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On Tue, 6 Aug 2019, 19:26 Bob Kozlarek, <njscan@...> wrote:

After discovering the Nanovna I decided to order one. A short introductory
discussion formed on AMFONE.NET, which mentioned this group, so I decided
to join. I’ve been reading through the posts and already learned a lot. It
sounds like most of you are part of an advanced user group. I’m wondering
if anyone can suggest any entry-level on-line resources which would
summarize what should / must be done when you first receive the Nanovna?
I’m wondering about matters such as does the firmware need to be updated
and from where it would be obtained, is calibrating required each time you
use it, and the matter about extra shielding be added to some units? I
apologize for asking these entry level questions in what appears to be a
very advanced user group, but I’ve always believed that the only dumb
questions are those we don’t ask.

Bob, WA2SQQ

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of tuckvk3cca via Groups.Io
Sent: Tuesday, August 6, 2019 8:26 PM
To: [email protected]
Subject: Re: [nanovna-users] NanoVNA Under The Covers

One useful reference for the 12.09 dB is the article of Ken Simmons W3UB : A bridge method of Sweep-Frequency Impedance measurement. QEX May 1986, You can find it on the internet archive.org site. The article goes through a rather long route to derive it but if you just use old school boy Wheatstone bridge theory for ZL=0 or infinity you can easily convince yourself of this number.



-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Stuart Landau via Groups.Io
Sent: Tuesday, August 6, 2019 4:40 AM
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 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 Tue, Aug 6, 2019 at 02:26 PM, Bob Kozlarek wrote:

After discovering the Nanovna I decided to order one. A short introductory
discussion formed on AMFONE.NET, which mentioned this group, so I decided
to join. I’ve been reading through the posts and already learned a lot. It
sounds like most of you are part of an advanced user group. I’m wondering
if anyone can suggest any entry-level on-line resources which would
summarize what should / must be done when you first receive the Nanovna?
I’m wondering about matters such as does the firmware need to be updated
and from where it would be obtained, is calibrating required each time you
use it, and the matter about extra shielding be added to some units? I
apologize for asking these entry level questions in what appears to be a
very advanced user group, but I’ve always believed that the only dumb
questions are those we don’t ask.

Bob, WA2SQQ

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Stuart Landau via Groups.Io
Sent: Tuesday, August 6, 2019 4:40 AM
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 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

-------- Original message --------From: Frank S <ka2fwc@...> Date: 06/08/2019 14:52 (GMT+01:00) To: [email protected] Subject: Re: [nanovna-users] The SMA Connectors The Tx port (port 1) is a? port that "sends" a signal and looks for a reflection (the arrow returning back to itself) this will give you RETURN LOSS.The Rx port (port 2) "receives" a signal (the arrow coming to it), and tells you what kind of loss your device has over the freq range you have set. If it is a cable , if shows cable loss. For other devices, it will show you the response so a filter would have a "bump" where the signal loss is less and shows the skirts where the signal rolls off.Does that help?FrankOn 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.>> >

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