Return-Path: X-Spam-DCC: paranoid 1233; 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=-0.7 required=5.0 tests=BAYES_00,HTML_MESSAGE, HTML_TITLE_EMPTY,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 u3SIdVQk001829 for ; Thu, 28 Apr 2016 20:39:33 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1avqlU-0005Sh-Jq for rs_out_1@blacksheep.org; Thu, 28 Apr 2016 19:34:16 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1avqlU-0005SY-0N for rsgb_lf_group@blacksheep.org; Thu, 28 Apr 2016 19:34:16 +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 1avqlR-0000Xh-V8 for rsgb_lf_group@blacksheep.org; Thu, 28 Apr 2016 19:34:14 +0100 Received: from dovecot03.posteo.de (dovecot03.posteo.de [172.16.0.13]) by mout01.posteo.de (Postfix) with ESMTPS id DDD7420B69 for ; Thu, 28 Apr 2016 20:34:12 +0200 (CEST) Received: from mail.posteo.de (localhost [127.0.0.1]) by dovecot03.posteo.de (Postfix) with ESMTPSA id 3qwlpr5p3Dz5vNG for ; Thu, 28 Apr 2016 20:34:12 +0200 (CEST) Message-ID: <572257A4.6090002@posteo.de> Date: Thu, 28 Apr 2016 20:34:12 +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> In-Reply-To: <5722503E.3000501@posteo.de> X-Scan-Signature: 5f3d51ad98dd7d967f54e1b86b99caac Subject: Re: VLF: T106-52 cores on VLF, continued, thoughts... Content-Type: multipart/alternative; boundary="------------090008050601020203090904" 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: 7898 This is a multi-part message in MIME format. --------------090008050601020203090904 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 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 >> --------------090008050601020203090904 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit 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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