Loop Location

[KC1UA]

First off, many thanks to those of you with Wellbrook and Pixel RF Pro-1A and 1B models for all of the information that you've provided regarding loop antennas. I "think" I am ready to take the plunge and get one.

I currently use an RF Space SDR-14 for SWL'ing (its primary use has been as a panadapter for my AOR AR5000A+3) in conjunction with SDR-Radio software. For an antenna I am using a Par EF-SWL that runs from about the 35' height of my tower, which is bolted to the right side of my house, directly over the roof of my 1 story ranch to a mast that is side mounted on the other end of the house. The property is a 1/4 acre lot that is surrounded on all sides by similar 1/4 acre lots. I expect that in most of these houses (and my own) numerous appliances that generate man-made noise are running constantly, especially during "prime time" which is when I do the bulk of my listening. I understand the concept of the EF-SWL but I have not been able to find a configuration that eliminates noise at MW and lower frequency HF. As a matter of fact I can't receive much of anything in the AM broadcast band. I understand the EF-SWL is not ideal due to its length.

So, after doing some reading here I've begun to think about a loop. I am leaning towards the Pixel RF Pro-1B simply because it's American made and if God forbid it arrives "DOA" I'd at least be able to easily exchange it. From what I gather from recent comments it seems that this loop may be equal to the latest Wellbrook ALA-1530S+.

My question is this. Given the small footprint of my lot combined with the close location of my neighbors, do you think I gain anything by mounting the antenna away from my house. No matter where I go with it it's going to wind up being closer to one of my neighbors. Ideally I'd like to mount it on the roof of my house. I currently have a 3' tripod available, and I have a Channel Master rotor waiting to go. I'm curious as to thoughts from the experienced users.

Another consideration is to try a different configuration of the EF-SWL, which would be the cheapest option obviously, but this thread is to primarily ask about loop location and the "experts" thoughts on it.

Thanks in advance!

 

[ka3jjz]

Scott I am far from an expert, but let me throw a few things out here from 20+ years in the business.

Getting the antenna - any antenna, whether it's the PAR or the loop - away from the house is a big step in the right direction. But my first concern would be to get rid of, or at least reduce, the source of the garbage that's hitting you on MW and lower HF. Your best bet here is to be a detective with a small el-cheapo portable AM (alright, MW) radio. As the old saying goes, kill everything in the house and reactivate, one appliance and one room at a time. If that doesn't identify it, it's time to go outside and see if you can at least get a rough direction from the noise. Noisy transformers on power poles and so much more can cause noise, whole books have been written on the subject. Once you have it more narrowed down, then the next step is remediation - and that deserves a separate discussion once you've found the source (if you can).

The detective business may also show you where the noise is least objectionable. That's where I would consider putting the antenna -regardless of what you use.

Now the next step is the ground. I know that a single 8 foot ground rod isn't going to cut it in New England (lived there for a couple of years), even though that's all the PAR instructions recommends. We've had extensive discussions about what makes a good RF ground, and you can look up the ARRL books, along with your own electrical codes.

HTH...Mike

 

[KC1UA]

Thanks Mike. I'm already pretty aware of the interference being generated inside the house. It's largely the home theatre system, which of course the wife is using during evenings. When it's not in use we kill the power to the entirety of it, which consists of the usual components, LCD TV, Blu Ray, cable box, home theatre receiver, etc. When the power to this is killed the difference is notable. Outside interference includes some above ground power lines (as you've lived in NE, you know what a jungle those can be and this is no exception). The mystery that remains is what some of the neighbors are using. I am friendly with all of them but have only been in about 50% of their houses. Similar issues generate out of those houses no doubt. My neighbor directly behind me is probably the least technology driven of them all and as a result I'd lean in her direction as a good point. The AM portable idea is a good one and easily accomplished. I'll give that a run through this weekend and proceed from there.

Thanks.

 

[ka3jjz]

If it's got a FM section make sure the antenna is fully collapsed and put into whatever locked position is available - you don't want accidental coupling in this exercise.

That situation sounds almost as bad as mine - GL...Mike

 

[KC1UA]

If it's got a FM section make sure the antenna is fully collapsed and put into whatever locked position is available - you don't want accidental coupling in this exercise.

A very interesting and simple test, and one I've overlooked completely. My problem simply is that the EF-SWL is running right over the top of my house. When I approach the house with the AM radio, the increase in static is incredible. It is at its highest where the electricity enters the house. If I walk the 25 feet or so out to my property line to the rear of the house the static is just about nonexistent. Left rear to center rear seems to be the best location.

The ideal solution will be a loop, ground mounted with a rotor. I may try to move the EF-SWL to the rear of the property as a sloper between two trees with the feed end at ground level directly connected to a ground rod as mentioned elsewhere. I am on a hill and the soil is not sandy, so I do have a reasonable shot at one 8 footer having some type of impact. As I already own this antenna I think it's at least prudent to try this approach before I drop nearly $500 for the "ideal" solution...

SWL'ing, particularly utility monitoring, is how I got my start in this hobby back in the mid 1980's. I've gotten so far away from it and into VHF/UHF/800 DX'ing, which is superb from here given my location close to the water. I guess I want to get back to my roots in some semi-serious aspect for the first time in quite some time....this is it. I know full well that the "glory days" of utility listening are past, but it still will be fun to be able to listen as well as I can with what I have.

Continued input is welcomed. Thanks!

 

[zl2taw]

Hey Scott, I too was in the same situation as you are. I started HF listening in the mid 80's and when I came back to HF I was astonished at the amount of RF noise about. After lots of research & question after question, I bit the bullet & got a loop from Wellbrook.
The QRM here was so bad I had built a portable station & headed out "bush" any chance I could.

Now I can play radio from my shack with the only problem being when our plasma tv is on, & then its still bearable here.

There are many here who use loops for that reason and sure someone else will give you their thoughts

have a nice day

Doug

 

[comsec1]

amazing loop performance

I fall into the same catagory as "scan" and "zl" , getting ito HF utility in the late 80's with 11.176 and 6761 being the popular freqs to monitor. HF was fairly unpolluted and fun to explore and when you did encounter noise it was probably some junk within your own house and easy to remedy. Now in the US with the FCC becoming a revenue generating agency rather than a regulatory/enforcment agency the noise on HF has become intolerable. The FCC is more concerned with tower registration numbers being clearly visible or someone advertising non HD TV's.
I just discovered, through this web site, the wellbrook and pixel magnetic loops and they have helped return HF utility monitoring and ham radio back to a hobby of monitoring and DXing rather than a engineering course in site noise mitigation.
I have both antennas, the wellbrook being purchased first about 2 years ago and just last week the pixel. both antennas appear to my ears as being similar in performance, one being hooked to my TT Jupiter and one to my TT omni7. The big thing is the elimination of much of the unwanted "buzzes, growl's, beeps and hash" that my 6-BTV and B&W end fed V pick up. I prefer the pixel in comparison to my ala1530 due to the transmit relay that my wellbrook does not have but I think they have added that feature since I purchased mine.
As far as the location I have mine mounted at 4' above the ground on a 2x4 stand with a TV rotator squeezed in between some pine trees and out of sight. I did experiment before picking this location and as others have stated try to get it as far from your house or your worst source of interference. In my case I have found that the rotator is not needed.
Many times I have to tune to WWV just to make sure it is working as the noise floor gets that quiet.
I don't know why these antennas are not advertised more as they do cure alot of reception problems.
Good luck with your set up.

 

[ka3jjz]

I think you have the right idea here, Scott. Get that PAR off the house, where it's in the middle of the noise field into a quieter spot, and make that ground connection as short as you can. If your house is any appreciable height, your current ground connection for that antenna is very likely acting as an unintended antenna for even more noise pickup. Remember that you can fool around with that transformer connection as well - from everything I've read on this subject, it does take some experimentation to get it right.

I would also be yelling at the electric company to fix that connection to your house. Leaky insulators and poor joints are well known to be radiators for all sorts of noise. Make yourself an annoying pest (the squeaky wheel gets the grease, as the old saying goes)! And if memory serves, you're a ham, so you can use that to your advantage as well.

Mike

 

[KC1UA]

Thanks for the comments. I am still very interested in the loop antennas and may well continue along with getting one. Over the past two days I've moved the EF-SWL from above the roof to an area in the left rear of my backyard.

The EF-SWL is installed as a sloper. The top end is about 25' tops off of the ground. The feed end is at ground level. The two grounding posts are shorted together and fed to 1 8' ground rod by about a 4" piece of solid copper groundwire. I'm running RG-6 coax to the side of the house, where it passes through a grounding block connected to another 8' ground rod.

I'm seeing a marked improvement in noise levels. As I type this I'm listening to 5598 and 5616 MWARA frequencies. The noise floor with the SDR-14's RF gain set to 0 db and the IF gain set to +12 db is about -115 dBm. In the 11 and 12 MHz range the noise floor falls to about -130 dBm. There is a definite improvement in the signal to noise ratio. Signals are not strong given the low profile of the antenna, but they are stronger in that there is far less noise, which is obviously the idea of these antennas and of course the loops as well.

Interestingly, although maybe it's due to the short length of the EF-SWL, I am still not hearing anything on MW. There, the noise floor rises to about -95 dBm as well.

I picked this position for the antenna after three trips through the backyard with the AM portable. I think I'm on the right track for location, and were I to get a loop I think it would be mounted in this area via some type of "Scott Special" setup, with a rotor.

Mike, I've picked on the electric company before for other reasons and they've actually been very responsive, so I'll give them another shot at some point in the near future. And Comsec, thanks for your input as well. I think these companies spread the word about these antennas more by word of mouth and end user reviews; they are pricey but obviously they're a real solution for many problems.

Thanks to all for the input, and I'd still love to hear from those using loops with your install stories.

 

[SCPD]

Scott,

Some quick points. Apologies if these were already mentioned -- I didn't have time to read the entire thread.

1. Get the loop out in the open -- away from any house or metal structure (shed.)
1b. Ideally, get it in an open area -- height is not a concern. I have mine at 17ft -- just to get it away/above any RFI.
2. Thankfully, I did not have to use their support but I've heard mixed reviews about Pixel's support. Someone here at RR had a bad preamp unit and they wanted $200 for a new one -- even though his loop was still under warranty. That was a head-scratcher.
3. I've had to contact Andy at Wellbrook for support and he was absolutely a joy to deal with. He is responsive via email and was willing to ship me out a part on their dime. I wouldn't worry about support. (Turned out I didn't need it.) Being that you're just across the pond, shipping would probably be 3-4 days at most. (Mine was 8 days to Seattle from the UK!)
4. Wellbrook preamp uses 12v dc which is very easy to supply.
5. Pro-1B uses 20v dc.
6. Preamp unit is mounted indoors (Wellbrook) vs outdoors (Pro-1B)
7. BNC connectors vs "F" connectors

Just some points I thought I'd mention. In the end, they're about the same performance. Neither will "beat" out the other if you have major RFI in the area however.


Cheers!

 

[Turbo68]

Hi Scott got 4 wellbrook active loops ALA330S is not mounted yet main intrest is monitoring aero,ndb,utilities signal to noise ratio on all is excellent took a while to get the right height distance and phasing direction all i can say im impressed do have other active antennas at dads shack from dx engineering,dressler,rf systems,winradio there just as good..

Regards Lino..

 

[mondomusique]

I'm in an urban area with closely spaced houses, I have a Wellbrook ALA-100M attic mounted and it works well for me. Like Comsec1, I think you'll find you won't need the rotor, which will simplify your installation plan.