Does anyone know how to use a SV4401A vector network analyzer ?

[chasedog1]

I have tried and tried but can not get any reading even after calibrating the unit. I have watched every video and still nothing at all.....

[KAF6045]

36 minutes ago, chasedog1 said:

I have tried and tried but can not get any reading even after calibrating the unit. I have watched every video and still nothing at all.....

How are you connecting the unit? What sweep range did you set? What plot type? There's a lot that "can not get any reading" doesn't answer. We would need to know the exact steps you took with the device.

For an antenna (reflected reading), you should be connecting to port 1, and port 2 should be left empty, and you need to ensure it is set for reflected measurements, not a through (port 1 to port 2) measurement.

[chasedog1]

I have the 55 page users manual and have read it front to back 2 times, followed every step and absolutely no luck at all.  I guess its return it or wait until someone does a step by step on how to use it to tune a duplexer. I don't need to bother with the the antenna at this point.

[KAF6045]

2 hours ago, chasedog1 said:

I have the 55 page users manual and have read it front to back 2 times, followed every step and absolutely no luck at all.  I guess its return it or wait until someone does a step by step on how to use it to tune a duplexer. I don't need to bother with the the antenna at this point.

Use the antenna as a learning tool -- that's a single port connection.

Duplexer might become a two port connection.

[chasedog1]

I messed with the VNA this morning and this is what I get after calibration. 

[Borage257]

What are you trying to measure? I suggest you remove some of the extra traces. Tap the boxes n the left hand side labeled Tr1, Tr2, Tr3, Tr4. One tap will turn the selected trace off, the next tap will turn it back on.

[Borage257]

13 hours ago, chasedog1 said:

I have the 55 page users manual and have read it front to back 2 times, followed every step and absolutely no luck at all.  I guess its return it or wait until someone does a step by step on how to use it to tune a duplexer. I don't need to bother with the the antenna at this point.

[KAF6045]

3 hours ago, Borage257 said:

What are you trying to measure? I suggest you remove some of the extra traces. Tap the boxes n the left hand side labeled Tr1, Tr2, Tr3, Tr4. One tap will turn the selected trace off, the next tap will turn it back on.

I'd have to concur -- that display has "LogMag" traces for both single port (s11) and dual port (s21), a Smith chart showing complex impedance, and something for phase (shift?).

I'd suggest starting simple -- one trace, configured for SWR, and again -- test using the antenna only until comfortable with reading the device.

 

[Borage257]

 I think he is trying to tune a duplexer. The above video is as step by step as i could find. It uses a smaller VNA than he has, but the basics are pretty much the same.

[Borage257]

@chasedog1What type of duplexer are you trying to tune?

[SteveShannon]

18 hours ago, chasedog1 said:

I don't need to bother with the the antenna at this point.

I agree with KAF6045; make sure you know how to sweep the antenna first and that you see something that makes sense to you.  Then sweep the antenna using the other port on the analyzer to make sure you're seeing the same results on both.  Only after you have confidence in the analyzer and your ability to analyze an antenna will you feel comfortable performing a two port analysis of a filter or one side of the duplexer.

[chasedog1]

I will give that a shot. that was the antenna but I will try removing the traces and leave just one and try to figure it out from there, thank you everyone.

[Borage257]

15 minutes ago, chasedog1 said:

I will give that a shot. that was the antenna but I will try removing the traces and leave just one and try to figure it out from there, thank you everyone.

Once you figure out how to change each trace format it will be a walk in the park. I have the smallest(and cheapest) version ant it works well.

[chasedog1]

I just tried everything he did step by step and I am getting on pattern at all.

[Borage257]

It appear tapping and holding (long tap?) on each trace will bring up a menu of some type (format likely).

 

[chasedog1]

yes it does and I have it hooked to a HT antenna and have went through every setting on and off but still no trace patterns. I am thinking I just got a bad one. The one page I showed was after calibration and nothing else was hooked to it.

[Borage257]

what do the graphs look like when you calibrate the device?

Edited December 10, 2022 by Borage257
changed question

[SteveShannon]

Rather than using the screen, it’s much easier for me (with my NanoVNA) to use the PC based software (VNASaver).  The screens are separate and the controls seem easier and more intuitive to use, at least for me.

I absolutely agree that you must turn off all the displays that you don’t need, like the Smith chart, etc.

Also, keep the bandwidth as narrow as possible.  Those jumbled mess traces with sharp inflections and straight nearly vertical traces are typical when viewing too much bandwidth at a time.  They’re a product of the fact that you have relatively few points (501 in your case it appears) being displayed, so the VNA simply draws straight lines between them.  Viewing all the way from 462 to 468 MHz is much wider than you want.  Instead, limit the width to 500KHz above and below the frequency you’re concentrating on.  Depending on what you’re measuring that may even be unnecessarily wide. 

Good luck!

[chasedog1]

ok, now that makes sense, nobody has said that b4. thank you. I am waiting on a new one I still think this one had issues. I am due to receive it Wednesday so we can go from there.... thanks again.

[chasedog1]

I received the new VNA last night and now I see the first one was definitely the problem Thanks to everyone who chimed in to help this new to vna guy... here is a pic of the sweep I am now getting...