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

Gary DeBock

Hello Michael,

Thanks for your interest in Ferrite Sleeve Loop antennas, and for your
comments on my post.

<<<Would it be possible to do a three-fold
comparison, including LW, between
the 4' loop, the FSL and a single-ferrite
such as the 7½" loopstick, all inductively
Cost unfortunately renders the FSL unfeasible,
and the big loop is unwieldy, so it would be
valuable/comforting to know to what degree
the basic single-ferrite would be inferior. >>>

Yes, it certainly would be possible to do such a comparison, although
because of limited experimental time here it's probably a little too
ambitious to consider for the near future. In general a 7.5" loopstick
(MW or LW) provides a quantum leap in DXing sensitivity over a stock
Tecsun loopstick, and a serious-sized FSL (8" or larger) or air core
tuned passive loop (4' side or larger) provides another quantum leap in
sensitivity over the 7.5" loopstick. Regarding the relative reception
capabilities of a 7.5" MW loopstick and a stock Tecsun-built model,
detailed TP-DXing records were kept during a November 2008 DXpedition
to Grayland, Washington, showing the huge sensitivity advantage
provided by a transplanted 7.5" loopstick in an Eton E100 model. This
"E100 Four Variant Shootout" article may be of interest to those who
have wondered about this sensitivity advantage
http://www.mediafire.com/?mjmn0xijxod . For those looking for an
additional signal boost, I've personally had very good results with
smaller air-core loops (2' and 3' sided) and FSL's (4" diameter),
either of which can provide some additional MW or LW sensitivity beyond
that of a 7.5" loopstick.

<<<There was mention of a basic FSL with fewer
ferrites spaced round the tube, but I have
not seen any further reference to this.
Not worth pursuing further?>>>

Both Steve and Kevin (among others) have done extensive FSL
experimentation before me, and I had a pretty late start because of a
need to finish up 7.5" Longwave loopstick testing. I did some limited
testing of a basic FSL with spacing between the ferrites, but was not
satisfied with the results. Others who have done such testing may have
other impressions, and I welcome their comments. In general (because of
limited time), my objective was to determine whether the FSL design
would provide a compact DXing breakthrough over existing antennas, and
devote the necessary resources to test out the most effective designs
as soon as possible. Presumably, the eBay sellers of surplus Russian
ferrite are extremely grateful for this kind of attitude, and for the
additional contributions of Steve and Kevin :-)

<<<What would happen if ferrites of different
origins, lengths and quality from old
radios were used in a compromise FSL?>>>

It's tough to give an accurate answer about this because nobody has yet
tried it, to my knowledge. The results would probably depend on the
size, quality and consistency in the ferrite rods, but it's doubtful
that any such composite FSL would be competitive with the larger,
standardized designs, in my opinion.

<<<As an off-shoot, I would like to have a
compact performing LW/MW receiver
with a genuinely portable antenna.
It would have to be either a single ferrite
or a small loop.>>>

This was the concept behind the recent development of the 7.5" MW and
LW loopsticks for the Tecsun DSP models, Michael. These loopsticks have
sensitive performance compared to the stock Tecsun antennas, and there
have been many positive comments about their DXing results.
Unfortunately there isn't much time here to make more of them in
quantity, but the MW version article is posted at
http://www.mediafire.com/?yummxhqeyjy , and the LW version article is
posted at http://www.mediafire.com/?845snah2h4ek9z9 . A PL-380 model
may be modified to accept either 7.5" loopstick (MW or LW) in a plug-in
design, or a stock PL-360 model will accept either loopstick without
the need for modification.

<<<I am also interested in phasing out local
interference from CFLs and digital sources
by using a second aerial and a canceling
circuit. Is there any information on this aspect
in the group?>>>

None that I am aware of, Michael. I know that this has been done
extensively in the amateur radio community with noise-canceling
antennas and phasing units, but not in relation to CFL's with
Ultralight radios.

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


Gary, was the 8" Diameter FSL Inductively or directly coupled to the PL 606? I ask this since in one of the pictures it looks like one of those big loops - the second one  is directly connected to the small Radio - the PL 380. Or did I miss something.

Gary DeBock

Hi Jerry,

All the antenna signal testing was done using inductive coupling,
during which a stock Tecsun PL-606 model was held about 6" in front of
the air-core loop coil, then about 6" in front of the FSL coil. The
optimum inductive coupling distance of 6" (for both loops) was
determined prior to the signal testing, and no direct wiring
connections were used to connect the radio to either of the antennas.

The relative-size photos (such as the one posted at
http://www.mediafire.com/i/?yr7grir83488ii3 ) do not reflect the
testing setup at all, since during the actual testing the air-core loop
and FSL were separated by about 70 feet outdoors (in my back yard) to
avoid any possible interaction. Large tuned passive loops (both
air-core and FSL) have the capability to project a signal boost over
astonishing distances (up to 25' in the case of the 9' sided air core
loop here), making it necessary to separate such antennas very far
apart for accurate testing results.

73, Gary

-----Original Message-----
From: Jerry Popiel <jerry_popiel@...>
To: ultralightdx <ultralightdx@...>
Sent: Fri, Jul 8, 2011 1:58 am
Subject: [ultralightdx] Re: 8" Diameter FSL vs. 4' Sided PVC Air-core
Loop Runoff

Gary, was the 8" Diameter FSL Inductively or directly coupled to the PL
606? I ask this since in one of the pictures it looks like one of those
big loops - the second one  is directly connected to the small Radio -
the PL 380. Or did I miss something.