Date   

Re: Ferrite Sleeve Antenna Permeability

ferrite61 <dxrx@...>
 

Yes, solid wire is much worse Q-wise than Litz. However, if you look at that best inductor, Ben used #31 solid wire of the same turns and coil length. The spacing is nearly 2 parts space to 1 part wire. But in general proper-spacing or more is better. Better to err on the side of empty space at least.

The un-mentioned part of this experiment...get a very good air-variable cap! If both cap and coil are Q = 1000, then the circuit Q is 500.

Paul S. in CT

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

I actually printed Ben's paper and chugged through it last night. I was
stunned to find how how bad "ordinary" (solid) wire was in these
applications, even when space wound to mitigate the proximity effect.

Your clarification is appreciated!

Jerry W
KI4IO
Warrenton, VA


On Wed, 2011-03-16 at 01:22 +0000, ferrite61 wrote:
I would like to respond here and clarify some points made by Ben in a more direct manner. The page referenced is an excellent page. Perhaps some should skip past some of the more technical parts, and look at the data published, and go back later when ready to tackle the equivilent descriptions of the inductor. What Ben did was in two parts; the first was to establish the Litz wire as best suitable for the application by trying different bundles of #46 Litz. Smaller and larger bundles were compared in making 250uH ferrite inductors. What he found was that at larger bundles, the length of the coil winding became too great, and small bundles did not occupy enough of the ferrite rod length. What did the best was one particular bundle that had 125 strands, that when wound upon the rod occupied about 1/3 of the ferrite rod length.

Part two involved using that "best" configuration directly on the rod, and then placing insulators between the rod, and the winding. Note the Q values encountered (Table 2)in the AM-BCB, especially those at the low (520kHz) and high (1710 kHz). There is a trade-off here, and one's needs might favor one set of results over another, thus, "your methods may vary". Also of note is the "Air-Core Inductance" in table 1. As the spacing between core and coil increases, the "Air Core" inductance increases. BUT NOTE the Ferrite Inductor does not change inductance much at all.

In brief, Ben has demonstrated a reduction of the Electric field (in the wire) that causes losses in the inductor by spacing the coil away from the ferrite rod by using an insulator: plastics, or air. When first written this was a large leap of understanding of ferrite inductors for most of us "ordinary" folks that wanted a High-Q but reletively small package.

Now lets look at the real-world of "what you may have seen". Some of the older pocket transistor radios used to wrap the coil on a paper or cardboard sleeve, and place that assembly on the powdered iron/ferrite strip/rod. This effect that Ben wites and exemplifies is what was to be achieved. Ben's choice of Polypropylene, and Polyehtylene plastics are novel, and quite good for finding a common material "around the house". I also would add that "heat-shrink tubing" is made of the same family of plastic as these other two, and can also work quite well.

So I am quite sure that Ben's theories and experimentaion leads one to believe that a shorter coil length was better than a longer one: keeping the perspective that such coil winding occupies about 1/3 of the ferrite rod length. Thus the aspect of one part of the Ferrite Sleeve Core Inductor has been established: the insulation of ferrite core and wire-wrapping.

Paul S. in CT


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

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

Jerry W



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

Yahoo! Groups Links



One new Station last nite

ferrite61 <dxrx@...>
 

Got busy today, so heres last nites happy recap.

The West opened up a lot, and I logged WQLR Kalamazoo, MI as several station mentions on 1660 kHz. WWRU and WBCN could only partially null, their signals here are quite strong. Power is 1kW distance is 1051km.

2 Prospects also caught, definate Ranchero/Mexican-style on 1630 in a WNW direction, and ESPN heard on 1660 also WNW.

Paul S. in CT


Re: Warnign: extra 20dB could shatter your ultralight dreams!

Gary DeBock
 

Hello Nick,

Thanks for the interesting story, and warning :-)

It's certainly true that fanatical receiving antennas can boost the
reception capability of Ultralight radios into the "big leagues,"
especially when compared to state-of-the-art receivers connected to
mediocre aerials. The effect is similar to that of an amateur radio QRP
operator breaking DX pileups with 2 watts to a multi-element quad
antenna, beating out others with 100 watts to a dipole.

I suppose that every Ultralight radio fanatic must choose the type of
antenna which provides the desired level of challenge. Just like with
QRP operation, a super antenna can turn a modest Ultralight radio into
a mean DXing machine. During the discussion of the new Ultralight
Longwave Awards Program, Steve R. and I both knew that huge external
antennas should not be in the same awards category as compact ferrite
systems-- which is why we created the "Handheld Class" and the
"Unlimited Class."

73, Gary DeBock (in Puyallup, WA, USA)

-----Original Message-----
From: VK2DX <nick@...>
To: ultralight <ultralightdx@...>
Sent: Wed, Mar 16, 2011 12:53 pm
Subject: [ultralightdx] Warnign: extra 20dB could shatter your
ultralight dreams!

 
Hi all -
 
two new ones, including TNK from VK8 - the last missing Australian
state.
 
Date            GMT   Freq      
ID                                                 Km       QTH
20110315 1850 272    TNK        1020 9         2308  TENNANT CREEK, NN,
AUS
20110316 1912 227    LVG   400  400  9         497   MOUNT LIVINGSTON,
VI, AUS
 
An observation: couple days ago I've decided to re-erect 600m
transmitting antenna for some on-air tests.
(I am licnesed as AX2VKX to operate on 500KHz as a part of WIA
scientific license program).
 
The antenna consists of 13m vertical aluminum tubing and 6m top loading
wire (horizontal)
tuned to 510KHz with 1mH variometer. The variometer is a big bucket
coil with a smaller coil
rotating inside. One end is directly grounded and  coax is connected
ont the tap
for  50 Ohm match.
 
The antenna was laying on the ground during summer months.
Anyway, after I got the antenna up, I've noticed that my ultralight
sounds funny:
there were more signals everywhere! Bringing the PL-380 close to
loading coil
signals increased to point where I could hear 2000Km beacons as strong
as I would hear them on "big " radio with external antenna!
It was an amazing experience. I can only estimate additional gain to at
least 20dB.
The TUT from American Samoa (4,300 Km)  was solid 599. I could also
copy another 6 beacons from VK6 and
dozen or so New Zealanders! Obviously my transmitting antenna was
coupled with
ferrite rod to variometer. The best coupling was with PL-380 placed directly on the ground
( antena stands over very decent ground system) and about 20cm away
from the loading coil.
The field was so strong that bringing the radio any closer would cause
overload.
 
Reception (and directivity) was so good that I am now a changed man :-(
but for the worse!
The mystique of chasing new ones is gone... I know that my ultralight
radio is
capable of hearing stuff I never thought was possible to hear. The
challenge is gone.
My Christmas toy was broken, my dreams shattered in pieces...
Chasing signals was like fishing in a fish pond at the fish market!
 
Next day transmitting antenna was taken down and darn variometer was
locked in garage.
It took me some time to pull my self together and
turn the ultralight ON once again... Thankfully, thing as now almost
back to normal ;-d
 
The bottom line is this: large tuned (and untuned) antenna structures
could "artificially" improve
your ultralight reception and you may (or may not) be even aware of it!
Yes, too much gain is not always desirable thing :-( unless of course,
this is what you want!
 
 
73 Nick VK2DX
 
ultralight total : 102 NDBs


Warnign: extra 20dB could shatter your ultralight dreams!

VK2DX <nick@...>
 

Hi all -
 
two new ones, including TNK from VK8 - the last missing Australian state.
 
Date            GMT   Freq       ID                                                 Km       QTH
20110315 1850 272    TNK        1020 9         2308  TENNANT CREEK, NN, AUS
20110316 1912 227    LVG   400  400  9         497   MOUNT LIVINGSTON, VI, AUS
 
An observation: couple days ago I've decided to re-erect 600m transmitting antenna for some on-air tests.
(I am licnesed as AX2VKX to operate on 500KHz as a part of WIA scientific license program).
 
The antenna consists of 13m vertical aluminum tubing and 6m top loading wire (horizontal)
tuned to 510KHz with 1mH variometer. The variometer is a big bucket coil with a smaller coil
rotating inside. One end is directly grounded and  coax is connected ont the tap
for  50 Ohm match.
 
The antenna was laying on the ground during summer months.
Anyway, after I got the antenna up, I've noticed that my ultralight sounds funny:
there were more signals everywhere! Bringing the PL-380 close to loading coil
signals increased to point where I could hear 2000Km beacons as strong
as I would hear them on "big " radio with external antenna!
It was an amazing experience. I can only estimate additional gain to at least 20dB.
The TUT from American Samoa (4,300 Km)  was solid 599. I could also copy another 6 beacons from VK6 and
dozen or so New Zealanders! Obviously my transmitting antenna was coupled with
ferrite rod to variometer. The best coupling was with PL-380 placed directly on the ground
( antena stands over very decent ground system) and about 20cm away from the loading coil.
The field was so strong that bringing the radio any closer would cause overload.
 
Reception (and directivity) was so good that I am now a changed man :-( but for the worse!
The mystique of chasing new ones is gone... I know that my ultralight radio is
capable of hearing stuff I never thought was possible to hear. The challenge is gone.
My Christmas toy was broken, my dreams shattered in pieces...
Chasing signals was like fishing in a fish pond at the fish market!
 
Next day transmitting antenna was taken down and darn variometer was locked in garage.
It took me some time to pull my self together and
turn the ultralight ON once again... Thankfully, thing as now almost back to normal ;-d
 
The bottom line is this: large tuned (and untuned) antenna structures could "artificially" improve
your ultralight reception and you may (or may not) be even aware of it!
Yes, too much gain is not always desirable thing :-( unless of course, this is what you want!
 
 
73 Nick VK2DX
 
ultralight total : 102 NDBs
 
 
 
 
 


Re: Ferrite Sleeve Antenna Permeability

Gerald Wolczanski <jerrywolczanski@...>
 

I actually printed Ben's paper and chugged through it last night. I was
stunned to find how how bad "ordinary" (solid) wire was in these
applications, even when space wound to mitigate the proximity effect.

Your clarification is appreciated!

Jerry W
KI4IO
Warrenton, VA

On Wed, 2011-03-16 at 01:22 +0000, ferrite61 wrote:
I would like to respond here and clarify some points made by Ben in a more direct manner. The page referenced is an excellent page. Perhaps some should skip past some of the more technical parts, and look at the data published, and go back later when ready to tackle the equivilent descriptions of the inductor. What Ben did was in two parts; the first was to establish the Litz wire as best suitable for the application by trying different bundles of #46 Litz. Smaller and larger bundles were compared in making 250uH ferrite inductors. What he found was that at larger bundles, the length of the coil winding became too great, and small bundles did not occupy enough of the ferrite rod length. What did the best was one particular bundle that had 125 strands, that when wound upon the rod occupied about 1/3 of the ferrite rod length.

Part two involved using that "best" configuration directly on the rod, and then placing insulators between the rod, and the winding. Note the Q values encountered (Table 2)in the AM-BCB, especially those at the low (520kHz) and high (1710 kHz). There is a trade-off here, and one's needs might favor one set of results over another, thus, "your methods may vary". Also of note is the "Air-Core Inductance" in table 1. As the spacing between core and coil increases, the "Air Core" inductance increases. BUT NOTE the Ferrite Inductor does not change inductance much at all.

In brief, Ben has demonstrated a reduction of the Electric field (in the wire) that causes losses in the inductor by spacing the coil away from the ferrite rod by using an insulator: plastics, or air. When first written this was a large leap of understanding of ferrite inductors for most of us "ordinary" folks that wanted a High-Q but reletively small package.

Now lets look at the real-world of "what you may have seen". Some of the older pocket transistor radios used to wrap the coil on a paper or cardboard sleeve, and place that assembly on the powdered iron/ferrite strip/rod. This effect that Ben wites and exemplifies is what was to be achieved. Ben's choice of Polypropylene, and Polyehtylene plastics are novel, and quite good for finding a common material "around the house". I also would add that "heat-shrink tubing" is made of the same family of plastic as these other two, and can also work quite well.

So I am quite sure that Ben's theories and experimentaion leads one to believe that a shorter coil length was better than a longer one: keeping the perspective that such coil winding occupies about 1/3 of the ferrite rod length. Thus the aspect of one part of the Ferrite Sleeve Core Inductor has been established: the insulation of ferrite core and wire-wrapping.

Paul S. in CT


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

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

Jerry W



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

Yahoo! Groups Links



ULR-NDB log from France - 2nd evening

Patrick <aunumero73@...>
 

Hi all,

Despite regular static crashes, this 2nd evening with my brand new
7.5" LW loopstick PL-380 was a success !
30 NEW ONES and 4 NEW DXCC ! (Bosnia, Luxembourg, Balearic and
Guernesey islands).

kHz DD/MM/YYYY UTC ID Location
-----------------------------------------------------------
468.0 15/03/2011 2119 FTZ D Fritzlar
429.0 15/03/2011 2125 LOS HRV Losinj
424.0 15/03/2011 2230 RUS E Reus
417.0 15/03/2011 2139 AX F Auxerre / Branches
412.0 15/03/2011 2142 SE F Strasbourg / Entzheim
408.0 15/03/2011 2143 BRK AUT Wien / Schwechat / Bruck
406.0 15/03/2011 2147 MJ F Marseille / Provence
400.0 15/03/2011 2150 AG F Agen / La Garenne
395.0 15/03/2011 2154 OB F Marseille / Provence
393.0 15/03/2011 2157 BX F Mende / Brenoux
392.5 15/03/2011 2200 TOP I Torino / Poirino
394.0 15/03/2011 2201 NV F Nevers / Fourchambault
393.0 15/03/2011 2202 BD F Bordeaux / Merignac
390.5 15/03/2011 2204 ITR F Istres / Le Tube
389.0 15/03/2011 2205 PX F Perigueux / Bassillac
389.0 15/03/2011 2208 ZRZ E Zaragoza
383.0 15/03/2011 2217 MAR F Marseille / Provence
379.0 15/03/2011 2240 PIS I Pisa
374.0 15/03/2011 2242 BGC F Bergerac / Roumaniere
368.5 15/03/2011 2244 ELU LUX Luxembourg
370.0 15/03/2011 2245 GAC BIH Gacko
367.0 15/03/2011 2246 ZAG HRV Zagreb / Pleso
343.0 15/03/2011 2249 AR F Aurillac
347.0 15/03/2011 2250 CVT F Chalons / Vatry
288.5 15/03/2011 2252 AVD F Avord
306.5 15/03/2011 2256 AV F Avord
301.0 15/03/2011 2256 RTN F Romorantin
384.0 15/03/2011 2301 ADX E Andraitx for Palma de Mallorca (EA6 :
Balearic Island)
383.0 15/03/2011 2300 ALD G Alderney (GU : Guernesey Island)
359.5 15/03/2011 2310 CDN F Chateaudun

TOTAL : 82 NDB - 13 DXCC

Patrick
South-East France


NE Oregon ULR NDB DX

Steve Ratzlaff <steveratz@...>
 

Better LF conditions this evening, one new logging. 268 total.
Steve
NE Oregon
PL-380, 40-rod FSL

224 DN MB CAN 901 MI


Re: Very 1st ULR-NDB log from France !

Gary DeBock
 

Hello Patrick,

Congratulations on your first day of Ultralight NDB-DXing in France,
and in receiving 9 DXCC countries. If you are a collector of
"wallpaper," you have already qualified for ther new ULR Longwave "5
Countries Heard" Award Certificate (and almost qualified for the 10
Countries Heard Award Certificate, which would be the first one issued
anywhere in the world).

Your modified PL-380 model is identical to the ones used by Rob Ross,
Kevin Schanilec and myself, and we have all discovered that our best
NDB-DXing results are obtained outside the house, away from electrical
noise. Kevin and I live in a relatively warm area compared to Rob, who
needed to face freezing cold to log his first 100 NDB's in London,
Ontario, Canada (and is now recovering on a tropical cruise ship :-)

Good luck in tracking down more Ultralight NDB's!

73, Gary DeBock (in Puyallup, WA, USA)

-----Original Message-----
From: Patrick <aunumero73@...>
To: ultralightdx <ultralightdx@...>
Sent: Tue, Mar 15, 2011 1:43 pm
Subject: [ultralightdx] Very 1st ULR-NDB log from France !

 
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

ferrite61 <dxrx@...>
 

I would like to respond here and clarify some points made by Ben in a more direct manner. The page referenced is an excellent page. Perhaps some should skip past some of the more technical parts, and look at the data published, and go back later when ready to tackle the equivilent descriptions of the inductor. What Ben did was in two parts; the first was to establish the Litz wire as best suitable for the application by trying different bundles of #46 Litz. Smaller and larger bundles were compared in making 250uH ferrite inductors. What he found was that at larger bundles, the length of the coil winding became too great, and small bundles did not occupy enough of the ferrite rod length. What did the best was one particular bundle that had 125 strands, that when wound upon the rod occupied about 1/3 of the ferrite rod length.

Part two involved using that "best" configuration directly on the rod, and then placing insulators between the rod, and the winding. Note the Q values encountered (Table 2)in the AM-BCB, especially those at the low (520kHz) and high (1710 kHz). There is a trade-off here, and one's needs might favor one set of results over another, thus, "your methods may vary". Also of note is the "Air-Core Inductance" in table 1. As the spacing between core and coil increases, the "Air Core" inductance increases. BUT NOTE the Ferrite Inductor does not change inductance much at all.

In brief, Ben has demonstrated a reduction of the Electric field (in the wire) that causes losses in the inductor by spacing the coil away from the ferrite rod by using an insulator: plastics, or air. When first written this was a large leap of understanding of ferrite inductors for most of us "ordinary" folks that wanted a High-Q but reletively small package.

Now lets look at the real-world of "what you may have seen". Some of the older pocket transistor radios used to wrap the coil on a paper or cardboard sleeve, and place that assembly on the powdered iron/ferrite strip/rod. This effect that Ben wites and exemplifies is what was to be achieved. Ben's choice of Polypropylene, and Polyehtylene plastics are novel, and quite good for finding a common material "around the house". I also would add that "heat-shrink tubing" is made of the same family of plastic as these other two, and can also work quite well.

So I am quite sure that Ben's theories and experimentaion leads one to believe that a shorter coil length was better than a longer one: keeping the perspective that such coil winding occupies about 1/3 of the ferrite rod length. Thus the aspect of one part of the Ferrite Sleeve Core Inductor has been established: the insulation of ferrite core and wire-wrapping.

Paul S. in CT

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

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

Jerry W


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



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