Network Analyzers are frequently used for measuring filters, making them extremely valuable for building radios and general mucking about with RF. They are, however, extremely expensive. You can, however, build one in an Altoids tin with an Arduino Nano, a small screen, and an AD9850 frequency synthesis module picked up on eBay.
The basic idea behind a network analyzer is to feed a frequency into a device, and measure the amplitude coming out of the device, and plot this relationship over a frequency. [Bill Meara] has been a human network analyzer before, changing frequencies and plotting the output of devices under test by hand. [DuWayne] (KV4QB) build a device to automate the entire process.
The block diagram is easy enough – an AD9850 sends a signal to the device, and this is measured by the Arduino with a small amplifier. The signal is measured again when it comes back from the device under test, and all this is plotted on a small display. Simple, and [DuWayne] is getting some very good readings with a lowpass filter and crystal filter made on a small solderless breadboard.
I want one. How much?
Maybe 50 bucks? Shop around and build your own. Looks like the AD9850 can be had for as little as $6 on eBay.
I’d hazard around $25.00 – if you pick up a Arduino Nano on eBay they are only $3.00… Diodes are cents.
No sketch, no schematic…….When?
Holy crap, I need to build one now… Might create a custom PCB for it though! How would you measure the signal strength though? A dedicated IC?
Analog Devices has dedicated ICs that do this sort of thing but if I read the writeup correctly, it sounds like he’s using diode detectors with a logarithmic amplifier.
Just a simple RF detector using diodes. No need for a custom PCB, you can Manhattan this one pretty easily.
It’s depressing me how much some of this stuff is still hard to acquire in my kneck of the woods.
Have you ever stopped to think how many electronic projects would never have existed if Altoids had not been invented?
Really surprised with all the interest in my project. It is still a work in progress. I am making a few changes to the circuit and modifying the circuit board. Also have to add a couple of things to the software. I am planning on writing a magazine article when it is complete. I will make the schematic and software available when finished. Will probably also make the circuit board layout available or offer a source for boards.
I would look forward to seeing that! This is a fantastic project!
What stands in the way of using this at higher frequencies? Is it strictly a matter of a divider/scaler to downconvert into the range of this project, or are there other board level/component considerations? Most of my work is in the upper VHF & the UHF bands and I’d love to know if this can be scaled accordingly.
Any chance of an incomplete schematic or high level illustration? I’d like to see what the frontend looks like, specifically the diodes replacing the resistive bridge. I have a project, currently on the back burner, to measure SWR with a resistive bridge and measure the output with a scope. Later I’d like to add a simple diode mixer so I can measure higher frequencies. It sounds like your circuit has this as a subset, but there’s not enough detail.
Its kind of depressing to see that many of the multi-thousand dollar pieces of equipment out there can be replicated for pennies on the dollar which offer the same reliability and sensitivity. What’s the use in purchasing (for example) a Rigol DSO for $350-$1000 when I could build one with the same features/sensitivity/reliability from a five year old laptop or other parts?
A warranty (which is not real useful if the thing works like its supposed to), technical support (which you often have to pay for, at least in part (and probably shouldn’t NEED if you actually know what you are doing)), additional functions outside of the “main” features (which you can probably add to something you build yourself if you really need it), you can start using it right out of the box (assuming you don’t need to use the aforementioned warranty or tech support (but if you play with this stuff for a hobby, building it in the first place is just more “hobby” anyway)), calibration (sorry, you’re on your own for this one), and probably a few more reasons that aren’t jumping off the top of my balding head.
OK, for the hobbyist, there isn’t a whole lot of reason to buy instead of build, unless you happen to NEED ‘x’ to build an ‘x’. Kind of like building a lathe. But even that is possible. My personal opinion, but all hobby builders (regardless of what they are interested in) should at the bare minimum have looked over or read Dave Gingery’s “Build Your Own Metal Working Shop From Scrap“. The lathe it describes isn’t a great lathe by any serious stretch of the imagination, but it IS a working lathe, and you will probably learn more than you would if you just bought a cheap chinese lathe.
Gingery’s was once asked for a biographical sketch, and what he answered was: “Most of my life was spent in trying to figure out how to do a $50.00 project for 50 cents, and the remainder of my time was spent in trying to scrounge up the 50 cents.” It is often possible to do, but only if you don’t have to factor in the cost of your own time. And when you are talking about a hobby that you do just for fun, or to learn electronics, you can’t beat building your own test gear.
Hey, got any info on the cheapo homebrew DSO scope thing?
I think only novena and redpitaya are even close to anything like that.
Maybe write up a project log or something?
I’d love to build something more modern from junkbox parts to complement my tek 465!
Even pointers on how to do the ADC and ADC –> computer stuff on the cheap would be very useful.
Have information on project with link to source schematic and board layout on my blog kv4qb.blogspot.com
DuWayne