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AP

Alexander Pummer

Sun, Aug 21, 2016 9:57 PM

there is a current mode feedback device [which does not follows the gain
bandwidth product role ] and has 1000V/usec rise time 92dB THD at 30MHz
3nV/rtHz noise, see here http://www.ti.com/lit/ds/symlink/ths4271.pdf, I
used it as a medical color Doppler application

Guanella's choke and Guanellas balun are two different animals, the
balun has a cross DC path, the choke does not have, it's other name is
1:1 transmission line transformer, in conjunction with an A/D converter
the choke has the function to prevent a current path to the ground via
one of the the differential inputs, also used in high dynamic range
medical ultrasound application

73

Alex

On 8/21/2016 1:29 PM, Attila Kinali wrote:

On Sun, 21 Aug 2016 10:04:10 -0700
Alex Pummer alex@pcscons.com wrote:

directional coupler/circulator could be made with high bandwidth [ up to
1GHz ] operational amplifiers, that circulator will work from DC..

While this is a valid option, it would then become the element in the
system that limits dynamic range. It's better to use a "noiseless"
passive circuit that has very little distortion.

Also keep in mind that even if the opamp has an GBW of 1GHz or more,
the slewrate kicks in quite early and in this case would limit the
maximum signal strength severely. There is a reason why GHz amplifiers
use so much power.

driving A/D converter input asymmetrically; drive trough a
Guanella-choke, but match the output of the choke

The Guanella balun, like all other transformer based baluns,
has the same upper and lower frequency limits: The inductance
sets the lower limit (more inductance -> lower frequency) and
the loss in the ferrite sets the upper limit (non-linear and thus
can be quite abrupt). Another issue here is symmetry of output
over frequency (c.f. [1]). I don't know how good the Guanella
baluns are in reality, but this is definitly something that should
be looked at.

		Attila Kinali

[1] http://www.markimicrowave.com/blog/2013/07/why-buy-a-high-quality-baluntransformer-for-an-analog-to-digital-converter-adc/

there is a current mode feedback device [which does not follows the gain bandwidth product role ] and has 1000V/usec rise time 92dB THD at 30MHz 3nV/rtHz noise, see here http://www.ti.com/lit/ds/symlink/ths4271.pdf, I used it as a medical color Doppler application Guanella's choke and Guanellas balun are two different animals, the balun has a cross DC path, the choke does not have, it's other name is 1:1 transmission line transformer, in conjunction with an A/D converter the choke has the function to prevent a current path to the ground via one of the the differential inputs, also used in high dynamic range medical ultrasound application 73 Alex On 8/21/2016 1:29 PM, Attila Kinali wrote: > On Sun, 21 Aug 2016 10:04:10 -0700 > Alex Pummer <alex@pcscons.com> wrote: > >> directional coupler/circulator could be made with high bandwidth [ up to >> 1GHz ] operational amplifiers, that circulator will work from DC.. > While this is a valid option, it would then become the element in the > system that limits dynamic range. It's better to use a "noiseless" > passive circuit that has very little distortion. > > Also keep in mind that even if the opamp has an GBW of 1GHz or more, > the slewrate kicks in quite early and in this case would limit the > maximum signal strength severely. There is a reason why GHz amplifiers > use so much power. > >> driving A/D converter input asymmetrically; drive trough a >> Guanella-choke, but match the output of the choke > The Guanella balun, like all other transformer based baluns, > has the same upper and lower frequency limits: The inductance > sets the lower limit (more inductance -> lower frequency) and > the loss in the ferrite sets the upper limit (non-linear and thus > can be quite abrupt). Another issue here is symmetry of output > over frequency (c.f. [1]). I don't know how good the Guanella > baluns are in reality, but this is definitly something that should > be looked at. > > > Attila Kinali > > [1] http://www.markimicrowave.com/blog/2013/07/why-buy-a-high-quality-baluntransformer-for-an-analog-to-digital-converter-adc/

DD

Dr. David Kirkby (Kirkby Microwave Ltd)

Sun, Aug 21, 2016 10:59 PM

On 21 Aug 2016 03:19, "Attila Kinali" attila@kinali.ch wrote:

Moin,

I stumbled over a new open hardware/source VNA design:

http://hforsten.com/cheap-homemade-30-mhz-6-ghz-vector-network-analyzer.html

Unlike other designs out there, this one is very well done and has very
little room for improvement, without increasing the price considerably.

I am not convinced that this is time-nuts related, although I am sure many
time-nuts either have a VNA or would like one. Such a project needs its own
forum.

That said, I don't know why the author is using directional couplers. A
bridge is much wider bandwidth. It is more lossy though.

The software is I believe the tricky part. The VNWA software is very
sophisticated, with a lot of useful features like it can design matching
networks, The software in the PNA-X is very sophisticated too, but in
different ways.

I don't know what the author uses, but Qt seems like best choice to me,
which can be be built on OSX, Linux and Windows.

For many measurements power levelling is not required, so that bit could be
dispensed with.

The author seems of the opinion that a lot of the hardware imperfections
can be corrected in software. Thak is true, but the the residual errors
that remain are a function of the quality of the hardware.

Anyway, it is an interesting project, but personally if I were going to
go to the effort of building a 2-port VNA, I would build one with 4
receivers.

Dave

On 21 Aug 2016 03:19, "Attila Kinali" <attila@kinali.ch> wrote: > > Moin, > > I stumbled over a new open hardware/source VNA design: > http://hforsten.com/cheap-homemade-30-mhz-6-ghz-vector-network-analyzer.html > > Unlike other designs out there, this one is very well done and has very > little room for improvement, without increasing the price considerably. I am not convinced that this is time-nuts related, although I am sure many time-nuts either have a VNA or would like one. Such a project needs its own forum. That said, I don't know why the author is using directional couplers. A bridge is much wider bandwidth. It is more lossy though. The software is I believe the tricky part. The VNWA software is very sophisticated, with a lot of useful features like it can design matching networks, The software in the PNA-X is very sophisticated too, but in different ways. I don't know what the author uses, but Qt seems like best choice to me, which can be be built on OSX, Linux and Windows. For many measurements power levelling is not required, so that bit could be dispensed with. The author seems of the opinion that a lot of the hardware imperfections can be corrected in software. Thak is true, but the the residual errors that remain are a function of the quality of the hardware. Anyway, it is an interesting project, but personally if I were going to go to the effort of building a 2-port VNA, I would build one with 4 receivers. Dave

BK

Bob kb8tq

Sun, Aug 21, 2016 11:25 PM

Hi

One option in the "1 GHz and down" range is to team up a surplus HP S-Parameter test set with your own electronics. That way you let HP do all of the fancy directional coupler stuff and relays. They don't sell well on the auction sites. The result is that a bit of time making lowball offers can generally get you one or more of them for not a whole lot of money.

Bob

On Aug 21, 2016, at 12:46 AM, Bob Albert via time-nuts time-nuts@febo.com wrote:

I was interested in this, but my needs are mostly below 100 MHz. I wonder what could be done similarly for this lower range...
Bob

On Saturday, August 20, 2016 8:54 PM, Richard (Rick) Karlquist <richard@karlquist.com> wrote:

Another great posting, Attila.

When I was with Agilent, we looked at all kinds of
simplified network analyzer architectures, and I
would have to say the author is really well informed.
One issue he doesn't seem to be aware of is that the
ADL5801, when driven single ended, has some quirks
below 100 MHz that I discovered experimentally.
(The data sheet is silent on this). IMHO, it
would be worth 7 Euro's to use a balun, however,
I would like to know the part number of this
supposed component. I am not so sure about MCL
actually covering 30 MHz to 6 GHz in the same
balun. Sometimes their advertising is confusing,
and when they say .03-6 GHz baluns, they mean
that the range can be covered in several bands
by several model numbers.

Still, quite impressive work by an individual
practitioner.

Rick

On 8/20/2016 7:19 PM, Attila Kinali wrote:
Moin,

I stumbled over a new open hardware/source VNA design:
http://hforsten.com/cheap-homemade-30-mhz-6-ghz-vector-network-analyzer.html

Unlike other designs out there, this one is very well done and has very
little room for improvement, without increasing the price considerably.

About the only things i would do different is to use two receiver
channels, one fix connected at the TX source to be able to do a
difference measurement between TX and the RX channels and thus
improving precision. And the other would be to use a dual ADC
with an FPGA for the data processing, again in order to increase
performance.

But as I wrote, both changes would increase complexity and price.

Other than being a well thought through design, the website also
explains all the big design choices and why this or that has been
done instead of one of the many alternatives. That alone makes it
worth reading, IMHO.

         Attila Kinali

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Hi One option in the "1 GHz and down" range is to team up a surplus HP S-Parameter test set with your own electronics. That way you let HP do all of the fancy directional coupler stuff and relays. They don't sell well on the auction sites. The result is that a bit of time making lowball offers can generally get you one or more of them for not a whole lot of money. Bob > On Aug 21, 2016, at 12:46 AM, Bob Albert via time-nuts <time-nuts@febo.com> wrote: > > I was interested in this, but my needs are mostly below 100 MHz. I wonder what could be done similarly for this lower range... > Bob > > > On Saturday, August 20, 2016 8:54 PM, Richard (Rick) Karlquist <richard@karlquist.com> wrote: > > > Another great posting, Attila. > > When I was with Agilent, we looked at all kinds of > simplified network analyzer architectures, and I > would have to say the author is really well informed. > One issue he doesn't seem to be aware of is that the > ADL5801, when driven single ended, has some quirks > below 100 MHz that I discovered experimentally. > (The data sheet is silent on this). IMHO, it > would be worth 7 Euro's to use a balun, however, > I would like to know the part number of this > supposed component. I am not so sure about MCL > actually covering 30 MHz to 6 GHz in the same > balun. Sometimes their advertising is confusing, > and when they say .03-6 GHz baluns, they mean > that the range can be covered in several bands > by several model numbers. > > Still, quite impressive work by an individual > practitioner. > > Rick > >> On 8/20/2016 7:19 PM, Attila Kinali wrote: >> Moin, >> >> I stumbled over a new open hardware/source VNA design: >> http://hforsten.com/cheap-homemade-30-mhz-6-ghz-vector-network-analyzer.html >> >> Unlike other designs out there, this one is very well done and has very >> little room for improvement, without increasing the price considerably. >> >> About the only things i would do different is to use two receiver >> channels, one fix connected at the TX source to be able to do a >> difference measurement between TX and the RX channels and thus >> improving precision. And the other would be to use a dual ADC >> with an FPGA for the data processing, again in order to increase >> performance. >> >> But as I wrote, both changes would increase complexity and price. >> >> Other than being a well thought through design, the website also >> explains all the big design choices and why this or that has been >> done instead of one of the many alternatives. That alone makes it >> worth reading, IMHO. >> >> Attila Kinali > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

B

bownes

Mon, Aug 22, 2016 1:51 AM

Comment inline

On Aug 21, 2016, at 18:59, Dr. David Kirkby (Kirkby Microwave Ltd) drkirkby@kirkbymicrowave.co.uk wrote:

I am not convinced that this is time-nuts related, although I am sure many
time-nuts either have a VNA or would like one. Such a project needs its own
forum.

VNWA@yahoogroups.com would be the place.

The intersection of HP equipment && Time-Nuts && VNWA mailing lists is >> 1 :)

Comment inline > On Aug 21, 2016, at 18:59, Dr. David Kirkby (Kirkby Microwave Ltd) <drkirkby@kirkbymicrowave.co.uk> wrote: > > I am not convinced that this is time-nuts related, although I am sure many > time-nuts either have a VNA or would like one. Such a project needs its own > forum. > VNWA@yahoogroups.com would be the place. The intersection of HP equipment && Time-Nuts && VNWA mailing lists is >> 1 :) >

BK

Bob kb8tq

Mon, Aug 22, 2016 12:05 PM

Hi

If you really want to work out the delays through all of this
GPS "stuff" ahead of the RF -> PPS conversion, a VNA is about
the only good way to do it.

Bob

On Aug 21, 2016, at 6:59 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkirkby@kirkbymicrowave.co.uk wrote: