Loop On The Ground - Part 4 Adding A Preamp

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A revisit to my Loop on the Ground Antenna, but this time with more gain....30dB in fact!
In this video I attempt to improve the LoG Antenna by adding a pre-amp at the antenna. See how I get on with this addition and how the revised antenna performs compared to the original loop.
Update: Some good comments for this video explaining the results. Worth a read 👍🏻
Parts 1, 2 & 3 of this series can be found at:
• Loop on the Ground Ant...
• Loop on the Ground Ant...
• Loop on the Ground Ant...
This is one of many amateur/ham radio related videos on my channel. Please feel free to browse 👀, like 👍🏻 and subscribe 🔔, remembering to hit the bell so you’re notified of new videos.
Other ham/amateur radio RU-vid channels you may like:
DX Commander: / m0mcx
Radio Prepper: / @radioprepper
Mike-M0MSN: / hollyend1
Tim G5TM: / @timg5tm941
2E0EZT amateur radio: / @m0szt
Tech Minds: / @techmindsofficial
The Gaz Lab: / @thegazlab
Chris M0RSF: / m0rsf
Matt Dixon: / @mattdixon5299
ZL1BQD - Roly: / @zl1bqdroly
Thanks.
Ian.

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Опубликовано:

3 сен 2020

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Комментарии : 64

@bobadkins7377 2 года назад

Well I’m glad to have found your video series at this time, because I’m just days away from testing the 15’ per side version. I just received my toroids today. Very interesting. Good job on these videos too. 73.

@ianxfs 2 года назад

Thanks Bob! Yes, I went back for the original version with no preamp. It’s great of you have a two VFO rig as the loop can be in one ear. Also good for long listens say on 80m nets etc. It’s a bit like “use the force”….ignore the meter and use it purely on sound quality. Have fun 👍🏻

@TintioT 3 года назад

Excellent, now I want to test this!

@ianxfs 3 года назад

TintioT Have fun!

@markg6jvy135 3 года назад

Motivational video Ian thanks, I’m thinking about trying a loop to see if it’ll cut down on the noise as most bands are s9, hence mainly /P - but this an interesting option 🤞👍👏👏

@ianxfs 3 года назад

Yes. Easy to try Mark 👍🏻

@Steve-GM0HUU 2 года назад

Very interesting and useful, thanks for posting. Quite amazing that an antenna buried in the ground offers very similar performance to the more conventional verticals. Also, perhaps the ultimate stealth RX antenna? As others have already suggested, I did wonder if the wideband pre-amp is just too wide and getting overloaded with out of band signals which might be generating all sorts of unwanted products. Maybe simple high and low pass filters on the pre-amp input would help? Going by your results, even a small improvement could make the loop perform better than your verticals?

@ianxfs 2 года назад

Thanks Steve. Yes, the preamp was just too much. I’ve got used to using the loop now in the second VFO, so happy with it in current form 😀

@bobmurton5869 3 года назад

An idea to kick along the road is making the Baluns with LITZ wire. LITZ wire is used in old BC transistor radio ferrite antennas windings as well from VGA monitors fly back yokes (a very fine multi insulated wire that has a high Q content and my have a high Silver/Nickle content) . The wire is sort after by the crystal set builders who build very high efficiency crystal sets ,so to me it would make sense to use the best wire available for making RX Baluns for LoG's. Any comment is welcome VK4ZOW.

@ianxfs 3 года назад

Thanks for the info Bob 👍🏻

@luckydubeinrc5165 2 года назад

Ian the first video i was really nodding my head to nonononono... with the loop, the 3rd video impressed me ... so the pre amp induce white noise. my setup is 4 directions 63 m wire 9:1 fed 470 ohm terminated and it really works well, 160 m to 40 m is where my interest is. by phasing you can increase the loop(s) gain, (i know lot of work)...but it works just fine zs2cx

@ianxfs 2 года назад

Sounds great!

@paulschmolke188 3 года назад

This will be great experiment this summer. I’m wondering if a resonant length would improve S/N and still keep background noise down.

@ianxfs 3 года назад

I’m not sure Paul. I think the resonance will be lost once it’s on/in the ground?

@ZL1BQDRoly 3 года назад

Ian, do you have any noise figures vs frequency for this preamp? The preamps i have been using are extremely low noise. Switching in the preamp only brings up the noise floor fractionally due ti the inherent preamp noise but the signal is amplified by +15 -20dB. Cheers.

@ianxfs 3 года назад

Not on this specific one, but another that looks exactly the same has a noise figure of 1.9dB.

@DonDegidio 3 года назад

Hi Ian, I've been watching videos about this KK5JY LOG. He used a 15 ft square loop that had lobes off the corners adjacent to the feed. I'm wondering if a circular loop would be omni-directional. What do you think? I also have space on my front lawn where I could site the loop away from my transmitting antennas. Now back to watching your videos on the LOG. Stay safe. 73 WJ3U

@ianxfs 3 года назад

Hi Don. Yes experiment away as it’s at least an easy antenna to mess about with as it’s at your feet! I think the radiating lobes are more a product of the feedpoint as opposed to the shape. 73

@kevin2e0kbxsouthampton6 3 года назад

Great Video, i was wondering what the small pre amp your using?

@ianxfs 3 года назад

This was the one Kevin: www.ebay.co.uk/itm/233606210963

@antennafarmer7380 3 года назад

I have one of these preamplifiers. They begin rolling off below around 5MHz. I did some reading about it and unfortunately there aren't any cheap off the shelf preamps available. The best option is homebrew.

@ianxfs 3 года назад

Ok, thanks for the info 😀

@oldsal8648 2 года назад

Thanks for the helpful video series! 73 de N9NY

@ianxfs 2 года назад

Thanks for watching! 😀

@brianfields4479 3 года назад

Good info, thanks. wonder if you tried the amp at the rig end instead of at the ant outside, and if so, what difference did you notice, as others have said either location for the amp, made no real difference, but it still worked quite well. I have just purchased this amp, and its easier to alter the voltage if inside near the rig, thats all I was thinking about. cheers : brian.

@ianxfs 3 года назад

Hi Brian! No I only tried at the loop end. Yes you can vary gain with voltage as I re-used this amp temporarily for something else and I had a variable DC supply feeding it. Good luck if you’re experimenting 👍🏻

@Scotscan 3 года назад

Hiya. Those broadcast stations you heard with the preamp in place should not be there - these will be images of broadcast stations further up or down the band. The preamp in place is overloading the Yaesu's front end so would be dubious about using it. Looking at documentation on the ground loop shows that some folk ground the wire at intervals to reduce noise further or alternatively mount underground.

@ianxfs 3 года назад

Thanks and yes you’re right. The broadcast stations are overload from somewhere else. My loop is now about 1cm under the lawn now at a guess. I think I’m going to leave as is 🤔

@TheGmr140 3 года назад

very nice, if only want 80meters, a 80m bpf before the preamp will go along way, this way the preamp will only be amplifying the 80m band as opposed to the whole hf spectrum. great stuff. 73s

@ianxfs 3 года назад

Thanks!

@sq7dqx Год назад

With small size of the LOG it should be interesting and quite easy to phase two loops for particular direction or try to make 4sq LOG. Gain of single loop is close to -30dB like other small receive loops. Essential is that wire close to ground is much much longer electricaly than its physical lenght (factor of two). May be bigger loop will has higher gain and better S/N ratio? Wire on ground is somehow isolated from human made local noise but can capture NVIS signals or lower angles signals as well. It is hard to model LOG in MMANA but it may be interesting to phase two loops in different distances with different delay lines. Any idea how to model LOG in MMANA? Any receiving antenna has a purpose not to make desired signal stronger but make a unwanted signal weak as possible. Matt SQ7D

@ianxfs Год назад

Hi Matt. I don’t think MMANA is able to calculate a LoG? I might give it a try to see what it shows…

@dxscotland5901 3 года назад

It’d be good if you could adjust the preamp gain to suit your surroundings Ian and check results again,thanks for the videos 👍

@ianxfs 3 года назад

Yes I agree 😀 Need a remote on/off and voltage regulator somehow. Bit of a faff in my setup...

@dxscotland5901 3 года назад

ianxfs definitely not a fad Ian,all projects start somewhere and it’s been interesting watching your projects,I wonder if an attenuator might be easier after preamp will be easier?Anyway thanks for great content 73

@ianxfs 3 года назад

I tinkered a bit with attenuation, but I made little difference in the end. I’m happy with the original LoG 👍🏻

@ZL1BQDRoly 3 года назад

Ian, i am interested in the differences between the two antennas for something considered DX from you. e.g. USA stations or JA.

@ianxfs 3 года назад

They’re a bit extreme DX for me Roly on 80/160. I’ve only worked USA once SSB on 160 and never on 80. The LoG can make a rag-chew more pleasant to listen to, as can twiddling knobs on the rig. It’s a rare case where an unworkable station becomes workable by bringing the LoG into play. Many become clearer and more readable, but finding one so low down that it just pushes them over the readability line is few and far between. I have the LoG on my second VFO and use it all the time in my right speaker/headphone when on 160 & 80. It improves the stereo effect and overall experience...

@ZL1BQDRoly 3 года назад

@@ianxfs I think you might be very pleasantly surprised Ian if you choose your times real carefully. Have a listen on 80mtrs at +/- 30mins either side of your sunset and sunrise.. i.e. your grey lines, particularly around the bottom end of the CW portion about 3 - 5Khz in. If you get some joy there, then try 3.795 SSB where it is common for DX to hang out..Cheers

@ianxfs 3 года назад

Will do Roly, thanks!

@snoboi79 3 года назад

Thanks for these videos Ian, you made a comment "you wouldn't use a preamp on 40 and below". Could you explain further? Pardon the ignorance. Cheers - de W1SFS

@ianxfs 3 года назад

Hi Jason and thanks! If I was referring to the rig, then if your noise floor is registering on the S-meter then you don’t normally engage a preamp. So in Yaesu speak, 40m and below is generally set to IPO1 i.e. no pre-amps engaged. 40 and below are usually that noisy to start with, a preamp doesn’t help, hence the loop experiment to reduce the noise floor but retain a station signal. If I was referring to the loop itself in the video, in my case this preamp at the loop didn’t help, so I’m back to how I set it up originally in video #1 and used it successfully like this ever since. I would not be without it 😀

@snoboi79 3 года назад

@@ianxfs Ok, I just recently upgraded to an FTDX3000 and learning about all the adjustments I have at my disposal. I spend a fair amount of time on 40 meters so I'm planning on building a LOG receive antenna as the 3000 has a receive-only antenna jack. Thanks again for the video. - Jason

@ianxfs 3 года назад

Nice rig 👍🏻 Have fun Jason 😀

@Ei2iP 3 года назад

Why don't you pull back your RF gain, you seem to be overloading your agc? start with the rf gain with an S1 noise and then check the antennas, I run 20db ATT on 80 and it's a pleasure to listen to 80M without the noise...you seem to be focused on S meter than the actual receive noise and the readability of the stations..

@ianxfs 3 года назад

Thanks Robbie. Yes I was using my ears and going for readability. I tried some attenuation too (via the switch), but didn’t think of the RF gain knob. Will have another test 👍🏻

@eddthirty4065 3 года назад

Hi Ian, Thanks for the videos. All very interesting. I have a AM BC transmitter a few miles away, as you'd imagine, it play havoc to my less sophisticated receivers. I've used an AM BC band stop, takes it down by a good 20dB. You could use something like that on your large loop on the ground before the preamp. The one I use is www.nooelec.com/store/sdr/sdr-addons/rf-blocks/flamingo-am.html

@ianxfs 3 года назад

Thanks Edd! Yes, living near to BC transmitters can’t be fun at all...

@MauriatOttolink 2 года назад

Hmmm Not wildly impressed. Is it worth the effort? Thanks for your video.

@ianxfs 2 года назад

Hi, no not with the preamp. I’ve gone back to having it as originally set up and I use it on the second VFO, especially on 80m. Really like it ….

@TheArtofEngineering Год назад

My experiences are similar....some it is better on, some the same....some worse? Perhaps it is the null that sometimes helps reduce noise....and sometimes also doesn't help by nulling signal if coming from the "wrong" direction. here is my attempt at the LOG ....no preamp. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-8Fx262iV5SE.html

@ianxfs Год назад

Yes, useful to have in the armoury when you need it. Will take a look, thanks.

@SuburbanDXing 3 года назад

Hi Ian. Thanks for posting this. I have been following your progress with interest, as a few of us in MN are also using LoG antennas (mostly for 160m and 80m DX work). It seems we are having better success with the S/N ratio; our LoGs in most cases, offer a nicely improved signal than our TX antennas. Have you tried a transformer with more windings/turns? K0SR tried many different transformers until he came up with the formula that we use (shown here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-wMb8i5QajW0.html ...at the 6 minute mark). We use a 12:3 ratio (or 24:6, depending on how you count the turns). Maybe something to try? Thank you again for your interesting videos, and 73! de WX0V

@ianxfs 3 года назад

WX0V Thanks for the feedback! I haven’t changed the windings. I’ll take a look and follow that up 👍🏻

@SuburbanDXing 3 года назад

@@ianxfs It's something to try. The KK5JY LoG has worked really well for us using the K0SR designed transformer. Anyway, really enjoy your videos, Ian...great work! 73! de WX0V

@urbanbushcraft3018 3 года назад

@@SuburbanDXing I notice that the wire used for the windings are multicore - does it make a difference if you use a solid core wire?

@SuburbanDXing 3 года назад

@@urbanbushcraft3018 I don't think it would matter, but I will add the disclaimer that this is all experimental. 😁 I used Temco 28ga Red Round copper magnet wire (MW0064) for my LoG. K0SR used similar wire. Hope this helps...73! de WX0V

@bobmurton5869 3 года назад

May I suggest a tunable gasfet pre amp adjustable gain 10-40 DB gain NF 0.25 DB then you would see the results you wanted .Chuck out those cheap Chinese amps they are just noisy junk. Also if you can borrow or get the ARRL vhf -uhf manual loads of ultra low noise circuits and a wealth of info. Low system noise is the key .cheers 73's VK4ZOW

@ianxfs 3 года назад

Thanks Bob! I went back to the original setup and have been using it like that since. Yes, a better and adjustable preamp would be another test.

@bobmurton5869 3 года назад

@@ianxfs Hi my old mate .Yes I have been playing around with ground loops for a few months now after seeing DxCommander videos on ground loops . May I suggest an HF preselector as a start but (not the chinese ) only japanese or U.S. ones as these are usually of good quality and robust units. My latest project is a headend gas-fets(from sat TV downconverters) build low noise preamps with vary- cap diodes to do remote tuning at the feed point. I have had thoughts to make the ground loops renasant fitting a tuning capacitor at the feed point to start the project. Also I Have made and Ebook that I Will send you a draft copy in( word) for you to give me a critique on if you would. My email address is as follows. generalnerds@gmail.com.Please send me yours and we can correspond a nd send you the draft copy of " The secrets in the Elimination of RF noise". Cheers Mate!

@w8rko470 3 года назад

I agree with the comments above. Most of the cheap preamps are made from MMIC devices. They provide a lot of gain over a wide frequency range but the noise figure is rather poor. Preamps can be easily overloaded especially with local AM broadcast transmitters. I live within 4 km of three 5000 watt AM stations (980, 1290, and 1410 KHz). I had to add a broadcast band notch filter to the front end of the preamp to eliminate the overload. In my case the preamp is on a low noise vertical (15 foot rod connected to the preamp. I have an attenuator on the output of the preamp because the receiver is easily overloaded. The receiver is a KiwiSDR 0 - 30 MHz web connected SDR. nippynet.com:8073/

@ianxfs 3 года назад

@@w8rko470 Thanks for the info Mike! That’s a lot of local AM broadcast you have to deal with.

@ronlanway6667 2 года назад

I had hopes for this as a new channel to follow but it’s too painful watching him struggle to figure out where he’s going wrong lol!!! Good luck to you but I would advise going back to the part 1 video and find out where you goofed. Antenna design isn’t magic it’s elementary. Sorry I really tried too like this channel!

@ianxfs 2 года назад

Hi Ron! Yes I went back to part 1 and used it like that ever since. Great RX on 80m and sometimes used on 160m & 40m. Good to experiment and learn as you go 😀