开云体育

See the slide on measuring phase noise almost at the end of this presentation


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NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK

If you take a VCO under test and phase lock it to an appropriate XO and use that XO to input to the PFA. Can you obtain close in PN as well via the Allen variance close in and then from a time jitter the PN at some offset, say 1 kHz?

I have a test for far offsets but limited on close in PN.

Alan

It depends on the accuracy you need
For 1e-13 accuracy the two input frequencies (could be harmonics) have to be within 0.5 Hz of each other.
If 1e-10 is sufficient accuracy you can first calibrate the internal TCXO of the tinyPFA with a GPSDO or other reference and than measure a source at any frequency between 100kHz and 300 MHz against the calibrated internal TCXO. It should even be possible to measure at a harmonic of this range.

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NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK

I have a NanoVNA-F and went through the calibration process and then was measuring a few of my HT antennas to get comfortable with the VNA. I noticed very different readings if I held the VNA with two hands, one hand, and not touching it on a wooden surface. Is there a specific way to hold or not hold the VNA when doing measurements? Do you need to ground it?

I was getting values like 1.3 with two hands, 1.5 - 2.3 with left or right hand, and 3+ with it resting on a wood table.

Brian
W1BKW

On Fri, Aug 4, 2023 at 06:34 PM, Ken Sejkora wrote:

is it necessary to do so if you have a balun or unun between the antenna and
coax?

Not if the transformer has continuity between inner and outer conductors, but it only takes a second, cultivates a good habit and will do no harm. 73, Don N2VGU

Fonts size, not possible change (or need more work for UI and text position and sizes)

Remember state (select and save config) allow save several state (like freq range, bandwidth, points count, options) while device power off (but battery present).

SD card better format in FAT32, for LiteVNA and Card reader mode better set bigger sector size (32-64k) this allow more faster read file structure from card and see card data. H4 and Lite also support ExFAT filesystem.

On Thu, Aug 3, 2023 at 11:33 PM, John Nightingale wrote:

Cheap used cable from the ham flea market is not the choice for those
interested in the frequencies in use with discone antennas as Manfred will
confirm. Also, painful though it is, what was installed as brand new,
expensive and high quality, cable is none of that twenty years later.

Interestingly I cannot confirm that coax cable necessarily degrades over time! Of course, if cable gets waterlogged, it will degrade. But properly used, which means avoiding water ingress, it can last for a very long time. I sometimes measure the loss of the various transmission lines in my station, and even a long piece of RG8, that is over 40 years old, still meets its specs!

It's right that I wouldn't buy a used flea-market-special cable without thoroughly checking it. But I would also not disregard it as being certainly bad. If the price is good, and I need it, I would test it, and buy it if it's still fine. It's easy enough to take the NanoVNA to the hamfest!

Three dB of power being lost in a run of cable across the yard and all
the way up the tower will produce a most misleading impression in the
mind of the unsophisticated investigator.

Yes, that error happens to many hams. I remember one who asked me to check why he couldn't hit the local UHF repeater. His radio and antenna were both new, he said, and the SWR was fine. I went to his place. He lived in a second floor of a 22 story building, had run an RG58 feedline through a ventilation shaft all the way to the roof, and installed his antenna there - and there was a solder short in his coax connector at the upper end of the cable. The SWR, as measured at his second floor shack, was absolutely great...

To be fair, I have to mention that he was a new ham. But many hams have real trouble understanding that the more lossy the coax cable is, the better will the SWR be, and that's still not a good idea to use bad cable to improve the SWR!

Hi Don,

I agree – always a good practice to short center conductor and shield together before connecting to an instrument. Even better is to short them together and connect the shorted junction to an earth ground. I try to do that whenever possible. As you point out, coax has an inherent capacitance, and considerable breakdown voltage, so a long run of coax can store up a considerable charge, especially when terminated to a well insulated wire antenna.

However, just for the sake of argument and to exercise the neural muscles, is it necessary to do so if you have a balun or unun between the antenna and coax? I would think both would shunt any static charge to ground unless you had a true galvanic isolation configuration, with no electrical coupling between the primary and secondary of the coupling transformer. Not likely in a transmitting antenna, but who know.

Again, I’m not disputing your comment. I’m just trying to promote understanding, including mine, of antenna configurations. Regardless, it is still an invaluable practice to short center-to-shield before measuring, just to prevent any unforeseen failures on a known configuration.

Ken -- WB?OCV

From: Donald S Brant Jr
Sent: Friday, August 4, 2023 05:51 PM
To: [email protected]
Subject: Re: [nanovna-users] Static Energy and Is This the Correct Group? #newbie #beginners1 #general_vna

On Fri, Aug 4, 2023 at 02:13 PM, Peter N0PGM wrote:

I need to know to short out any static electricity that may be in the antenna
before I connect it to the NanoVNA

This is good practice before connecting any cable to any instrument. I usually short the inner and outer conductors against the outer conductor of the connector to which it will be attached; I wouldn't use my hand, especially with an antenna feedline which may be quite long and hold a considerable charge which could pack a wallop.
73, Don N2VGU

On 8/4/23 2:42 PM, W0LEV wrote:

Thanks, David, for answering my question. So the reference must be quite
close to the measured frequency. Won't work with my 10 MHz GPS reference.
Of course, I have several signal generators, but none as good as the GPS
referenced 10 MHz.

You might wait for Erik to weigh in. I don't know that it wouldn't work with appropriately harmonically related frequencies. I suppose it sets the receive LO, and the back end only has a few kHz BW. But if you had a 10 MHz and a 20 MHz, it might work, since you'd be beating the 2nd harmonic of the LO for the 20, and the first harmonic for the 10.


But this is also why you see a lot of folks rigging up various and sundry programmable dividers to get it down to 1 pps, which you can compare with TAPR TICC or similar - For ADEV, anyway.

And tons of emails over the years on the time-nuts list about how to make this or that measurement, where you don't want the measurement system to degrade the measurement (after all, that divider isn't noise free!) - you know, when you're comparing your cryogenic sapphire resonator against your active hydrogen maser in the garage.

Dave - W?LEV
On Fri, Aug 4, 2023 at 8:45?PM David McQuate <mcquate@...> wrote:

I believe that the maximum frequency difference between the PFA's two
inputs in 200 Hz (not kHz or MHz), so the two signals you are comparing
must be very close in frequency.

Dave - WA8YWQ

On 2023-08-04 13:25, W0LEV wrote:

So if I have a GPS reference of a couple of parts in 10^13, that will be

my

accuracy, and only at 10 MHz output from my GPS "clock"? With the 10

MHz

reference from GPS, will it measure ADEV on other non-10 MHz frequencies
(I'm thinking of DTV unmodulated carriers and HF signals off the
ionosphere)?

In the past for DTV carriers, I've dumped my 10 MHz GPS referenced output
into a comb generator and picked the tine which is closest to the DTV
carrier. That is selected on the a spectrum analyzer which is then

zeroed

to the tine. Then I measure the frequency of the DTV carrier. The
measurement is "sort'a" referenced to the 10 MHz GPS derived output

through

the comb generator. Not perfect, but it gets me down to 0.001 Hz.

Dave - W?LEV

Dave - W?LEV

On Fri, Aug 4, 2023 at 7:36?PM Erik Kaashoek <erik@...> wrote:

On Fri, Aug 4, 2023 at 10:56 AM, W0LEV wrote:

To what is this new PFA referenced? I have a piece of HP equipment that
offers Allen Variance measurements, but the reference is internal, not

GPS.

The tinyPFA can measure the phase difference of two 10MHz signals with
1e-13 accuracy in one second
Its accuracy and resolution is better than any of the big timer/counters
but less then the phasestation devices.
It's sole purpose it to measure frequency stability or ADEV of one source
against another source
--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK

--

*Dave - W?LEV*

--
Dave - W?LEV

On Fri, Aug 4, 2023 at 02:13 PM, Peter N0PGM wrote:

I need to know to short out any static electricity that may be in the antenna
before I connect it to the NanoVNA

This is good practice before connecting any cable to any instrument. I usually short the inner and outer conductors against the outer conductor of the connector to which it will be attached; I wouldn't use my hand, especially with an antenna feedline which may be quite long and hold a considerable charge which could pack a wallop.
73, Don N2VGU

Thanks, David, for answering my question. So the reference must be quite
close to the measured frequency. Won't work with my 10 MHz GPS reference.
Of course, I have several signal generators, but none as good as the GPS
referenced 10 MHz.

Dave - W?LEV

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Dave - W?LEV

I believe that the maximum frequency difference between the PFA's two
inputs in 200 Hz (not kHz or MHz), so the two signals you are comparing
must be very close in frequency.

Dave - WA8YWQ

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Dave - W?LEV

So if I have a GPS reference of a couple of parts in 10^13, that will be my
accuracy, and only at 10 MHz output from my GPS "clock"? With the 10 MHz
reference from GPS, will it measure ADEV on other non-10 MHz frequencies
(I'm thinking of DTV unmodulated carriers and HF signals off the
ionosphere)?

In the past for DTV carriers, I've dumped my 10 MHz GPS referenced output
into a comb generator and picked the tine which is closest to the DTV
carrier. That is selected on the a spectrum analyzer which is then zeroed
to the tine. Then I measure the frequency of the DTV carrier. The
measurement is "sort'a" referenced to the 10 MHz GPS derived output through
the comb generator. Not perfect, but it gets me down to 0.001 Hz.

Dave - W?LEV

Dave - W?LEV

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Dave - W?LEV

The coax cable capacitance stores up a charge and if you short the ends of the coax together you discharge it. When shorted you can also touch the terminals to ground of you want to be really cautious.

Roger

On Fri, Aug 4, 2023 at 10:56 AM, W0LEV wrote:

To what is this new PFA referenced? I have a piece of HP equipment that
offers Allen Variance measurements, but the reference is internal, not GPS.

The tinyPFA can measure the phase difference of two 10MHz signals with 1e-13 accuracy in one second
Its accuracy and resolution is better than any of the big timer/counters but less then the phasestation devices.
It's sole purpose it to measure frequency stability or ADEV of one source against another source
--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK

Hello,

I own the "Upgraded AURSINC NanoVNA-H4 V4.3 Vector Network Analyzer 10KHz-1.5GHz HF VHF UHF 4''" (purchase link is here ). I am posting this link here to see if this si the correct group for my specific NanoVNA. I have been in Ham radio for many years but I am totally new to NanoVNA. I did just download the "Absolute Beginers Guide" and I will begin to read through that shortly.

I have a 10 meter DX Commander antenna (vertical multi-band antenna with about 6 vertical wires and a 32 wire ground plane) and I need to know to short out any static electricity that may be in the antenna before I connect it to the NanoVNA. I read in another post that simply touching the the end of trhe coax with a "moist" hand will do the trick.

Thank you in advance,

Peter,
N0PGM

On 8/4/23 10:56 AM, W0LEV wrote:

Thanks, Jim! I was embarrassed to ask, but....
Having worked on the GPS (rubidium) clocks in the formative days of the
birds, I am all too familiar with Allen Variance (most of which I've
forgotten).
But, doing Doppler from WWV to look at the ionosphere, I have learned that
precision time keeping and frequency references is addicting. Who needs
drugs for addiction to something - precision frequency references?!
To what is this new PFA referenced? I have a piece of HP equipment that
offers Allen Variance measurements, but the reference is internal, not GPS.
Dave - W?LEV

It has two inputs, so you (by calculation) beat one input against the other, using the internal clock.



If you want to get into this kind of measurement (which is, as you say, addictive) the TAPR TICC is a useful piece of gear:

it measures the time of zero crossing with fraction of a ns accuracy - useful for, say, 1pps ticks.

And, of course, the time-nuts mailing list.



Erik is on the time-nuts list, and there's been some discussion of the TinyPFA there.

On Fri, Aug 4, 2023 at 5:46?PM Jim Lux <jimlux@...> wrote:

On 8/4/23 10:35 AM, W0LEV wrote:

Please forgive me for not being familiar with all the "new" acronyms
infiltering our standard english language. Although PFA is undoubtedly

an

RF acronym, I am unfamiliar with its meaning? "Pretty Fast Analyzer"?

?

Dave - W?LEV

Phase/Frequency Analyzer - a box that measures the Allan Deviation and
Phase Noise of a source.

On Fri, Aug 4, 2023 at 2:49?PM Jan Boutsen <jan.boutsen@...>

wrote:

Erik,

Delivered within 24 hours!
Everything seems to be there for the experimenter without doing any
software manipulation.
I didn't realize it had its own 'PFA-markings' on the nanoVNA.
Now, 'real' experimenting can start.

Jan ON4MMW

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of

Erik

Kaashoek
Sent: Wednesday, August 2, 2023 1:59 PM
To: [email protected]
Subject: [nanovna-users] TinyPFA

Fully configured tinyPFA for sale at Eleshop.


--
For more info on the tinyPFA go to

Erik, PD0EK

Thanks, Jim! I was embarrassed to ask, but....

Having worked on the GPS (rubidium) clocks in the formative days of the
birds, I am all too familiar with Allen Variance (most of which I've
forgotten).

But, doing Doppler from WWV to look at the ionosphere, I have learned that
precision time keeping and frequency references is addicting. Who needs
drugs for addiction to something - precision frequency references?!

To what is this new PFA referenced? I have a piece of HP equipment that
offers Allen Variance measurements, but the reference is internal, not GPS.

Dave - W?LEV

--
Dave - W?LEV

On 8/4/23 10:35 AM, W0LEV wrote:

Please forgive me for not being familiar with all the "new" acronyms
infiltering our standard english language. Although PFA is undoubtedly an
RF acronym, I am unfamiliar with its meaning? "Pretty Fast Analyzer"? ?
Dave - W?LEV

Phase/Frequency Analyzer - a box that measures the Allan Deviation and Phase Noise of a source.

On Fri, Aug 4, 2023 at 2:49?PM Jan Boutsen <jan.boutsen@...> wrote:

Erik,

Delivered within 24 hours!
Everything seems to be there for the experimenter without doing any
software manipulation.
I didn't realize it had its own 'PFA-markings' on the nanoVNA.
Now, 'real' experimenting can start.

Jan ON4MMW

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Erik
Kaashoek
Sent: Wednesday, August 2, 2023 1:59 PM
To: [email protected]
Subject: [nanovna-users] TinyPFA

Fully configured tinyPFA for sale at Eleshop.


--
For more info on the tinyPFA go to

Erik, PD0EK

Please forgive me for not being familiar with all the "new" acronyms
infiltering our standard english language. Although PFA is undoubtedly an
RF acronym, I am unfamiliar with its meaning? "Pretty Fast Analyzer"? ?

Dave - W?LEV

--
Dave - W?LEV