Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-di06.r1000.mx.aol.com (Internet Inbound) with ESMTP id DFFDD38000093; Sun, 2 Dec 2012 17:23:07 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1TfHvY-0004py-51 for rs_out_1@blacksheep.org; Sun, 02 Dec 2012 22:22:20 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1TfHvX-0004pp-Cl for rsgb_lf_group@blacksheep.org; Sun, 02 Dec 2012 22:22:19 +0000 Received: from imr-mb02.mx.aol.com ([64.12.207.163]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1TfHvU-0006Ay-9w for rsgb_lf_group@blacksheep.org; Sun, 02 Dec 2012 22:22:18 +0000 Received: from mtaout-db03.r1000.mx.aol.com (mtaout-db03.r1000.mx.aol.com [172.29.51.195]) by imr-mb02.mx.aol.com (Outbound Mail Relay) with ESMTP id 6E548380000A0 for ; Sun, 2 Dec 2012 17:21:54 -0500 (EST) Received: from White (nrbg-4dbe4015.pool.mediaWays.net [77.190.64.21]) by mtaout-db03.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id 43483E0000AE for ; Sun, 2 Dec 2012 17:21:51 -0500 (EST) Message-ID: From: "Markus Vester" To: References: <003f01cdd0cd$7ba8de30$6600a8c0@dupaod6d2sep9z> Date: Sun, 2 Dec 2012 23:21:50 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 12.0.1606 X-MIMEOLE: Produced By Microsoft MimeOLE V12.0.1606 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1354486914; bh=Nx83AChVlmgtH+XzXBP8n5gHOlN31ES5Jyi7MTYOOOw=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=ggME07tRZsMl9awz9FtgC+SiSQ7m9uid8xHhSHaYxn1l8m6JmKaNXhg1YQAU8tbL0 NGmqQEk2th1UTl7omCdbszZaHSjJN5mTMLG1gV1jfUmZTRIsKVcD9NSjOUoBMm1kTT wA0Deh6NGInM7W95gEP5600MjKvbymW2mPjDnIjg= X-AOL-SCOLL-SCORE: 0:2:471590944:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Marcin, happy to read about upcoming Dreamers band activity! Just a few comments: - 70 mH inductance seems too small for the antenna capacitance. Using capacitors (4 nF) in parallel to the antenna is unfortunately very inefficient, as only a small part of the coil current will go to the antenna. This would decrease the effective coil Q by a large factor (Cant+Cp)/8, ie about 8. It would be better to use more turns of thinner wire to bring the inductance up. [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [64.12.207.163 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (markusvester[at]aol.com) -0.0 SPF_PASS SPF: sender matches SPF record -0.0 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 3d5b8cd6516ff44ac46de53952029be0 Subject: Re: LF: Problem with generator to VLF transmitter Content-Type: multipart/alternative; boundary="----=_NextPart_000_001B_01CDD0E3.CE520DD0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_30_40,HTML_MESSAGE, MISSING_OUTLOOK_NAME 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-AUTHENTICATION: mtain-di06.r1000.mx.aol.com ; domain : mx.aol.com DKIM : pass x-aol-sid: 3039ac1da60a50bbd4cb6431 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Dies ist eine mehrteilige Nachricht im MIME-Format. ------=_NextPart_000_001B_01CDD0E3.CE520DD0 Content-Type: text/plain; charset="iso-8859-2" Content-Transfer-Encoding: quoted-printable Marcin, happy to read about upcoming Dreamers band activity! Just a few = comments: - 70 mH inductance seems too small for the antenna capacitance. Using = capacitors (4 nF) in parallel to the antenna is unfortunately very = inefficient, as only a small part of the coil current will go to the = antenna. This would decrease the effective coil Q by a large factor = (Cant+Cp)/8, ie about 8. It would be better to use more turns of thinner = wire to bring the inductance up. - according to the photo, the IGBT module seems to be wired as a = half-bridge, with the transistors internally connected in series at = C2E1. You would have to break up that connection to use them in grounded = emitter push-pull configuration. - do you want to change the duty cycle to modulate the output power? = With both transistors off, the current will have to go through the = freewheeling diodes, which will probably have unwanted effects on the = voltage waveforms. - SpecLab with samplerate correction is probably the easiest choice for = an 8.97 kHz sinusoidal signal generator. But with some PC's there can be = problems with sampling gaps or glitches on the output. In my opinion, an = optimal hardware solution is a programmable Rubidium synthesizer, = followed by a fixed divider eg /1024. Chinese second-hand FE5680-A = modules are available around 80 Euro on eBay. - Stefan mentioned linear AM by outphasing. For this you would need two = half bridges with two independent drivers, which can be driven by two = channels from a stereo soundcard. Wishing the best of luck, 73, Markus (DF6NM) From: Marcin=20 Sent: Sunday, December 02, 2012 9:42 PM To: rsgb_lf_group@blacksheep.org=20 Subject: LF: Problem with generator to VLF transmitter Hi All! We're building an 8,970kHz VLF transmitter at SP2KDS club. We almost have everything in place: a.. transmitter (on IGBT transistors - diagram attached)=20 b.. antenna coil 76mH = http://www.sp2kds.pl/136khz/303-klubowa-cewka-vlf-na-897khz=20 c.. 4 capacitors 4nF/30kV=20 d.. 100m long, 20m high antenna=20 e.. supply 60V 50 A What we still need is a generator to feed the transmitter. Required = parameters are the following: a.. 8,970kHz frequency=20 b.. regulating range +-0.05Hz=20 c.. adjusting duty cycle of 5 to 45%, at 5% for two signals at the = same time=20 d.. two signals shifted by 180 degrees A friend of mine has promised to build it but it's been over a year now = and nothing has happened. Is there a software which would use a soundcard with the aforementioned = parameters? 73! Marcin SQ2BXI ------=_NextPart_000_001B_01CDD0E3.CE520DD0 Content-Type: text/html; charset="iso-8859-2" Content-Transfer-Encoding: quoted-printable
Marcin,
 
happy to read about upcoming Dreamers = band=20 activity! Just a few comments:
 
- 70 mH inductance seems too = small for=20 the antenna capacitance. Using capacitors (4 nF) in parallel to the=20 antenna is unfortunately very inefficient, as only a = small part=20 of the coil current will go to the antenna. This would decrease the = effective coil Q by a large factor (Cant+Cp)/8, ie about 8. It = would=20 be better to use more turns of thinner wire to bring the inductance = up.
 
- according to the photo, the IGBT = module seems to=20 be wired as a half-bridge, with the transistors = internally connected=20 in series at C2E1. You would have to break up that connection = to use=20 them in grounded emitter push-pull configuration.
 
- do you want to change the duty cycle = to modulate=20 the output power? With both transistors off, the current will have to go = through=20 the freewheeling diodes, which will probably have unwanted = effects on=20 the voltage waveforms.
 
- SpecLab with samplerate correction is = probably=20 the easiest choice for an 8.97 kHz sinusoidal signal generator. = But with=20 some PC's there can be problems with sampling gaps or glitches = on the=20 output. In my opinion, an optimal hardware solution is a = programmable=20 Rubidium synthesizer, followed by a fixed divider eg /1024. Chinese = second-hand=20 FE5680-A modules are available around 80 Euro on eBay.
 
- Stefan mentioned linear AM by = outphasing. For=20 this you would need two half bridges with two independent drivers, which = can be=20 driven by two channels from a stereo soundcard.
 
Wishing the best of luck,
 
73, Markus (DF6NM)
 
 
 

From: Marcin
Sent: Sunday, December 02, 2012 9:42 PM
To: rsgb_lf_group@blacksheep.org= =20
Subject: LF: Problem with generator to VLF=20 transmitter

Hi All!
We’re building an 8,970kHz VLF transmitter at SP2KDS = club.
We almost have everything in place:
  • transmitter (on IGBT transistors – diagram attached)=20
  • antenna coil 76mH http= ://www.sp2kds.pl/136khz/303-klubowa-cewka-vlf-na-897khz=20
  • 4 capacitors 4nF/30kV=20
  • 100m long, 20m high antenna=20
  • supply 60V 50 A
 
What we still need is a generator to feed the transmitter. Required = parameters are the following:
  • 8,970kHz frequency=20
  • regulating range +-0.05Hz=20
  • adjusting duty cycle of 5 to 45%, at = 5% for two=20 signals at the same time=20
  • two signals shifted by 180 = degrees
A friend of mine has promised to build it but it’s been over = a year now and=20 nothing has happened.
Is there a software which would use a soundcard with the = aforementioned=20 parameters?
 
73! Marcin = SQ2BXI
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