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boundary="-67346210-717020614-1317245230=:93206" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: ** X-Spam-Status: No, hits=2.2 required=5.0 tests=FORGED_YAHOO_RCVD,HTML_20_30, HTML_MESSAGE,NO_EXPERIENCE,TO_ADDRESS_EQ_REAL autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:475253312:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m016.1 ; domain : yahoo.com DKIM : fail x-aol-sid: 3039ac1d61874e83918a7090 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none ---67346210-717020614-1317245230=:93206 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hello Wolf, thank you for sharing this informstion. Yes I fully agree with = you that patch cords with crocodile clips could be an issue. I plan to re-d= o some measurements as soon as I will have given a more suitable "mechanica= l" look to the set.=0ABest 73=0ADaniele=0A=0A=0A___________________________= _____=0ADa: wolf_dl4yhf =0AA: rsgb_lf_group@blacksheep.o= rg=0AInviato: Mercoled=EC 28 Settembre 2011 22:46=0AOggetto: Re: LF: Re: My= first ferrite experiments=0A=0A=0AHi Daniele,=0A=0ALooking at those alliga= tor clips: Did you ever remove the rubber=0A insulation, and check the c= onnection between clip and cable, and=0A check the 'copper diameter' of = these cables ?=0AI did, and found that...=0A=0Aa) they didn't even solder t= hem, but used a trashy loose "crimp"=0A (well, not really crimped but cr= ippled) connection, the copper=0A conductor folded back over the wire's = insulation, sometimes only=0A slightly touching the chrome surface of th= e clip,=0A=0Ab) there's a ridiculously low amount of copper in those wire != =A0 (lot=0A of PVC which makes you *think* the wire is thick, but it's c= rap)=0A=0ACure: Replaced the wire with other colourful cabling salvaged fro= m a=0A PC power supply, and SOLDERED the wire to the clips. =0A=0AEffect= : DC resistance "from clip to clip" droppe to less than 25 %=0A of the o= riginal, for the same cable length.=0A=0AMaybe, if those cables are part of= your parallel resonant circuit on=0A the test bench, they are a show st= opper - besides the close=0A aluminium shield, which should really be a = bit closer away from the=0A rod / coil, or be slotted, as already sugges= ted by Peter.=0A=0ACheers,=0A=A0=A0 Wolf .=0A=0AAm 28.09.2011 21:05, schrie= b Daniele Tincani: =0AHello Stefan, =0A>=A0 =0A>this morning I received the= litz wire and tried another build, using a 16 mm PVC tube to enclose the 3= x ferrite rods. I wound 70 turns of litz (as good as I could) and went to = the test bench again to measure Q (please see the attached picture). In fac= t, things have improved a bit. With the air varcap I'm using for these test= s, tuning can range from about 235 KHz up to about 978 KHz. Using nominal m= in/max valued of capacitor, this gives approx L =3D 670uH which is very goo= d for my purposes. =0A>Unfortunately Q - although improved - is still quite= low: about 104 @ 235 KHz, about 60 @ 978 KHz. =0A>As I don't plan to try a= nother build of the ferrite-cored coil, I can only hope=A0that Q=A0will imp= rove further with shorter and better connections with the capacitor. =0A>Ma= ny thanks to you, Stefan, for the very helpful suggestions! =0A>=A0 =0A>Bes= t regards =0A>Daniele =0A>=A0 =0A>=0A> =0A>Da: Stefan Sch=E4fer =0A>A: rsgb_lf_group@blacksheep.org=0A>Inviato:= Marted=EC 27 Settembre 2011 22:42=0A>Oggetto: Re: LF: Re: My first ferrite= experiments=0A>=0A>=0A>Hi Daniele, =0A>=0A>Am 27.09.2011 17:15, schrieb Da= niele Tincani: =0A>Hello Stefan, =0A>>=A0 =0A>>> but maybe the Q is reduced= by the aluminium shield! =0A>>Do you think the aluminium could be the pro= blem or the distance between the coil and the core? =0AThe wire shouldn'= t wound directly on the rod. I have a PVC tube above the rod and so the wir= e is in a distance of about 3 mm to the rod. I used litz wire and got a Q o= f 485...=0A>=0A>=0A>I could replace the aluminium tube with a plastic tube,= if shielding is not necessary, but this would not improve the Q if the pro= blem is the gap between the coil and the core. =0AJust experiment what i= s the best solution. But the aluminium shield - if used - should be thin an= d can be applied above the winding in some distance. I know you have much Q= RM at home so probably an E field shield makes sense here. Anyway you will = be bothered by the local magnetic QRM of course. =0A>I personally think tha= t a shield is not necessary if you=0A are /p and far away from= man made noise. Then, a higher Q=0A helps more than the shiel= d and a Q of 30!=0A>=0A>=0A>=A0 =0A>>> Are the rods galvanically separated = from each other by a thin plastic tape? What type is the ferrite material? = =0A>>Yes I put two layers of plastic tape on tips of each rod. The ferrite = material is russian MU400HH. =0AFine! I also use the same ferrite type a= nd 55 turns. Your cap is surely the best what you can use. So shorten the w= ires between L and C and measure the Q on 137 kHz. If it is still in the ra= nge of 30, i assume the shield causes high losses.=0A>Another idea: There i= s some conducting spray available.=0A Maybe this can help here= ? No experience with that, just a=0A spontaneous idea... =0A>h= ttp://it.farnell.com/_/kontakt-chemie-emv-35-200ml/rivestimento-conductive-= emv-35/dp/220115 =0A>=0A> =0A>=0A>73, Stefan/DK7FC=0A> =0A>=0A> ---67346210-717020614-1317245230=:93206 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Hello Wolf, thank you= for sharing this informstion. Yes I fully agree with you that patch cords = with crocodile clips could be an issue. I plan to re-do some measurements a= s soon as I will have given a more suitable "mechanical" look to the set.
Best 73
Daniele

Da:= wolf_dl4yhf <dl4yhf@freenet.de>
A: rsgb_lf_group@blacksheep.org
Inviato: Mercoled=EC 28 Settembre 2011 22:46Oggetto: Re: LF: Re: My f= irst ferrite experiments

=0A =0A=0A= =0A =0A =0A Hi Daniele,
=0A
=0A Looking at those alli= gator clips: Did you ever remove the rubber=0A insulation, and check the= connection between clip and cable, and=0A check the 'copper diameter' o= f these cables ?
=0A I did, and found that...
=0A
=0A a)= they didn't even solder them, but used a trashy loose "crimp"=0A (well,= not really crimped but crippled) connection, the copper=0A conductor fo= lded back over the wire's insulation, sometimes only=0A slightly touchin= g the chrome surface of the clip,
=0A
=0A b) there's a ridicul= ously low amount of copper in those wire !  (lot=0A of PVC which ma= kes you *think* the wire is thick, but it's crap)
=0A
=0A Cure= : Replaced the wire with other colourful cabling salvaged from a=0A PC p= ower supply, and SOLDERED the wire to the clips.
=0A
=0A Effe= ct: DC resistance "from clip to clip" droppe to less than 25 %=0A of the= original, for the same cable length.
=0A
=0A Maybe, if those = cables are part of your parallel resonant circuit on=0A the test bench, = they are a show stopper - besides the close=0A aluminium shield, which s= hould really be a bit closer away from the=0A rod / coil, or be slotted,= as already suggested by Peter.
=0A
=0A Cheers,
=0A &nbs= p;  Wolf .
=0A
=0A Am 28.09.2011 21:05, schrieb Daniele T= incani:=0A
=0A
=0A
Hello Stefan,=
=0A
 
=0A
this m= orning=0A I received the litz wire and tried another build, usin= g a 16=0A mm PVC tube to enclose the 3 x ferrite rods. I wound 7= 0=0A turns of litz (as good as I could) and went to the test=0A = bench again to measure Q (please see the attached picture).=0A = In fact, things have improved a bit. With the air varcap I'm=0A = using for these tests, tuning can range from about 235 KHz=0A = up to about 978 KHz. Using nominal min/max valued of=0A = capacitor, this gives approx L =3D 670uH which is very good=0A f= or my purposes.
=0A
Unfortunately=0A = Q - although improved - is still quite low: about 104 @ 235=0A = KHz, about 60 @ 978 KHz.
=0A
As I don't=0A = plan to try another build of the ferrite-cored coil, I can=0A = only hope that Q will improve further with shorter and= =0A better connections with the capacitor.
=0A =
Many thanks=0A to you, Stefan, for the very helpful= suggestions!
=0A
 
=0A =
Best=0A regards
=0A =
Daniele
=0A
 
= =0A

=0A
=0A
=0A
=0A Da: Stefan=0A Sch=E4fer <Stefan.Schaefer@iup.uni-heidelberg.de><= br>=0A A:=0A = rsgb_lf_group@blacksheep.org=0A Inviato:=0A Marted=EC 27 Settembre 2011 22:42
=0A = Oggetto: Re:=0A = LF: Re: My first ferrite experiments
=0A
=0A = =0A
Hi Daniele,
=0A =
=0A Am 27.09.2011 17:15, schrieb Daniele Tincani:=0A =
=0A
=0A
=0A
=0A
Hello=0A Stefan,
=0A =
&nb= sp;
=0A
>=0A= but maybe the Q is reduced by the aluminium=0A = shield!
=0A
<= span id=3D"yiv884365265yui_3_2_0_14_1317135667750148">Do=0A = you think the aluminium could be the problem=0A = or the distance between the coil and the core?
=0A =
=0A
=0A
= =0A
=0A The wire shouldn't wound dir= ectly on the rod. I have a PVC=0A tube above the rod and so th= e wire is in a distance of=0A about 3 mm to the rod. I used li= tz wire and got a Q of=0A 485...
=0A
=0A =
=0A
=0A
=0A
=0A
I=0A could replace th= e aluminium tube with a=0A plastic tube, if shield= ing is not necessary,=0A but this would not improv= e the Q if the=0A problem is the gap between the c= oil and the=0A core.
=0A =
=0A
=0A
=0A =
=0A Just experiment what is the best soluti= on. But the=0A aluminium shield - if used - should be thin and= can be=0A applied above the winding in some distance. I know = you=0A have much QRM at home so probably an E field shield mak= es=0A sense here. Anyway you will be bothered by the local=0A = magnetic QRM of course.
=0A I personally thin= k that a shield is not necessary if you=0A are /p and far away= from man made noise. Then, a higher Q=0A helps more than the = shield and a Q of 30!
=0A
=0A
=0A
=0A
=0A =
=0A =
 
=0A
> Are the rods=0A galvanically separ= ated from each other by a=0A thin plastic tape? Wh= at type is the ferrite=0A material?
= =0A
Yes=0A I put two layers of plastic tape= on tips of=0A each rod. The ferrite material is r= ussian=0A MU400HH.
=0A =
=0A
=0A
=0A =
=0A Fine! I also use the same ferrite type an= d 55 turns. Your=0A cap is surely the best what you can use. S= o shorten the=0A wires between L and C and measure the Q on 13= 7 kHz. If it=0A is still in the range of 30, i assume the shie= ld causes=0A high losses.
=0A Another idea: Th= ere is some conducting spray available.=0A Maybe this can help= here? No experience with that, just a=0A spontaneous idea... =
=0A http://it.farnell.co= m/_/kontakt-chemie-emv-35-200ml/rivestimento-conductive-emv-35/dp/220115=0A
=0A =

=0A
=0A =
=0A
=0A
=0A
=0A= 73, Stefan/DK7FC
=0A
=0A
=0A
=0A
=0A =
=0A =0A
=0A
=0A =0A
=0A
=0A
=0A
=0A =0A= =0A


---67346210-717020614-1317245230=:93206--