Date   

Inexpensive source of ferrite for FSL not recommended for an LF FSL

Steve Ratzlaff <steveratz@...>
 

I received the shipment of ferrite today and made an LF FSL with them and tested it. It is quite a bit inferior to other FSLs I've built--I really can't recommend it, unfortunately. It might work OK for a MW FSL but I haven't built any MW FSLs yet and don't have anything to compare one to.
If you're still interested, a major US distributor, www.digikey.com, carries this ferrite that looked promising, classed as small ferrite used for EMI reduction on ribbon cable. The specific Digi Key part number is P11388--just enter that in the search engine on their home page and it will take you to the item. Each piece is around 35 cents in quantity of 50 or more up to 100 pieces where it's 30.5 cents each. The ferrite is about 1.3" long x 0.39" wide x about 0.25" thick. To use it as a ferrite "bar", you would butt the 0.39" sections together around the form, and wind the coil on the 1.3" section.
I used a standard 4" sytrene coupler as a form, which is obtainable in the plumbing section of stores like Home Depot. It has an outer diameter of 4.5". 37 bars fit around it almost perfectly, with just a small space left over. Two wraps of 1/8" foam were used to give a 1/4" spacing of the coil from the ferrite. Previous tests have shown that 1/4" to 3/8" spacing of coil from ferrite is needed otherwise FSL output drops.
I would a 60-turn closewound coil using 40/44 Litz over the full 1.3" ferrite length, this gave 1118 microhenries. With the recommended dual 338 pF polyvaricon tuning capacitor, this would tune to about 183 kHz at the lowest frequency, which would cover the full NDB band but not all of the LWBC band.
I have a FSL test setup I've developed very recently where I can measure the output of a FSL and compare one FSL to another. Of the several FSLs I've built so far, the original 40-rod one gives the highest output--that's also the one I've been using to do ULR NDB DXing. I firmly believe that the FSL with the highest output is also the most sensitive, and thus the most desirable.
I will show what the 40-rod ferrite FSL measured on the FSL test setup and what the new EMI ribbon cable ferrite FSL gave, then discuss what the numbers mean.

40-rod FSL
450 kHz -74 dBm
350 kHz -74 dBm
250 kHz -74 dBm

EMI FSL
450 kHz -76 dBm
350 kHz -78 dBm
250 kHz -81 dBm

Unless you have worked in electronics it's unlikely you have any idea what the numbers after the frequency mean. "dBm" is an abbreviation for "decibels referred to one milliwatt, measured in a 50 ohm system". More positive numbers (toward zero) indicate a higher output from the FSL (in this case). Thus -74 is a higher output than -76 or -81. Decibels are a logarithmic type notation--the greater the difference the greater the change in power, or in terms of a radio signal, a -3 decibel (dB) difference means the signal is half as strong compared to a signal at 0 dB. Each 3 dB halves that signal power again. A one decibel change is the smallest change that you can hear with your ears, if comparing sound levels. For a radio signal, when it's converted to sound in the radio, that still applies, so the RF signal difference of 1 dB is the smallest change in audio level you would notice if you listened very carefully. Thus, the 40-rod FSL and the EMI FSL are about equal at the high end, 450 kHz, but then the gap steadily widens as the frequency is lowered. You would definitely be missing the weaker signals down at 250 kHz, compared to the 40-rod FSL at 250 kHz.
If the differences between the two antennas were only several dB then I would still recommend the EMI ferrite, but not with the large differences noted as frequency decreases.
As mentioned before, perhaps this ferrite is suitable for MW use in a FSL, but I don't know.
So it appears this fairly inexpensive ferrite is not suitable for use for an LF FSL, unfortunately.
On eBay, searching "ferrite rods" still turns up some Russian sellers with ferrite that has been tested and found to work very well in FSL, both ferrite rods and ferrite bars. If you don't mind paying considerably more, the US distributor Amidon also sells ferrite rods. The -33 type would be the ones to choose to make LF FSL; the -61 type to make MW FSLs, though either type would work for either LF or MW, though -61 might not have enough space to wind a coil with enough inductance to work at LF. Amidon's URL for ferrite rods is https://www.amidoncorp.com/categories/6
Gary DeBock uses Amidon rods for both his MW and LF ULR antennas he builds.
73,
Steve


Very 1st ULR-NDB log from France !

Patrick <aunumero73@...>
 

Hi all,
Yesterday I received my long-awaited 7.5" LW loopstick PL-380 from Gary :-)
I was happy and excited like a little child opening his Christmas present...

Gary did a great job, as usual, the radio  works wonderfully. I
briefly checked daytime reception in the afternoon, about 1 km from
home to avoid local interferences, but at this period of the year one
can not expect distant catches from here under daylight conditions.
I'm living 300m only from a 400,000V electrical power line...  You
guess what I mean :-( Terrible noise on several bands., especially on
HF. On LF, the disturbance is there, but not too strong. Nulling out
the QRM with the loopstick helps a lot in some cases.

Well, I started logging the first NDBs ysterday evening, from home, indoors.
I had a second listening session a couple of hours ago but I had to
stop because of heavy static crashes.

Considering the indoors location and the very short listening period
(a single day), results are pretty fine : 52 NDBs heard from 9 DXCC
countries
(Switzerland, Austria, Italy, Spain, Germany, Czech Republic, Poland,
Croatia and France of course).

kHz Date UTC ID Ctry Location
-----------------------------------------------------------------------------
289.0 14/03/2011 2145 HR FRA Hericourt
291.0 14/03/2011 1805 WS FRA Grenoble / St Geoirs
299.0 15/03/2011 1804 EB FRA St Etienne / Boutheon
302.0 14/03/2011 2200 ROM FRA Rodez / Marcillac
303.0 14/03/2011 2201 RTT AUT Innsbruck / Rattenberg
306.0 14/03/2011 2209 PAR ITA Parma
316.0 14/03/2011 2203 TNJ HRV Tounj
318.0 14/03/2011 1735 GEN ITA Genoa / Sestri
320.0 14/03/2011 2207 VE FRA Valence / Chabeuil
327.0 14/03/2011 2217 LNZ AUT Linz
333.5 14/03/2011 1805 VOG ITA Voghera
335.0 14/03/2011 2220 BER SUI Bern / Belp
339.0 14/03/2011 2222 NE FRA Nancy / Essey
344.0 15/03/2011 0710 TR FRA Villefranche / Tarare
346.0 14/03/2011 1910 CH FRA Chambery / Aix les Bains
348.0 15/03/2011 1815 CL FRA Cahors / Lalbenque
350.0 15/03/2011 1812 BLA ITA Biella / Cerrione
362.0 15/03/2011 1758 BZO ITA Bolzano
364.0 15/03/2011 1759 MAL ITA Milano / Malpensa
367.0 15/03/2011 1759 CF FRA Clermont-Ferrand / Aulnat
371.0 15/03/2011 1745 LEV ITA Cuneo / Levaldigi
372.0 15/03/2011 1802 PY FRA Le Puy / Loudes
375.0 15/03/2011 0709 GLA SUI Gland for Geneva / Cointrin
376.5 15/03/2011 0407 ORI ITA Bergamo / Orio al Serio
379.0 15/03/2011 1804 EB FRA St Etienne / Boutheon
380.0 15/03/2011 0405 VNV ESP Villanueva
384.0 15/03/2011 0708 AT FRA Annecy / Meythet
388.0 15/03/2011 0708 BR FRA Lyon / Bron
391.0 15/03/2011 0707 CC FRA Chalon / Champforgueil
397.0 15/03/2011 0707 EG FRA Grenoble / St Geoirs
400.5 15/03/2011 1752 COD ITA Codogno
403.0 15/03/2011 0400 VZ FRA Vichy / Charmeil
403.0 15/03/2011 1752 LPS SUI Les Eplatures
404.0 15/03/2011 0357 LRD ESP Lerida
413.0 14/03/2011 1855 KTI AUT Innasbruck / Kuhtai
413.0 14/03/2011 1912 BOA ITA Bologna
419.0 14/03/2011 1911 EMT FRA Epinal / Mirecourt
420.0 14/03/2011 1856 INN AUT Innsbruck
423.0 15/03/2011 1857 FOR ITA Forli
427.0 14/03/2011 1857 AUB FRA Aubenas / Val Lanas
428.0 14/03/2011 1910 CTX FRA Chateauroux / Deols
430.0 14/03/2011 1812 SN FRA St Yan
434.0 14/03/2011 2239 MV FRA Melun / Villaroche
438.0 14/03/2011 2237 KO HRV Rijeka / Krk / Kozala
440.0 14/03/2011 1745 PIA ITA Piacenza
444.0 14/03/2011 2235 NRD POL Inowroclaw
448.0 14/03/2011 2234 HLV CZE Holesov
452.0 15/03/2011 0343 ANS DEU Ansbach
480.0 15/03/2011 1846 VIB ITA Viterbo
488.0 14/03/2011 2229 ILM DEU Illesheim
492.0 14/03/2011 2230 TBV CZE Moravska Trebova
525.0 14/03/2011 2227 WRW POL Wroclaw / Strachowice

I hope the layout will be OK (copy/past from Excel). If it's not, tell
me how to show a proper log here (I suppose this is plain text format
?)

Regards,
Patrick, south-east France


Re: Ferrite Sleeve Antenna Permeability (Amidon -61 rods)

Pollock,Raphael E <rpollock@...>
 

Whew, good…had me worried for a minute. In my day job I supervise 121 other surgeons here in Houston, and learned the hard way a while back about the strengths and weaknesses of the email as a means of communicating. Again, I deeply appreciate what you are doing as well as your willingness to share with the rest of us less knowledgeable mortals…

 

Raph Pollock

 

From: ultralightdx@... [mailto:ultralightdx@...] On Behalf Of Steve Ratzlaff
Sent: Tuesday, March 15, 2011 2:16 PM
To: ultralightdx@...
Subject: Re: [ultralightdx] Re: Ferrite Sleeve Antenna Permeability (Amidon -61 rods)

 

 



Hi Raph,

I attempted to respond in the same "tongue in cheek" vein--I never thought you were serious! I used some internet "extreme smiley" characters, to attempt to convey that thought--I guess it didn't convey very well.  :))))))

 

I don't expect the FSL is going to change the world but it's been fun playing with it, and I'm still doing experiments and having fun.

73,

Steve

 

----- Original Message -----

Sent: Tuesday, March 15, 2011 12:04 PM

Subject: RE: [ultralightdx] Re: Ferrite Sleeve Antenna Permeability (Amidon -61 rods)

 

Oh my gosh, sorry Steve, I was being a little “tongue-in-cheek”, and my sincere apologies to you at that. The cost of 40 Amidon 61 ferrite rods would be several hundred dollars, almost as much as a Pixel RP Pro antenna w/o the certainty of definitive results. I so very much appreciate the experimentation that you and several other knowledgeable and intrepid explorers are carrying out on behalf of the rest of us. I am hopeful that an optimized ferrite sleeve system will result from the various experiments now being conducted, such that the purchase of sufficient Amidon 61 rods might then be justified as part of a debugged and optimized finished product. I anticipate that a ferrite sleeve antenna with top of the line ferrite bar and litz wire components, with really good protective coverings given the fragility of the ferrite arrays, will easily run at least $100-150, which is a lot more than some throw down PVC from Lowe’s, some Dave Schmarder litz wire, and a piece of ferrite from Stormwise.

 

 My deep apologies if my one liner email below was misinterpreted as either an offer or a teaser!

 

Raph


Re: Ferrite Sleeve Antenna Permeability (Amidon -61 rods)

Steve Ratzlaff <steveratz@...>
 


Hi Raph,
I attempted to respond in the same "tongue in cheek" vein--I never thought you were serious! I used some internet "extreme smiley" characters, to attempt to convey that thought--I guess it didn't convey very well.  :))))))
 
I don't expect the FSL is going to change the world but it's been fun playing with it, and I'm still doing experiments and having fun.
73,
Steve
 

----- Original Message -----
Sent: Tuesday, March 15, 2011 12:04 PM
Subject: RE: [ultralightdx] Re: Ferrite Sleeve Antenna Permeability (Amidon -61 rods)

Oh my gosh, sorry Steve, I was being a little “tongue-in-cheek”, and my sincere apologies to you at that. The cost of 40 Amidon 61 ferrite rods would be several hundred dollars, almost as much as a Pixel RP Pro antenna w/o the certainty of definitive results. I so very much appreciate the experimentation that you and several other knowledgeable and intrepid explorers are carrying out on behalf of the rest of us. I am hopeful that an optimized ferrite sleeve system will result from the various experiments now being conducted, such that the purchase of sufficient Amidon 61 rods might then be justified as part of a debugged and optimized finished product. I anticipate that a ferrite sleeve antenna with top of the line ferrite bar and litz wire components, with really good protective coverings given the fragility of the ferrite arrays, will easily run at least $100-150, which is a lot more than some throw down PVC from Lowe’s, some Dave Schmarder litz wire, and a piece of ferrite from Stormwise.

 

 My deep apologies if my one liner email below was misinterpreted as either an offer or a teaser!

 

Raph


Re: Ferrite Sleeve Antenna Permeability (Amidon -61 rods)

Steve Ratzlaff <steveratz@...>
 


Hi Raph,
I attempted to respond in the same "tongue in cheek" vein--I never thought you were serious! I used some internet "extreme smiley" characters, to attempt to convey that thought--I guess it didn't convey very well.  :))))))
 
I don't expect the FSL is going to change the world but it's been fun playing with it, and I'm still doing experiments and having fun.
73,
Steve
 

----- Original Message -----
Sent: Tuesday, March 15, 2011 12:04 PM
Subject: RE: [ultralightdx] Re: Ferrite Sleeve Antenna Permeability (Amidon -61 rods)

Oh my gosh, sorry Steve, I was being a little “tongue-in-cheek”, and my sincere apologies to you at that. The cost of 40 Amidon 61 ferrite rods would be several hundred dollars, almost as much as a Pixel RP Pro antenna w/o the certainty of definitive results. I so very much appreciate the experimentation that you and several other knowledgeable and intrepid explorers are carrying out on behalf of the rest of us. I am hopeful that an optimized ferrite sleeve system will result from the various experiments now being conducted, such that the purchase of sufficient Amidon 61 rods might then be justified as part of a debugged and optimized finished product. I anticipate that a ferrite sleeve antenna with top of the line ferrite bar and litz wire components, with really good protective coverings given the fragility of the ferrite arrays, will easily run at least $100-150, which is a lot more than some throw down PVC from Lowe’s, some Dave Schmarder litz wire, and a piece of ferrite from Stormwise.

 

 My deep apologies if my one liner email below was misinterpreted as either an offer or a teaser!

 

Raph


Re: Ferrite Sleeve Antenna Permeability (Amidon -61 rods)

Pollock,Raphael E <rpollock@...>
 

Oh my gosh, sorry Steve, I was being a little “tongue-in-cheek”, and my sincere apologies to you at that. The cost of 40 Amidon 61 ferrite rods would be several hundred dollars, almost as much as a Pixel RP Pro antenna w/o the certainty of definitive results. I so very much appreciate the experimentation that you and several other knowledgeable and intrepid explorers are carrying out on behalf of the rest of us. I am hopeful that an optimized ferrite sleeve system will result from the various experiments now being conducted, such that the purchase of sufficient Amidon 61 rods might then be justified as part of a debugged and optimized finished product. I anticipate that a ferrite sleeve antenna with top of the line ferrite bar and litz wire components, with really good protective coverings given the fragility of the ferrite arrays, will easily run at least $100-150, which is a lot more than some throw down PVC from Lowe’s, some Dave Schmarder litz wire, and a piece of ferrite from Stormwise.

 

 My deep apologies if my one liner email below was misinterpreted as either an offer or a teaser!

 

Raph

 

From: ultralightdx@... [mailto:ultralightdx@...] On Behalf Of Steve Ratzlaff
Sent: Tuesday, March 15, 2011 1:40 PM
To: ultralightdx@...
Subject: Re: [ultralightdx] Re: Ferrite Sleeve Antenna Permeability (Amidon -61 rods)

 

 



Hi Raph,

I'd be happy to experiment with Amidon -61 rods if you'd be willing to purchase them. :)))  Just have them sent to me, I'd send them back to you to keep after the tests.  :)   (Are we talking about the 7.5" rods, 40 of them?)

73,

Steve

----- Original Message -----

Sent: Tuesday, March 15, 2011 9:21 AM

Subject: RE: [ultralightdx] Re: Ferrite Sleeve Antenna Permeability

 

Agreed—this is all consistent—now awaiting some “optimization” of the ferrite sleeve approach—waiting for someone to buy 40 of the Amidon 61 bars…

 

Optimal aperture size?

Optimal wire for coil winding?

Optimal positioning of coil on bars?

Optimal # of turns in coil?

Tight versus loose coil winding?

Position/# of turns, etc. for pick-up coil?

Distance between primary coil and ferrite bars?

Optimal length of ferrite bars?

 

It will be interesting to see how this evolves. Still hoping for some “hands on” evaluation of the sleeve versus monster ferrite bar approach for MW reception. There must be some comparabilities; e.g., the old teaching that length of ferrite bar is proportionate to diagonal measure of air core box loop regarding Q, depth, of null, etc. A bit concerned that the ferrite sleeve comparisons with Terk loop are only a bit (1.7-fold?) better…How much gain can one really make use of? Is the selectivity of the sleeve so much better than that of the single monster ferrite rod or air core loop. The selectivity issue is key, and includes “nullability” as well as low(est) achievable noise floor. And of course all of these concerns are trumped by being in the right location; i.e., not in RFI heaven like downtown Houston, Texas…!

 

Awaiting the verdict of the mavens!


Re: Ferrite Sleeve Antenna Permeability (Amidon -61 rods)

Steve Ratzlaff <steveratz@...>
 


Hi Raph,
I'd be happy to experiment with Amidon -61 rods if you'd be willing to purchase them. :)))  Just have them sent to me, I'd send them back to you to keep after the tests.  :)   (Are we talking about the 7.5" rods, 40 of them?)
73,
Steve

----- Original Message -----
Sent: Tuesday, March 15, 2011 9:21 AM
Subject: RE: [ultralightdx] Re: Ferrite Sleeve Antenna Permeability

Agreed—this is all consistent—now awaiting some “optimization” of the ferrite sleeve approach—waiting for someone to buy 40 of the Amidon 61 bars…

 

Optimal aperture size?

Optimal wire for coil winding?

Optimal positioning of coil on bars?

Optimal # of turns in coil?

Tight versus loose coil winding?

Position/# of turns, etc. for pick-up coil?

Distance between primary coil and ferrite bars?

Optimal length of ferrite bars?

 

It will be interesting to see how this evolves. Still hoping for some “hands on” evaluation of the sleeve versus monster ferrite bar approach for MW reception. There must be some comparabilities; e.g., the old teaching that length of ferrite bar is proportionate to diagonal measure of air core box loop regarding Q, depth, of null, etc. A bit concerned that the ferrite sleeve comparisons with Terk loop are only a bit (1.7-fold?) better…How much gain can one really make use of? Is the selectivity of the sleeve so much better than that of the single monster ferrite rod or air core loop. The selectivity issue is key, and includes “nullability” as well as low(est) achievable noise floor. And of course all of these concerns are trumped by being in the right location; i.e., not in RFI heaven like downtown Houston, Texas…!

 

Awaiting the verdict of the mavens!


Re: Ferrite Sleeve Antenna Permeability

Gerald Wolczanski <jerrywolczanski@...>
 

Henry, I like your "rules". They're easier to understand than:
http://www.bentongue.com/xtalset/29MxQFL/29MxQFL.html

Jerry W

On Tue, 2011-03-15 at 17:23 +0100, ehydra wrote:
The classic assumption is approx. 20:1 as somewhere optimal. So this
fits it very good if one think of logarithmic functions.

BTW: The coil fill-factor is optimum at approx. 60% to 80% of the
rod-length.
Single-layer improves Q. Separating turns does good more.

- Henry


Re: Ferrite Sleeve Antenna Permeability

ehydra
 

The classic assumption is approx. 20:1 as somewhere optimal. So this fits it very good if one think of logarithmic functions.

BTW: The coil fill-factor is optimum at approx. 60% to 80% of the rod-length.
Single-layer improves Q. Separating turns does good more.

- Henry


--
ehydra.dyndns.info



Gerald Wolczanski schrieb:

In Polydoroff's most recently posted paper ("The Ferromagnetic Loop
Antenna") he suggests there is a REDUCTION in pickup past L/D ratios of
40. He wrote this in the context of a cylindrical antenna, but it
sounds like a statement of fact for L/D ratios in general. Your 19" rod
seems to fit that L/D ratio. Pretty good observation!
Jerry W
KI4IO
Warrenton, VA


Re: Ferrite Sleeve Antenna Permeability

Pollock,Raphael E <rpollock@...>
 

Agreed—this is all consistent—now awaiting some “optimization” of the ferrite sleeve approach—waiting for someone to buy 40 of the Amidon 61 bars…

 

Optimal aperture size?

Optimal wire for coil winding?

Optimal positioning of coil on bars?

Optimal # of turns in coil?

Tight versus loose coil winding?

Position/# of turns, etc. for pick-up coil?

Distance between primary coil and ferrite bars?

Optimal length of ferrite bars?

 

It will be interesting to see how this evolves. Still hoping for some “hands on” evaluation of the sleeve versus monster ferrite bar approach for MW reception. There must be some comparabilities; e.g., the old teaching that length of ferrite bar is proportionate to diagonal measure of air core box loop regarding Q, depth, of null, etc. A bit concerned that the ferrite sleeve comparisons with Terk loop are only a bit (1.7-fold?) better…How much gain can one really make use of? Is the selectivity of the sleeve so much better than that of the single monster ferrite rod or air core loop. The selectivity issue is key, and includes “nullability” as well as low(est) achievable noise floor. And of course all of these concerns are trumped by being in the right location; i.e., not in RFI heaven like downtown Houston, Texas…!

 

Awaiting the verdict of the mavens!

 

From: ultralightdx@... [mailto:ultralightdx@...] On Behalf Of Gerald Wolczanski
Sent: Tuesday, March 15, 2011 11:00 AM
To: ultralightdx@...
Subject: RE: [ultralightdx] Re: Ferrite Sleeve Antenna Permeability

 

 

In Polydoroff's most recently posted paper ("The Ferromagnetic Loop
Antenna") he suggests there is a REDUCTION in pickup past L/D ratios of
40. He wrote this in the context of a cylindrical antenna, but it
sounds like a statement of fact for L/D ratios in general. Your 19" rod
seems to fit that L/D ratio.

Pretty good observation!

Jerry W
KI4IO
Warrenton, VA

On Mon, 2011-03-14 at 15:40 -0500, Pollock,Raphael E wrote:
>
>
> Not to be at all contrarian (we have seen a lot of that around these
> parts lately!), but I have made three ferrite rod antennas using 19”,
> 27”, and 48” ferrite rods from Stormwise designed for MW reception.
> All have 125 mu permeability, all have primary pick up coils (38
> turns of 660/46 Litz wire) that are tight wound over the measured
> center of each bar, each terminate in a 365 pfd variable capacitor,
> and all three have equivalent gain and null patterns as measured (with
> a fair bit of empiricism) using the LED panel (10 LEDs) on my Sony
> 2010—inductive coupling. In fact, the nulls on the 19” antenna are
> slightly sharper (less total angular arc with slightly deeper audible
> nulling) than either of the other two longer antennas. I believe that
> information about diameter versus length was reported in older posts
> from John Popelish, which are likewise consistent with the above
> observations that longer is not always better, at least regarding
> ferrite rods…!
>
>
>
> Raph Pollock
>
>
>
> From: ultralightdx@...
> [mailto:ultralightdx@...] On Behalf Of Gerald Wolczanski
> Sent: Monday, March 14, 2011 3:17 PM
> To: ultralightdx@...
> Subject: Re: [ultralightdx] Re: Ferrite Sleeve Antenna Permeability
>
>
>
>
>
>
> Very nice job you've done!
>
> So, if you consider an 11" air loop to be the equivalent, that
> suggests
> a effective permeability of 4.5. In separate correspondence with Paul
> S. in CT, he thought the Ue might be in the neighborhood of 3 - 3.5,
> pretty good agreement with your observations, no matter how you slice
> it. You could call it a Ue = 4 as a compromise!
>
> This really puts the whole discussion of Ferrite Sleeve Antennas on a
> proper footing. Do I buy the Ferrite or opt for a traditional loop
> with
> roughly 4 times the area?
>
> Or (another area), does somebody with a large stash of ferrite rods,
> glue them together and make an improbably long antenna, achieving a Ue
> of maybe 500 or so? Then the cross sectional area eats your lunch -
> maybe.
>
> Gentlemen, start your spreadsheets.
>
> Jerry W
> KI4IO
>
> On Mon, 2011-03-14 at 19:39 +0000, dhsatyadhana wrote:
> > Hi Jerry/all:
> >
> > What I have seen thus far is that a 5.2" coil diameter FSL loop,
> > coupled passively to an Ultralight, is the equivalent of perhaps a
> > 11" or 12" diameter air-core loop on MW, based on what I am hearing
> > and the relative SNR figures on the Tecsun. In my case, the 5.2" FSL
> > (45 turns of 175/46 Litz over 400 permeability ferrite, wound around
> a
> > 4.5 inch polystyrene form) is a fair bit better than a Terk Loop (30
> > turns over a 9 inch form), but falls short of a 15x15 inch box loop
> > (equivalent of a 17" diameter circular loop) with 24 turns of
> regular
> > stranded wire. Since the FSL is closer in performance to the 9"
> Terk,
> > that is why I estimate that the FSL is performing like a 11" or 12"
> > air-core loop.
> >
> > Q on the FSL is easily the sharpest of the three; the box loop was
> > measured to have a coil Q of about 200, so not bad for a box loop.
> > Chugging through area and numbers of turns, Ue=1.7 is likely a
> decent
> > figure to use, and the additional Q (basically, efficiency) of the
> FSL
> > may be what's allowing it to get up to the 11" or 12" equivalent
> > range. Ferrite permeability may also be a factor; mu = 100 ferrite
> may
> > bump this up even more for MW, and mu=800 ferrite for LW.
> >
> > Further construction of actual antennas will hopefully determine
> > what the optimum design criteria are. One possible direction to look
> in
> > is the 10 to 20 length/diameter ratio suggested by Polydoroff in the
> > 1960 excerpt, who by then was also using a bunch of
> > commercially-available rods for the sleeve.
> >
> >
> > Kevin S, Bainbridge Island, WA
> >
> > --- In ultralightdx@..., Gerald Wolczanski
> > <jerrywolczanski@...> wrote:
> > >
> > > I've asked about the effective permeability (Ue) of the sleeve
> antenna
> > > because it dramatically reduces the initial permeability of the
> > ferrite
> > > material being used. The proper way to find this is to build two
> > > antennas, one of the Polydoroff variety (Ferrite Sleeve) and the
> other
> > a
> > > conventional frame (air) loop.
> > >
> > > This is exactly what Polydoroff describes in his paper (and
> provides a
> > > real number for Ue)!
> > >
> > > #1
> > > First he discusses the efficiency of the frame aerial. That is:
> > > 2 * pi * Area * Turns/ wavelength times the Q
> > >
> > >
> > > He constructs two loops, wound to the same inductance.
> > > The ferrite loaded loop has 40 turns with a Q of 250.
> > > The frame aerial has 52 turns with a Q of 190.
> > >
> > > Because of the above equation, the greater turns of the frame
> aerial
> > > offsets the lower Q, i.e., both antennas have the same pickup
> > > efficiency, i.e., a signal received by both antennas from the same
> > > source should produce the same magnitude voltage on the same
> receiver.
> > > (This is the effective height)
> > >
> > > YET, THE CORED LOOP SHOWED AN INCREASE IN SIGNAL STRENGTH BY
> > > APPROXIMATELY 70% WHICH NUMERICALLY CORRESPONDS TO THE EFFECTIVE
> > > PERMEABILITY (Ue).
> > >
> > > This then is a Ue of 1.7.
> > >
> > > #2
> > > The formula for a ferrite loaded antenna is:
> > > 2 * pi * Area * Turns * Ue/ wavelength times the Q
> > >
> > >
> > > In his second example, his Ue comes out to 1.4. These numbers are
> > > consistent with the L/D charts.
> > >
> > > - - - - - - - - -
> > >
> > > IN PRACTICAL TERMS. A 4.5" DIAMETER FERRITE SLEEVE ANTENNA OUGHT
> TO BE
> > > COMPARABLE TO A 6" AIR LOOP (using the Ue = 1.7 example). An air
> loop
> > > would need to be 70% larger, in terms of area, to equal the
> > performance
> > > of a ferrite loaded [sleeve] antenna.
> > >
> > > - - - - - - - - -
> > >
> > > Air has a permeability of 1.
> > >
> > >
> > >
> > > Jerry Wolczanski
> > > KI4IO
> > > Warrenton, VA
> > >
> >
> >
> >
> >
> > ------------------------------------
> >
> > Yahoo! Groups Links
> >
> >
> >
>
>
>
>
>
>


Re: Ferrite Sleeve Antenna Permeability

Gerald Wolczanski <jerrywolczanski@...>
 

In Polydoroff's most recently posted paper ("The Ferromagnetic Loop
Antenna") he suggests there is a REDUCTION in pickup past L/D ratios of
40. He wrote this in the context of a cylindrical antenna, but it
sounds like a statement of fact for L/D ratios in general. Your 19" rod
seems to fit that L/D ratio.

Pretty good observation!

Jerry W
KI4IO
Warrenton, VA

On Mon, 2011-03-14 at 15:40 -0500, Pollock,Raphael E wrote:


Not to be at all contrarian (we have seen a lot of that around these
parts lately!), but I have made three ferrite rod antennas using 19”,
27”, and 48” ferrite rods from Stormwise designed for MW reception.
All have 125 mu permeability, all have primary pick up coils (38
turns of 660/46 Litz wire) that are tight wound over the measured
center of each bar, each terminate in a 365 pfd variable capacitor,
and all three have equivalent gain and null patterns as measured (with
a fair bit of empiricism) using the LED panel (10 LEDs) on my Sony
2010—inductive coupling. In fact, the nulls on the 19” antenna are
slightly sharper (less total angular arc with slightly deeper audible
nulling) than either of the other two longer antennas. I believe that
information about diameter versus length was reported in older posts
from John Popelish, which are likewise consistent with the above
observations that longer is not always better, at least regarding
ferrite rods…!



Raph Pollock



From: ultralightdx@...
[mailto:ultralightdx@...] On Behalf Of Gerald Wolczanski
Sent: Monday, March 14, 2011 3:17 PM
To: ultralightdx@...
Subject: Re: [ultralightdx] Re: Ferrite Sleeve Antenna Permeability






Very nice job you've done!

So, if you consider an 11" air loop to be the equivalent, that
suggests
a effective permeability of 4.5. In separate correspondence with Paul
S. in CT, he thought the Ue might be in the neighborhood of 3 - 3.5,
pretty good agreement with your observations, no matter how you slice
it. You could call it a Ue = 4 as a compromise!

This really puts the whole discussion of Ferrite Sleeve Antennas on a
proper footing. Do I buy the Ferrite or opt for a traditional loop
with
roughly 4 times the area?

Or (another area), does somebody with a large stash of ferrite rods,
glue them together and make an improbably long antenna, achieving a Ue
of maybe 500 or so? Then the cross sectional area eats your lunch -
maybe.

Gentlemen, start your spreadsheets.

Jerry W
KI4IO

On Mon, 2011-03-14 at 19:39 +0000, dhsatyadhana wrote:
Hi Jerry/all:

What I have seen thus far is that a 5.2" coil diameter FSL loop,
coupled passively to an Ultralight, is the equivalent of perhaps a
11" or 12" diameter air-core loop on MW, based on what I am hearing
and the relative SNR figures on the Tecsun. In my case, the 5.2" FSL
(45 turns of 175/46 Litz over 400 permeability ferrite, wound around
a
4.5 inch polystyrene form) is a fair bit better than a Terk Loop (30
turns over a 9 inch form), but falls short of a 15x15 inch box loop
(equivalent of a 17" diameter circular loop) with 24 turns of
regular
stranded wire. Since the FSL is closer in performance to the 9"
Terk,
that is why I estimate that the FSL is performing like a 11" or 12"
air-core loop.

Q on the FSL is easily the sharpest of the three; the box loop was
measured to have a coil Q of about 200, so not bad for a box loop.
Chugging through area and numbers of turns, Ue=1.7 is likely a
decent
figure to use, and the additional Q (basically, efficiency) of the
FSL
may be what's allowing it to get up to the 11" or 12" equivalent
range. Ferrite permeability may also be a factor; mu = 100 ferrite
may
bump this up even more for MW, and mu=800 ferrite for LW.

Further construction of actual antennas will hopefully determine
what the optimum design criteria are. One possible direction to look
in
is the 10 to 20 length/diameter ratio suggested by Polydoroff in the
1960 excerpt, who by then was also using a bunch of
commercially-available rods for the sleeve.


Kevin S, Bainbridge Island, WA

--- In ultralightdx@..., Gerald Wolczanski
<jerrywolczanski@...> wrote:

I've asked about the effective permeability (Ue) of the sleeve
antenna
because it dramatically reduces the initial permeability of the
ferrite
material being used. The proper way to find this is to build two
antennas, one of the Polydoroff variety (Ferrite Sleeve) and the
other
a
conventional frame (air) loop.

This is exactly what Polydoroff describes in his paper (and
provides a
real number for Ue)!

#1
First he discusses the efficiency of the frame aerial. That is:
2 * pi * Area * Turns/ wavelength times the Q


He constructs two loops, wound to the same inductance.
The ferrite loaded loop has 40 turns with a Q of 250.
The frame aerial has 52 turns with a Q of 190.

Because of the above equation, the greater turns of the frame
aerial
offsets the lower Q, i.e., both antennas have the same pickup
efficiency, i.e., a signal received by both antennas from the same
source should produce the same magnitude voltage on the same
receiver.
(This is the effective height)

YET, THE CORED LOOP SHOWED AN INCREASE IN SIGNAL STRENGTH BY
APPROXIMATELY 70% WHICH NUMERICALLY CORRESPONDS TO THE EFFECTIVE
PERMEABILITY (Ue).

This then is a Ue of 1.7.

#2
The formula for a ferrite loaded antenna is:
2 * pi * Area * Turns * Ue/ wavelength times the Q


In his second example, his Ue comes out to 1.4. These numbers are
consistent with the L/D charts.

- - - - - - - - -

IN PRACTICAL TERMS. A 4.5" DIAMETER FERRITE SLEEVE ANTENNA OUGHT
TO BE
COMPARABLE TO A 6" AIR LOOP (using the Ue = 1.7 example). An air
loop
would need to be 70% larger, in terms of area, to equal the
performance
of a ferrite loaded [sleeve] antenna.

- - - - - - - - -

Air has a permeability of 1.



Jerry Wolczanski
KI4IO
Warrenton, VA



------------------------------------

Yahoo! Groups Links







Re: Ferrite Sleeve Antenna Permeability

graham.maynard1
 

An earlier post by Henry questioned about rods being coupled.
I truly did not understand the wording.

Henry e-mailed me separately; I eventually understood the nature of his question; and I feel my reply to him had real importance because it is related to the title of this thread and the way in which 'old fashioned' thought processes are as like being fitted with blinkers.

I am repeatedly told that I should not try to communicate electron orbit theory within ferrite, but avoiding same has been creating a big hurdle for others that I have already crossed.

Ferrite Sleeve Antenna Permeability -
As long anyone thinks that this is all that the FS Loop is about (as Polydoroff did about his own sleeve antenna construction) then the advantages of a ferrite sleeve inductor cannot be appreciated.

I agreed with Henry that increasing the permeability within the core of a ferrite rod antenna effectively increases its aperture and thus its effective sensitivity.
I also agree with Henry that the noise is also increased, thus a bigger ferrite rod (especially at beacon frequencies) might increase 'signal' level at receiver input, but it will not equally improve the wanted signal to noise level.

It is only when electron orbits with ferrite are conceptualised as a result of alternating field generated by the antenna coil, that one can begin to appreciate those spins cannot remain axial within the rod much beyond the coil, or within the centre of the rod, and that it is these un-aligned spins which cause the noise level to rise with rod size or increasing frequency.

If the ferrite core is not too long with respect to the coil, and does not have a solid centre, then the field induced electron misalignments CANNOT exist, and thus CANNOT generate that same increased noise level within a Ferrite Sleeve Loop Antenna.

Those who are merely applying PERMEABILITY calculations to an FS Loop are working out only half of the story, because although they are quite correct about absolute sensitivity they are totally missing out on the reduced noise level aspect and thus reception quality.

This is why reception quality reports are more valuable than signal strength readings.

I trust this has clarified FS Loop operation for those who have chosen to not read my (heavy going) text.

Cheers ............ Graham.


Re: Tecsun R9710 short review

mischabronstring
 

Last night there were again excellent DX-conditions for shortwave: I received Radio Canada International, Radio Habana Cuba (their French language broadcast), and even Radio Marti (in Spanish, obviously), which I had never heard before. All with a barefoot R9710, and quite intelligible (though my knowledge of French is not as good as my Spanish:)).

I cannot wait till tonight:).


NE Oregon ULR NDB DX, Monday night

Steve Ratzlaff <steveratz@...>
 

Solar activity finally decreased and some improved LF conditions. One new one. Conditions would be quiet for a few minutes then go very noisy, then back quiet again in another 5 minutes, if you wanted to wait and see if something would show up. 267 logged.
Steve
NE Oregon
PL-380 and 40-rod FSL

408 JDM KS 955 MI


Lousy Conditions tonite

ferrite61 <dxrx@...>
 

Same as last nite, actually. Chicago is just about absent on 670, 720, 780, 890 and 1000, and Detroit on 760 barely there. Atlanta in the mush on 750.nothing new 1500 kHz and up.

Paul S. in CT


Re: Ferrite Sleeve Antenna Permeability

graham.maynard1
 

Chris has sent me another e-mail via this group ensisting my work is
"still a copy of work by others"

I don't do that; and besides, how could I copy work which I did not know existed ?

He also appears to be speaking for the group when he writes -
"It's because we really don't care to see people such as yourself taking credit for the work of others."

However, my work is my own - only Chris seems incapable of accepting this. Many times in this world different people have independently had the same ideas, and there is so often more than one way of viewing any given problem.

There is no way I can respond to a person making false statements about me and such underhand attacks, so I am sure members here will understand why I have blocked further e-mails from Chris.

Cheers .......... Graham.

--- In ultralightdx@..., "Graham" <graham.maynard1@...> wrote:

As the text in my FS Loop Article is 100% truthful in reporting all of *my own work* and findings -
and,
this evening via an e-mail from the Ultralight Group under the 'Ferrite Sleeve Antenna Permeability' heading,
Chris Trask - Senior member of the IEEE -
has virtually accused me of being a plagiarist and *a liar* (neither of which I could ever do because I was not brought up that way !)
by stating - (copy-paste)

" There is no difference between the magnetic functions of powdered iron
and ferrites, nor does it matter that Polydoroff did his measurements at LF. He was developing small antennas to be used in aircraft ADF receivers, the very antenna that you have been copying and elaborating on all this time."

I refute this accusation and add - of course there is no difference related to noted permeability at any given frequency, but there is due to core size related iron molecule losses being quite different to those within a ferrite sleeve with increasing frequency! This likely being why Polydoroff's work did not come to light for use on MW at that time. The FS Loop was even expected to work at SW, and it did, better than expected.

I have never come across such accusative behaviour before on any forum, and most certainly not from a member of the IEEE !
A copy of the e-mail is retained in case anyone doubts the truthfulness of this copy-paste.

It was not Polydoroff who brought this design to our attention, if he had then I too would have used it myself long ago, and sung its praises.
So why are there those here who are attempting to shoot the messenger, and distract themselves and everybody else about permeability calculations before they have even tried this design for themselves.

Chris - the electron spins in dust iron *are* different to those in ferrite because the molecular structures are different.

The FS Loop design is about improved antenna performance, not just outright permeability related sensitivity. Also if what Jerry has just posted is true -
"Polydoroff said that his sleeve antenna (sic) was "more directional and
less affected by adjoining metal parts"

then there really is something significantly different between his iron dust core loop and an FS Loop which Polydoroff could not have known about, because, and as I have already stated, the FS Loop field is so large that it *IS* seriously affected by nearby metalwork !

A loop, is a loop, is a loop = figure of with deep nulls (if properly constructed). Polydoroff used skewed coils to increase directional discrimination in one direction at the expense of the other.

I suggest that the difference between our antennas relates to the electron spins within the two different materials, and this has been the whole point of my work, because those who think merely of magnetic parameters are missing out on what the electron spin orbits within the sleeve are doing, and Polydoroff had shown no recognition of this.


Cheers ........... Graham.


Re: First FSL - Some test result Handheld vs. FSL, vs Terk Advantage

graham.maynard1
 

Hi Gregory,

The coil form is most important. I think the turns would have become too separated to be a good inductor at MW frequencies.
The coil form must be priority, and I think it likely your rods are still a very useful length.

Swamping the rod antenna on a Tecsun Ultralight affects the way the meter reads both signal strength and S/N, and the way it controls itself. Best listening as expressed by weak/fair etc. can be acheived with different degrees of coupling, and where there are no interference problems then overcoupling can sound best, though with wrong meter readings.

Cheers ......... Graham.

--- In ultralightdx@..., "gmosherat" <gmosherat@...> wrote:









Graham,

I will look at a coil covering only the center 4 inches, I had not done this as my reading here and (I thought - your site?) said the coil has to be spread out over the length of the rods and only leave a bit of the rods on each end exposed? Is that wrong or perhaps only an issue as my rods are of a longer variety?

W/ respect to sensitivity, after some experimentation on where to place the radio on&#92;near the FSL, the reading reported were taken with the radio sitting next to the FSL, back side of radio laying against the FSL coil. This provided most gain in signal.

Regarding "It is also essential to obtain the right spacing between an FS Loop and any receiver because a radio will work differently if so close that the FS Loop controls the radio's antenna."

I thought that was the whole idea? place the radio close enough to the FSL so that the radio's internal antenna is "swamped" by the FSL? DO I have this concept wrong?

Regards,

Gregory

--- In ultralightdx@..., "Graham" <graham.maynard1@> wrote:

Hi,

Great to see independent feedback.

You might have an inefficient coil form wound over the ferrite.
23 turns spread over 7 to 8 inches would not be great.

Can I suggest these are wound over the centre 4" section only, and spaced with string.

It is also essential to obtain the right spacing between an FS Loop and any receiver because a radio will work differently if so close that the FS Loop controls the radio's antenna. Especially with the reactively peaked ferrite rods in the Tecsun Ultralights.

The way Gary has compared reception in the past - eg. 0, Wk, Fr, Gd, Ex might be useful too.

Cheers ........... Graham.

--- In ultralightdx@..., "gmosherat" <gmosherat@> wrote:

I have built my first FSL and ready to share some test results

FSL consists of:

37 200x10mm Russian Ebay Ferrite rods formed around a empty 2-liter soda bottle. Unit then wrapped in two layers of plastic bubble wrap, then covered in a few wraps of paper towels.

Onto this I wrapped 23 turns of 22 guage copper wire (approx 31 feet), the coil is spread across the FSL, leaving approx 1cm of exposed ferrite rod on either end. Coil wire ends connected to a 384pf variable capacitor purchaed from Stormwise.com.

This setup tunes the AM broadcast band.

Prior to test results a few notes

A> This antenna is not as sensitive as my 60 foot outdoor longwire, although it's rotatable so I can null stations. Mixed bag vs. Terk Advantage.

B> I worked out a successfull way to couple the antenna to a communications receiver. I had (laying around) a home made Gary Debock Type A LW Amidon antenna. Connect this into a communications receiver and sit the type A antenna up against the FSL coil - works well.


Onto the first daytime tests
Sensitivity tests were conducted inside, between 10:30AM-Noon Local time Sunday 3/13.

Radios used:
Tecsun PL310 modified with a home made Gary Debock Type G LW antenna attached - note antenna peaked for LW reception, not MW.
Stock Tecsun PL390

Unless stated otherwise the station tuned was copyable.

1490 WBTA, 1KW, 45MI Dist
PL310 Handheld dBu&#92;dB 20&#92;00 no copy
PL310 w/FSL dBu&#92;dB 32&#92;25
PL310 w/ Terk dBu&#92;dB 32&#92;25
PL390 Handheld dBu&#92;dB 34&#92;03
PL390 w/ FSL dBu&#92;dB 45&#92;16
PL390 w/ Terk dBu&#92;dB 41&#92;25

1310 WSRB, 1KW, 25MI Dist
PL310 Handheld dBu&#92;dB 25&#92;25
PL310 w/ FSL dBu&#92;dB 57&#92;25
PL310 w/ Terk dBu&#92;dB 59&#92;25
PL390 Handheld dBu&#92;dB 49&#92;25
PL390 w/ FSL dBu&#92;dB 57&#92;25
PL390 w/ Terk dBu&#92;dB 63&#92;25

1070 WSCP, 2.5KW 125MI Dist
PL310 Handheld dBu&#92;dB 22&#92;00 no copy
PL310 w/ FSL dBu&#92;dB 37&#92;16
PL310 w/ Terk dBu&#92;dB 37&#92;13
PL390 Handheld dBu&#92;dB 39&#92;00
PL390 w/ FSL dBu&#92;dB 49&#92;10
PL390 w/ Terk dBu&#92;dB 43&#92;11

900 CHML, 50KW 90MI Dist
PL310 Handheld dBu&#92;dB 22&#92;00 Just audible
PL310 w/ FSL dBu&#92;dB 42&#92;10
PL310 w/ Terk dBu&#92;dB 33&#92;08
PL390 Handheld dBu&#92;dB 25&#92;14
PL390 w/ FSL dBu&#92;dB 38&#92;10
PL390 w/ Terk dBu&#92;dB 35&#92;10

800 CJBQ, 10KW 70MI Dist
PL310 Handheld dBu&#92;dB 27&#92;25
PL310 w/ FSL dBu&#92;dB 50&#92;25
PL310 w/ Terk dBu&#92;dB 54&#92;25
PL390 Handheld dBu&#92;dB 44&#92;25
PL390 w/ FSL dBu&#92;dB 50&#92;25
PL390 w/ Terk dBu&#92;dB 52&#92;25
Notes: Distance mostly over water.

710 CJRN, 10KW 70MI Dist
PL310 Handheld dBu&#92;dB 20&#92;09
PL310 w/ FSL dBu&#92;dB 44&#92;07
PL310 w/ Terk dBu&#92;dB 38&#92;08
PL390 Handheld dBu&#92;dB 28&#92;11
PL390 w/ FSL dBu&#92;dB 41&#92;07
PL390 w/ Terk dBu&#92;dB 35&#92;08


570 WSYR, 5KW 70MI Dist
PL310 Handheld dBu&#92;dB 22&#92;07
PL310 w/ FSL dBu&#92;dB 38&#92;05
PL310 w/ Terk dBu&#92;dB 27&#92;07
PL390 Handheld dBu&#92;dB 25&#92;15
PL390 w/ FSL dBu&#92;dB 32&#92;06
PL390 w/ Terk dBu&#92;dB 34&#92;07


General notes:
I was suprized at how close the Terk is to the FSL. More experimantation is due, perhaps lookig at distance betrween coil and Ferrite - I did not measure the thickness of two layers of bubble wrap.

As I got lower in the MW band frequencies lots more noise - perhaps due to RF interfernece w/in the house?

Comments welcome


Didn't receive the expected ferrite shipment today

Steve Ratzlaff <steveratz@...>
 

Last week I mentioned I had a line on a cheaper source of ferrite and had some on order--expecting to receive it today. It didn't arrive today--maybe tomorrow. I'll build a FSL with the ferrite and test it and report the results eventually, assuming the ferrite works like I'm hoping.
73,
Steve


Re: First FSL - Some test result Handheld vs. FSL, vs Terk Advantage

gmosherat
 

Graham,

I will look at a coil covering only the center 4 inches, I had not done this as my reading here and (I thought - your site?) said the coil has to be spread out over the length of the rods and only leave a bit of the rods on each end exposed? Is that wrong or perhaps only an issue as my rods are of a longer variety?

W/ respect to sensitivity, after some experimentation on where to place the radio on&#92;near the FSL, the reading reported were taken with the radio sitting next to the FSL, back side of radio laying against the FSL coil. This provided most gain in signal.

Regarding "It is also essential to obtain the right spacing between an FS Loop and any receiver because a radio will work differently if so close that the FS Loop controls the radio's antenna."

I thought that was the whole idea? place the radio close enough to the FSL so that the radio's internal antenna is "swamped" by the FSL? DO I have this concept wrong?

Regards,

Gregory

--- In ultralightdx@..., "Graham" <graham.maynard1@...> wrote:

Hi,

Great to see independent feedback.

You might have an inefficient coil form wound over the ferrite.
23 turns spread over 7 to 8 inches would not be great.

Can I suggest these are wound over the centre 4" section only, and spaced with string.

It is also essential to obtain the right spacing between an FS Loop and any receiver because a radio will work differently if so close that the FS Loop controls the radio's antenna. Especially with the reactively peaked ferrite rods in the Tecsun Ultralights.

The way Gary has compared reception in the past - eg. 0, Wk, Fr, Gd, Ex might be useful too.

Cheers ........... Graham.

--- In ultralightdx@..., "gmosherat" <gmosherat@> wrote:

I have built my first FSL and ready to share some test results

FSL consists of:

37 200x10mm Russian Ebay Ferrite rods formed around a empty 2-liter soda bottle. Unit then wrapped in two layers of plastic bubble wrap, then covered in a few wraps of paper towels.

Onto this I wrapped 23 turns of 22 guage copper wire (approx 31 feet), the coil is spread across the FSL, leaving approx 1cm of exposed ferrite rod on either end. Coil wire ends connected to a 384pf variable capacitor purchaed from Stormwise.com.

This setup tunes the AM broadcast band.

Prior to test results a few notes

A> This antenna is not as sensitive as my 60 foot outdoor longwire, although it's rotatable so I can null stations. Mixed bag vs. Terk Advantage.

B> I worked out a successfull way to couple the antenna to a communications receiver. I had (laying around) a home made Gary Debock Type A LW Amidon antenna. Connect this into a communications receiver and sit the type A antenna up against the FSL coil - works well.


Onto the first daytime tests
Sensitivity tests were conducted inside, between 10:30AM-Noon Local time Sunday 3/13.

Radios used:
Tecsun PL310 modified with a home made Gary Debock Type G LW antenna attached - note antenna peaked for LW reception, not MW.
Stock Tecsun PL390

Unless stated otherwise the station tuned was copyable.

1490 WBTA, 1KW, 45MI Dist
PL310 Handheld dBu&#92;dB 20&#92;00 no copy
PL310 w/FSL dBu&#92;dB 32&#92;25
PL310 w/ Terk dBu&#92;dB 32&#92;25
PL390 Handheld dBu&#92;dB 34&#92;03
PL390 w/ FSL dBu&#92;dB 45&#92;16
PL390 w/ Terk dBu&#92;dB 41&#92;25

1310 WSRB, 1KW, 25MI Dist
PL310 Handheld dBu&#92;dB 25&#92;25
PL310 w/ FSL dBu&#92;dB 57&#92;25
PL310 w/ Terk dBu&#92;dB 59&#92;25
PL390 Handheld dBu&#92;dB 49&#92;25
PL390 w/ FSL dBu&#92;dB 57&#92;25
PL390 w/ Terk dBu&#92;dB 63&#92;25

1070 WSCP, 2.5KW 125MI Dist
PL310 Handheld dBu&#92;dB 22&#92;00 no copy
PL310 w/ FSL dBu&#92;dB 37&#92;16
PL310 w/ Terk dBu&#92;dB 37&#92;13
PL390 Handheld dBu&#92;dB 39&#92;00
PL390 w/ FSL dBu&#92;dB 49&#92;10
PL390 w/ Terk dBu&#92;dB 43&#92;11

900 CHML, 50KW 90MI Dist
PL310 Handheld dBu&#92;dB 22&#92;00 Just audible
PL310 w/ FSL dBu&#92;dB 42&#92;10
PL310 w/ Terk dBu&#92;dB 33&#92;08
PL390 Handheld dBu&#92;dB 25&#92;14
PL390 w/ FSL dBu&#92;dB 38&#92;10
PL390 w/ Terk dBu&#92;dB 35&#92;10

800 CJBQ, 10KW 70MI Dist
PL310 Handheld dBu&#92;dB 27&#92;25
PL310 w/ FSL dBu&#92;dB 50&#92;25
PL310 w/ Terk dBu&#92;dB 54&#92;25
PL390 Handheld dBu&#92;dB 44&#92;25
PL390 w/ FSL dBu&#92;dB 50&#92;25
PL390 w/ Terk dBu&#92;dB 52&#92;25
Notes: Distance mostly over water.

710 CJRN, 10KW 70MI Dist
PL310 Handheld dBu&#92;dB 20&#92;09
PL310 w/ FSL dBu&#92;dB 44&#92;07
PL310 w/ Terk dBu&#92;dB 38&#92;08
PL390 Handheld dBu&#92;dB 28&#92;11
PL390 w/ FSL dBu&#92;dB 41&#92;07
PL390 w/ Terk dBu&#92;dB 35&#92;08


570 WSYR, 5KW 70MI Dist
PL310 Handheld dBu&#92;dB 22&#92;07
PL310 w/ FSL dBu&#92;dB 38&#92;05
PL310 w/ Terk dBu&#92;dB 27&#92;07
PL390 Handheld dBu&#92;dB 25&#92;15
PL390 w/ FSL dBu&#92;dB 32&#92;06
PL390 w/ Terk dBu&#92;dB 34&#92;07


General notes:
I was suprized at how close the Terk is to the FSL. More experimantation is due, perhaps lookig at distance betrween coil and Ferrite - I did not measure the thickness of two layers of bubble wrap.

As I got lower in the MW band frequencies lots more noise - perhaps due to RF interfernece w/in the house?

Comments welcome


Grundig

nonlinear@rogers.com <nonlinear@...>
 

Dear Marc


I have a Grundig also and you are right it has the fluted somewhat longish round ferrite rod inside.


best Paul

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