Re: Testing directional coupler directivity and bandwidth
Poke around in "RFCafe.com". Yes, one can use the NANOVNA's to determine the parameters of directional couplers. However, describing the setup for each parameter would be a bit long and maybe a bit ambiguous in just verbiage. Diagrams are really needed to do the description justice and clarity. "Microwaves101.com" might also offer some good information. Dave - W?LEV On Tue, Apr 28, 2020 at 10:45 AM Dragan Milivojevic <d.milivojevic@...> wrote: Termination depends on the design of the coupler, some like "tandem match"
or stripline require termination
into their designed impedance, others like "douma bridge" and similar
don't.
The connections to the VNA depend on that you want to measure and that is
up to you.
On Tue, 28 Apr 2020 at 18:15, Pierre Martel <petem001@...> wrote:
Anyone have some idea if it is possible to test a directional coupler
function. Like how much signal is coupled out on fwd or rev with is the max
bandwidth it can be used on and what would be needed as connection to each
port. I am pretty sure a variable load at the out port should be there to
simulate miss match but would it need a 50 ohm load at the un tested port?
(Fwd/rev) where should s0 and s1 plunged to? The input of the coupler or to
the sampling port?
Thanks
Pretty new with vna and learning a lot
Pierre
Ve2pf
-- *Dave - W?LEV* *Just Let Darwin Work* *Just Think*
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Re: Testing directional coupler directivity and bandwidth
Termination depends on the design of the coupler, some like "tandem match"
or stripline require termination
into their designed impedance, others like "douma bridge" and similar
don't.
The connections to the VNA depend on that you want to measure and that is
up to you.
toggle quoted message
Show quoted text
On Tue, 28 Apr 2020 at 18:15, Pierre Martel <petem001@...> wrote: Anyone have some idea if it is possible to test a directional coupler
function. Like how much signal is coupled out on fwd or rev with is the max
bandwidth it can be used on and what would be needed as connection to each
port. I am pretty sure a variable load at the out port should be there to
simulate miss match but would it need a 50 ohm load at the un tested port?
(Fwd/rev) where should s0 and s1 plunged to? The input of the coupler or to
the sampling port?
Thanks
Pretty new with vna and learning a lot
Pierre
Ve2pf
|
Re: OT: looking for testers for a tiny handheld spectrum alayzer
I tune many reject (notch) and band pass/band reject (BPBR) duplexers using a fairly large HP spectrum analyzer with tracking generator in 450-512MHZ band. It is almost impossible to to haul the unit up to a remote site, so a smaller portable unit would be welcome. It has about -80db dynamic range.
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Testing directional coupler directivity and bandwidth
Anyone have some idea if it is possible to test a directional coupler function. Like how much signal is coupled out on fwd or rev with is the max bandwidth it can be used on and what would be needed as connection to each port. I am pretty sure a variable load at the out port should be there to simulate miss match but would it need a 50 ohm load at the un tested port? (Fwd/rev) where should s0 and s1 plunged to? The input of the coupler or to the sampling port?
Thanks
Pretty new with vna and learning a lot
Pierre
Ve2pf
|
Re: OT: looking for testers for a tiny handheld spectrum alayzer
I'd be interested in helping test, I have a pair of 20ghz antennas I am restoring that I could use more test tools for.
Thanks,
Michael AE1TE
|
Re: NanoVNA firmvare, compiled by DiSlord
#firmware
DiSlord,
I have instability problems with this version, sometimes 50 Ohms measurement is instable after calibration other time through measurement , I will go back to an earlear version and see what happens.
Is my VNA instable ? I don't know
Jos
Op 28-4-2020 om 16:10 schreef Jos Stevens:
toggle quoted message
Show quoted text
DiSlord,
Well, I said problem solved, but I flashed Firmware 0.8.4.4 (Built 27/04/2020 -21:32:13) again,? calibrated NanoVNA standalone 10kHz to 2.7 GHz and calibrated NanoVNA-Saver 290MHz to 320 MHz.
After this I measured my 49.85 OHms standard the result was brilliant..... I also measured S21 Gain (S21 through), I expected to see 0 dB , but please look at my pictures. that I attached here.
This time I calibrated with CH1 not loaded while S11 calibration
Jos
Op 28-4-2020 om 15:01 schreef Jos Stevens:
DiSlord,
I reinstalled NanoVNA-Saver, left the firmware as it was (previous working) and calibrated in NanoVNA-Saver, same problem.
After this I realized that while calibrating 2 port I had CH1 loaded with 50 Ohms all the time except when calibrating "through", so I repeated the whole calibration without the 50 Ohms load on CH1 for short, open and load, connected it just for Isolation. This solved the problem !!! .... I think I had done the termination of Ch1 while doing 2 port calibration before without problems, but I might be wrong, very sorry abt that !
Now I don't know what to load best of your latest 4 versions, please be so kind to tell me.
Sorry again for waisting your time !
Jos
Op 28-4-2020 om 11:30 schreef Jos Stevens:
DiSlord,
Don't understand either, I always do reset before calibration. Will flash the previous working firmware again today to check if it still works.
Jos
Op 27-4-2020 om 23:44 schreef DiSlord:
i don`t understand
1 variant is last firmware
2 variant - is 0.8.4.3 (Only 8kHz IF change)
3 variant - is old 0.8.4.4 (2x external freq)
You not fogot reset self NanoVNA calibration before calibrate in NanoVNA Saver?
Try restore last worked firmware
|
Re: OT: looking for testers for a tiny handheld spectrum alayzer
Hi Erik, I am chairman of my local amateur radio club and we would really like to help out.
Although we don't have a project as such we would like to use one for teaching the UK intermediate and advanced course, once the lockdown is finished.
We have an application in tracing localised interference along with testing the output of radio transmitters owned by the club members.
While testing transmitter output it would be useful to check on HF data streams while setting up systems to minimise signal spreading.
I hope this is sufficient to help you.
Regards and stay safe.
Ian G7ESY
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Re: NanoVNA firmvare, compiled by DiSlord
#firmware
DiSlord,
Well, I said problem solved, but I flashed Firmware 0.8.4.4 (Built 27/04/2020 -21:32:13) again,? calibrated NanoVNA standalone 10kHz to 2.7 GHz and calibrated NanoVNA-Saver 290MHz to 320 MHz.
After this I measured my 49.85 OHms standard the result was brilliant..... I also measured S21 Gain (S21 through), I expected to see 0 dB , but please look at my pictures. that I attached here.
This time I calibrated with CH1 not loaded while S11 calibration
Jos
Op 28-4-2020 om 15:01 schreef Jos Stevens:
toggle quoted message
Show quoted text
DiSlord,
I reinstalled NanoVNA-Saver, left the firmware as it was (previous working) and calibrated in NanoVNA-Saver, same problem.
After this I realized that while calibrating 2 port I had CH1 loaded with 50 Ohms all the time except when calibrating "through", so I repeated the whole calibration without the 50 Ohms load on CH1 for short, open and load, connected it just for Isolation. This solved the problem !!! .... I think I had done the termination of Ch1 while doing 2 port calibration before without problems, but I might be wrong, very sorry abt that !
Now I don't know what to load best of your latest 4 versions, please be so kind to tell me.
Sorry again for waisting your time !
Jos
Op 28-4-2020 om 11:30 schreef Jos Stevens:
DiSlord,
Don't understand either, I always do reset before calibration. Will flash the previous working firmware again today to check if it still works.
Jos
Op 27-4-2020 om 23:44 schreef DiSlord:
i don`t understand
1 variant is last firmware
2 variant - is 0.8.4.3 (Only 8kHz IF change)
3 variant - is old 0.8.4.4 (2x external freq)
You not fogot reset self NanoVNA calibration before calibrate in NanoVNA Saver?
Try restore last worked firmware
|
Re: OT: looking for testers for a tiny handheld spectrum alayzer
I'd be interested , I have a DSP Receiver which also has people working on a spectrum analyzer program for it which I've been playing with. It, however it has to be tired to a computer to use it. Still I've only played with it and haven't done the tests of the TX 2-M spectrum of the five Baofeng HTs I have.
A portable one would be good to have for various tasks such as RFI location and characterization.
How large is the screen? Is it the original small screen or the newer F version larger screen?
I also assume that it will save some results? It should be able to do that so that the image (jpg?) can be downloaded to the computer for a larger view and/or printing or putting on a web site.
I have five Baofeng HTs I'd like to see the 2-M transmit spectrum of. I think my other DSP Receiver can do that but simply haven't found the time to try that.
-- 73 de KE3FL
Phil
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Re: OT: looking for testers for a tiny handheld spectrum alayzer
Hi Erik, I am retired and already participating in firmware evaluation and testing for the OpenGD77 project. This is a project putting hotspot MMDVM code and replacement firmware inside a GD77 Radioddity DMR radio.
I've got an Instek GSP-730 spectrum analyzer at home (150khz to 3ghz; -100DBm noise floor); an Agilent/Keysight VSA E4406A (Vector Signal Analyzer) which also has digital spectrum analysis capability, a HP/Agilent 53181a counter (with oven and preselector) and HP8644a Signal generator.
I'm also using a NanoVNA-F for antenna work.
I'm interested in working with a Spectrum Analyzer with tracking generator and low noise floor for tuning duplexers and mechanical filters.
Write me at: skilled@...
--
Marc, KD2LH
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Re: NanoVNA firmvare, compiled by DiSlord
#firmware
DiSlord,
I reinstalled NanoVNA-Saver, left the firmware as it was (previous working) and calibrated in NanoVNA-Saver, same problem.
After this I realized that while calibrating 2 port I had CH1 loaded with 50 Ohms all the time except when calibrating "through", so I repeated the whole calibration without the 50 Ohms load on CH1 for short, open and load, connected it just for Isolation. This solved the problem !!! .... I think I had done the termination of Ch1 while doing 2 port calibration before without problems, but I might be wrong, very sorry abt that !
Now I don't know what to load best of your latest 4 versions, please be so kind to tell me.
Sorry again for waisting your time !
Jos
Op 28-4-2020 om 11:30 schreef Jos Stevens:
toggle quoted message
Show quoted text
DiSlord,
Don't understand either, I always do reset before calibration. Will flash the previous working firmware again today to check if it still works.
Jos
Op 27-4-2020 om 23:44 schreef DiSlord:
i don`t understand
1 variant is last firmware
2 variant - is 0.8.4.3 (Only 8kHz IF change)
3 variant - is old 0.8.4.4 (2x external freq)
You not fogot reset self NanoVNA calibration before calibrate in NanoVNA Saver?
Try restore last worked firmware
|
Re: NanoVNA firmvare, compiled by DiSlord
#firmware
DiSlord,
I flashed the previous firmware (Built Apr 25-2020 -23:08:04) that worked well for me before and now it behaves the same as the later firmwares, so probably something has changed in my NanoVNA-Saver installation, did not change anything myself so I'm confused.
I will delete and install a new download of NanoVNA-Saver again and see what happens.
Will let you know the result.
Sorry,
Jos
Op 27-4-2020 om 22:15 schreef DiSlord:
toggle quoted message
Show quoted text
Check this 3 variants (all of them work good on my H4, try set threshold to 300MHz)
Need recalibrate
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Re: NanoVNA firmvare, compiled by DiSlord
#firmware
DiSlord,
This morning I started using the NanoVNA-H4 loaded with your firmware number 3 as yesterday. .
1) Started NanoVNA-Saver.
2) Did a reset in "calibration".
3) Did a full calibration (2 port).
After calibration (doing the "through"calibration) NanoVNA showed as picture number 1 (not pressed "Apply")
After pressing "Apply" NanoVNA showed as picture Number 2
After running again NanoVNA shows same as picture 2
Normally after calibration NanoVNA-Saver shows as picture Number 1 just after pressuring "Apply" if I remember well....Looks very much like saving the callibration is wrong !!!.... Did you check in NanoVNA-Saver ?
Jos
Op 27-4-2020 om 23:44 schreef DiSlord:
toggle quoted message
Show quoted text
i don`t understand
1 variant is last firmware
2 variant - is 0.8.4.3 (Only 8kHz IF change)
3 variant - is old 0.8.4.4 (2x external freq)
You not fogot reset self NanoVNA calibration before calibrate in NanoVNA Saver?
Try restore last worked firmware
|
Re: NanoVNA firmvare, compiled by DiSlord
#firmware
DiSlord,
Don't understand either, I always do reset before calibration. Will flash the previous working firmware again today to check if it still works.
Jos
Op 27-4-2020 om 23:44 schreef DiSlord:
toggle quoted message
Show quoted text
i don`t understand
1 variant is last firmware
2 variant - is 0.8.4.3 (Only 8kHz IF change)
3 variant - is old 0.8.4.4 (2x external freq)
You not fogot reset self NanoVNA calibration before calibrate in NanoVNA Saver?
Try restore last worked firmware
|
On Mon, Apr 27, 2020 at 02:41 AM, Roger Need wrote:
Here is a second report on the effect of calibrating the NanoVNA on SWR and
Return Loss measurements. This time a 20M dipole was used as the antenna. It
was surprising to me to see how good the measurements were when using the
default 50 kHz. to 900 MHz. calibration and setting the Stimulus range to 13
to 15 MHz. Interpolation works well under certain conditions.
I have made a *table* to better see what is the result of the measurements from the PDF file. Calibration MHz Scan MHz SWR RL dB 0.05 - 900 1 - 30 1.20 20.56 1 - 30 1 - 30 1.19 21.12 0.05 - 900 13 - 15 1.12 24.42 good result for practical use 1 - 30 13 - 15 1.12 24.74 13 - 15 13 - 15 1.12 24.67 14 - 14.35 14 - 14.35 1.12 24.74 *Result* : A full span calibration is sufficient for practical use. How smaller the scan width, the better the SWR / Return Loss. 73, Rudi DL5FA
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On Mon, Apr 27, 2020 at 02:13 AM, Roger Need wrote:
I did some measurements today on a vertical whip antenna tuned for the top end
of the 2 m amateur band.
I have made a table to better see what is the result of the measurements from the PDF file. For my understanding here the *precision of the frequency* is important. Calibration MHz Scan MHz Step KHz SWR RL dB Lag KHz 0.05 - 900 0.05 - 900 9000 1.25 19.04 153.041-147.76= 5281 0.05 - 900 140 - 155 150 1.06 29.6 148.400-147.76= 800 140 - 155 140 - 155 150 1.07 29.13 147.600-147.76= 200 140 - 155 146 - 150 40 1.06 29.61 147.800-147.76= 40 146 - 150 146 - 150 40 1.06 30.34 0 *Result* : The frequency lag of maximum RL can not be (much) better, than the measuring step size. So, watch the *Step Size* = scan width / 100. 73, Rudi DL5FA
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Re: OT: looking for testers for a tiny handheld spectrum alayzer
On Mon, Apr 27, 2020 at 01:51 PM, <aleks07111971@...> wrote:
What is the approximate cost of the device?
Not sure yet. Target is comparable to one of the nanoVNA family -- NanoVNA Wiki: /g/nanovna-users/wiki/homeNanoVNA Files: /g/nanovna-users/filesErik, PD0EK
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Re: OT: looking for testers for a tiny handheld spectrum alayzer
If you really still need testers, I might be able to contribute.
For my day job, I use an HP3585A for phase noise measurements.? Impressive dynamic range on that tank.
Also a Rigol for field measurements of RFI in the HF band at the 'other' US radio quiet zone you nave never heard about.? Near Boulder Colorado.
I'm doing radio astronomy and HF and LVHF and have several NIST calibrated diode noise sources.
If I can help.
Terry
W0ASP
toggle quoted message
Show quoted text
On 4/27/20 8:43 PM, Terry VK5TM wrote:
This very timely as I have spent the last couple of days looking at
Spectrum analyzers to replace my old CTE one.
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Re: OT: looking for testers for a tiny handheld spectrum alayzer
This very timely as I have spent the last couple of days looking at Spectrum analyzers to replace my old CTE one.
--
Terry VK5TM
( )
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Dave is correct. The VSWR doesn't vary along the transmission line except for a small variation due to loss of the transmission line. If you do see the VSWR vary, that indicates imbalance on the transmission line. For coax, this means RF is on the outside of the coax shield. 73, Carey, WB4HXE On Mon, Apr 27, 2020 at 4:38 AM Dr. David Kirkby, Kirkby Microwave Ltd < drkirkby@...> wrote: On Fri, 24 Apr 2020 at 15:51, <whdpc113@...> wrote:
If you have a bad mismatch, the reactive part of the impedance will vary
along the length of the feed line. What your rig sees at the end of the
feedline, and what the MFJ sees with a jumper and your rig behind it may
differ. Does the SWR reading on the rig change with and without the MFJ
inline? I have found VHF and UHF antenna SWR very sensitive to small
changes in length/tuning.
With a VSWR > 1, *both* the real and imaginary (reactive) part of the
impedance vary as one moves along a transmission line. It is not just the
imaginary component as you say. If that transmission lines was lossless,
the VSWR would remain a *constant*, not vary as you say. The impedance
varies along the transmission line, but the VSWR remains constant.
What any piece of test equipment shows depends on its quality.
Dave, G8WRB.
--
Dr. David Kirkby,
Kirkby Microwave Ltd,
drkirkby@...
Telephone 01621-680100./ +44 1621 680100
Registered in England & Wales, company number 08914892.
Registered office:
Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United
Kingdom
-- Carey Fisher careyfisher@...
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