quoted text
On Mon, Jan 16, 2023 at 8:29 PM Leif M <leif.michaelsson@...> wrote: I read about first TV sets and their tubes, thats history. And began to
wonder if anyone has measured tubes with VNAs. Do you get meaningfull
results. Connecting something with 200V supply voltage to NanoVna must be
interesting.
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Yes, I did this kind of testing for HF to UHF range bias-T's. As others said, just connect 2 RF ports to to VNA ports, no DC of course. Look at S21 and S11.
I settled on 30 turns on FT37-43 for the choke, <1dB loss in 2-150MHz range.
Chinese units with SMD inductors work ok on VHF and UHF, add noticeable loss below 10MHz.
73, Mike AF7KR
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Mike C.
PA1ES