Random Wire Antenna FT140-43 Toroids Tested 

Check out my Chokes, Baluns and Ununs Playlist: ru-vid.com/group/PLm8ROkpFeqoqkGQtBYfcT9Y-2GCKxBuuk

TheSmokinApe doing all the hard thinking for the rest of us. Thanks Ape.

A serious effort at getting decent data to help understanding. Very well presented and detailed enough for the average Joe like me to get understanding. One of the best, if not the best, U-Tube presentation of this subject. Thank you. !!!!!

Loved watching this thorough and methodical analysis of each number of windings. it's also quite cool to witness someone having all the right test gear.

I think my head exploded. Excellent work and very methodical testing.

Appreciate the lesson Professor!

Very good explanation of a trifiler . Thanks.

Thank you Mr Ape

Awesome work. Thank you. We can go even further in this quest. I’ve measured my 42ft random wire antenna impedance without any transformer from 7mhz to 28mhz. The impedance varies a lot and it’s very high on the lower bands (1270+324j on 7mhz) and starts going down as you increase frequency (790-1380j at 10mhz, 127-310j at 14mhz, 330-144j at 18mhz, 209-577j at 21mhz and 122-230j at 28mhz). So the 450ohm is a very simplistic assumption and the fact that a unun is not constant across the whole spectrum is not necessarily a bad thing depending on the impedance your antenna exhibits. Looking forward to see more videos of this kind! 73 de F4JAW

Very good job, thank you.

Hi Ape, really enjoyed the video. It's great to see things outside of the box. I have not tested my 9 to 1's for loss, but have found that a 9-1 made with a FT-240-43 has better SWR in the low band, 20-160m and one made with a T-200 powder core has better SWR in the higher bands, 6-20. Twenty meters appears to be the point that both are somewhat close in SWR. I've finally broke down and bought a VNA, so I will be doing more testing in the future. My unun's are all 9 wraps. Have not tried anything different in that regard. I always enjoy you technical videos. Keep up the good work.

Man this is good stuff

Thanks for the demonstration. Lower number of turns would be good for higher frequencies because of increase in inter-winding capacitance and higher number of turns would be good for lower frequencies. Ni-Zn ferrites like #43 (ui850), #52(ui250),#61(ui125) and the "K" material can be tested for the specific frequency band/s. Higher permeability cores can be used for lower end of the HF spectrum and lower permeability cores can be used for the higher end of the HF spectrum. But then, the magnitude of power handling becomes an important factor too. Higher permeability cores would get saturated quickly when operated on the lower end of the HF bands; so, you have to select bigger, bulkier cores. For the higher end of the HF spectrum you can use lower permeability cores and with lower number of turns; you get the required inductance and at the same time the inter-winding capacitance is also taken care of. De VU2RZA

Many thanks for making these measurements. The measurements made here are one way to start, but we might reach quite different conclusions regarding the relative merits of the three items if the items were tested more fully. Vector network analyzers are wonderful tools, but we must be careful in interpreting results. This first test with two ununs connected “back-to-back” reveals just how an unun will perform (at least for small signals) when it is connected to another unun. This point is obvious, but we must not assume that this tells us how the unun will perform when connected to a different load. The use of the S21 measurement tells us the ratio of the output wave to the incident wave, but by itself it tells us nothing directly about the power loss or efficiency of the device or devices under test. For instance, suppose we test a lossless device that presents a bad mismatch at its input. We will see a low magnitude of S21 but that is due to a high magnitude of S11. A high S11 tells us that incident power is being reflected back at the input rather than being lost as heat inside the device. We have to distinguish between the power incident on the device and the power that that actually goes into the device. The formula to calculate the efficiency of the device, expressed as a ratio of the net power that actually goes into the device at the input port to the power that comes out the output port, is S21 magnitude squared / (1 - S11 magnitude squared), where the magnitudes are expressed as ratios rather than dB. The other test looking at only S11, when the device is connected to a resistive load, shows us that there is transformer action going on assuming the loss in the device is low, but it doesn’t tell us anything about the relative merits of these three devices when used in an actual system that will in general exhibit some other impedance. To determine by measurement of s-parameters how the unun (or any device for that matter) will perform with other loads, we need to measure all its s-parameters as complex numbers and apply a set of formulas that include the actual complex load impedance that will be connected to the device. It looks like the measurement loop may have an inductance of roughly 250 nanohenries due to the wire lengths and loop area. At 30 MHz, that would be an inductive reactance of about 47 ohms, or about 10% of the intended 450-ohm impedance level. Thus, the wire length is probably having some noticeable effect on the measurements at 30 MHz. At the low frequencies, there would be proportionally less effect. We also need to keep in mind that the answers we get when testing with small signals may not be representative of what will happen when we apply substantial rf power from a transmitter. For instance, the magnetic core may exhibit enough nonlinear behavior to throw things off, and the device may be heated enough that the wire resistance changes and the core loss factor changes. Given the tests that were done, plus assumptions that there will not be too much power dissipation or nonlinear behavior when used in our system, we can say that all three are candidates for use. We can’t say which would be absolute best in our system, but since all the results are similar, it seems likely that we wouldn’t notice any difference in on-the-air contacts and we would be okay with any of these as long as the impedance presented to our transmitter is within acceptable boundaries.

This is a cool video for sure…I made one of these using a ft37-43 core, just much smaller. A 470 ohm on the input showed the nearly 1-1 SWR, but not over the full hf band on mine. Interesting way to do it using two of these back to back for the insertion loss and match z on the second port on the nanovna.

Spot on Ape. Trying to improve those losses is pointless as to what you would gain. I honestly thought the loss would be more. I have those 2 little cores here set up to do that test. I think there will be a difference with materials and geometries but not a massive amount. 61 material may be a good shout for 40-10 as Evil Lair has demonstrated.

Nicely done Ape! I look forward to the "different mixes" comparisons as well Sir! 73 - KF6IF

Great to see the differences in performance - but there's another test you could do. Its not a test the NanoVNA can do, however. Using an actual transmitter, vary the power level in and compare to the power level out. At some point, the core will saturate and you start losing power as heat. You should probably do this with T140 AND T240 cores, to help users decide when a bigger core is a good idea.

Thanks Ape. Which one is on the CaHR antennas? BTW, when are you gonna break out the LibreVNA?

Maybe throw a 49:1 in there maybe?? that is some very interesting data. Great video! If I still had the gear to test this myself I"d try it in a second. It would be very interesting to know if I'm using the wrong unun!

I was using this method to test a 1:49 toroid wind and was scrambling to find just a few resistors to out in series for a load…when it hit me that I had an inexpensive resistor decade box. Dialed the 2,450 ohms in and tested. I think I paid < $20 on Amazon.

That's great. Did you use a standard or non-inducting resistor? If it was standard, wonder when it's important to use a non-inducting style?

I only could fit 8 turns on my core. It works so far. I’ll have to test it out in rig expert. Wonder if odd turns vs even turns matters?

nice Ape explains why everyone says 9:1 :) btw to get 450 ohm, try a 270 and 180 in series, or if you have an 820 and a 1k, use them in parallel (but thats closer to 451ohms)

Would 11 or 12 wraps make it moar better?

Why do you use 2 ununs for insertion loss test? Couldn't you use one? Love the video gotta get me a nano vna....

Chameleon now makes several UnUns, 9:1, 6:1, 4:1, 1:1, selling for 115 bucks. Wondering if you will be testing the 9:1?

Love me some toe-roids! :) Also, more uses for my NanoVNA... I like it.

140 size toroids are good for about 25 watts. I use 240-43 for 100 watts and mostly 2 stacked together.

More cat videos!

And that's a wrap! Thanks for showing us how it's done, Ape.

Now I know a 7:1 is better on higher bands, who knew? Lol Thats alot of work for one video, especially a blind Ape.😂 Go get some spectacles Son.🍻🤓👍