MLA-30 Plus vs. Modified YouLoop VLF-HF Shootout
Вставка
- Опубліковано 23 жов 2024
- I made some initial indoor observations on how my modified YouLoop magnetic loop compares to a MLA-30+ antenna. I am sure I am not the 1st person to try this but I have not seen it done before so I thought I would give it a try and share the results with you.
I enjoy your methodical comparison approach, no nonsense. YouLoop received in the mail an hour ago, feeding HF+ Discovery. YouLoop bought for portable use, not expecting much indoors with my metal roof ;-)
I enjoyed your video. I suspect that the larger size of the modified YouLoop, being larger in relation to the wavelength at the higher frequencies helps explain its poorer performance at those frequencies. As the diameter approaches and becomes greater than about a 10th of the wavelength, it starts to favor the electrical component of the signal rather than the magnetic component. So at that size, it is not a good electrical antenna (too small) nor a good magnetic antenna (too large), at the higher frequencies.
As I found out much later the amplifier in the MLA30 is extremely poor. It is very noisy. Also this is a MLA30 clone so it really was not a fair test at VLF. Something tells me if I had a low noise amplifier in the antenna it would have worked better across all frequencies.
@@w8bya Your video and response has inspired me to do my own comparison of my MLA30+ and passive YouLoop. Both loops are about the same size. Furthermore, there is a gain control potentiometer inside the MLA's box that some people have played with to get better signal-to-noise performance. And differences in bias-t voltage also seems to have an effect on gain and performance. I haven't tried yet.
@@alhearn3209 Awesome that you are running your own experiments ! I knew about the pot when I got the antenna and adjusted it as I listened to several stations. I also made sure I was using a good quality bias-T at the receiver. Do not recommend using the voltage available from the RSPdx or any wallwarts that do not use a linear PS. Let me know what you learned. 73
The passive loops like the youloop is passive and they are made for SDR radios that can do HDR mode. I have a sdrplay RSP-DX and it works great with it but only on the hdr antenna port the bnc one. Get yourself a coaxial line isolator from my antennas or Palomar Engeneers it will take out most all of the noise and boost SNR a lot
An interesting comparison, tempting to try my standard MLA-30 with a larger loop...
For sure. Let us know what the larger loop is and what you discovered. 73
Did you ever try? I know, I know time flies.
@@DonnyHooterHoot no, not yet, lots of other radio projects going on, but thank you for the reminder
How 'bout now? Tried it yet?
@@DG-kq8zf I didn't answer yesterday because the answer is embarrassing. TBH I have moved to a vertical for transmit which is less noisy than my previous TX antenna, I still have the MLA-30 and it is not forgotten!
Nice video comparison. Just wondering if you had left the Youloop with it's original dimensions, if it would perform better at higher HF frequencies like the MA-30.
Hi Doug. Yes it would, absolutely. Before I modified it they were very close in performance to each other on HF but when I saw the need for better VLF performance it was a test I had to perform. With the two of them you can have complete coverage.
@@w8bya I recently tested Youloop and understand that the bands above 17 MHz re not so sensitive as expected . RSP1 is not so sensitive as the Discovery by around 6 db
A fairer test would be to use same size loop on both. I made my MLA-30 loop slightly larger using small aluminum tubing. After watching this I plan to make the loop much larger. How about a test with both loops same size and posting results here?
I can understand exactly what you are saying and why, and that would be an interesting test but I also see great benefit to stack one antenna up against the other even if they are not the same size just to see which one comes out on top and if so by how much and at what frequencies.
It was very helpful just ordered the mla-30
Cool ! Thanks for the feedback. Let us know how you like yours when it comes in. 73
On the SDRplay the Bias-T will severely attenuate anything below 500 kHz. For any kind of active loop you need to use a extremal power inserter to correctly test it :)
Also you can use SDRuno for much more accurate power levels.
TU for your comments. For this test I was using the RSPdx. For fun I did try an external bias-T that came with the MLA-30+ and saw no differences in noise floor or antenna performance below 500 kHz. Still, it would not be hard to hang a 12 VDC "AAA" power pack and "proper" VLF home brew bias-T at the antenna and test it again.
Also thank you for reminding me about s-meter accuracies. I think today I will at least determine if each s-unit is a fixed number of dB difference at different gain settings using SDR Console. Will also check it out with SDRuno. Too bad uno does not have the user friendly interface of console as I like many of it's features :-(
@@w8bya Yeah, It's unfortunate it can't have the UI like SDR-Console does.
Anyhow the comment about the Bias-T is from the SDRplay itself. I came across when setting up a Cross Country Wireless loop antenna and they made it notice. At least here I can say it does make a huge difference at stuff lower then 500 Khz using a Bias-T inserter instead of one the one on the RSPdx.
I own a MLA-30 and the Cross Country and the Cross Country is significantly better on LF and VLF.
@@pclover Neat, tnx for sharing that. I have looked through several documents specifically for the RSPdx and cannot find that note about the frequency limitations of the bias-T. Did you see that specifically for the dx model and if so where? I would like to look into this some more since they claim this model has been improved for frequencies below 500 kHz.
@@w8bya This unfortunately isn't advertised but it's a kind of a hidden thing that some know. I became aware of it buying a Cross Country loop antenna. I can confirm myself that it is true. If you look around groups.io/g/CrossCountryWireless you can see the same thing.
I would suggest asking SDRplay directly about to get an official response.
I wonder perhaps if i should create a demo showing the issue? :)
@@pclover I think a demo would be very helpful. There is nothing like looking and listening closely to a couple different signals/frequencies and note possible differences. Looking forward to your post. Tnx agn.
The standard MLA-30 loop is ok but not really good. You can either increase the diameter or, what I have done, you can connect a big YouLoop to the MLA-30 amplifier. It's a homemade loop out of 2 x 1.5 meters coax. You don't need the transformer/balun, just connect the shielding together and the two center wires to the MLA-30 amp.
I see the German time signal on 77.5 KHz very strong. I think the deepest signal was around 17-18 KHz. MUCH better than the small original loop. And nice to have a single antenna for VLF to HF.
I agree. That is why I first tried increasing the circumference of the YL by X2. I wanted to see how good a pure passive design could be. Do you by chance have any videos showing your loop or loop in action?
@@w8bya No videos, sorry. I also discovered it just recently. Wasn't happy with the original passive YouLoop so I didn't touch it for a long time. Now inspired by another positive YL review I thought there must be something to it. And I saw another video a while ago where someone put the YL on the MLA-30.
Usually I have the MLA-30 with a bigger wire loop next to the house under a roof, because of stupid neighbors.
Now with the homemade YL on it the diameter is much smaller but reception is still awesome if not better.
I might put it away from the house and higher when the weather gets better. F* the neighbors. Some plastic ivy around it and it will look good.😁
@@w8bya ua-cam.com/video/yjqdo_lYc7Q/v-deo.html
I saw him doing it first. And his slightly crappy setup ;) worked pretty well.
@@-Tris- ABSOLUTELY !!!!!
I say go for it.......stupid neighbors, like a small loop on your property is going to hurt them in some way ! IDIOTS.
You know, just now I read some earlier questions a person asked right after I posted this video......his YT name was "D" and he asked about using the MLA-30 with a larger loop and I replied I saw a YT video where someone tried it but did not notice much improvement. So it seems you have found a video or two that have better results than the person I saw several years ago.
I will look around on YT and see if I can find a few of the videos on the larger (modified) MLA-30 and have a look. Of course the best thing would be for me to just modify mine and me try it out !
Oh also......I do not know if you have seen my video about CMC but two things that I have noticed REALLY make a huge difference in allowing me to see weak signals and lower my NF are using CMC's (like in my video) and also removing the loop/antennas away from the house as far as possible. GL 73
@@-Tris- I wish there was a way I could translate German to English on YT 😞
Anyway, I could see what he did and what I find interesting (and confusing) is that he is using the high-Z input on his SDR. Since he is using the amplifier from the MLA-30 that should provide a low output impedance, more suitable for the standard input port. Makes me wonder why he used the High-Z port?
if you were using the Airspy discovery you could surely be OK in LF and VLF bands
of course this design cn offer quite better noise cancellation and higher gain . I m sure that in discovery the 'needle could peak '
I have 2 MLA 30+ antennas. The Biasing Tee powers up fine on a USB plug in power adapter but when I try and power it through a portable power bank the power cuts off after a few minutes. This happens with both antenna Biasing Tees and with several different portable power banks different power cords. I would like to use the antenna for portable use but cannot power it. Is this normal or do I have two defective antennas.
What is weird is that you are using the same LNA (which also has 1/2 of the bias-T network) and those seem to work when USB powered so it looks like your portable battery pack setup is suspect. Can you describe your battery packs in detail and most importantly have you measured the DC voltages inside the LNA compartment box using both power sources? I suspect you will quickly find your answer as you monitor the DC voltage to the actual LNA between the two setups.
A lot of power bank stop working if the charge don't draw enough current. The power switching off because it thing there is nothing using it. You have to find a basic power bank or a simple set off battery.
Common mode chokes are only used to stop RF going back down the coax.
No need for receive antennas.
Sorry but that is simply wrong. CMC are extremely important in helping RFI induced onto the feedline in and around the home (where dozens & dozens of RF noise makers exist) from getting onto the feedline and using it as a radiator which your receive antenna will then pick up. In the vast majority of cases if you want an effective, low-noise receive antenna then you will want to install a CMC at the receiver, midway to the antenna, and at the antenna feedpoint.
A good common mode choke / coaxial line isolator will cut the noise level in half to 2/3 and improve SNR a ton an air choke only removes a small part of the noise . Palomar Engeneers or my antennas make the best about 80 usd.
Chuck AA4CP Florida
Could you just use longer coax to modify the you loop ? Just double the length of each one?would that work?thanks
Hi Patrick. yes I think so. As noted in the video that is exactly what I did to the original Youloop. Once I got it I saw they were using "common" RG-402 semi-rigid coax with SMA connectors that you can get off E-Bay. I purchased 4 of the identical coax jumpers along with some SMA barrel connectors and doubled the circumference. The difference in VLF performance was immediately noticed. I suspect if you doubled it again the performance below 100 kHz would be even better. Note this is speculation on my part as I have not doubled the already doubled loop.
What happens if you use a larger loop with the preamplifier?
I saw one video where someone tried that and if memory serves me right he noted no improvement. I wanted to try that but I am not sure it will be with this amplifier, it seems quite noisy. Plenty of gain but very noisy so I may substitute my own.
Larger loop lower main frequency
CMC on receive only ?
CMC should be used for most transmit and receive antennas. For example on transmit on 630m (474 kHz) my 600' long Inv-V antenna uses a CMC, so does the 40m rotatable dipole and 75m inv-v antenna used in these tests. CMC help XMT & RCV. On RCV it helps lower noise on XMT it helps the antenna have the correct radiation pattern.
what is CMC?
@@zach0gr Common Mode Choke