Return-Path: X-Spam-DCC: paranoid 104; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-0.3 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_30_40,HTML_MESSAGE,RATWARE_GECKO_BUILD,SPF_PASS autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id u3SNa2hH002412 for ; Fri, 29 Apr 2016 01:36:02 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1avvP0-0006JC-7A for rs_out_1@blacksheep.org; Fri, 29 Apr 2016 00:31:22 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1avvOz-0006J3-66 for rsgb_lf_group@blacksheep.org; Fri, 29 Apr 2016 00:31:21 +0100 Received: from mout01.posteo.de ([185.67.36.65]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1avvOw-0001VF-Lp for rsgb_lf_group@blacksheep.org; Fri, 29 Apr 2016 00:31:20 +0100 Received: from dovecot03.posteo.de (dovecot03.posteo.de [172.16.0.13]) by mout01.posteo.de (Postfix) with ESMTPS id 0EE5920A44 for ; Fri, 29 Apr 2016 01:31:15 +0200 (CEST) Received: from mail.posteo.de (localhost [127.0.0.1]) by dovecot03.posteo.de (Postfix) with ESMTPSA id 3qwtPZ6v0Zz5vMw for ; Fri, 29 Apr 2016 01:31:14 +0200 (CEST) Message-ID: <57229D42.5040008@posteo.de> Date: Fri, 29 Apr 2016 01:31:14 +0200 From: DK7FC User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <571CF2AD.9030207@posteo.de> <571D2966.5080104@posteo.de> <571D3034.8020204@mbsks.franken.de> <571D31EE.9030106@posteo.de> <571DD4DE.3080703@abelian.org> <571E54B9.9010208@posteo.de> <571E5C16.2090102@mbsks.franken.de> <571E5F26.1080605@mbsks.franken.de> <571E92A0.3000608@posteo.de> <571E98A7.5070503@posteo.de> <571F87A2.7000700@abelian.org> <571FC3E8.1000706@posteo.de> <5720D81D.6020609@abelian.org> <5720E958.2010104@posteo.de> <572102E9.7020607@posteo.de> <5722503E.3000501@posteo.de>,<572257A4.6090002@posteo.de> <1461874994878.61188@fys.kuleuven.be> In-Reply-To: <1461874994878.61188@fys.kuleuven.be> X-Scan-Signature: fcf77e2759cb043d8839e008dc214d5a Subject: Re: VLF: T106-52 cores on VLF, continued, thoughts... Content-Type: multipart/alternative; boundary="------------070303070107050405070000" 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-Scanned-By: MIMEDefang 2.56 on 10.1.3.11 Status: O X-Status: X-Keywords: X-UID: 7903 This is a multi-part message in MIME format. --------------070303070107050405070000 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Hi Rik, the experiment with 5 cores has shown that the iron powder cores are not so efficient at a low l/d. But of course they help a bit, like seen in the current transmit coil configuration that i use. I'm going to order the 3C-85 ferrites and continue with the experiments. These high ur ferrites are useful for several applications anyway.. 73, Stefan Am 28.04.2016 22:23, schrieb Rik Strobbe: > > Hi Stefan, > > what about a "fatter" (length/diameter = 1) coil filled with some core > stacks in parallel? > > For a slim coil (large length/diameter ratio) the inductance is more > or less proportional to the number of windings while for a fat coil > inductance is more or less proportional to the square of the number of > windings. > > But I don't know how effective the cores will be in such a fat coil. > > 73, Rik ON7YD - OR7T > > ------------------------------------------------------------------------ > *Van:* owner-rsgb_lf_group@blacksheep.org > namens DK7FC > *Verzonden:* donderdag 28 april 2016 20:34 > *Aan:* rsgb_lf_group@blacksheep.org > *Onderwerp:* Re: VLF: T106-52 cores on VLF, continued, thoughts... > OK, after a break in the sunset i thought: > If µr tends to 6.5 and L/l to 22 mH/m for 0.5mm wire for l -> > infinity, and if i want to keep the coil length at 0.8m, which would > be 17.6 mH for 0.5mm wire. However i need 788 mH! So i need a 6.7 > times smaller wire, i.e. 0.074mm diameter. This is impossible and i > wouldn't carry the antenna current. > A new coil would only make sense if i can rise the signal by at least > 6 dB. I just measured 260 mA. So let's say 600 mA would be fine. And i > like the 0.4mm wire and would like to use that. > In the moment i see no chance for a single layer coil using this > technique :-( > > 73, Stefan > > Am 28.04.2016 20:02, schrieb DK7FC: >> Hmm, well, ok, after some discussions, the show ehm the experiments >> must go on. >> >> I'm continuing with a higher l/d ratio. 13 of these cores are >> available, the other ones are parts of my transmit coil now. I like >> to get 3 measurements to approximate a curve showing L/l and µr(eff) >> over the ratio l/d. So a useful number of cores is 5 (already done, >> see below), 9 and 13. >> >> *_5 core stack (yesterdays measurement):_* >> The ratio coil diameter / coil length, *l/d = 49/33 = 1.48*. >> Effective *µr = 3.75* >> L/l = 452 µH / 49 mm = *9.22 mH/m* >> >> *_9 core stack:_* >> As a resonance C i use 0.3 uF (measured C = 306 nF) >> The resonance is at 7.26 kHz. The bandwidth is (7.36 - 7.18) kHz = >> 180 Hz. Q = 40. L = 1.75 mH >> Without the cores inside, the resonance is found at f = 17.1 kHz. BW >> is (17.6 - 16.69) kHz = 1.05 kHz. Q = 16.8. L = 283 µH. >> https://dl.dropboxusercontent.com/u/19882028/VLF/9%20cores.jpg >> *l/d = 96/33 = 2.91* >> So now the effective *µr is 6.18* >> L/l = 1.75 mH / 96 mm = *18.23 mH/m* >> L/l (9) / L/l (5) = 1.98 >> >> _*13 core stack:*_ >> C= 202 nF >> Resonance (with cores) at 6.485 kHz. BW = (6.56 - 6.42) kHz = 140 Hz. >> Q = 46. L = 2.98 mH >> https://dl.dropboxusercontent.com/u/19882028/VLF/13cores.jpg >> Resonance (without cores) at 16.78 kHz. BW = (17.26 - 16.38) kHz = >> 880 Hz. Q = 19. L = 445 µH. >> *l/d = 145/33 = 4.39* >> The effective *µr = 6.70* >> L/l = 2.98 mH / 145 mm = *20.55 mH/m* >> >> OK, now, this tends to a certain value for L/l, maybe 22 mH/m (see >> attachment) for a 0.5mm diameter wire. Hmm, so my coil would be just >> 35m high, about as high as the feed point of the antenna :-) >> So a thinner wire is needed or a tube with 3 or more cores in parallel. >> More soon... >> >> 73, Stefan >> >> >> Am 27.04.2016 20:20, schrieb DK7FC: >>> Hi VLF, >>> >>> I've done a quick experiment with the T106-52 cores which could give >>> some more ideas regarding these cores for a compact VLF coil. >>> >>> I wound a coil with 0.5mm enameled cu wire, 85 turns at 33mm >>> diameter. Inside the coil there are 5 of these cores stacked on >>> another. In parallel there is a suitable C of 1 uF. >>> https://dl.dropboxusercontent.com/u/19882028/VLF/20160427_195530.jpg >>> >>> The resonance was found at 7.49 kHz. The 3 dB bandwidth is >>> (7.64-7.36) kHz = 280 Hz. Q = 27. L = 452 uH. >>> Without the cores inside, the resonance frequency rises to 14.54 kHz >>> and the bandwidth is (15.12-14.07) kHz = 1.05 kHz. Q = 14. L = 120 uH. >>> >>> Hmm, so in this configuration, the *effective µr (ur) seems to be >>> just 3.75*! :-/ >>> That means i still need half of the number of turns for a single >>> layer VLF transmit coil?!? >>> >>> 73, Stefan >>> --------------070303070107050405070000 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Hi Rik,

the experiment with 5 cores has shown that the iron powder cores are not so efficient at a low l/d. But of course they help a bit, like seen in the current transmit coil configuration that i use.
I'm going to order the 3C-85 ferrites and continue with the experiments. These high ur ferrites are useful for several applications anyway..

73, Stefan

Am 28.04.2016 22:23, schrieb Rik Strobbe:

Hi Stefan,

 

what about a "fatter" (length/diameter = 1) coil filled with some core stacks in parallel?

For a slim coil (large length/diameter ratio) the inductance is more or less proportional to the number of windings while for a fat coil inductance is more or less proportional to the square of the number of windings.

But I don't know how effective the cores will be in such a fat coil.

 

73, Rik  ON7YD - OR7T

 

Van: owner-rsgb_lf_group@blacksheep.org <owner-rsgb_lf_group@blacksheep.org> namens DK7FC <selberdenken@posteo.de>
Verzonden: donderdag 28 april 2016 20:34
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: VLF: T106-52 cores on VLF, continued, thoughts...
 
OK, after a break in the sunset i thought:
If µr tends to 6.5 and L/l to 22 mH/m for 0.5mm wire for l -> infinity, and if i want to keep the coil length at 0.8m, which would be 17.6 mH for 0.5mm wire. However i need 788 mH! So i need a 6.7 times smaller wire, i.e. 0.074mm diameter. This is impossible and i wouldn't carry the antenna current.
A new coil would only make sense if i can rise the signal by at least 6 dB. I just measured 260 mA. So let's say 600 mA would be fine. And i like the 0.4mm wire and would like to use that.
In the moment i see no chance for a single layer coil using this technique :-(

73, Stefan

Am 28.04.2016 20:02, schrieb DK7FC:
Hmm, well, ok, after some discussions, the show ehm the experiments must go on.

I'm continuing with a higher l/d ratio. 13 of these cores are available, the other ones are parts of my transmit coil now. I like to get 3 measurements to approximate a curve showing L/l and µr(eff) over the ratio l/d. So a useful number of cores is 5 (already done, see below), 9 and 13.

5 core stack (yesterdays measurement):
The ratio coil diameter / coil length, l/d = 49/33 = 1.48.
Effective µr = 3.75
L/l = 452 µH / 49 mm = 9.22 mH/m

9 core stack:
As a resonance C i use 0.3 uF (measured C = 306 nF)
The resonance is at 7.26 kHz. The bandwidth is (7.36 - 7.18) kHz = 180 Hz. Q = 40. L = 1.75 mH
Without the cores inside, the resonance is found at f = 17.1 kHz. BW is (17.6 - 16.69) kHz = 1.05 kHz. Q = 16.8. L = 283 µH.
https://dl.dropboxusercontent.com/u/19882028/VLF/9%20cores.jpg
l/d = 96/33 = 2.91
So now the effective µr is 6.18
L/l = 1.75 mH / 96 mm = 18.23 mH/m
L/l (9) / L/l (5) = 1.98

13 core stack:
C= 202 nF
Resonance (with cores) at 6.485 kHz. BW = (6.56 - 6.42) kHz = 140 Hz. Q = 46. L = 2.98 mH
https://dl.dropboxusercontent.com/u/19882028/VLF/13cores.jpg
Resonance (without cores) at 16.78 kHz. BW = (17.26 - 16.38) kHz = 880 Hz. Q = 19. L = 445 µH.
l/d = 145/33 = 4.39
The effective µr = 6.70
L/l = 2.98 mH / 145 mm = 20.55 mH/m

OK, now, this tends to a certain value for L/l, maybe 22 mH/m (see attachment) for a 0.5mm diameter wire. Hmm, so my coil would be just 35m high, about as high as the feed point of the antenna :-)
So a thinner wire is needed or a tube with 3 or more cores in parallel.
More soon...

73, Stefan


Am 27.04.2016 20:20, schrieb DK7FC:
Hi VLF,

I've done a quick experiment with the T106-52 cores which could give some more ideas regarding these cores for a compact VLF coil.

I wound a coil with 0.5mm enameled cu wire, 85 turns at 33mm diameter. Inside the coil there are 5 of these cores stacked on another. In parallel there is a suitable C of 1 uF.
https://dl.dropboxusercontent.com/u/19882028/VLF/20160427_195530.jpg

The resonance was found at 7.49 kHz. The 3 dB bandwidth is (7.64-7.36) kHz = 280 Hz. Q = 27. L = 452 uH.
Without the cores inside, the resonance frequency rises to 14.54 kHz and the bandwidth is (15.12-14.07) kHz = 1.05 kHz. Q = 14. L = 120 uH.

Hmm, so in this configuration, the effective µr (ur) seems to be just 3.75! :-/
That means i still need half of the number of turns for a single layer VLF transmit coil?!?

73, Stefan

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