pixel loop on the roof

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I installed my pixel loop on my house roof yesterday and I am very impressed with its ability to pull signals out of the noise on 17 and 20 meters now compared to my mono band resident wire antennas. It was previously useless on these 2 bands at 10 feet off the ground.

http://s707.photobucket.com/user/llavaseur/media/DSC_0177_zpszdiay45b.jpg.html

http://s707.photobucket.com/user/llavaseur/media/DSC_0178_zpscviaijyn.jpg.html

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Larry - W8LLL

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Posted 3 years ago

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Rob N4GA

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That looks cool. What's the large vertical, a Penetrator 10/12m?
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Larry - W8LLL

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The large vertical is a Zero Five 10 meter.

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k3Tim

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How does it get out?  Well one would assume...
Thanks for the report on the loop also...
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Larry - W8LLL

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The zero five does a good job on 10 meters its a 5/8 wave.
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k3Tim

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Thanks!

Tim
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Andrew Russell

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I can only agree. I have a Pixel loop on a rotator on a chimney and use it on all bands with better S/N than my wire antennae.

Andrew de VK5CV

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KY6LA - Howard, Elmer

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Larry
It's ironic that you should do this the same day as I did..

Here is my Pixel Loop sitting on a PVC tripod in the backyard

Hear somethings, about 20% uniques but nowhere near as effective as my SteppIR MonstIR



Here is the Ocean View from my 50' vertical backyard hill with the MonstIR below us nested at 27', a 160-10M Dipole and several VHF/UHF Antennas on the roof..



I had recently cut down the top 2/3 of a 60' pine tree on my hill leaving a perfect 20' antenna mast tree trunk




So we used some Radio Shack (RIP) Chimney Mount to mount the very light (only 3 lb)
 and tiny Pixel Loop on the tree trunk that used to support 1,000's of Lb of tree branches..







Here is the final look



Turns out that by bypassing the internal (BC-30MHz) LNA, the Loop is actually a good TV antenna..

I did some experimentation using the Loop today and I was surprised to see all sorts of Local TV Channels ( usually the Subchannels e.g 8-1, 8-2, etc) which I never get on cable TV,  That turned out to be a very desirable Free bonus  - hard to say no to Free...

Magnetic loops are supposed to be mounted within 10' of the ground..

How does it play at 20' .. significantly better than when it was mounted on the ground
Why.. its pretty obvious that the 50' hill behind my house really blocks the magnetic loop..
Height fixed it - YMMV.

Bottom Line:  Even if it does not get anywhere as much use as a diversity antenna as my MonstIR main beam,  it will definitely be used all the time as a TV Antenna...  In fact, i have had TV antennas before which were swamped by RFI from the 18 local TV towers 2,900' away which forced me to use cable TV if I ever wanted to see TV... this antenna seems to be immune to that RFI.
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Larry - W8LLL

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On 17 meters mid day today I pulled out japan with the loop and had a qso with him when my wire could not even hear him. The noise is still very low.

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EA4GLI - 8P9EH - Salvador

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I am really interested in getting one of these antennas. I have a 400ft loop for 160m, 80 and 40m but I still get a lot of noise from power transformers on wood poles on the street. Not much I can do about it... I also have a couple AM stations fairly close.

Searching about loops I found this http://www.wellbrook.uk.com/Loop_Antennas

They are cheaper to buy and to ship to Barbados. Anyone, by any chance has had any experience with the Wellbrooks?
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KY6LA - Howard, Elmer

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I read some reviews in RADCOM which seem to indicate that the Wellbrook performed better than the Pixel Loop..
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EA4GLI - 8P9EH - Salvador

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Thanks for the complete report and the pictures Howard, forgot to mention anything on the previous message, I appreciate when people take the time to take pictures and do a complete report.

I imagine radcom might be a bit inclined to look favorably at the National product. Still, at a considerable discount, if it performs the same, it might be the best buy for me.
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Larry - W8LLL

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I can't comment on the wellbrook but the pixel loop makes 160 very usable for me. I also added the array solutions model as-402 broadcast band filter that really cleaned up the band for me.  http://www.arraysolutions.com/Products/AS402.htm
(Edited)
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EA4GLI - 8P9EH - Salvador

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I imagine you use that filter in line with the loop and not your tx antenna.... Right?
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Larry - W8LLL

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The broadcast band filter is for receive only, you will ruin it if you transmit through it. It is inline with the loop on the RX receive only port.
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KY6LA - Howard, Elmer

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There is not a filter but rather there is a 27db low noise amplifier located at the pixel antenna. I found that I had to bypass that amp and put in 50MHz to 1 GHz LNa to get a TV Signal. So my design uses 2 different Amos now

Adds about 1/2 lb so it's not an issue


The first is a paper from Pixel claiming theirs is better

http://www.cliftonlaboratories.com/Do...


This is a paper favoring wellbrook


http://www.wellbrook.uk.com/reviews/A...


Each was written by the respective companies. Both purport scientific evidence that their competitor is crap.


Bottom Line: likely not much difference between them

No filters on my main antenna. It's a SteppIR MonstIR so it is always tuned to the correct frequency.
(Edited)
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Andrew Russell

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I decided that I wouldn't notice any difference. It came down to delivery time/cost and the fact that I had some US$ and avoided another currency change.

Small problem with the AC plug pack being for 110V rather than 240V with no response from the vendor (not Pixel/Inlogis).

Very happy with the mounting and how it went together and like the Clifton Labs amp with PTT switching.

Andrew de VK5CV

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EA4GLI - 8P9EH - Salvador

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What do you guys think of building the actual loop here and just buying the Amp? Is there anything fancy in the loop itself that will make building it difficult? The shipping of a 1m loop is quite high on air freight to Barbados regardless if it comes from the US or the UK. If I can just get the amp and build my own loop that might be the way to go.

However, I read the the loop is "low impedance" not sure if that infers there is something special about it.
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Bill W2PKY

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W8JI.com has a lot of good info about loops.
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Ross - K9COX

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There is absolutely nothing special about the loop, I've had mine apart (long story). The magic is in the preamp.
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KY6LA - Howard, Elmer

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I believe that the strip is a Mobius strip design not a simple loop

BUT there are all sorts of designs for Do It Yourself magnetic loop in QST
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Andrew Russell

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The principals of the loop are on the website. There are home brew amps suitable. The main difficulty is loop impedance matching with impedance rising with frequency.

http://pa0fri.home.xs4all.nl/Ant/Active%20antenna/Active%20receiving%20%20loop%20antenna%20eng.htm


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N7AIG

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Also - beware that the Pixel loop amplifier comes with a relay installed to drop DC power when you transmit. You tie it to your key-out line on the rig. The Wellbrook, as I understood when I first looked, does not have that RF bypass protection. So you have to take care to have some good distance between the Welbrook and your TX antenna, or else roll your own relaying.

My own installation uses the Pixel loop about 10 m from the 40m doublet that I use for Tx. I have nothing but praise for the Pixel loop, but I have never used the Wellbrook.

73 de Dave, N7AIG

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KY6LA - Howard, Elmer

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So far I have not blown up my Pixel Loop and I run full 1,500W Expert 2K-FA into a 9dBi gain MonstIR.. ERP at least 10KW . The separation is 60' between antennas... so the TX DC bypass has not been used or needed..
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N7AIG

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I should point out that yours is an interesting and possibly isolated case... Others with the Wellbrook antenna have found otherwise. It also has a lot to do with how much signal your receiver front-end can handle. The Pixel amplifier may be pretty robust, but 27 dB amplification of your Tx signal delivered to your receiver might become a problem. This would be especially true if you are using a separate receiver from the transmitter.
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N7AIG

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Whew! I read through the expose on magnetic loops at the website 
http://w8ji.com/magnetic_receiving_loops.htm
and I have to say, you engineers are brilliant, but totally lousy communicators. That was about as clear as mud to me. I'll have to go back and study it again, and try to fill in the details with my own orientation toward E&M theory as a physicist. 

[ I totally understand the disdain for humanities in college by engineering students, I was there myself. But honestly, a little bit of communication theory (spoken & written) wouldn't hurt your better chances in the future career path... ]

73 de Dave, N7AIG
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EA4GLI - 8P9EH - Salvador

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This reminds me of the quote from book/movie "Contact" when the scientist says that they should have sent a poet to describe the beauty of what she was seeing.
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EA4GLI - 8P9EH - Salvador

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I am reading a lot of good information in this website. They also sell a sub $100 amp that might be a good purchase.
http://active-antenna.eu/amplifier-kit/technical-documentation/