Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id w2GCZuq5010290 for ; Fri, 16 Mar 2018 13:35:58 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ewoVr-00007P-F8 for rs_out_1@blacksheep.org; Fri, 16 Mar 2018 12:31:11 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ewoVq-00007G-R2 for rsgb_lf_group@blacksheep.org; Fri, 16 Mar 2018 12:31:10 +0000 Received: from rhcavuit03.kulnet.kuleuven.be ([2a02:2c40:0:c0::25:136]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1ewoVo-0005e0-1W for rsgb_lf_group@blacksheep.org; Fri, 16 Mar 2018 12:31:09 +0000 X-KULeuven-Envelope-From: rik.strobbe@kuleuven.be X-KULeuven-Scanned: Found to be clean X-KULeuven-ID: D156812032F.A3BA2 X-KULeuven-Information: Katholieke Universiteit Leuven Received: from icts-p-smtps-2.cc.kuleuven.be (icts-p-smtps-2e.kulnet.kuleuven.be [134.58.240.34]) by rhcavuit03.kulnet.kuleuven.be (Postfix) with ESMTP id D156812032F for ; Fri, 16 Mar 2018 13:31:03 +0100 (CET) Received: from ICTS-S-EXMBX1.luna.kuleuven.be (icts-s-exmbx1.luna.kuleuven.be [10.112.11.9]) (using TLSv1.2 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by icts-p-smtps-2.cc.kuleuven.be (Postfix) with ESMTPS id CED0D2003B; Fri, 16 Mar 2018 13:31:03 +0100 (CET) Received: from ICTS-S-EXMBX28.luna.kuleuven.be (10.112.11.63) by ICTS-S-EXMBX1.luna.kuleuven.be (10.112.11.9) with Microsoft SMTP Server (TLS) id 15.0.1320.4; Fri, 16 Mar 2018 13:31:03 +0100 Received: from ICTS-S-EXMBX27.luna.kuleuven.be (10.112.11.62) by ICTS-S-EXMBX28.luna.kuleuven.be (10.112.11.63) with Microsoft SMTP Server (TLS) id 15.0.1320.4; Fri, 16 Mar 2018 13:31:03 +0100 Received: from ICTS-S-EXMBX27.luna.kuleuven.be ([fe80::291a:cc4f:6953:698a]) by ICTS-S-EXMBX27.luna.kuleuven.be ([fe80::291a:cc4f:6953:698a%25]) with mapi id 15.00.1320.000; Fri, 16 Mar 2018 13:31:03 +0100 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: LineOne CC: Chris Wilson Thread-Topic: LF: Pre amp *after* BPF?? Thread-Index: AQHTvRwmOeyQw/a1AEaWc4vpzgg5aqPSsACAgAAYMAw= Date: Fri, 16 Mar 2018 12:31:03 +0000 Message-ID: <1521203464226.5324@kuleuven.be> References: <772364530.20180316113613@gmail.com>, In-Reply-To: Accept-Language: nl-BE, en-GB, en-US Content-Language: nl-BE X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.112.50.1] MIME-Version: 1.0 X-Spam-Score: -0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Keep in mind that you only need a pre amp if the "antenna noise" is below the receiver noise. Most receivers have reduced sensitivity at LF / MF, but the noiselevels at these frequencies is high compared to HF. [...] Content analysis details: (-0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 3547ef0bd9aa4f6a2596c8a6b1b20265 Subject: Re: LF: Pre amp *after* BPF?? Content-Type: multipart/alternative; boundary="_000_15212034642265324kuleuvenbe_" 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_FONTCOLOR_UNSAFE,HTML_MESSAGE 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 --_000_15212034642265324kuleuvenbe_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Keep in mind that you only need a pre amp if the "antenna noise" is below t= he receiver noise. Most receivers have reduced sensitivity at LF / MF, but the noiselevels at = these frequencies is high compared to HF. Easy to check: Listen (with connected antenna) on a quiet frequency (only n= oise, no signal). Next disconnect the antenna. If the noise level decreases= you do not need a pre amp (in fact a pre amp will only deteriorate the IMD= behavior and thus create more ghost signals). 73, Rik ON7YD - OR7T ________________________________ Van: owner-rsgb_lf_group@blacksheep.org namens Andy Talbot Verzonden: vrijdag 16 maart 2018 12:54 Aan: LineOne CC: Chris Wilson Onderwerp: Re: LF: Pre amp *after* BPF?? After, definitely Before is applicable to VHF and up where equipment noise figure dominates s= ensitivity and a filter in the antenna side wold add loss and degrade overa= ll NF At HF and certainly LF, atmos noise dominates to noise figure is unimportan= t. That way you get the benefit of rejecting strong OOB signals that may = stress even the preamplifier 'jnt On 16 March 2018 at 11:36, Chris Wilson > wrote: Hello LF'ers, Been Googling and see a mixed response to should a receive pre-amp go before or after a BPF. I have mine before the pre-amp, does the panel concur with this being correct? Thanks! Aerial, isolation transformer for ground loops, BPF, pre-amp, Red Pitaya as the LF receiver. -- Best regards, Chris mailto:dead.fets@gmail.com --_000_15212034642265324kuleuvenbe_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Keep in mind that you only need a pre amp if the "antenna noise&quo= t; is below the receiver noise.

Most receivers have reduced sensitivity at LF / MF, but the noiselevels = at these frequencies is high compared to HF.

Easy to check: Listen (with connected antenna) on a quiet frequency (onl= y noise, no signal). Next disconnect the antenna. If the noise le= vel decreases you do not need a pre amp (in fact a pre amp will only d= eteriorate the IMD behavior and thus create more ghost signals).


73, Rik  ON7YD - OR7T


Van: owner-rsgb_lf_group@bl= acksheep.org <owner-rsgb_lf_group@blacksheep.org> namens Andy Talbot = <andy.g4jnt@gmail.com>
Verzonden: vrijdag 16 maart 2018 12:54
Aan: LineOne
CC: Chris Wilson
Onderwerp: Re: LF: Pre amp *after* BPF??
 
After, definitely

Before is applicable to VHF and up where equipment noise figure domina= tes sensitivity and a filter in the antenna side wold add loss and degrade = overall NF

At HF and certainly LF, atmos noise dominates to noise figure is unimp= ortant.   That way you get the benefit of rejecting strong OOB si= gnals that may stress even the preamplifier

'jnt


On 16 March 2018 at 11:36, Chris Wilson <dead.fets@gmai= l.com> wrote:


Hello  LF'ers,

Been  Googling and see a mixed response to should a receive pre-amp go=
before  or after a BPF. I have mine before the pre-amp, does the panel=
concur with this being correct? Thanks!

Aerial,  isolation  transformer  for  ground  loop= s, BPF, pre-amp, Red
Pitaya as the LF receiver.

--
Best regards,
 Chris                  &= nbsp;       mailto:de= ad.fets@gmail.com



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