High-Q LW loop for the PL-380
Though fascinated by the ferrite stick transplants of Gary I have still scruples to alter the outer appearance of my URLs and prefer the passive loop approach.
On Henry's homepage http://homepage.ntlworld.com/henry01 I fell on an small and simple loop antenna that is more than a gadget.
Following his plan and calculations I constructed such a loop of
12" x 9" for LW. For a better Q I built it with foamboard 5mm instead of corrugated cardboard and invested a roll of 60x005 litz wire for 55 turns instead of copper wire.Now having sacrificed so much litz an
air variable tuning cap was mandatory.The result is a relatively small and easy transportable LW antenna. If you are interested I can put a self declaring photo in the photo section.
The performance boost of this "gadget" was far beyond my expectations.
The tuning of the loop is extremly sensitive (small bandwith), so that the reduction drive of the cap is helpful. Average s/n gain is 15-20 db on the PL 380.Here are some day measurements:
Barefoot with loop
162 kHz France Inter 15 01 barely audible 29 25
177 Deutschlandrad. 15 02 not aud. 20 18
207 Deutschlandfunk 15 13 38 25
234 RTL 15 00 barely aud. 28 25
270 Czechsk.Prag 15 00 not aud. 15 18
This PL-380 loop combination is now equal in performance to my
best LW receiver: no, it is not the Sony ICF-2010 it is the sowiet
Peter K. in Schaffhausen/Switzerland
Thanks very much for sharing the details of Henry's compact LW loop with us, and also the performance report on your new loop's LW sensitivity. The experiment sounds very interesting, and Henry's loop does seem to provide a serious boost in LW performance.
The 2000 uh coil LW 7.5" plug-in loopsticks (for the PL-360, PL-380 etc.) were primarily designed to provide performance competitive with a stock ICF-2010 on LW, and they do seem to exceed this sensitivity level on the LW international broadcast band (153-279 kHz), and equal it on the lower NDB frequencies (up to about 300 kHz).
Inductive coupling to large LW air core loops can certainly provide even greater ULR performance on the LW band, and one of the designs tested here was a 6.5' sided LW tuned passive PVC Loop with 22 turns of #18 wire (564'), which tunes from 148- 374 kHz. It was described in the PVC Loop article posted at http://www.mediafire.com/?igw1zjwfzmw , and probably would run wild on the LW band (if I had the time to DX with it :-)
73, Gary DeBock (in Puyallup, WA, USA)
In a message dated 8/9/2010 5:27:00 A.M. Pacific Daylight Time, peter.keller@... writes:
Hello Garytoggle quoted message Show quoted text
Thank you for your comment that is much appreciated.
I agree, that a 6' or even bigger loop would boost LW reception
wildly and I hope, that you'll find time to prove it.
My idea was to get maximum sensitivity with a small antenna.What is
very useful here in Europe with stations only 6 kHz apart (177,183)
is the small bandwith of the loop.
I put a photo of the loop into the photo section. In the background
you see my reference receiver Selena 212, that is definitely better on LW than my Sony ICF-2010.
73, Peter K. in Schaffhausen/Switzerland
--- In ultralightdx@..., D1028Gary@... wrote:
Thank you for posting the photo of your loop. I enjoyed seeing the Selena 212 receiver in the background, but it will never qualify as an ultralight radio. I own several of the Soviet era receivers and ultralight they aren't. My favorite is an Ocean 214 which weigh 4.6 kilograms (10.14 pounds) with six D cells. The export version was the Selena B215. Sadly, I've never been able to get the 214 to work properly. But it's a fantastic conversation piece. And, it might not blow away in a tornado.
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