Cables, Connectors (N/SMA/BNC) & Adapters with Measured Results for Comparisons - Page 1
Forum section: electronics / testgear

author: KungFuJosh
author_rank: Super Contributor
timestamp: May 31, 2025, 03:22:00 pm
content: Quote from: mawyatt on May 31, 2025, 02:04:53 pmWe need to set some standard testing parameters that people can do with scopes. I don't have a VNA yet to test cables.Maybe we should set some test parameters for different devices.Thanks,Josh

author: KungFuJosh
author_rank: Super Contributor
timestamp: May 31, 2025, 03:32:36 pm
content: Quote from: Performa01 on May 31, 2025, 10:07:12 amM&P's datasheet seems to be pretty good. It even suggest using thicker cables for specific situations.In my case, at least for the moment, I won't be going above 1 or 2GHz, so I hope I can get away with the 6GHz max attenuator Mike suggested, the UNAT-10A+ (datasheet attached). It was only ~$30 on Mouser. A few dollars cheaper on DigiKey.Thanks,Josh

author: Kosmic
author_rank: Super Contributor
timestamp: May 31, 2025, 03:36:16 pm
content: If you don't have the money for a real VNA, just use a nanovna or litevna. Pretty sure you would get better result than trying to macgyver something with a scope and siggen. At least it's going to be simpler.

author: mawyatt
author_rank: Super Contributor
timestamp: May 31, 2025, 04:03:46 pm
content: ^^^ Agree@ JoshGet one of those inexpensive VNAs, this can serve as a "Reference" for the cable DUT. Then the DSO results will have a good comparison to work with, if the cable, like your M&P, comes with a measured data sheet all the better!!Anyway, thanks for creating this thread, think it will be very useful of many folks!!Best

author: KungFuJosh
author_rank: Super Contributor
timestamp: May 31, 2025, 09:51:47 pm
content: Fine, fine. I'll buy a VNA. I'm planning to anyway, I'm just waiting for a good deal. I probably won't buy a TinyVNA. I have a TinySA Ultra, and it still makes me want a real SA or VNA.We still need parameters for test setups. I don't know how to setup a cable test on a VNA, considering I've never used a VNA.Thanks,Josh

author: Martin72
author_rank: Super Contributor
timestamp: May 31, 2025, 10:02:17 pm
content: At the time, I was advised to buy an inexpensive Nano VNA first before embarking on the adventure of a “real” VNA.I am still grateful for this advice today, because I recently sold my Nano VNA—it was all too fiddly for me, and then there was always the calibration before every use.(Well, I could now convert my new SSA3021Xplus into a 3.2 GHz VNA, but I still need to think about that very carefully).

author: KungFuJosh
author_rank: Super Contributor
timestamp: May 31, 2025, 10:40:27 pm
content: My experience with the TinySA Ultra was similar. All it did was convince me I need a full size / more powerful SA. I think I'll skip that step this time.

author: egonotto
author_rank: Super Contributor
timestamp: June 01, 2025, 08:07:45 am
content: Quote from: Martin72 on May 31, 2025, 10:02:17 pmHello,Calibration is also necessary for expensive VNAs. However, there are certain automatic devices available.There are good PC programs for the NanoVNA, which make it convenient to use.But VNAs are great.The PicoVNA manual is good, as it can also be applied to other VNAs.Best regardsegonotto

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 01, 2025, 01:56:33 pm
content: Which version of the NanoVNA is good? I might get one to screw with until I find a decent deal on a "real" VNA.

author: Grandchuck
author_rank: Super Contributor
timestamp: June 01, 2025, 02:08:09 pm
content: LiteVNAhttps://video.search.yahoo.com/search/video?fr=mcafee&p=lite+vna+joe+smith&type=E210US105G91906#id=2&vid=21b38ba6f56bd4d68b3de47b72ec2abf&action=click

author: Martin72
author_rank: Super Contributor
timestamp: June 01, 2025, 02:09:53 pm
content: The one I had is supposed to be good.I asked myself the same question last year, Josh:https://www.eevblog.com/forum/testgear/nano-vna-like-sand-on-the-sea-who-is-the-good-one/msg5567911/#msg5567911

author: Kosmic
author_rank: Super Contributor
timestamp: June 01, 2025, 02:14:26 pm
content: Quote from: KungFuJosh on June 01, 2025, 01:56:33 pmNanoVNA is good at low freq, LiteVNA at higher freq. I bought from Zeenko store in the past and they are reliable (https://zeenko.ja.aliexpress.com/store/1101394653).The screen size and battery might not matter if you are planning to use it connected to a computer.

author: Kosmic
author_rank: Super Contributor
timestamp: June 01, 2025, 02:18:04 pm
content: Quote from: Martin72 on May 31, 2025, 10:02:17 pmYou can save calibration on the device or PC if using a external software.I normally use it via a computer and have bunch of calibration saved for different setups.

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 01, 2025, 02:18:41 pm
content: Would I be better off with the LibreVNA if I'm going to use it on a computer anyway?

author: Martin72
author_rank: Super Contributor
timestamp: June 01, 2025, 02:20:15 pm
content: Quote from: Kosmic on June 01, 2025, 02:18:04 pmToo late...But thanks anyway.

author: Kosmic
author_rank: Super Contributor
timestamp: June 01, 2025, 02:21:57 pm
content: Quote from: KungFuJosh on June 01, 2025, 02:18:41 pmI personally have no experience with the LIbreVNA, but the electronic calibration kit for it is interestinghttps://www.aliexpress.com/item/1005008002497171.html

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 01, 2025, 02:23:48 pm
content: Quote from: Kosmic on June 01, 2025, 02:21:57 pmApparently it can be used to calibrate other VNAs too. A user on this site used it on a Siglent VNA.

author: Kosmic
author_rank: Super Contributor
timestamp: June 01, 2025, 02:27:33 pm
content: Quote from: Kosmic on June 01, 2025, 02:21:57 pmAlso look like the LibreVNA is a full 2 ports device (can measure all S parameters) and the other cheap VNA are not (only S11, S21).

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 01, 2025, 02:31:17 pm
content: There's also the NanoVNA SV4401A. That looks interesting too. 7" screen with 2 N ports.

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 01, 2025, 03:22:10 pm
content: Quote from: Kosmic on June 01, 2025, 02:14:26 pmWhy? What makes one better than the other?LiteVNA-64 max is 6GHz, and NanoVNA-F V3 is also maxed at 6GHz. Is there something else that makes one better than the other in your opinion?I'm leaning towards the NanoVNA-F V2 that Martin had, since 3GHz is probably good enough for me, and the price is better.More importantly- can these devices be used for the purpose of this thread- to accurate test cables?Thanks,Josh

author: joeqsmith
author_rank: Super Contributor
timestamp: June 01, 2025, 03:41:10 pm
content: Quote from: KungFuJosh on June 01, 2025, 03:22:10 pmMaybe 9G with harmonics.QuoteYou mention testing them with a scope so I am assuming you are referring to typical patch cables for low frequency use around the home lab. I would just eye ball the connectors for damage, clean them and check if flexing them causes any problems.Obviously all cables are not the same. Higher grade cables like you may use with a VNA could costs thousands of USD each! They can be easily damaged.Someone was recently shitting on various brands for making cables that did not meet spec. I made an attempt to measure a few and provide further details.https://www.eevblog.com/forum/testgear/dont-buy-sma-cable-assemblies-from-centricrf/The very last post I made was using the LiteVNA to measure insertion loss of a Mini-Circuits cable. That particular cable is spec'ed out to 18GHz which is outside what could be measured with the LiteVNA.https://www.eevblog.com/forum/testgear/dont-buy-sma-cable-assemblies-from-centricrf/msg5923980/#msg5923980

author: joeqsmith
author_rank: Super Contributor
timestamp: June 01, 2025, 03:54:23 pm
content: QuoteThe following link shows using a T-check with the LiteVNA. This is just a simple method to verify your setup after calibration. After attempts to remove as many variables as possible, I was able to squeeze decent performance to 3GHz with it.https://www.eevblog.com/forum/rf-microwave/nanovna-custom-software/msg5685217/#msg5685217Showing the dynamic range of the three hardware revisions of the LiteVNA to 9GHz. Consider you would normally want about 10dB margin. Still, for very rough measurements, it could be useful.https://www.eevblog.com/forum/rf-microwave/nanovna-custom-software/2450/

author: Kosmic
author_rank: Super Contributor
timestamp: June 01, 2025, 09:17:39 pm
content: Quote from: KungFuJosh on June 01, 2025, 03:22:10 pmI remember reading/listing joeqsmith experiments with the litevna and he was mentioning the original nanovna was performing better at lower freq. Maybe joe could elaborate more.

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 01, 2025, 09:22:05 pm
content: I'll have the NanoVNA-F V2 tomorrow. Now I just need to learn how to use a VNA. 🤷

author: joeqsmith
author_rank: Super Contributor
timestamp: June 01, 2025, 09:45:08 pm
content: From a black box view point, the original NanoVNA had lower noise and could be used for narrow band measurements (crystal filters) which the LiteVNA, V2+ can't. The cost was less than half.We bought two H4s which are similar to the original NanoVNA with a 4" display. These never performed as well as the original NanoVNAs we bought. I ended up damaging my H4 and while trying to repair it stumbled onto that the mixers they used in the original NanoVNA induced less noise. I ended up adding a few caps and changing the mixers on the H4 and it out performed the original NanoVNA. I ended up making the same mods to my friend's H4 and the performance was on-par with mine. Maybe the early H4's were better. I posted about it here:https://www.eevblog.com/forum/rf-microwave/nanovna-custom-software/msg5695997/#msg5695997The H4 and NanoVNA are only good for about 300MHz. They support harmonics but the dynamic range is poor. So, < 300MHz, narrow band, PDN sort of measurements, NanoVNA. Greater than 300, LiteVNA. They are low cost, so if you play with RF, get them both and you're set.Just don't be fooled into thinking they are going to compete with a name brand VNA. They are slower, missing key features and use a square wave. People will post how the square wave doesn't matter. I agree in most applications that is true. Certainly for passive devices. However, if you are playing with active circuits that may not be the case, even when working with very low frequencies. Here I demonstrate a 1MHz amplifier that I purposely designed to show how the square wave can be problematic.

author: Martin72
author_rank: Super Contributor
timestamp: June 01, 2025, 09:46:31 pm
content: @Josh:I'm currently on chapter 4...

author: joeqsmith
author_rank: Super Contributor
timestamp: June 01, 2025, 09:55:04 pm
content: Quote from: KungFuJosh on June 01, 2025, 09:22:05 pmLooks similar to my V2+4. The LiteVNA quickly obsoleted it. The Lite provided a wider sweep range, input protection and the biggest advantage, Dislord!! After dealing with so much crap firmware, it was refreshing to see how polished the the Lite was. I only use these with a PC, so I really could care less about 90% of the features added to the firmware. But the Lite has features that the V2+4 will never have because of the closed architecture.Cost wise, I suspect you could buy the Lite + original Nano for the same amount as the V2+4.

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 01, 2025, 10:24:16 pm
content: I bought the NanoVNA-F V2 for $125. The LiteVNA-64 is $160. It's a small price difference if you think it's that much better.These seem like toys to learn on. Is the LibreVNA a more serious device, or is it just a more expensive toy?

author: joeqsmith
author_rank: Super Contributor
timestamp: June 02, 2025, 12:55:10 am
content: Quote from: KungFuJosh on June 01, 2025, 10:24:16 pmI have used mine for professional work. I wouldn't call them toys. When you do something stupid, you're not out much $$$. We had to replace a 3.5mm short standard a while back. $1000 USD. My guess is someone allowed the center pin to rotate in it. That's all it takes. The LiteVNA has some input protection but my NanoVNA and H4 did not. I have no idea how I damaged my H4 as I normally work on an ESD mat and wear a strap but something blew out the front end. I ended up doing the repairs and adding a TVS to both ports. This isn't something I would ever consider with an expensive VNA.Like buying anything else, I would have no way to know what metrics are important to you. I run them from a PC. Things like a large LCD (which is turned off when connected to USB), card readers, built in measurements, battery life, are not something I care about. Even the mechanical robustness is not a concern. Like the handheld DMMs, I don't own a VNA that would fit all my needs. Like the DMMs, these low cost VNAs are good enough that they cover a lot of my needs. I often use them over my old Agilent/HP equipment!Overall, if you wanted to compare what you have with my LiteVNA + NanoVNA combo, sure, you would win on a cost basis but for me even $100 cost savings wouldn't be something I would consider over the performance. Specs for the three are below. I'm not sure I would trust them though. For example, they may claim a 100dB dynamic range but fail to tell you it requires an hour to do a sweep. Beware. I try to provide details about any measurements I post about.I saw they now have an e-cal for the LibreVNA, and I understand they can do a full 2-port measurement with it. But I started seeing everyone sticking massive heat sinks to them. As soon as it was released, the designer was talking about the next generation (couldn't see buying a second one down). The software interface was locked (eventually opened up) but the developer warned me that it could very well change. Then the performance just wasn't there. With the ecal, say $700ish, we are not really talking disposable for many hobbyist.I think they all have a bit of a fan following. Many seem to be hams wanting to measure their antenna VSWR in the most complex manner possible and will refer to them as an antenna analyzer. Because I write my own software, I have shown using the VNA being used to measure radiation patterns (in 3D). All automatically. Being able to write custom software for any test equipment is a must have. My choice on the low cost VNAs were based on performing tasks far beyond measuring antennas.Sysjoint NanoVNA-F V2Measuring frequency: 50kHz~3000MHzRF output power: - 9dbmS11 dynamic range: 50dB(<1.5GHz), 40dB(<3GHz)S21 dynamic range: 70dB(<1.5GHz), 60dB(<3GHz)Frequency tolerance: <0.5ppmPort SWR: <1.1Display: 4.3" IPS TFT(800x480)Output capability: 5V/1AUSB interface: USB Type-CPower consumption: 3.7V Li-Po, 5000mAhNumber of scan points: 101Display trace: Up to 4Marker points: Up to 4Calibration result: Up to 5 groupsScanning time: 2.7s/every timeLooking at the LiteVNA 64Frequency range 50kHz ~ 6.3GHzSystem dynamic range>70dB f < 3GHz, calibrated>50dB f >= 3GHz, calibratedS11 noise floor<-50dB f <3GHz, calibrated<-40dB f >= 3GHz, calibratedFrequency stability <0.5ppmSweep rate >550 points/s Avg=1Sweep points (on device) 10 ~ 1001 points, adjustable -Sweep points (USB) 1 ~ 1024 points, adjustable -Power supply USB, 5V +/- 0.5V 600mA MAXBattery Li-polymer 3.7V 1300mAh LiteVNAOperation ambienttemperature -10deg C ~ 50deg CRF connectors SMA femaleDisplay 3.95"TFT LCD (480x320)NANOVNA-H4ABS case: 75mm x 133mm x 18mm (excluding protrusions)Measurement frequency: 10KHz-1.5GHzRF output: 0dbm (+-2dbm)Measurement range: 70dB (50kHz-300MHz), 60dB (300M-900MHz), 40dB(0.9G-1.5GHz));Port SWR: < 1.1Display: 3.95 inch TFT (320 x 480)USB interface: USB type-C communication mode: CDC (serial)Power: USB 5V 200mA, built-in 1950mAh battery, maximum charging current 1ANumber of scanning points: 101 (fixed)Display Tracking: 4, Marking: 4, Setting Save: 5Frequency Tolerance:<2.5ppmFrequency Stability:<0.5ppm

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 02, 2025, 01:34:52 am
content: I think I'll try out the NanoVNA, and if I like it, I'll return it and buy a LiteVNA64. 😉

author: joeqsmith
author_rank: Super Contributor
timestamp: June 02, 2025, 12:52:54 pm
content: If you download my last user's manual for Solver64 (see dropbox in sig), section 20.0, I talk about the modifications I made to the H4. Shown sweeping from 1.6 to 10kHz after mods.While this is the best I have seen with these low cost VNAs, it's still not great for power distribution measurements. At best, I would say I can measure the difference between a 1mOhm and 100uOhms, with little accuracy.If you do at some point feel you need the LibreVNA and want to buy something new, I suggest you have a look at that Pico VNA. The hardware specs look really good. It's a four receiver design. Cost was around $10k USD. At the time their software was not very impressive but that's been several years ago. Sure, 10X the cost but you may find saving up for a much better unit would be better money spent. For now, keep it under $200. Learn how to use it, how not to damage it, what the limitations are....

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 03, 2025, 03:17:39 am
content: I got the 10dB attenuator Mike recommended, and did a bandwidth sweep comparing 3 M&P cables.1 cable is made by M&P in Italy, using their Stealthflex 7 cable and connectors.Martin made me a Hyperflex 5 cable, about the same length as the M&P cable.I made a Hyperflex 5 cable, less than half the length of the others.It seems the cable length here is likely the reason for the improved flatness compared to the other 2? The longer cables are really close.This is the short cable:Thanks,JoshPS. I received the nanoVNA today...and charged it. That's progress, right?

author: joeqsmith
author_rank: Super Contributor
timestamp: June 03, 2025, 01:19:38 pm
content: Looks like you may only be interested in insertion loss. This thread is similar but OP was asking about impedance.https://www.eevblog.com/forum/rf-microwave/vna-for-cable-characterization/

author: joeqsmith
author_rank: Super Contributor
timestamp: June 04, 2025, 01:37:30 am
content: More than 3dB insertion loss at 600MH, you can assume that your setup is the problem. Just to give you something to chew on when for when you get the VNA setup,Shown is a 74" 50 ohm cable made from Pasternak RG400/U and terminated with HP 1250-0256 BNCs.https://www.pasternack.com/images/ProductPDF/RG400-U-BULK.pdfTo calibrate the setup, I had attached two SMA to BNC adapters. One male, one female. Took a sweep and stored that as the reference (normalizing only). Swapped out the female for a second male then attached the test cable. Not a great setup but gets us in the ballpark.I ran two tests. One from 1M to 600MHz. You can see at 400MHz I measure an insertion loss of 0.523dB. The cable is spec'ed at 0.555dB. Of course that doesn't account for the connectors or the errors in our cal. But again in the ballpark and a whole lot closer to what I would expect your cables to actually be.I repeated the test from 1M to 3GHz. At 1HGz we measure and insertion loss of 0.883dB. Cable is spec'ed at 0.888. The ripple is are crap cal. Ignoring that and looking at the worse case 2.679GHz, insertion loss was 2.414dB. At 3dB, the cable is spec'ed at 1.659dB. Considering the poor setup, I would say we are close enough.You could also try moving the cable around and making sure the graph remains stable.

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 04, 2025, 02:16:31 pm
content: Quote from: joeqsmith on June 04, 2025, 01:37:30 amThe scope is 500MHz. What makes you say there's something wrong with the test setup with -3dB at 569MHz?I did start messing with the VNA. The only thing I've determined for sure is that if I get a real one, I want it to do SA and VNA stuff in one unit.I made similar cables to test with my power meter, and both the SML and RF power meter were well within spec for accuracy and flatness. Using adapters to test the cables in the test above gives similar results.Thanks,Josh

author: kmoonwalker
author_rank: Frequent Contributor
timestamp: June 04, 2025, 02:56:43 pm
content: he meant that what you see in results is more your setup characteristic than the cable itself on that rangeas I wrote you back then you are measuring your scopes frontend and ADCto prove my point even those few key points where the curve has local maximum seems to be in same places just amount of how it goes up/drops down variesand this is also normal as it is not only cable but connectors even when you exchange single cable only - you press some force on connctors to mount it and this you may see it is so sensitivethat is why for some connctors there are those fancy torque wrenches to tighten em properly

author: kmoonwalker
author_rank: Frequent Contributor
timestamp: June 04, 2025, 03:04:40 pm
content: also with ADC and software "treatment" you could also see some slight variations while repeating the measurements on same cable(but you would need to set markers on each point of local max and min and note that

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 04, 2025, 03:21:02 pm
content: Quote from: kmoonwalker on June 04, 2025, 02:56:43 pmYes, I understand (that part at least 😉). The point of those tests was to measure the effective bandwidth of the scope. I don't consider anything after the -3dB test point particularly useful here. The scope can "bravely" count up to around 930MHz, but I'm ignoring everything over 600MHz anyway.My curiosities were about the cable & test setupwithinthe scope's bandwidth. What affects that, how to flatten it, etc.For larger range stuff I would need to use different tools. That's why I'm screwing around with this cheapo VNA, and will probably get a better one eventually.The wiggles may partially come from the scope frontend/ADC, but certainly better flatness can be achieved, as seen with the attenuator in place.Thanks,Josh

author: joeqsmith
author_rank: Super Contributor
timestamp: June 04, 2025, 03:26:30 pm
content: Correct, wrong equipment for the job. It wasn't clear from your post what your goal was.Personally, I can't see much of an advantage of integrating different tools into one. I guess as long as you get the performance you need. I suspect you would end up with something that can't perform these two tasks very well. I've demonstrated using the LiteVNA directly detecting a local radio station and demodulating the audio as a post process. It was very poor as expected, but I was surprised I could get it to work at all. If I got a new SA, I would go for a real time unit (over swept) but with wider bandwidth than my Signal Hound BB60C. If I were to replace my VNA, I would get another 4-receiver unit with wider range (upper and lower) and faster Ethernet. Maybe 3 ports.Oscilloscope will be the next thing I replace, if I ever find something I like. It doesn't need to be a logic analyzer, spectrum analyzer, vector network analyzer, power supply, function generator..... just a scope.

author: kmoonwalker
author_rank: Frequent Contributor
timestamp: June 04, 2025, 03:34:55 pm
content: those small VNA units are surprisingly good, especially when one gets a "better" made unit

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 04, 2025, 04:31:22 pm
content: Quote from: joeqsmith on June 04, 2025, 03:26:30 pmI'm not looking for a single device to do it all.The scope I want is the SDS5000X HD. I currently have the regular 5000X and the 2000X HD. I like the 2000X HD, but I want higher bw, HDMI out, active probe terminals, external clock input, etc.I want an SA/VNA combo because it's not something I needat all(just for fun/education), and there are some good options including the Siglent SVA series, or the X-R stuff should be better than my needs for the VNA stuff I'll very rarely use. Even better if I can find somebody that wants to trade one. 😉😉Thanks,Josh

author: kmoonwalker
author_rank: Frequent Contributor
timestamp: June 04, 2025, 04:43:40 pm
content: Quote from: KungFuJosh on June 04, 2025, 04:31:22 pmlets see how it will work when it comes out regarding the scopeas for VNA better models have sets of probes to check EMC, you can use reflectometry which is very useful thing sometimes when strange things with supposedly new good cable etc

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 04, 2025, 04:50:43 pm
content: Quote from: kmoonwalker on June 04, 2025, 04:43:40 pmIt'll be fine. Whatever needs to be fixed, will get fixed.QuoteWhat decent VNA can't do S11?My needs are very limited anyway. You would probably want something more capable than what covers my needs. You gotta buy the device that meets your needs, not my needs. 😉

author: kmoonwalker
author_rank: Frequent Contributor
timestamp: June 04, 2025, 10:54:33 pm
content: we have a saying that appetite grows with eating and yours develops at pretty fast rate

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 05, 2025, 12:55:28 am
content: Quote from: kmoonwalker on June 04, 2025, 10:54:33 pmI'll try and take smaller bites. 😉

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 13, 2025, 11:49:45 pm
content: So, anyway...I watched Joe's video, and a bunch of Paul's videos, and I have a much better understanding of this stuff. I'll try and do some measurements with the SV4401A I got instead of the nanoVNA-F V2.The F V2 is too small for me. I found it terribly annoying to work with, and much prefer the full size N connectors on the SV4401A.BTW- Both of them go to 4.4GHz now. I dunno why they don't advertise that?Thanks,JoshETA: The SV4401A is trash. It can't stay connected to USB to save it's life. I'm probably going to return both and buy something real.

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 25, 2025, 01:14:51 am
content: I added definitions to run the V3500A power meter and the R&S SMIQ and SML series sig gens with TestController. TestController has a great "Param Sweeper" function, which I used to run these tests going from 10MHz to 6GHz with 10MHz steps (600 total).First, I ran the test with a nice quality cable going from the V3500A to the UNAT-10A+ attenuator connected at the back of the SMIQ06B (I seriously hate the B19 option; I can't wait to convert it).Then I removed the cable and tested again with just the attenuator.Then I ran a full self cal on the SMIQ and Zero on the V3500A.Finally, I removed the attenuator and connected the meter directly to the SMIQ.I thought the results were interesting, though mostly expected. I knew the direct connection would be the best. However, I was surprised to see the attenuator wasn't really helpful with the SMIQ. It looks (to me) like it made things worse below 3.5GHz, and really only helped above 5GHz.Here's the comparison:(for our colorblind friends, the legend from left to right matches the plotlines from bottom to top)I'm going to run the direct tests with and without the attenuator on the SML03 for comparison.Thanks,Josh

author: HKJ
author_rank: Super Contributor
timestamp: June 25, 2025, 06:51:42 am
content: Quote from: KungFuJosh on June 25, 2025, 01:14:51 amIn TC you can use any value for x-axis, not only time, try right clicking on the hh:mm:ss text at the bottom. You can select a log scale if you want.You can also combine curves from different files with the import function.

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 27, 2025, 04:52:38 pm
content: I returned that SV4401A, and ordered one from another reseller to rule out a hardware fault. Of course, it was all the same. No reliable connection.Today I found Sysjoint released a new firmware version for the SV4401A, and a custom version of the nanoVNA App. It works now. Shocking, right?Anyway...I want to make a comparison to the M&P provided test. How do I need to setup the nanoVNA to match their test? Or is their test result questionable?I tried testing the cable 50Ω terminated, and connected to port 2 (full calibration done including through).From their equipment range and description, I'm assuming they're also using some version of the nanoVNA, maybe the SAA2. I dunno though. Is SRL the same as RL, or is there something else I'm missing here?Thanks,Josh

author: Rubo
author_rank: Regular Contributor
timestamp: June 28, 2025, 01:03:59 pm
content: Quote from: KungFuJosh on June 27, 2025, 04:52:38 pmJust to make sure. Avre you talking about SV4401A or nanoVNA when you say it works now?

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 28, 2025, 04:16:07 pm
content: Quote from: Rubo on June 28, 2025, 01:03:59 pmThe SV4401A is a nanoVNA variant. I'm talking about the SV4401A, and a custom Sysjoint released version of the nanoVNA app. The SV4401A still won't work with the "official" releases of the apps (at least not for me on Win11), but hopefully that will be rectified eventually also.I'm happy to use it with the custom nanoVNA app, and the SVXX01A-Tools app is cute too if you want to control the SV4401A the same on your computer as it looks on the device.New fw:https://www.sysjoint.com/ueditor/php/upload/file/SV4401A_App_v0.7.0.zipSysjoint nanoVNA-App:https://www.sysjoint.com/ueditor/php/upload/file/NanoVNA-App_by_SYSJOINT.zipSVXX01A-Tools:https://www.sysjoint.com/ueditor/php/upload/file/SVXX01A_Tools.zipThanks,Josh

author: Rubo
author_rank: Regular Contributor
timestamp: June 28, 2025, 06:13:32 pm
content: Now it's much clearer.So you use the Sysjoint custom nanoVNA app with your second SV4401A and it's working. Got it.I've been thinking about getting one to play with, but the only feedback about it was your thread here and it wasn't positive.Might give it a shot now.My Agilent N9340A doesn't have a lot of the functionality of these cheap chinese units, but at least I can compare the two (as a sanity check).I also need to do something about it's dim display (N9340a that is), but haven't gotten around to it yet.

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 28, 2025, 06:36:17 pm
content: I think all SV4401As are the same, and made by Sysjoint. I did not like dealing with ARSINC (pronounced Arse Inc.), and they charge more than other suppliers. The 2nd one I got was $319 (instead of $499 from ARSINC), both on Amazon.I also have an SAA2N, though sanity checking isn't the best going between two very similar devices, but still better than nothing. I hope to get a Siglent VNA eventually.Thanks,Josh

author: Rubo
author_rank: Regular Contributor
timestamp: June 28, 2025, 06:43:30 pm
content: I've been eyeing Siglent's SHA850 & SHA860 series, just can't justify the price for a hobby.

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 28, 2025, 06:54:20 pm
content: lol, I don't think I'm worthy of that one either. 🤣

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 28, 2025, 09:16:38 pm
content: I still don't know how to convert S11 to SRL, so I'll ignore the M&P test sheet for now.I assume these are more relevant to the tests we're doing with our scopes anyway.Thanks,Josh

author: Rubo
author_rank: Regular Contributor
timestamp: June 29, 2025, 04:16:17 pm
content: I'm a little puzzled by the screenshots. Is that a 1-port measurement or 2-port? Are you measuring insertion loss or return loss? Numbers don't make sense???

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 29, 2025, 05:05:53 pm
content: Quote from: Rubo on June 29, 2025, 04:16:17 pmS11 is always 1 port. It's easier to see on the attached graph. For example, at 500MHz, attenuation is -0.29dB, and at 600MHz attenuation is -0.32dB. This is useful when doing the fun FFT bandwidth tests on a 500MHz scope, because I know that if I go to exactly the -3dB point on the scope, I'm actually not showing the true -3dB point because 10% of that attenuation is coming from this specific cable.I highly recommend watching some or all of Paul's videos on VNAs:I didn't understand any of this stuff before I watched some of these...2 or 3 times. 🤣Thanks,Josh

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 29, 2025, 05:21:35 pm
content: Here's a comparison of 3 cables (S11 cable loss). I couldn't figure out how to move marker labels (maybe not possible?), or any option to show the memory labels. Does anybody know how to do that in nanoVNA-App?Green = short Hyperflex 5Orange = Stealthflex 7Purple = long Hyperflex 5Thanks,Josh

author: kmoonwalker
author_rank: Frequent Contributor
timestamp: June 29, 2025, 05:35:01 pm
content: https://blog.teledynelecroy.com/2020/05/reading-s-parameters-ripples.htmlhttps://blog.teledynelecroy.com/2014/12/what-s-parameters-reveal-about.htmlhttps://blog.teledynelecroy.com/2014/12/what-s-parameters-reveal-about_9.htmlhttps://blog.teledynelecroy.com/2014/12/what-s-parameters-reveal-about_17.html

author: Rubo
author_rank: Regular Contributor
timestamp: June 29, 2025, 05:42:45 pm
content: That's the part I'm having trouble with. Are the cables that you are testing terminated with 50 Ohm load?Because this is what i'm getting with my Agilent N9340A using a directional coupler from Mini-Circuits part #ZFDC-20-4-N+, measuring Agilent cable part #15NNF50-1.5AOpen:Terminated with 50 Ohm Mini-Circuits load part #KARN-50-18+:

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 29, 2025, 05:59:16 pm
content: No load. Paul's video said to test either open or shorted at the other end, so I left them open.What's the directional coupler for?

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 29, 2025, 06:07:20 pm
content: I was measuring cable loss, based on this video:

author: Rubo
author_rank: Regular Contributor
timestamp: June 29, 2025, 06:10:24 pm
content: Ok, now I know why it didn't make sense to meIf you don't terminate it the other end, almost everything is reflected back, so your return loss is huge.That's why your VSWR is off the charts.You need to terminate it to know how much power is reflected back. It should look more like the second picture in my previous post.Since Agilent N9340A can't make one port measurements, I need a directional coupler to measure the reflected power.Idealy your return loss will be -30dbm or more. The closer your get -50dbm to closer you are to "ideal" load.I have not had good results using one port measurements for cable loss.I just use two ports to measure insertion loss.

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 29, 2025, 06:14:41 pm
content: lol, yeah, I guess it's good I left the VSWR in that graph so I could learn how to do that too...eventually. 😉😉

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 29, 2025, 06:18:27 pm
content: How's this look? The 50Ω termination is crap. I had to use an N-N through with the 50Ω cal load.Thanks,JoshETA: I have some Amphenol 50Ω terminators for N, BNC, and SMA in my Mouser cart.

author: Rubo
author_rank: Regular Contributor
timestamp: June 29, 2025, 06:49:41 pm
content: That's more like it 😁

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 29, 2025, 07:03:42 pm
content: Can somebody explain this one? What's different here between the S11 logmag (cable loss?) vs Coax Loss?Thanks,Josh

author: Rubo
author_rank: Regular Contributor
timestamp: June 29, 2025, 08:15:03 pm
content: Not having that particular device, I'm not certain.But for cable loss, I personally would not use S11.I would use S21 (2-port) measurements.That way after you normalize/calibrate/zero out your device, you are measuring the actual cable loss.For a decent coax, the loss @ 2GHz should be way under 1db (for few feet/around a meter).I'll let someone with more knowledge about your VNA interpret the screenshots.

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 29, 2025, 08:50:35 pm
content: My understanding on this stuff is quite limited, however...whether measuring S11 or S21 the device should be calibrated appropriately.I will try to do an S21 transmission test, but doing that in this case is difficult because the cables go from N to BNC, and it's hard to calibrate the Thru right now. I did make a DUT cable for this, let's see how it works out. 🤔

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 29, 2025, 09:12:41 pm
content: Here's an S21 test. I don't trust it though since the DUT cable is lower quality than the cable being tested...and I dunno if it's calibrated out properly.The image with two traces is comparing the same cable with the VNA calibrated differently, and the cable reversed. Blue is with a DUT cable on port 2 calibrated out with a crappy through, and the white trace is with the crappy adapter calibrated out on port 1 instead.Thanks,Josh

author: kmoonwalker
author_rank: Frequent Contributor
timestamp: June 29, 2025, 10:34:20 pm
content: do you have any N to N connector cable at hand to make the test on it?

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 29, 2025, 11:15:34 pm
content: Quote from: kmoonwalker on June 29, 2025, 10:34:20 pmYes, but please describe exactly what you want me to test, and how I should calibrate it first.Thanks,Josh

author: Rubo
author_rank: Regular Contributor
timestamp: June 29, 2025, 11:24:11 pm
content: That looks more like what a cable loss measurement shoud be.All those dips & peaks are reflections caused in the connectors and difference in velocity of propogation of different cable types.You want a pretty good quality cable to connect the two ports of the VNA for calibration/normalization, so that measurement plane is at the end of the cable.That way when you measure your DUT cable, any loss is in the DUT and not in the setup.Again, I'm not familiar with your VNA, so I can't help with propper calibration procedure.On the Agilent it's pretty straight forward to normalize the cables/through/etc. for a propper setup.Once I get myself one of those VNA's, I'll post back with what it looks like on my end.Give me a few days

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 29, 2025, 11:30:45 pm
content: The DUT cable I'm referring to is a cable connecting the VNA to the DUT, which in this case (the DUT) is also a cable. 😉My question isn't about this VNA specifically, but about calibration in general on a two-port VNA. If you have two DUT cables to connect the DUT (in this case, a cable), and a high-quality pass-through adapter, it's pretty straight forward.But if I want to test with a single adapter or single DUT cable, it becomes trickier to calibrate those things out. It will be easier once I order the other calibration adapters...but this does get a little ridiculous.

author: Rubo
author_rank: Regular Contributor
timestamp: June 30, 2025, 12:32:14 am
content: Just for reference, this is what the above cable looks like when I do S21 measurement:

author: Rubo
author_rank: Regular Contributor
timestamp: June 30, 2025, 12:42:02 am
content: I know what you meanIf you want to measure a cable, I wouldn't use 2 cables for calibration.I would calibrate with one cable for OSL & connect that same cable to the second port for a through.That way your measurement plane will be at the connector of the second port, to which you connect DUT cable to test.Idealy you would not use any gender adapters, but even if you do, they should not introduce too much loss (if they are from a reputable manufacturer).And the adapter loss should be stated in the datasheet.In my experience, N adapters have a loss of 0.1db to 0.4db depending on frequency (up to 3GHz).

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 30, 2025, 01:07:31 am
content: Quote from: Rubo on June 30, 2025, 12:42:02 amRight, I want to set up the DUT cable on port one, but since the cables I'm testing are N to BNC, so is the DUT cable (but with female BNC), and that requires an adapter to connect to the 2nd N port. That means I need a male BNC calibration kit, right? I don't have that yet. I'm going to order some BNC loads to try, but I'm not going to spend a lot of money on this. Close enough is good enough. 😉IME, the adapters add reflections and loss.

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 30, 2025, 01:16:46 am
content: Quote from: Rubo on June 30, 2025, 12:32:14 amAssuming any accuracy on my S21 test, that's double the attenuation compared to the Stealthflex 7 cable I tested. Can you adjust the scale to show more detail?Thanks,Josh

author: Rubo
author_rank: Regular Contributor
timestamp: June 30, 2025, 01:19:09 am
content: Quote from: KungFuJosh on June 30, 2025, 01:07:31 amYou need OSL at the end of the cable on port 1 (the transmit port). So if it end with a male BNC, you would need female BNC OSL or vice versa.Quote from: KungFuJosh on June 30, 2025, 01:07:31 amAbsolutely, especially between diferent types of connectors.

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 30, 2025, 01:28:40 am
content: Quote from: Rubo on June 30, 2025, 01:19:09 amExactly. The DUT cable is male N to female BNC, so I'll need male BNC OSL, but I'm going to get female also, cause who knows what stupid thing I'll do next.The problem is, I'll want to make a nicer DUT cable after I do those things.

author: Rubo
author_rank: Regular Contributor
timestamp: June 30, 2025, 01:29:52 am
content: Sure. The lowest I can go is 1db/div.Frequency range is 100kHz to 3GHz

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 30, 2025, 01:46:08 am
content: Quote from: Rubo on June 30, 2025, 01:29:52 amSeriously? That kinda sucks. Shame on you, Agilent!The nanoVNA App / device can both go to some fairly ridiculous scales.

author: tautech
author_rank: Super Contributor
timestamp: June 30, 2025, 02:23:56 am
content: Quote from: KungFuJosh on June 30, 2025, 01:46:08 amYup, so can the SVA1032X you want howeveryoushould well know resolution does not equal accuracy.....for that we must consult datasheets.

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 30, 2025, 02:43:24 am
content: Quote from: tautech on June 30, 2025, 02:23:56 amThanks, Captain Obvious. 😉😉Datasheets don't account for bad accuracy due to my dumbass screwing up the test setup and/or calibration. 🤣

author: KungFuJosh
author_rank: Super Contributor
timestamp: June 30, 2025, 07:57:46 pm
content: It was suggested to me to calibrate both ports, and so I did. I used a different DUT cable, with an assumed higher quality N-BNC adapter. Attached are the results.Is that a normal thing? Do people calibrate both ports on their VNAs? What's the process normally like if you do?Never mind. Unless I'm wrong, that's only useful for VNAs that can do more than S11 and S21.Thanks,Josh

author: Rubo
author_rank: Regular Contributor
timestamp: June 30, 2025, 09:08:16 pm
content: Looks goodYou are correct, 2-port calibration is performed if both ports can transmit.I'm with you on your previous question:What are they showing under "Coax Loss" graph???

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 16, 2025, 08:31:21 pm
content: Two tests of my SDG6052X.Chart 1 is using a nice HF5 cable.Chart 2 is direct connection through a cheap adapter.