ATU vs 49:1 Transformer For Portable Antenna ? How Many Bands ?
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- เผยแพร่เมื่อ 3 ส.ค. 2022
- I was curious if for portable work I should use the 49:1 impedance transformer, or an ATU ? Here you have a quick comparison using the same 20m of wire antenna, as a half wave 40m band antenna.
73, YO6DXE
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Thanks for the comparison testing. I would have assumed the antenna matched would have performed better but I think I’ll stick with my 64:1 and 49:1 transformers instead.
If you look on my latest video about the EFHW antenna... I keep experimenting trying to get the best out of the antenna with no use of the ATU. They are great in some situation or if you want to work a band that the antenna is not really designed for... but the losses that come sometime with the use of an ATU.. I don't know. I try to avoid it as much as I can and use the antenna built the best I can. 😁😁 But this is just the way I think hehe. Is still good to have an ATU on hand at times.. but I still prefer an antenna with a simple impedance transformer. 73, YO6DXE.
Getting all the bands in one antenna will be a compromise. However I don’t see why it won’t be impossible.
And there is always more wire. Or even multiple wires.
I haven’t seen a multi wire endfed antenna yet. I can’t see why that won’t work either.
But! That’s the beauty of our hobby. To experiment.
Keep up the good work my friend. 👌🏻
Thank you JD. I want to build it like that just because its the best for me with the space I have. Initially I wanted to go vertical instead similar to DX Commander antenna... but I don't have the space for the counterpoise wires. So I go horizontally instead hehehe. We will see what I can achieve. No rush though.. I only have 5 bands available on the (tr)uSDX ))). Meanwhile I'm doing a little work on the VHF / UHF side as the sattelites seem very appealing to me as well )) 73 my friend.
The transformer you are using, made with FT140-43 and two turns in the primary, there is not enough inductance for 3.5 Mhz. You have to do it 3 : 21 turns. You must also use a correction coil for all amateur bands to be usable.
Thank you James. Ohhh I wish you posted this comment two weeks ago hahaha. I got it figured out at the end. As I made a 40 meters wire long antenna... 1/2 halwave on 80m and I had a high SWR on 80m still. It also didn't resonate well on the other bands. I had the compensation coil figured out at the end... but still dealing with the high SWR on 80m. I discovered the transformer is the issue at the end. I didn't had the yine to rebuild it yet. Thank you one more time. 73
P.S. I mean just by using the impedance transformer and no antenna tunner at all. I was trying to get the best of the antenna withought the need of the ATU.
Hi Chip, thank you for another nice video. Antenna setup is always fun. I have a 20m wire for portable operation and tried it with a manual tuner. I think it needed about 8uH and about 70pF to tune on 40m but SWR was nice and low. Maybe your tuner doesn't have quite enough inductance? Anyway 49:1 unun works great. I've also tried the 49:1 with a tuner and that works on some of the "in between" bands. Just an idea, you could maybe build a smaller simpler tuner to work with the 49:1 or build a 49:1 (or other ratio) into a tuner. Lots of fun! I don't worry that I might need to use a tuner when portable because the coax is really short so no loss to worry about. And also, a half wave on 40 is a quarter wave on 80, etc! With a quarter wave you'll need some radials but maybe not even any matching network needed. Take care, see ya, 73, VK7IAN
Thank you Ian. Ohh yes that may be the possible issue. I think all I have on the ATU is 7.5uH because I couldn't fit more turns on the toroid. I will rebuild it and try to squeeze a few more turns on it when I will also get the switch with more positions so I have more inductance options. I also tried the 49:1 transformer together with the tuner with the same results hehehe. I wanted to build something complicated... that would maybe work way better combining the two. But then the "complicated" part didn't sound so appealing to me hahaha. So instead I opted for the other way... and play with the wire instead. Let's see what I will be able to get out of that ))) 73 Ian and have a wonderful weekend.
Glad to see that you also get 15m and 10m with your EFHW!
Ohh yes me too. You were right. Well... 10m is a little too narrow... but it works ))) But I have some idea in my head that I want to implement at some point. All HF bands EFHW )) 73 Stew.
@@dxexplorer yeah shame about 10m but it is usable for the SSB voice portion of the band (and 10m is a large band to operate on anyway) EFHW will always be a 'jack-of-all-trades' antenna but still very effective on 40m and 20m (which is all you need for day/night CW). 73 DE 2E0HIA
@@stewpot3971 Indeed is not like a perfect antenna. But well adjusted it does a good job. The advantage for me is that it fits the space I have perfectly. But I have a feeling I will test many other more from now on and at some point I will figure out what antenna performs better hehehe. 73
@@dxexplorer th-cam.com/video/PKJ77POxQdE/w-d-xo.html
This is a great video on the EFHW, might give you some inspiration!
@@stewpot3971 Thanks so much. I will watch it just now 😁 Inspiration its always good ))
I found in my tests mast height is critical to prevent ground reflections affecting Z of antenna&final vswr.Also for QRP RF resonant antenna worked far better than traps,coils,atu etc
Simple linked dipole to extend wires worked best with a 1:1 balun with taps for (tx side)50r:to:25r,50r,75r tap (antenna side) selections,less RF loss and lighter to carry.A spider pole fibre push up pole mast in ground stake.
Love the VNA very handy device 👍
Rob P
The VNA is really nice indeed Rob. I love it too and it saved me from a lot of headaches and wasted time trying in blind. About the antennas... I agree with you. The only reason I keep trying and testing here all sort of antennas is more from curiosity to see how each works and how well. I know I will get bored at some point and just have a few built to last hahaha. Thanks so much for watching. 73 DE YO6DXE.
Made some myself, but are not very pleased by its transmit performance. Now I'm staring a multi tap unun for a number of transforming ratios. I found that only a 49:1 cannot cover all harmonic bands with an acceptable Q. What I do not find on TH-cam, is a real near field signal measurement of a EFHW. In other words, what about efficiency? Thanks for the video.
True... I also wonder about those measurements. Clearly dor RX is great... but we keep experimenting I guess and we will sure find out all the answers 😁😁 73 DE YO6DXE
Does it make sense to you to use a lower ratio of impedance match, say 9:1 or 5:1, and then also use the tuner to get all the bands?
I haven't tested or tried that. Technically it could work... As far as I know the 49:1 for example is for the tuned antennas... and 9:1 for random length wires. So I guess it depends on the length of the antenna as well. Ideally if you would have a switch that will allow you to have as many inctuctsnce values as possible and also a larger variable capacitor... you could end up having a tunner that would tune even a fence and turn it into an antenna ))) It would probably not work great, but is tunned.
Hi there! Where i can buy this nanoVNA? I have seen a lot of them online with different prices. 73
Nikos some friends told me they purchased them from Alliexpress. I don't like / trust that store so much as I have bad memories frim a few years back when someone tried to scam me for 1000€. I usually look on online stores local here in Romania. The one I have is a present my sister and brother in law got for me from a store here in Romania. 73 Nikos.
@@dxexplorer thank you! I want to buy one but i will postpone it. Summer is coming and we have to work on the antennas hehe. 73
Antennas are the magic word for me too this summer ))).
Strange results Chip, is the antenna cut for 40m on its lowest frequency? The rest of your results are perfectly normal. If you get 1:15 on most frequency you are good to go. Don't worry about 2 or
So to 1.
I use regularly 2:1 on hf on some frequency. Don't get hung up on it. Enjoy
Very strange indeed. Yes the wire i was using was tuner for the 49:1 impedance transformer for the 40m band. Works great with that one. Is strange that with the ATU was not the same. Maybe it has to do with the hight of the antenna as it was only about 3-4m high. I have a feeling that having more taps on the inductor would allow me to get closer to a better SWR on all bands. I will experiment some more in time with a longer wire maybe. Usually I don't worry much about 1.2 SWR... but with QRP.. knowing that I still have loses both using the ATU or the impedance transformer ... every little detail matters hahaha. I'm sure I can do better than that with a little more effort. But at least now I know I'm on the right path. With ought the nanoVNA I was pretty much blind ))).
On the NanoVNA, you can program the Markers to automatically center themselves on the SWR dips. You instruct #1 Marker to find the lowest min, and the others to search left or right. I was doing this on my recently purchased NanoVNA-H4 when putting up an 80m dipole. I found it very convenient. Your NanoVNA May Vary.
Thank you. Yes yes mine does that too. I know I did it a few times so far, but when I'm filming I always rush and I just can't remember how to do that so I just do all stuff by hand hahaha. 73 and have an amazing weekend.
another home brew antenna th-cam.com/video/xnH7ItynPGw/w-d-xo.html
Now that is one heck of a homebrew 😁😁 I won't get to that pretty soon... hehehe. Thanks... 73
How do you make such beautiful equipment? Everything I build looks ugly and thrown together
Justin... it depends. Usually with a lot of work as all I do is nearly 100% handmade with no power tools... so it takes me a lot of time and patience testing hahaha. But this is just because I want to build stuff that will last a long time from now for me to use. If I just make a few tests and I'm not sure about what I'm doing... don't worry that doesn't look to great for me either hehehe. 73
@@dxexplorer what kind of tools do you use? I couldn’t imagine drilling the metal face plate with a hand drill.
@@justinelliott3529 Actually not even a hand drill lol. Sometimes I just use a drill bit with the hand and some pliers hahaha. The dremell tool i have only takes small drill bits. Usually I pick materials so they are easy to work with and easy to file or drill. I think that helps a lot. Aluminum is easy to work with most of the time... wood and plastic too. Other than that.. just a lot of sandpaper work )))
@@dxexplorer I’m very surprised, everything looks like you bought it already made. I watch your videos, but I don’t know if you’ve built your own transceiver, have you?
@@dxexplorer I’m very surprised, everything looks like you bought it already made. I watch your videos, but I don’t know if you’ve built your own transceiver, have you?
My SOTA HWEF works 40m to 10. 1 Alligator clip link at 9.7mhz giving 1.7T1 vswr in 30m allocation BUT a correct vswr in 17m join up clip to make normal bands work good. It even give reasonable vswr on 24mhz. I have done experiment wspr testing no tuner to ft817 also ft8 qso with 4 watts on every band 40mto 10m no external tuner. I have qualified to 44 qso several vkff parks on ssb cw data modes. QRP this efhw ft 817 scu17 interface. vk5cz..
That is some great stuff. I did thought as well about a similar design for portable trying to squeeze more bands out of the wire. Alligator clips seem like a great idea. I'm happy to hear that it works well... that is pushing me to build a version like that as well. Thanks for sharing this. 73 DE YO6DXE.