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Message-ID: <1317245230.93206.YahooMailNeo@web29501.mail.ird.yahoo.com>
Date: Wed, 28 Sep 2011 22:27:10 +0100 (BST)
From: Daniele Tincani <danieletincani@yahoo.com>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
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Subject: Re: LF: Re: My first ferrite experiments
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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 <dl4yhf@freenet.de>=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 <Stefan.Sch=
aefer@iup.uni-heidelberg.de>=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>    
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<html><body><div style=3D"color:#000; background-color:#fff; font-family:ar=
ial, helvetica, sans-serif;font-size:10pt"><div><span>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.</=
span></div><div><span>Best 73</span></div><div><span>Daniele</span></div><d=
iv><br></div><div style=3D"font-family: arial, helvetica, sans-serif; font-=
size: 10pt;"><div style=3D"font-family: times new roman, new york, times, s=
erif; font-size: 12pt;"><font size=3D"2" face=3D"Arial"><div style=3D"margi=
n: 5px 0px; padding: 0px; border: 1px solid rgb(204, 204, 204); height: 0px=
; line-height: 0; font-size: 0px;" class=3D"hr" contentEditable=3D"false" r=
eadonly=3D"true"></div><b><span style=3D"font-weight: bold;">Da:</span></b>=
 wolf_dl4yhf &lt;dl4yhf@freenet.de&gt;<br><b><span style=3D"font-weight:
 bold;">A:</span></b> rsgb_lf_group@blacksheep.org<br><b><span style=3D"fon=
t-weight: bold;">Inviato:</span></b> Mercoled=EC 28 Settembre 2011 22:46<br=
><b><span style=3D"font-weight: bold;">Oggetto:</span></b> Re: LF: Re: My f=
irst ferrite experiments<br></font><br><div id=3D"yiv884365265">=0A  =0A=0A=
    =0A  =0A  =0A    Hi Daniele,<br>=0A    <br>=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 ?<br>=0A    I did, and found that...<br>=0A    <br>=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,<br>=0A    <br>=0A    b) there's a ridicul=
ously low amount of copper in those wire !&nbsp; (lot=0A    of PVC which ma=
kes you *think* the wire is thick, but it's crap)<br>=0A    <br>=0A    Cure=
: Replaced the wire with other colourful cabling salvaged from a=0A    PC p=
ower supply, and SOLDERED the wire to the clips. <br>=0A    <br>=0A    Effe=
ct: DC resistance "from clip to clip" droppe to less than 25 %=0A    of the=
 original, for the same cable length.<br>=0A    <br>=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.<br>=0A    <br>=0A    Cheers,<br>=0A    &nbs=
p;&nbsp; Wolf .<br>=0A    <br>=0A    Am 28.09.2011 21:05, schrieb Daniele T=
incani:=0A    <blockquote type=3D"cite">=0A      <div style=3D"color: rgb(0=
, 0, 0); font-family: arial, helvetica, sans-serif; font-size: 10pt; backgr=
ound-color: rgb(255, 255, 255);">=0A        <div><span>Hello Stefan,</span>=
</div>=0A        <div><span></span>&nbsp;</div>=0A        <div><span>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.</span></div>=0A        <div><span>Unfortunately=0A         =
   Q - although improved - is still quite low: about 104 @ 235=0A          =
  KHz, about 60 @ 978 KHz.</span></div>=0A        <div><span>As I don't=0A =
           plan to try another build of the ferrite-cored coil, I can=0A   =
         only hope&nbsp;that Q&nbsp;will improve further with shorter and=
=0A            better connections with the capacitor.</span></div>=0A      =
  <div><span>Many thanks=0A            to you, Stefan, for the very helpful=
 suggestions!</span></div>=0A        <div><span></span>&nbsp;</div>=0A     =
   <div><span>B<var id=3D"yiv884365265yui-ie-cursor"></var><var id=3D"yiv88=
4365265yui-ie-cursor"></var>est=0A            regards</span></div>=0A      =
  <div><span>Daniele</span></div>=0A        <div><span></span>&nbsp;</div>=
=0A        <div><br>=0A        </div>=0A        <div style=3D"font-family: =
arial, helvetica, sans-serif; font-size: 10pt;">=0A          <div style=3D"=
font-family: times new roman, new york, times, serif; font-size: 12pt;"><fo=
nt size=3D"2" face=3D"Arial">=0A              <b><span style=3D"font-weight=
: bold;">Da:</span></b> Stefan=0A              Sch=E4fer <a class=3D"yiv884=
365265moz-txt-link-rfc2396E" href=3D"mailto:Stefan.Schaefer@iup.uni-heidelb=
erg.de" rel=3D"nofollow" target=3D"_blank" ymailto=3D"mailto:Stefan.Schaefe=
r@iup.uni-heidelberg.de">&lt;Stefan.Schaefer@iup.uni-heidelberg.de&gt;</a><=
br>=0A              <b><span style=3D"font-weight: bold;">A:</span></b>=0A =
             <a class=3D"yiv884365265moz-txt-link-abbreviated" href=3D"mail=
to:rsgb_lf_group@blacksheep.org" rel=3D"nofollow" target=3D"_blank" ymailto=
=3D"mailto:rsgb_lf_group@blacksheep.org">rsgb_lf_group@blacksheep.org</a><b=
r>=0A              <b><span style=3D"font-weight: bold;">Inviato:</span></b=
>=0A              Marted=EC 27 Settembre 2011 22:42<br>=0A              <b>=
<span style=3D"font-weight: bold;">Oggetto:</span></b> Re:=0A              =
LF: Re: My first ferrite experiments<br>=0A            </font><br>=0A      =
      =0A            <div id=3D"yiv884365265">Hi Daniele, <br>=0A          =
    <br>=0A              Am 27.09.2011 17:15, schrieb Daniele Tincani:=0A  =
            <blockquote type=3D"cite">=0A                <div style=3D"colo=
r: rgb(0, 0, 0); font-family: arial, helvetica, sans-serif; font-size: 10pt=
; background-color: rgb(255, 255, 255);">=0A                  <div id=3D"yi=
v884365265">=0A                    <div style=3D"color: rgb(0, 0, 0); font-=
family: arial, helvetica, sans-serif; font-size: 10pt; background-color: rg=
b(255, 255, 255);">=0A                      <div id=3D"yiv884365265yui_3_2_=
0_14_131713566775043"><span id=3D"yiv884365265yui_3_2_0_14_131713566775057"=
>Hello=0A                          Stefan,</span></div>=0A                 =
     <div><span id=3D"yiv884365265yui_3_2_0_14_1317135667750107"></span>&nb=
sp;</div>=0A                      <div id=3D"yiv884365265yui_3_2_0_14_13171=
35667750132"><span id=3D"yiv884365265yui_3_2_0_14_1317135667750134">&gt;=0A=
                          but maybe the Q is reduced by the aluminium=0A   =
                       shield! </span></div>=0A                      <div><=
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?</span></div>=0A     =
               </div>=0A                  </div>=0A                </div>=
=0A              </blockquote>=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...<br>=0A              <br>=0A  =
            <blockquote type=3D"cite">=0A                <div style=3D"colo=
r: rgb(0, 0, 0); font-family: arial, helvetica, sans-serif; font-size: 10pt=
; background-color: rgb(255, 255, 255);">=0A                  <div id=3D"yi=
v884365265">=0A                    <div style=3D"color: rgb(0, 0, 0); font-=
family: arial, helvetica, sans-serif; font-size: 10pt; background-color: rg=
b(255, 255, 255);">=0A                      <div><span id=3D"yiv884365265yu=
i_3_2_0_14_1317135667750148">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.</span></div>=0A              =
      </div>=0A                  </div>=0A                </div>=0A        =
      </blockquote>=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. <br>=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!<br>=0A              <br>=0A              <blockquote =
type=3D"cite">=0A                <div style=3D"color: rgb(0, 0, 0); font-fa=
mily: arial, helvetica, sans-serif; font-size: 10pt; background-color: rgb(=
255, 255, 255);">=0A                  <div id=3D"yiv884365265">=0A         =
           <div style=3D"color: rgb(0, 0, 0); font-family: arial, helvetica=
, sans-serif; font-size: 10pt; background-color: rgb(255, 255, 255);">=0A  =
                    <div><span id=3D"yiv884365265yui_3_2_0_14_1317135667750=
1155"></span>&nbsp;</div>=0A                      <div id=3D"yiv884365265yu=
i_3_2_0_14_13171356677501281"><span id=3D"yiv884365265yui_3_2_0_14_13171356=
677501283">&gt; Are the rods=0A                          galvanically separ=
ated from each other by a=0A                          thin plastic tape? Wh=
at type is the ferrite=0A                          material?</span></div>=
=0A                      <div><span id=3D"yiv884365265yui_3_2_0_14_13171356=
677501306">Yes=0A                          I put two layers of plastic tape=
 on tips of=0A                          each rod. The ferrite material is r=
ussian=0A                          MU400HH.</span></div>=0A                =
    </div>=0A                  </div>=0A                </div>=0A          =
    </blockquote>=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.<br>=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... =
<br>=0A              <a class=3D"yiv884365265moz-txt-link-freetext" href=3D=
"http://it.farnell.com/_/kontakt-chemie-emv-35-200ml/rivestimento-conductiv=
e-emv-35/dp/220115" rel=3D"nofollow" target=3D"_blank">http://it.farnell.co=
m/_/kontakt-chemie-emv-35-200ml/rivestimento-conductive-emv-35/dp/220115</a=
>=0A              <div style=3D"color: rgb(0, 0, 0); font-family: arial, he=
lvetica, sans-serif; font-size: 10pt; background-color: rgb(255, 255, 255);=
">=0A                <div style=3D"font-family: arial, helvetica, sans-seri=
f; font-size: 10pt;" id=3D"yiv884365265yui_3_2_0_14_131713566775047">=0A   =
               <div style=3D"font-family: times new roman, new york, times,=
 serif; font-size: 12pt;"><br>=0A                  </div>=0A               =
 </div>=0A              </div>=0A              <br>=0A              <br>=0A=
              73, Stefan/DK7FC<br>=0A              <blockquote type=3D"cite=
">=0A                <div style=3D"color: rgb(0, 0, 0); font-family: arial,=
 helvetica, sans-serif; font-size: 10pt; background-color: rgb(255, 255, 25=
5);">=0A                </div>=0A              </blockquote>=0A            =
</div>=0A            =0A            <br>=0A            <br>=0A          </d=
iv>=0A        </div>=0A      </div>=0A    </blockquote>=0A    <br>=0A  =0A=
=0A</div><br><br></div></div></div></body></html>
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