Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-ma03.r1000.mx.aol.com (Internet Inbound) with ESMTP id 81C5338000060; Wed, 17 Aug 2011 15:20:48 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Qtleg-0001Np-8G for rs_out_1@blacksheep.org; Wed, 17 Aug 2011 20:19:58 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Qtlef-0001Ng-Ir for rsgb_lf_group@blacksheep.org; Wed, 17 Aug 2011 20:19:57 +0100 Received: from out1.ip01ir2.opaltelecom.net ([62.24.128.237]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Qtled-0003Qw-74 for rsgb_lf_group@blacksheep.org; Wed, 17 Aug 2011 20:19:57 +0100 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AtcAAAIUTE5cHYkx/2dsb2JhbABCgk2BfJRRj1h4gTsFAQEFCAEBAxYKKQIsAQEDBQIBAxEEAQEKIQICFAEEGgYWCAYTCgECAgEBh2ECpReRWYU4gRAEglGhOA X-IronPort-AV: E=Sophos;i="4.68,240,1312153200"; d="scan'208,217";a="362562659" Received: from host-92-29-137-49.as13285.net (HELO xphd97xgq27nyf) ([92.29.137.49]) by out1.ip01ir2.opaltelecom.net with SMTP; 17 Aug 2011 20:19:48 +0100 Message-ID: <005701cc5d12$9709fb30$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" To: References: <68BE37BD69E54DEE89CEBA8E30E9B94E@PcMinto> <4E47FFE9.10100@iup.uni-heidelberg.de> <3ED8E5422F1F45DBB8186E9D9870AD63@PcMinto> <4E480E02.9020706@iup.uni-heidelberg.de> <938BF599006244949F6CDDB5BA91F347@PcMinto> <4E482FBD.7030402@freenet.de> <4E484183.9090805@iup.uni-heidelberg.de> <4E494A57.90105@freenet.de> <4E4956DA.1060201@iup.uni-heidelberg.de> <4E49643E.5090708@freenet.de> <4E496FF9.4040608@iup.uni-heidelberg.de> <0A4ED65EC3B244A3BD0DAD6ACFF43793@JimPC> <4E4A5597.4070709@iup.uni-heidelberg.de> <3746D901368F4C139E414F9110153EEE@JimPC> <4E4A9A1F.2060600@iup.uni-heidelberg.de> <1B55B625C3CD4D529EC361D9C5D79D96@JimPC> <4E4AD4C8.8000509@iup.uni-heidelberg.de> <4E4AEF31.5010306@iup.uni-heidelberg.de> <1FF2FAD9854F4890A338A9F862D93FE9@JimPC> <8CE2AD319756ED7-1C20-14370@Webmail-m104.sysops.aol.com> <4E4BC177.6050902@iup.uni-heidelberg.de> <001f01cc5cf9$4b734780$0401a8c0@xphd97xgq27nyf> <4E4BF289.2070500@iup.uni-heidelberg.de> Date: Wed, 17 Aug 2011 20:19:30 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: Ferrite RX antennas Content-Type: multipart/alternative; boundary="----=_NextPart_000_0054_01CC5D1A.F89774B0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.1 required=5.0 tests=HTML_20_30, HTML_FONTCOLOR_UNKNOWN,HTML_MESSAGE,HTML_TITLE_EMPTY 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: 0:2:483369024:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d600b4e4c148f219d X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. ------=_NextPart_000_0054_01CC5D1A.F89774B0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Stefan Just about visible on ur grabber at present. A little tweak should do = the trick de mal/g3kev ----- Original Message -----=20 From: Stefan Sch=C3=A4fer=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Wednesday, August 17, 2011 5:55 PM Subject: Re: LF: Ferrite RX antennas Mal,=20 I know. But anyway one can compare the SNR levels between different = antennas. I'll set up a beacon now on 137.73 kHz, testing in QRSS-3. Maybe you want to call CQ or so. If i can receive you, i will send a = capture. But i still cannot answer. Am in Darmstadt now, not in = Heidelberg. The UHF link for transmitting works just in a range of 5 km = and is disabled now. I expect that i need a preamp and will not get the necessary sensitivy = now. Anyway i can compare the antennas and check how many dBs are = missed. RX QRV in half an hour. Beacon starting at 17:30 UTC 73, Stefan/DK7FC Am 17.08.2011 18:18, schrieb mal hamilton:=20 Stefan But what sort of strength do you Receive weak Radio Amateur signals. = That is the real test=20 Commercial radio stations a different matter with their Megawatts de mal/g3kev ----- Original Message -----=20 From: Stefan Sch=C3=A4fer=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Wednesday, August 17, 2011 2:26 PM Subject: Re: LF: Ferrite RX antennas Hello Markus, Jim, LF,=20 Tnx for suggestions. Have to think about that later. I want to go = on in small steps now.=20 I added a 100 pF vari-cap which allows to resonate in the desired = range (up to 137.8 kHz and down to 136.3). As a first test a added a small winding, just 3 turns, 3 cm far = for the rods end, matched to 50 Ohm. So now it works as a passive = antenna and can be fed to my RX 50 Ohm input. This is the complete LF RX arrangement, suitable to see and hear = on 137 wideband: http://dl.dropbox.com/u/19882028/LF/LF-P%20RX%20RIG.JPG The ferrite antenna is just as broad a the netbook now. Of course = the distance to the netbook must be increased later. It still has no = electric shield but a suitable housing to protect the Litz winding, = necessary to go on with tests on various locations. The DCF-39 strength is 50 dB S/N in 1 Hz while the antenna (3 dB = bandwidth =3D 280 Hz) is tuned to 137.0 kHz (cannot tune to 138.83). The = band noise within the passband is 10 dB above the soundcards noise but = this may be different in a quiet location on a quiet day. This looks all promising to me. I'll try the BF862 as a preamp = soon. Will do further tests with a test signal in the passband and = compare this to my 1m diameter single turn loop. And i will try my 50 = Ohm preamp in front of the RX. Looking forward to the first QSOs! 73, Stefan/DK7FC Am 17.08.2011 10:59, schrieb Markus Vester:=20 Stefan, Jim, you could increase the signal bandwidth without compromising SNR = by connecting a low impedance preamplifier. This technique has been used = widely and successfully in magnetic resonance imaging ("preamp = decoupling"). The preamp is designed to have an input impedance that = differs largely from the noise-optimum source impedance, so that you can = preserve the noise match but create an intentional signal mismatch. In practice, you would still want to use a low-noise FET = connected to the high impedance point of a parallel resonant antenna. = Normally the gate input impedance (megohms) is higher than the noise = optimum (tens of kiloohms), so you would have no preamp damping at all. = The trick is then to lower the input impedance by lossless feedback, = which has neglegible effect on the noise parameters.=20 One configuration is a compromise between common source and = common gate circuit configuration ("Zwischenbasisschaltung"), which can = be realised by inserting an additional negative-feedback winding in the = source-to-ground path. This is similar to the old regenerative audion, = but with the feedback coil polarity reversed. Another configuration is = parallel feedback from drain to gate, by intentionally increasing the = Miller capacitance. Best regards, Markus (DF6NM) -----Urspr=C3=BCngliche Mitteilung-----=20 Von: James Moritz An: rsgb_lf_group Verschickt: Mi, 17 Aug 2011 1:13 am Betreff: Re: LF: Ferrite RX antennas Dear Stefan, Looking good so far... A Q of 486 is certainly reaching the point where it becomes inconvenient = -=20 but remember that it is easy to reduce Q (probably connecting a preamp,=20 putting it in a container, etc, will reduce Q a bit anyway), and that = the=20 higher Q is, the better the SNR. So I would test it as an antenna with a = preamp - if there is more SNR than you need, you could experiment with = some=20 damping resistance. Cheers, Jim Moritz 73 de M0BMU=20 ------=_NextPart_000_0054_01CC5D1A.F89774B0 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable =EF=BB=BF
Stefan
Just about visible on ur grabber at present. A = little=20 tweak should do the trick
de mal/g3kev
 
----- Original Message -----
From:=20 Stefan Sch=C3=A4fer =
Sent: Wednesday, August 17, = 2011 5:55=20 PM
Subject: Re: LF: Ferrite RX=20 antennas

Mal,

I know. But anyway one can compare the SNR = levels=20 between different antennas.

I'll set up a beacon now on 137.73 = kHz,=20 testing in QRSS-3.
Maybe you want to call CQ or so. If i can = receive you, i=20 will send a capture. But i still cannot answer. Am in Darmstadt now, = not in=20 Heidelberg. The UHF link for transmitting works just in a range of 5 = km and is=20 disabled now.

I expect that i need a preamp and will not get = the=20 necessary sensitivy now. Anyway i can compare the antennas and check = how many=20 dBs are missed.

RX QRV in half an hour. Beacon starting at = 17:30=20 UTC

73, Stefan/DK7FC

Am 17.08.2011 18:18, schrieb mal = hamilton:=20
Stefan
But what sort of strength do you Receive = weak Radio=20 Amateur signals. That is the real test
Commercial radio stations a different matter = with=20 their Megawatts
de mal/g3kev
 
-----=20 Original Message ----- From:=20 Stefan=20 Sch=C3=A4fer To:=20 rsgb_lf_group@blacksheep.org Sent:=20 Wednesday, August 17, 2011 2:26 PM Subject:=20 Re: LF: Ferrite RX antennas

Hello Markus, Jim, LF,

Tnx for suggestions. = Have to=20 think about that later. I want to go on in small steps now. =

I=20 added a 100 pF vari-cap which allows to resonate in the desired = range (up=20 to 137.8 kHz and down to 136.3).
As a first test a added a = small=20 winding, just 3 turns, 3 cm far for the rods end, matched to 50 = Ohm. So=20 now it works as a passive antenna and can be fed to my RX 50 Ohm=20 input.
This is the complete LF RX arrangement, suitable to see = and hear=20 on 137 wideband: http://dl.dropbox.com/u/19882028/LF/LF-P%20RX%20= RIG.JPG

The=20 ferrite antenna is just as broad a the netbook now. Of course the = distance=20 to the netbook must be increased later. It still has no electric = shield=20 but a suitable housing to protect the Litz winding, necessary to = go on=20 with tests on various locations.

The DCF-39 strength is 50 = dB S/N=20 in 1 Hz while the antenna (3 dB bandwidth =3D 280 Hz) is tuned to = 137.0 kHz=20 (cannot tune to 138.83). The band noise within the passband is 10 = dB above=20 the soundcards noise but this may be different in a quiet location = on a=20 quiet day.

This looks all promising to me. I'll try the = BF862 as a=20 preamp soon.

Will do further tests with a test signal in = the=20 passband and compare this to my 1m diameter single turn loop. And = i will=20 try my 50 Ohm preamp in front of the RX.
Looking forward to the = first=20 QSOs!

73, Stefan/DK7FC

Am 17.08.2011 10:59, schrieb = Markus=20 Vester:=20
Stefan, Jim,
 
you could increase the signal bandwidth without = compromising SNR by=20 connecting a low impedance preamplifier. This technique has = been=20 used widely and successfully in magnetic resonance imaging = ("preamp=20 decoupling"). The preamp is designed to have an input = impedance=20 that differs largely from the noise-optimum source impedance, so = that=20 you can preserve the noise match but create an intentional = signal=20 mismatch.
 
In practice, you would still want to use a = low-noise=20 FET connected to the high impedance point of a parallel resonant = antenna. Normally the gate input impedance (megohms) = is higher than=20 the noise optimum (tens of kiloohms), so you would have no = preamp=20 damping at all. The trick is then to lower the input = impedance by=20 lossless feedback, which has neglegible effect on the=20 noise parameters.
 
One configuration is a compromise between common source and = common=20 gate circuit configuration ("Zwischenbasisschaltung"), = which can be=20 realised by inserting an additional negative-feedback winding in = the=20 source-to-ground path. This is similar to the=20 old regenerative audion, but with the feedback coil = polarity=20 reversed. Another configuration is parallel feedback from drain = to gate,=20 by intentionally increasing the Miller capacitance.

Best=20 regards,
Markus (DF6NM)
-----Urspr=C3=BCngliche=20 Mitteilung-----
Von: James Moritz <james.moritz@btopenworld.com>
An: = rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Vers= chickt:=20 Mi, 17 Aug 2011 1:13 am
Betreff: Re: LF: Ferrite RX = antennas

Dear Stefan,

Looking good so far...

A Q of 486 is certainly reaching the point where it becomes inconvenient =
-=20
but remember that it is easy to reduce Q (probably connecting a preamp,=20
putting it in a container, etc, will reduce Q a bit anyway), and that =
the=20
higher Q is, the better the SNR. So I would test it as an antenna with a =

preamp - if there is more SNR than you need, you could experiment with =
some=20
damping resistance.

Cheers, Jim Moritz
73 de M0BMU=20
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