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On 8/6/2019 2:42 AM, Leith Cullen wrote:

I only use to one connector, could someone please explain to me how these
both work and what the arrows mean.

Thanks.

-------- Original message --------From: Dave Daniel <kc0wjn@...> Date: 06/08/2019 10:55 (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] NanoVNA Under The Covers I’d be interested to see those references and also the HP app note numbers.DaveDSent from a small flat thingy> On Aug 6, 2019, at 03:49, tuckvk3cca <tuckvk3cca@...> wrote:> > Sure Alan. The proper calibration of a vna is a 12 point method. It takes work and good quality dummies. Agilent and HP have detail application notes for these. So did Dieter Baier who wrote up a good summary. However be warned, there's lots of Math. I think you can find these online.? I can dig out these refs if someone is interested.Sent from my Samsung Galaxy smartphone.> -------- Original message --------From: alan victor <avictor73@...> Date: 06/08/2019? 03:26? (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] NanoVNA Under The Covers I published my findings on the standards multiple messages in the past. I have the white unit and the black and again as I reported the black kit was supplied with significantly better RTL. If I recall, 44 dB at 900 MHz. The white unit standard 50 ohm was pathetic at 18 dB RTL at 900 MHz. As well, I verified both standards on a hp VNA after performing an independent cal with an independent set of standards. I obtained essentially identical results.Regards, Alan________________________________From: [email protected] <[email protected]> on behalf of kh6sky <kh6sky@...>Sent: Tuesday, August 6, 2019 12:01 AMTo: [email protected] <[email protected]>Subject: Re: [nanovna-users] NanoVNA Under The CoversIt would be interesting for those with accurate meters to measure their loads supplied with their nanoVNAs.? I am measuring 51.4 ohms with an AN870 meter. This was a white gecko purchase.? Not great.> >

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of tuckvk3cca
Sent: Tuesday, 6 August 2019 19:56
To: [email protected]
Subject: Re: [nanovna-users] NanoVNA Under The Covers

Yes, one place I last saw that was a 1986 copy of QEX on the internet archive. I will try and dig it out for you. It's quite easy to work it out yourself too.Sent from my Samsung Galaxy smartphone.
-------- Original message --------From: "Stuart Landau via Groups.Io" <stuartl73@...> Date: 06/08/2019 04:40 (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] NanoVNA Under The Covers Do you have any reference source for the 12.09 constant? I have never heard of that before and could not find anything in the literature. I don't doubt you, but I would like to know how that influences the reading.?I really don't care how the RL bridge works, as long as it is accurate and repeatable. I understand that dynamic range is an important consideration also.Thanks,Stuart K6YAZLos Angeles, USA-----Original Message-----From: tuckvk3cca <tuckvk3cca@...>To: nanovna-users <[email protected]>Sent: Mon, Aug 5, 2019 4:11 pmSubject: Re: [nanovna-users] NanoVNA Under The CoversYes of course, but all RLBs will give an absolute value of k plus the actual return loss of the DUT. For 50 ohm source and detectors this constant is theoretically 12.09dB but in reality changes with loads and frequency. Part of the calibration process is to eliminate this constant. In practice it also eats into the dynamic range of the generator and detector. So to measure a max of X dB will require borh generator and detector to have X +12dB, assuming the bridge was calibrated with a load that is better than or equal to XdB max in the first place.Sent from my Samsung Galaxy smartphone.-------- Original message --------From: "Stuart Landau via Groups.Io" <stuartl73@...> Date: 05/08/2019? 23:24? (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] NanoVNA Under The Covers An opencircuit on a transmission line has infinite impedance. A short circuit has zeroimpedance. An opencircuit,short circuit, or pure reactance terminating a transmission line are incapableof absorbing power fromaforward, or incident, wave. Thus, all incident current and voltage arereflected back toward the source.When this condition occurs,the return loss is said to be 0 dB.?The source:? ttps://www.scte.org/TechnicalColumns/05-10-01%20return%20loss.pdf?If you are measuring the return loss of a device with some attenuation in the path, such as coaxial cable losses, the return loss will be twice the cable loss because the RF travels twice through the attenuation. The first is the incidence wave, the second the reflected wave. The more attenuation in the path, the better the load looks; but it isn't telling you the truth with regard to the device under test.Stuart K6YAZ?Los Angeles, USA-----Original Message-----From: tuckvk3cca <tuckvk3cca@...>To: nanovna-users <[email protected]>Sent: Mon, Aug 5, 2019 1:29 pmSubject: Re: [nanovna-users] NanoVNA Under The CoversNo the return loss of open and short is theoretically 12dB. The RLB has a voltage factor of 8 and the transmission has a factor of 2 .?Sent from my Samsung Galaxy smartphone.-------- Original message --------From: Jeff Anderson <jca1955@...> Date: 05/08/2019? 21:26? (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] NanoVNA Under The Covers On Mon, Aug? 5, 2019 at 10:06 AM, tuckvk3cca wrote:>> You measure an open load, you measure a shorted load both of which should give> 12dB return loss>I'm probably missing something here, but shouldn't opens and shorts give 0 dB of return loss, not 12?? After all, their Gamma ought to be equal to 1.- Jeff, k6jca

-------- Original message --------From: "Stuart Landau via Groups.Io" <stuartl73@...> Date: 06/08/2019 04:40 (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] NanoVNA Under The Covers Do you have any reference source for the 12.09 constant? I have never heard of that before and could not find anything in the literature. I don't doubt you, but I would like to know how that influences the reading.?I really don't care how the RL bridge works, as long as it is accurate and repeatable. I understand that dynamic range is an important consideration also.Thanks,Stuart K6YAZLos Angeles, USA-----Original Message-----From: tuckvk3cca <tuckvk3cca@...>To: nanovna-users <[email protected]>Sent: Mon, Aug 5, 2019 4:11 pmSubject: Re: [nanovna-users] NanoVNA Under The CoversYes of course, but all RLBs will give an absolute value of k plus the actual return loss of the DUT. For 50 ohm source and detectors this constant is theoretically 12.09dB but in reality changes with loads and frequency. Part of the calibration process is to eliminate this constant. In practice it also eats into the dynamic range of the generator and detector. So to measure a max of X dB will require borh generator and detector to have X +12dB, assuming the bridge was calibrated with a load that is better than or equal to XdB max in the first place.Sent from my Samsung Galaxy smartphone.-------- Original message --------From: "Stuart Landau via Groups.Io" <stuartl73@...> Date: 05/08/2019? 23:24? (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] NanoVNA Under The Covers An opencircuit on a transmission line has infinite impedance. A short circuit has zeroimpedance. An opencircuit,short circuit, or pure reactance terminating a transmission line are incapableof absorbing power fromaforward, or incident, wave. Thus, all incident current and voltage arereflected back toward the source.When this condition occurs,the return loss is said to be 0 dB.?The source:? ttps://www.scte.org/TechnicalColumns/05-10-01%20return%20loss.pdf?If you are measuring the return loss of a device with some attenuation in the path, such as coaxial cable losses, the return loss will be twice the cable loss because the RF travels twice through the attenuation. The first is the incidence wave, the second the reflected wave. The more attenuation in the path, the better the load looks; but it isn't telling you the truth with regard to the device under test.Stuart K6YAZ?Los Angeles, USA-----Original Message-----From: tuckvk3cca <tuckvk3cca@...>To: nanovna-users <[email protected]>Sent: Mon, Aug 5, 2019 1:29 pmSubject: Re: [nanovna-users] NanoVNA Under The CoversNo the return loss of open and short is theoretically 12dB. The RLB has a voltage factor of 8 and the transmission has a factor of 2 .?Sent from my Samsung Galaxy smartphone.-------- Original message --------From: Jeff Anderson <jca1955@...> Date: 05/08/2019? 21:26? (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] NanoVNA Under The Covers On Mon, Aug? 5, 2019 at 10:06 AM, tuckvk3cca wrote:>> You measure an open load, you measure a shorted load both of which should give> 12dB return loss>I'm probably missing something here, but shouldn't opens and shorts give 0 dB of return loss, not 12?? After all, their Gamma ought to be equal to 1.- Jeff, k6jca

-------- Original message --------From: Warren Allgyer <allgyer@...> Date: 06/08/2019 02:42 (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] NanoVNA Under The Covers Then, given Thalus, you are somewhere between London and Berlin...... LOLOK... got it. Yes I did misunderstand you. I think we would find that as the RL numbers go past -40 dB their accuracy also goes way down. It is harder to accurately measure power at those levels. So I am honestly unable to determine which is more accurate, the nanoVNA or the Rigol/RF bridge. But, once the number goes past -30 dB where the two dead nuts agree, I quickly lose interest because it is of no practical value to me.Great discussion! Let's do it again!Warren AllgyerWA8TOD

-------- Original message --------From: alan victor <avictor73@...> Date: 06/08/2019 03:26 (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] NanoVNA Under The Covers I published my findings on the standards multiple messages in the past. I have the white unit and the black and again as I reported the black kit was supplied with significantly better RTL. If I recall, 44 dB at 900 MHz. The white unit standard 50 ohm was pathetic at 18 dB RTL at 900 MHz. As well, I verified both standards on a hp VNA after performing an independent cal with an independent set of standards. I obtained essentially identical results.Regards, Alan________________________________From: [email protected] <[email protected]> on behalf of kh6sky <kh6sky@...>Sent: Tuesday, August 6, 2019 12:01 AMTo: [email protected] <[email protected]>Subject: Re: [nanovna-users] NanoVNA Under The CoversIt would be interesting for those with accurate meters to measure their loads supplied with their nanoVNAs.? I am measuring 51.4 ohms with an AN870 meter. This was a white gecko purchase.? Not great.

-----Original Message-----
From: tuckvk3cca <tuckvk3cca@...>
To: nanovna-users <[email protected]>
Sent: Mon, Aug 5, 2019 4:11 pm
Subject: Re: [nanovna-users] NanoVNA Under The Covers

Yes of course, but all RLBs will give an absolute value of k plus the actual return loss of the DUT. For 50 ohm source and detectors this constant is theoretically 12.09dB but in reality changes with loads and frequency. Part of the calibration process is to eliminate this constant. In practice it also eats into the dynamic range of the generator and detector. So to measure a max of X dB will require borh generator and detector to have X +12dB, assuming the bridge was calibrated with a load that is better than or equal to XdB max in the first place.Sent from my Samsung Galaxy smartphone.
-------- Original message --------From: "Stuart Landau via Groups.Io" <stuartl73@...> Date: 05/08/2019? 23:24? (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] NanoVNA Under The Covers An opencircuit on a transmission line has infinite impedance. A short circuit has zeroimpedance. An opencircuit,short circuit, or pure reactance terminating a transmission line are incapableof absorbing power fromaforward, or incident, wave. Thus, all incident current and voltage arereflected back toward the source.When this condition occurs,the return loss is said to be 0 dB.?The source:? ttps://www.scte.org/TechnicalColumns/05-10-01%20return%20loss.pdf?If you are measuring the return loss of a device with some attenuation in the path, such as coaxial cable losses, the return loss will be twice the cable loss because the RF travels twice through the attenuation. The first is the incidence wave, the second the reflected wave. The more attenuation in the path, the better the load looks; but it isn't telling you the truth with regard to the device under test.Stuart K6YAZ?Los Angeles, USA-----Original Message-----From: tuckvk3cca <tuckvk3cca@...>To: nanovna-users <[email protected]>Sent: Mon, Aug 5, 2019 1:29 pmSubject: Re: [nanovna-users] NanoVNA Under The CoversNo the return loss of open and short is theoretically 12dB. The RLB has a voltage factor of 8 and the transmission has a factor of 2 .?Sent from my Samsung Galaxy smartphone.-------- Original message --------From: Jeff Anderson <jca1955@...> Date: 05/08/2019? 21:26? (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] NanoVNA Under The Covers On Mon, Aug? 5, 2019 at 10:06 AM, tuckvk3cca wrote:>> You measure an open load, you measure a shorted load both of which should give> 12dB return loss>I'm probably missing something here, but shouldn't opens and shorts give 0 dB of return loss, not 12?? After all, their Gamma ought to be equal to 1.- Jeff, k6jca

On 6 Aug 2019 01:54, "Warren Allgyer" <allgyer@...> wrote:

Not so fast my down under friend! LOL

The highest possible quality in the load will lead to the highest quality
measurements. I do not know the quality of the supplied load but, having
lived and worked in the Chinese electronics industry for many years, it is
suspect to me. Nevertheless, the supplied load will give perfectly adequate
measurements with accuracy sufficient for any normal hobbyist or even
professional.

I do not agree that the supplied load is 38 dB. There is not way to
substantiate that number except with a calibrated, lab grade VNA. It may be
38 dB..... but nothing I am able to do can confirm that. And it is of
little consequence anyway. The accuracy rendered by calibrating with a true
38 dB load versus a true 70 dB load is reflected in decimal points so far
to the right that they are not significant for 99% of applications.

I do not calibrate my volt meter or my ammeter to 6 decimal places. I do
calibrate my frequency standards to GPS which is 10 to the minus 12 I
believe but that is only because it is convenient to do so.

My recommendation is to use the supplied load and enjoy both the learning
experience and the utility of a marvelous, low cost instrument.

Warren Allgyer
WA8TOD

-------- Original message --------From: Warren Allgyer <allgyer@...> Date: 05/08/2019 21:01 (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] NanoVNA Under The Covers TuckI am not sure if you are misunderstanding (I don't think so) or simply miss-stating the concept. A load, any load, does not have an inherent return loss. It only has a return loss as measured relative to a reference. Typically the reference is understood to be 50 ohms. Minute differences in the resistance and reactance of the reference load can lead to huge differences in return loss, especially when you are talking RL on the order of 40 or more dB.The numbers that I have shown are not the result of design or calibration routine errors but, in fact, differences in the characteristics of the loads themselves.As a verification I have re-run the tests I made prior with the nanoVNA on my spectrum analyzer/tracking generator/RF bridge combination. It has an inherent dynamic range of 100 dB at a resolution bandwidth of 1 kHz..... 130 dB if I engage the preamp. I again used each of the three loads as a reference on the bridge with the other two measured for return loss in succession. Here is a comparison table of the nanoVNA as compared to the professional setup.As you can see, the results are remarkably close. Especially at return losses less than 40 dB. I have no concerns whatsoever about relying on the nanoVNA results for hobby and home lab use.Warren AllgyerWA8TOD

-------- Original message --------From: "Stuart Landau via Groups.Io" <stuartl73@...> Date: 05/08/2019 23:24 (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] NanoVNA Under The Covers An opencircuit on a transmission line has infinite impedance. A short circuit has zeroimpedance. An opencircuit,short circuit, or pure reactance terminating a transmission line are incapableof absorbing power fromaforward, or incident, wave. Thus, all incident current and voltage arereflected back toward the source.When this condition occurs,the return loss is said to be 0 dB.?The source:? ttps://www.scte.org/TechnicalColumns/05-10-01%20return%20loss.pdf?If you are measuring the return loss of a device with some attenuation in the path, such as coaxial cable losses, the return loss will be twice the cable loss because the RF travels twice through the attenuation. The first is the incidence wave, the second the reflected wave. The more attenuation in the path, the better the load looks; but it isn't telling you the truth with regard to the device under test.Stuart K6YAZ?Los Angeles, USA-----Original Message-----From: tuckvk3cca <tuckvk3cca@...>To: nanovna-users <[email protected]>Sent: Mon, Aug 5, 2019 1:29 pmSubject: Re: [nanovna-users] NanoVNA Under The CoversNo the return loss of open and short is theoretically 12dB. The RLB has a voltage factor of 8 and the transmission has a factor of 2 .?Sent from my Samsung Galaxy smartphone.-------- Original message --------From: Jeff Anderson <jca1955@...> Date: 05/08/2019? 21:26? (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] NanoVNA Under The Covers On Mon, Aug? 5, 2019 at 10:06 AM, tuckvk3cca wrote:>> You measure an open load, you measure a shorted load both of which should give> 12dB return loss>I'm probably missing something here, but shouldn't opens and shorts give 0 dB of return loss, not 12?? After all, their Gamma ought to be equal to 1.- Jeff, k6jca

-----Original Message-----
From: tuckvk3cca <tuckvk3cca@...>
To: nanovna-users <[email protected]>
Sent: Mon, Aug 5, 2019 1:29 pm
Subject: Re: [nanovna-users] NanoVNA Under The Covers

No the return loss of open and short is theoretically 12dB. The RLB has a voltage factor of 8 and the transmission has a factor of 2 .?Sent from my Samsung Galaxy smartphone.
-------- Original message --------From: Jeff Anderson <jca1955@...> Date: 05/08/2019? 21:26? (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] NanoVNA Under The Covers On Mon, Aug? 5, 2019 at 10:06 AM, tuckvk3cca wrote:>> You measure an open load, you measure a shorted load both of which should give> 12dB return loss>I'm probably missing something here, but shouldn't opens and shorts give 0 dB of return loss, not 12?? After all, their Gamma ought to be equal to 1.- Jeff, k6jca

-----Original Message-----
From: Jeff Anderson <jca1955@...>
To: nanovna-users <[email protected]>
Sent: Mon, Aug 5, 2019 6:41 am
Subject: Re: [nanovna-users] NanoVNA Under The Covers

Warren, excellent illustrative post demonstrating that if a VNA measures a load to have a return loss of 70 dB, it isn't necessarily so.

Over the years I've purchased a number of 50 ohm loads (generic as well as calibration loads) at swap meets, and upon returning home I'll usually do a quick check of their resistance (at DC) with a 4-wire ohm-meter (e.g. HP 3468A).? The measured resistance can deviate significantly from the ideal of 50 ohms.

For a 50 ohm load to have a return loss of greater than 70 dB, assuming it has no reactive component, its resistive component must be less than 50.032 ohms.? Anyone can do a quick check of their own calibration load if they have a 4-wire ohmmeter.? This won't be a guarantee of return loss at high frequencies (where reactance effects become more prevalent), but, if you have a selection of a few loads designed for calibration (i.e. designed to minimize reactive effects), I believe this would allow you to find the one which ought to have the best "actual" return loss.

- Jeff, k6jca