8" Diameter FSL vs. 4' Sided PVC Air-core Loop Runoff

Gary DeBock

Hello All,

With a DXpedition trip scheduled to the Oregon coast in about a week
(with the family) and only enough space to pack a relatively compact
antenna, it was time to choose the best performer for DU-chasing this

The 4' sided portable PVC Loop had performed very well in the August
20-22 DXpedition to Lincoln City last year, receiving over 30 South
Pacific stations when inductively coupled to to a C.Crane SWP Slider
model (as described in the article posted at
http://www.mediafire.com/?9tjd0pqpa4ld2f0 ). But recently there has
been a lot of experimentation with Ferrite Sleeve Loop antennas,
indicating that these compact ferrite-based antennas provide a real
DXing breakthrough for hobbyists with limited setup space. As such, it
was time to see if one of the new FSL's could really compete on MW with
a proven DXpedition performer like the 4' portable PVC Loop.

An 8" diameter FSL was constructed w/ 63 Russian surplus 100mm x 10mm
ferrite rods, purchased on eBay from an Eastern European seller (who,
presumably, is amazed at his recent financial bonanza). The ferrite rod
assembly was secured on soft rubber form filled with padding material,
then wrapped with 18 turns of 660/46 Litz wire from the eBay seller
"Mingmak222." A 381 pf variable capacitor from Crystal Radio Supply
(part # N50P) was used to tune the compact loop, providing frequency
coverage from 450-1700 kHz. The design and construction of this FSL was
chosen based on extensive A/B testing with another 8" diameter FSL
control model, and a photo of the FSL twins is posted at
http://www.mediafire.com/i/?pp9sa4pl56dm4kf (with the DXpedition model
on the right, before MW frequency conversion).

At local noon here in Puyallup, WA four fringe stations were chosen to
test the two compact loop systems, most of which were well over 100
miles distant. 550-KARI and 550-KOAC are fringe stations in the
Vancouver, BC and Portland, Oregon market, while 1040-CKST is a station
in Vancouver, BC. 1070-CFAX is in Victoria, BC, and 1110-KWDB is in
Whitbey Island, northwest of Seattle. In all four MP3's the reception
on the 4' sided PVC air core loop is first (about 15 seconds), then the
reception on the 8" diameter FSL:

550-KARI-KOAC mix http://www.mediafire.com/?akf4xkx3sjwlwp3
1040-CKST http://www.mediafire.com/?jvcps6shc99i0q7
1070-CFAX http://www.mediafire.com/?bn16gdvoa2bdcnn
1110-KWDB http://www.mediafire.com/?ea3zczjet3mw1cj

Although the antenna testing was done with a completely open mind, it
soon became quite clear which antenna provided a low-noise signal
advantage, especially on the weaker stations! The above recordings were
all made on a stock PL-606 model, which was inductively coupled to both
loop antennas at the optimum range. The new 8" FSL can easily be
converted to an "LW Optimized" antenna by switching in about 700 pf of
capacitance in parallel with the N50P variable cap, providing the best
of both DXing worlds in a compact system taking up only one cubic foot
of space. A photo of the relative size of these two antenna systems is
also posted at http://www.mediafire.com/i/?yr7grir83488ii3 , which
hopefully will be of interest to picnic-table DXers like me!

73 and Good DX,
Gary DeBock (in Puyallup, WA, USA)

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