Improved Impedance Measurement with the RigExpert (054)
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- เผยแพร่เมื่อ 2 ต.ค. 2024
- So you own a totally AWESOME RigExpert and you need to measure a capacitor or an inductor or the impedance of some device with the best accuracy you can.
The RigExpert does a pretty good job right out of the box. But, you can do even better than this with accuracy rivaling the nanoVNA or other such devices.
In this video I am going to show you exactly how to do this.
Time Markers for Your Convenience
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00:05 Introductory Comments
01:17 The Problem with Impedance Measurements
01:26 Application #1: Measuring at the Connector
02:21 DEMO #1
04:04 Application #2: Measuring at the End of a Cable
04:37 DEMO #2
06:23 The Solution: User Calibration
07:01 Preparations for Measurement
09:49 Calibration Procedure
11:59 RESULTS #1: At the Connector
12:47 RESULTS #2: At the End of a Cable
14:21 Final Comments and Toodle-Oots
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Thank you for explaining that the factory calibration isn’t lost. I was worried about that.
Yeah, so was I as this was a borrowed unit. Thankfully it is just a temporary calibration for a fixed frequency. 🙂
Thank you for this! You have added value to my RigExpert!
Fantastic! You are welcome!🙂
Good stuff Ralph!!! Keep 'em coming!
Thanks, man! As long as I can, they'll keep rolling out. 🙂
Excellent explanation and demonstration! 👍
Thanks! 🙂
Super helpful, and can also be used with the RigExpert Stick (Pro, in this case). Many thanks.
You are very welcome! I am very glad it is so helpful to you! 🙂
Nice job sir sure wish my AA-200 had the cal feature.
Thanks! I wish I owned a Rig Expert (I borrowed one for the video) instead of the MFJ-259. 🙂
maybe get a rig ,,always need new toys,,thanks Ralph for helping me spend money LOL
I wish I'd bought a RigExpert instead of the MFJ-259. OK, so it is twice the price, but you get what you pay for!
Yes! Awesomeness!!
Now, what is the correct spelling of "tootleloots"?😂
73 de K4WRF
🤣LOL! Thanks, man!
Ya know, I have no idea. I spell it "toodle-oots" in my scripts.
Can you link where I can purchase the calibration standards from?
Unfortunately, real validated standards are not cheap! However, for the kind of things we are doing, we can cheat a bit and get close enough.
The short and open standards are easy enough to DIY. For the OPEN you can use an unpopulated connector. For the SHORT you can thoroughly short a connector. I used some braid from some stripped coax or a length of solder wick. Just make sure it is very substantial so as to avoid inductance and resistance.
The LOAD is a bit more tricky. You *could* use 4x200 Ohm, 0.1% surface mount resistors with your connector --OR-- you could simply purchase a 50 Ohm terminating load (be careful to look closely at the specs for accuracy, frequency limits and SWR at the various frequencies). For a N-type, this one looks pretty good: www.mouser.com/ProductDetail/Amphenol-RF/202109-10?qs=%252Bm72Q7GxMuxG78p4FokgEg%3D%3D
Hope all of this helps. 🙂
I think this model has been discontinued by the manufacturer but is still available to buy off the shelf. I've had one of these for a few years now and yes, it was pricey but it's hard to beat for ease of use, setup and portability. I made up a couple of sets of calibration loads with different connectors. I've found the factory calibration to be pretty close on the lower HF bands but as you point out in the video, the difference between factory and bespoke calibration widens considerably as you approach V/UHF. I also have a VNA but it's a bit more of a faff to setup so still regularly use the Rigexpert.👍
I wouldn't be surprised if it has been discontinued. There are newer, fancier models. I'd also be very surprised if all of their models didn't have this capability.
I don't own one :-( . I bought an MFJ analyzer years ago and in so many ways it is definitely sub-par. But it is convenient and does basic SWR stuff OK. For any kind of accurancy, you cannot beat the VNA.
What is really cool is that I can actually mount my miniVNA tiny at the feedpoint and run a USB cable down to the computer (for relatively short runs). This way I have minimized feedline. :-)
Will this feature work on my RegExpert-AA-55 Zoom? (BTW, great demonstration).
Thank you for the compliment! :-)
Check out your manual, page 32
rigexpert.com/files/product_documentation/aa55zoom/AA-55-ZOOM_Antenna_Analyzer_User_Manual.EN.pdf
🙂
@@eie_for_you Thanks for the reply. I will check it out.
I see why you borrowed it. I just looked up the price! I think I'll be going for the VNA option.
After I did this video, I, too, checked out the price with the same reaction. It is a fantastic unit and worth every penny spent to purchase it, but I have everything I need to do what I am doing and cannot justify the expense. If I had known about it BEFORE I bought the MFJ-259 years ago, I would have happily bought it instead.
anybody tell what to do at the antenna
@@hobojon44 I'm not sure what you are referring to. I went back over the various comments on this video and ???
I know I had someone ask on another video about ladder line and the like. To that question I have gotten back the sound of crickets. In the end, the RF Explorer and the nanoVNA are 50 Ohm systems. If someone wants to see what the impedance of an antenna is that is fed with ladder line, they will have to calibrate the Rig Expert or nanoVNA at the point where they connect it to the feedline, measure the impedance at that point and then, using a Smith Chart back calculate what the impedance might be at the antenna end of the feedline.
I did something like this (with coax) in this video here:
th-cam.com/video/bPmtIVmlJok/w-d-xo.html
Exactly what I needed to determine the accurate impedance of my HF vertical that I just added 60 radials. Tnx es 73 K7OGW
Perfect! Glad it was a help! 🙂