Ultralight DXing with a Ten Foot Box Loop


Gary DeBock
 

Hello Guys,
 
Our ultralight radios are certainly capable of amazing receptions in stock form, and I never cease to admire those determined DXers like Rob Ross, John Cereghin and Greg Schoom, who persevere to log many huindreds of stations with barefoot ULR's.
 
Unfortunately, I really don't have the patience of those distinguished gentlemen. The "solution" for DXing success (at least for me) is to give ULR's the biggest possible boost in weak-signal capability, both internally and externally.
 
Last year's experimentation on the E100 and SWP models was fascinating, and I was privileged to work with great experimenters like Steve Ratzlaff, Guy Atkins and John Bryant. The resulting Slider E100's and Slider SWP's are extremely fun to play with (and ridiculously effective for overseas DXing), but even with "barefoot" Slider receptions of Fiji-639, Vietnam-675 and Tonga-1017, a little more DXing gain would have been a big thrill.
 
Unfortunately, the Slider models (and the Sony ICF-S5W, Panasonic RF-2200 and other highly sensitive models) are not impressed at all with the gain provided by the smaller box loop designs. Trying to get a significant signal boost from them is usually not possible. Consequently, for weak-signal DXing this year, I thought a series of monster PVC-framed passive loops would be an interesting project. Actually, it became more than interesting-- it is one of the most fascinating hobby projects imaginable.
 
The use of lightweight, rugged, waterproof PVC pipe makes the building of huge box loops a very simple task. The larger sizes are actually the easiest to make, with the ten foot (diagonal) size being the quickest to construct. Getting totally carried away, I made two 18" loops, two 24" loops, and  3', 4', 5', 6" and 7.5' (side) models. Photos of several of these have been uploaded to the ultralightdx photo area. Fortunately, I have a very understanding neighbor.
 
The DXing performance of these PVC loops has been all I could have hoped for. Even the 24" (side) size provides a serious gain boost for the Sliders. It cleared up two UnID mysteries that had been hanging around for weeks (Auburn Parks Department TIS on 1700, and Voice of Vashon TIS on 1650). The larger sizes provide overwhelming gain on any frequency to which they are tuned (and even on frequencies 50 kHz away from the frequencies to which they are tuned). For example, setting the 10' box loop on 1700 kHz will make the Tecsun R9012 perform phenomenally on the entire X band-- as long as it is within 2 feet of the monster loop. Tuning the Tecsun R9012 to 1700 kHz will cause it to overload on the Auburn Parks Department TIS-- a signal which is completely inaudible on the stock unit (and barely noticeable on the Sliders). In fact, the 10' box loop will make even the Sliders overload on the Auburn 1700 TIS-- the antenna is truly an equal-opportunity overloader.
 
Of course, 10' box loops are impractical for most of us, so a lot of the experimental effort had been focused on maximizing the performance of the 18" and 24" (side) sizes, and creating 3' and 4' "field assembly" models, so townhouse and apartment dwellers can assemble one of these PVC loops at their favorite picnic, or beach area. The 5' and larger models are great for patios, and for those with generous back yards (and understanding neighbors). Full details will be upcoming in an article, including all construction details.
 
73, Gary DeBock
 
 
                


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John Cereghin <jcereghin@...>
 

To be honest, I'm just either too lazy to make a bigger box loop (I have a 2X2 foot loop) or just too incompetent to construct a slider.  That's a big reason why I do a lot of my DXing barefoot.  :)

John Cereghin

On Thu, Apr 30, 2009 at 6:50 PM, <D1028Gary@...> wrote:


Hello Guys,
 
Our ultralight radios are certainly capable of amazing receptions in stock form, and I never cease to admire those determined DXers like Rob Ross, John Cereghin and Greg Schoom, who persevere to log many huindreds of stations with barefoot ULR's.
 

 
 
                


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kevin redding <amfmdx@...>
 


Gary,

I am interested in making the 10 foot loop. I have a rotor and can get all the stuff. How about letting me know how to make it. I am going to permanently mount it on a concrete footing and run the wires in the house. All I need to figure out is how to adjust the variable cap from inside the house....

Kevin

On Apr 30, 2009, at 5:50 PM, D1028Gary@... wrote:

The use of lightweight, rugged, waterproof PVC pipe makes the building of huge box loops a very simple task. The larger sizes are actually the easiest to make, with the ten foot (diagonal) size being the quickest to construct. Getting totally carried away, I made two 18" loops, two 24" loops, and  3', 4', 5', 6" and 7.5' (side) models. Photos of several of these have been uploaded to the ultralightdx photo area. Fortunately, I have a very understanding neighbor.


Gary DeBock
 

Hi Kevin,
 
Thanks for your interest in the ten foot PVC loop project. I've often thought about permanently mounting one of these beasts outside myself, with the variable capacitor within strategic reach of my window when the loop is optimized to receive TP's. Unfortunately, the best performance and nulling ability seem to occur when the monster is in the middle of my back yard, away from the house wiring, etc.
 
Anyway, if you have some PVC assembly and/or woodworking experience, you should be good to go with some simple instructions. I'll plan to write some summarized details for you, and the others who want basic plans like PVC pipe sizes, fittings, coil turn counts, etc., prior to the "full construction" article (which will give even a beginner the skill to work with PVC). The ten foot size is especially easy, since you only need to get four pre-cut 5' PVC pipes of 1.25" diameter from your Lowe's hardware store, glue them to a 1.25" "cross" PVC fitting, and your frame is already well along. Be forewarned that these cheap, effective loops are seriously habit-forming, though :>)
 
73, Gary    
 
In a message dated 4/30/2009 5:02:54 P.M. Pacific Daylight Time, amfmdx@... writes:



Gary,

I am interested in making the 10 foot loop. I have a rotor and can get all the stuff. How about letting me know how to make it. I am going to permanently mount it on a concrete footing and run the wires in the house. All I need to figure out is how to adjust the variable cap from inside the house....

Kevin

On Apr 30, 2009, at 5:50 PM, D1028Gary@aol.com wrote:

The use of lightweight, rugged, waterproof PVC pipe makes the building of huge box loops a very simple task. The larger sizes are actually the easiest to make, with the ten foot (diagonal) size being the quickest to construct. Getting totally carried away, I made two 18" loops, two 24" loops, and  3', 4', 5', 6" and 7.5' (side) models. Photos of several of these have been uploaded to the ultralightdx photo area. Fortunately, I have a very understanding neighbor.



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