Re: Calibration of the 4 track nanoVNA
Thank you Alan W4AMV,
Finnally I have my nanoVNA correctly calibrated. I am happy now with the measurements!
Cheers and 73
Luís, CT2FZI
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Re: Narrow band filters and LO phase noise/jitter?
There is a filter spurious on the high side of the skirt. This shows up as a spike on the VNA display. There is none on the low side skirt, despite what appears to be a spurious on the VNA display. I put together a 4 pole 77 MHz crystal filter and its swept response on the nanoVNA as well on another analyzer are in excellent agreement. This filter has a reasonable transition BW compared to its center frequency; 1800 Hz at 77 MHz. At this point I would say there is no issue. I will capture its response and post. Alan ________________________________ From: nanovna-users@groups.io <nanovna-users@groups.io> on behalf of alan victor <avictor73@...> Sent: Thursday, July 11, 2019 6:19 PM To: nanovna-users@groups.io Subject: Re: [nanovna-users] Narrow band filters and LO phase noise/jitter? This 500 Hz bandwidth filter is problematic. Upon further measurements with another instrument there are issues. I will find another baseline network and report findings again. Alan ________________________________ From: nanovna-users@groups.io <nanovna-users@groups.io> on behalf of dk1vi <dk1vi@...> Sent: Thursday, July 11, 2019 4:09 PM To: nanovna-users@groups.io Subject: Re: [nanovna-users] Narrow band filters and LO phase noise/jitter? In crystal factories crystals are measured in a 50Ohm system with a pi-network on both sides as per enclosed picture. Don't know if the resistance values are readable in the compressed picture so here the are: Input R1=159 ohms to ground, R2=66,2 ohms in series and R3=14,2 ohms to ground. On the outputside the network is mirrored. Please do not ask me where this strange resistor values come from.
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Re: Narrow band filters and LO phase noise/jitter?
Never one to back away from a puzzle, the resistive pi network for crystal testing reverse-engineers to a 50 to 12.5 ohm matching pad with just under 15 dB loss (14.774).? Probably trying to "match" the series resonant resistance of the crystal.
Bob C
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Re: SRH508S Antenna SWR with NanoVNA
It was tested with a small ground plane. Tried other configurations too, but with only very small changes.
This antenna was bought on eBay for US$0.99 with free shipping. So it was probably a poor rip-off.
If someone just needs a 430 MHz band antenna it might work out.
Anyway, it's nice to know that the Nano worked well enough to find the missing band problem.
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Re: SRH508S Antenna SWR with NanoVNA
Does it require a ground plane? I would put an SMA connector centered on a plate of PC clad card. Then feed the cable thru back to the VNA.
________________________________
From: nanovna-users@groups.io <nanovna-users@groups.io> on behalf of George <steber@...>
Sent: Thursday, July 11, 2019 7:12 PM
To: nanovna-users@groups.io
Subject: [nanovna-users] SRH508S Antenna SWR with NanoVNA
Decided to test this SRH805S wide band antenna. They claim it covers 144/430/1200 MHz.
While the nano doesn't cover 1200 MHz, it does handle the lower two bands.
Clearly there is a problem as 144 MHz band is not showing any reasonable SWR.
By the way, my graph shows the SWR (left scale in red) and reflected power in percent (right scale in green).
As for the SRH805S, I must have gotten a bad one. One band missing!
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SRH508S Antenna SWR with NanoVNA
Decided to test this SRH805S wide band antenna. They claim it covers 144/430/1200 MHz.
While the nano doesn't cover 1200 MHz, it does handle the lower two bands.
Clearly there is a problem as 144 MHz band is not showing any reasonable SWR.
By the way, my graph shows the SWR (left scale in red) and reflected power in percent (right scale in green).
As for the SRH805S, I must have gotten a bad one. One band missing!
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Re: Measurement of output signal
"Have searched the net, but did not find a copy of the QEX 2017/05. Do you know any source for this reference?"
Try searching for, or emailing, the author. Often they will provide a copy to you as a courtesy.
Also try searching for related material to FA-VA5 antenna analyzer. It should be easy to find on web.
He has also written material showing how to connect his unit to DG8SAQ VNWA software.
(Very powerful software but with a steep learning curve.).
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Re: Narrow band filters and LO phase noise/jitter?
This 500 Hz bandwidth filter is problematic. Upon further measurements with another instrument there are issues.
I will find another baseline network and report findings again.
Alan
________________________________
From: nanovna-users@groups.io <nanovna-users@groups.io> on behalf of dk1vi <dk1vi@...>
Sent: Thursday, July 11, 2019 4:09 PM
To: nanovna-users@groups.io
Subject: Re: [nanovna-users] Narrow band filters and LO phase noise/jitter?
In crystal factories crystals are measured in a 50Ohm system with a pi-network on both sides as per enclosed picture.
Don't know if the resistance values are readable in the compressed picture so here the are:
Input R1=159 ohms to ground, R2=66,2 ohms in series and R3=14,2 ohms to ground. On the outputside the network is mirrored.
Please do not ask me where this strange resistor values come from.
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Re: Measurement of output signal
QEX is a magazine published by the ARRL for communications experimenters. The articles and papers in it are much more technically-oriented than most of what is in the QST ARRL magazine. One must be an ARRL member to access the QEX files and maybe even a QEX subscriber (I am one - I don't know if an ARRL member can access the QEX files without having a QEX subscription).
I haven't tried to access any QEX papers in a while. The papers as published in the physical magazine are limited in length and so, make available more technical details, software, schematics, etc., etc., there are a bunch of additional files for many of the papers on the ARRL/"QEXfiles" web pages. It appears that the original text of the published papers is not available but the supplemental files referenced above are.
Remember that the magazines published by the ARRL are all copyrighted and so it is not strictly lawful to pass PDF copies of them around, at least to non-subscribers. I'm guessing that that is the reason that one cannot just download PDF copies of the articles.
I will look to see if I can find my paper copy of the 2017 May/June issue of QEX. I think I unpacked my QST and QEX magazines a while back.
As an aside, QEX is a pretty good technical publication.
DaveD
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On 7/11/2019 11:47 AM, dk1vi wrote: Have searched the net, but did not find a copy of the QEX 2017/05. Do you know any source for this reference?
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Re: Narrow band filters and LO phase noise/jitter?
In crystal factories crystals are measured in a 50Ohm system with a pi-network on both sides as per enclosed picture.
Don't know if the resistance values are readable in the compressed picture so here the are:
Input R1=159 ohms to ground, R2=66,2 ohms in series and R3=14,2 ohms to ground. On the outputside the network is mirrored.
Please do not ask me where this strange resistor values come from.
|
Re: Measurement of output signal
Have searched the net, but did not find a copy of the QEX 2017/05. Do you know any source for this reference?
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I can pull mine apart and see if I can come up with something. I agree, the "external" parts need dome protection
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On 7/11/2019 11:39 AM, alan victor wrote: There is some value added packaging if it can be done at a reasonable cost. The slide switch and the rotary wheel switch are subject to failure or breakage. Especially when used in the field. The LCD display in the field is nearly impossible to read unless you shield it from the sun. I used it to measure an antenna outdoors and had to either put it in a black box or wait till I had some cloud cover. Some sort or reasonable shroud for protection and enhanced viewing for field use would be great. The USB port seems ok. A port for firmware updates would be nice. Comments? Alan
________________________________
From: nanovna-users@groups.io <nanovna-users@groups.io> on behalf of Larry Rothman <ac293@...>
Sent: Thursday, July 11, 2019 2:50 PM
To: nanovna-users@groups.io
Subject: Re: [nanovna-users] Extended back cover
Folks,
Instead of reinventing the wheel to design a case, have a look at the 1553BBK series Hammond housing.
It's approx $12 CAD.
It looks like a small amount of internal trimming might be needed but it looks perfect.
Regards,
Larry
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Some people don't have the "ability" to modify that box. This way, if you just wanted to add a (or bigger) battery, it is only 4 screws and double sided tape (which I could probably throw in).
Shipping is the other variable, but it could be put in a padded envelope and mailed (I will have to look into the hazardous material rules)
Frank
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On 7/11/2019 10:50 AM, Larry Rothman wrote: Folks,
Instead of reinventing the wheel to design a case, have a look at the 1553BBK series Hammond housing.
It's approx $12 CAD.
It looks like a small amount of internal trimming might be needed but it looks perfect.
Regards,
Larry
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There is some value added packaging if it can be done at a reasonable cost. The slide switch and the rotary wheel switch are subject to failure or breakage. Especially when used in the field. The LCD display in the field is nearly impossible to read unless you shield it from the sun. I used it to measure an antenna outdoors and had to either put it in a black box or wait till I had some cloud cover. Some sort or reasonable shroud for protection and enhanced viewing for field use would be great. The USB port seems ok. A port for firmware updates would be nice. Comments? Alan ________________________________ From: nanovna-users@groups.io <nanovna-users@groups.io> on behalf of Larry Rothman <ac293@...> Sent: Thursday, July 11, 2019 2:50 PM To: nanovna-users@groups.io Subject: Re: [nanovna-users] Extended back cover Folks, Instead of reinventing the wheel to design a case, have a look at the 1553BBK series Hammond housing. It's approx $12 CAD. It looks like a small amount of internal trimming might be needed but it looks perfect. Regards, Larry
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I think it depends on the battery. I'm looking for "surplus" batteries to keep the cost down. I had mine open, and never looked to see the mAh rating on the battery. I figure under 1000mAh should be good
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On 7/11/2019 10:27 AM, Eric Haskell [KC4YOE] wrote: I am still interested, depending on price.
Norman Eric Haskell, KC4YOE
3709 Oakbriar Lane
Colleyville, TX 76034 USA
________________________________
From: nanovna-users@groups.io <nanovna-users@groups.io> on behalf of Frank S <ka2fwc@...>
Sent: Thursday, July 11, 2019 7:25 AM
To: nanovna-users@groups.io
Subject: Re: [nanovna-users] Extended back cover
If anyone is interested, I'll find a battery and make up a package with
screws and figure out a price. I can make the backs in black or white
(or other colors)
Frank
On 7/11/2019 5:44 AM, Nuno wrote:
Nice job!
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Folks,
Instead of reinventing the wheel to design a case, have a look at the 1553BBK series Hammond housing.
It's approx $12 CAD.
It looks like a small amount of internal trimming might be needed but it looks perfect.
Regards,
Larry
|
I am still interested, depending on price. Norman Eric Haskell, KC4YOE 3709 Oakbriar Lane Colleyville, TX 76034 USA ________________________________ From: nanovna-users@groups.io <nanovna-users@groups.io> on behalf of Frank S <ka2fwc@...> Sent: Thursday, July 11, 2019 7:25 AM To: nanovna-users@groups.io Subject: Re: [nanovna-users] Extended back cover If anyone is interested, I'll find a battery and make up a package with screws and figure out a price. I can make the backs in black or white (or other colors) Frank On 7/11/2019 5:44 AM, Nuno wrote: Nice job!
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If anyone is interested, I'll find a battery and make up a package with screws and figure out a price. I can make the backs in black or white (or other colors)
Frank
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On 7/11/2019 5:44 AM, Nuno wrote: Nice job!
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Re: Narrow band filters and LO phase noise/jitter?
In this video, Alan also correctly designates the IF BW as Resolution BW in his notes.
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On Thu, Jul 11, 2019 at 07:28 AM, <hellhound604@...> wrote:
Another video nice video explaining RBW is this one
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Re: Narrow band filters and LO phase noise/jitter?
and is it the same as IF BW ? Nope. Traditional analyzers with non-baseband IF scan wider bands
mixed down to some intermediate frequency,
so IF BW must be wide enough to pass all signals to be subsequently resolved.
Spectrum (and Network) analyzers have multiple up/down conversions in their RF chain before reaching the last IF section. The IF BW of those middle converters (before the last IF) is fairly wide however the BW of in the last IF section before the detector is indeed the same as Resolution BW There are multiple LC or crystal filters which determine the IF BW which is in fact the RBW at this stage (such as 1MHz, 100KHz, 30KHz, 1KHz and so on) so if we define the IF BW of the whole RF section as the narrowest BW which always occurs in the last IF of any receiver then yes IF BW is the same as RBW in spectrum or network analyzers. in older SA, in order to implement very narrow RBW such as 1Hz or 10Hz, they would actually do another down conversion in the last IF section would do the filtering at several KHz and then up convert it back again to the IF frequency. in modern SA they implement these very narrow RBW in DSP after detector and sampling by using digital filtering. As such, they can achieve much faster frequency scans at very narrow RBW
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CT2FZI
Eric Haskell [KC4YOE]