Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lipkowski.org X-Spam-Level: * X-Spam-Status: No, score=1.3 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, HTML_MESSAGE,RCVD_IN_DNSWL_MED,RCVD_IN_SORBS_WEB,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 X-Spam-DCC: EATSERVER: mailn 1166; Body=2 Fuz1=2 Fuz2=2 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by lipkowski.org (8.14.4/8.14.4/Debian-8+deb8u1) with ESMTP id v4C9mhx4014124 for ; Fri, 12 May 2017 11:48:44 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1d977F-0005qf-Bs for rs_out_1@blacksheep.org; Fri, 12 May 2017 10:44:05 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1d977E-0005qW-E8 for rsgb_lf_group@blacksheep.org; Fri, 12 May 2017 10:44:04 +0100 Received: from gmy2-mh804.smtproutes.com ([94.186.192.133]) by relay1.thorcom.net with esmtp (Exim 4.89) (envelope-from ) id 1d977A-0001W4-8w for rsgb_lf_group@blacksheep.org; Fri, 12 May 2017 10:44:03 +0100 X-Katharion-ID: 1494582227.13661.gmy2-mh804 Received: from servigilant.vigilant.es ([85.60.35.36]) by gmy2-mh804.smtproutes.com [(94.186.192.133)] with ESMTP via TCP (TLSv1/TLS_RSA_WITH_AES_256_CBC_SHA); 12 May 2017 09:43:47 +0000 Received: from servigilant.vigilant.local ([fe80::c40d:8140:d722:5448]) by servigilant.vigilant.local ([fe80::c40d:8140:d722:5448%13]) with mapi id 14.03.0123.003; Fri, 12 May 2017 11:43:04 +0200 From: =?iso-8859-1?Q?VIGILANT_Luis_Fern=E1ndez?= To: "rsgb_lf_group@blacksheep.org" Thread-Topic: LF: Some improvements in VLF Rx Thread-Index: AQHSx9nZWsQEGQ1Vj0+K4FRSFr5O6aHvBxsAgAFnWIA= Date: Fri, 12 May 2017 09:43:03 +0000 Message-ID: <579355A36AEE9D4FA555C45D556003AB8FDDBABF@servigilant.vigilant.local> In-Reply-To: <591469D4.1020401@posteo.de> Accept-Language: es-ES, en-US Content-Language: es-ES X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [192.168.0.2] MIME-Version: 1.0 X-Scan-Signature: e3d323418d60e0f7f0af176deb9f3e2b Subject: RE: LF: Some improvements in VLF Rx Content-Type: multipart/alternative; boundary="_000_579355A36AEE9D4FA555C45D556003AB8FDDBABFservigilantvigi_" 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 2.75 Status: RO X-Status: X-Keywords: X-UID: 11675 --_000_579355A36AEE9D4FA555C45D556003AB8FDDBABFservigilantvigi_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Clemens and Stefan Thank you for the ideas to improve Rx in VLF Yes the noise background is dominated by 'horizontal' traces, not by vertic= al traces, i.e. QRM (unwanted) instead of QRN (expected in a clean location= ). This domination is very expressed. So either your ground is hopeless con= taminated or maybe something is even wrong connected? Will recheck this sunday if possible Are you using the BF862 as the first FET? I observed VHF oscillations in th= e past and would now suggest a ferrite bead as close as possible to the gat= e of the JFET. Using SMD SOT23 BF862,215 http://es.farnell.com/nxp/bf862-215/jet-n-ch-20v-sot-23/dp/1758058?ost=3D17= 58058&anyFilterApplied=3Dfalse&searchView=3Dtable&iscrfnonsku=3Dfalse&ddkey= =3Dhttp%3Aes-ES%2FElement14_Spain%2Fsearch I can add an SMD ferrite bead (0805) in the gate Are you sure the FET is working correctly? You can measure/calculate the dr= ain current by measuring the voltage across the drain resistor. The voltage in the coax down in the shack after the 390R is 6V. Power suppl= y is 14V. So there must be some current trought the FET Will measure the current What is the length (or better: estimated capacity) of the probe now and wha= t is the height above the ground/roof/sourroundings? This is the picture of the 5m mast, which is metal. The last section is a P= VC pipe which holds the MiniWhip. The VLF probe is hold in a plastic box containing the FET and attached to the metal mast using a metal adaptor. So= it is quite close to the metal mast, which can provide high capacity ? Probe lenght is 1m https://dl.dropboxusercontent.com/u/7162072/fotos%20varias/MF/IMG_20170430_= 125017.jpg Did you try to use a bettery for testing the effect on the QRM? Yes. Using the battery there was no difference, once the ground loop was re= moved. I did also used a simple way to notice the noise, which is to route the soundcard to the speakers. Then you can clearly hear the hum of t= he QRM noises and the clicks which should be QRN PS: There are a number of settings you could improve in this wideband spect= rogram. If you send me your usr file i would send you one back with some ch= anges, if you like. That will be fine ! File is here https://dl.dropboxusercontent.com/u/7162072/fotos%20varias/MF/VLF_Soundcard= _32KHz.USR Also it may be worth to start a second spectrogram now, centered on 8270 Hz= . It could run in 424 uHz Is not in the grabber, but I'm running a 283uHz with the 11904 Alpha. It is= slow enought to see the improvement when the ground loop was removed last sunday. And it also shows the shutdown of the Alphas which happened ye= sterday ;-) https://dl.dropboxusercontent.com/u/7162072/fotos%20varias/MF/283uHz%20Alph= a%20station%2011904.JPG The 32uHz instance in 8270 has been also running for some time. You can als= o see the noise improvement here https://dl.dropboxusercontent.com/u/7162072/fotos%20varias/MF/32uHz%20VLF%2= 036Km%20band%208750.JPG If I get the time, will test the probe in a different place. Not so high bu= t mounted in a totally isolated (PVC) pole Will try also a twisted pair instead of the coax Will keep you updated 73 de Luis EA5DOM --_000_579355A36AEE9D4FA555C45D556003AB8FDDBABFservigilantvigi_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Clemens and Stefan=
 
Thank you for the ideas to improv= e Rx in VLF
 
Yes the = noise background is dominated by 'horizontal' traces, not by vertical trace= s, i.e. QRM (unwanted) instead of QRN (expected in a clean location). This = domination is very expressed. So either your ground is hopeless contaminated or maybe something is even wrong conn= ected?
Will recheck this sunday if possi= ble
 
Are you = using the BF862 as the first FET? I observed VHF oscillations in the past a= nd would now suggest a ferrite bead as close as possible to the gate of the= JFET.
Using SMD SOT23 BF862,215
 
I can add an SMD ferrite bead (0805) in the gate
 
Are you sure the FET is working cor= rectly? You can measure/calculate the drain current by measuring the voltag= e across the drain resistor.
The voltage in the coax down in the shack after the 390R is = 6V. Power supply is 14V. So there must be some current trought the FET
Will measure the current
 
What is the length (or better: esti= mated capacity) of the probe now and what is the height above the ground/ro= of/sourroundings?
 
This is the picture of the 5m mast, which is metal. The last= section is a PVC pipe which holds the MiniWhip. The VLF probe is hold in a= plastic box
containing the FET and attached to the metal mast using a me= tal adaptor. So it is quite close to the metal mast, which can provide high= capacity ?
Probe lenght is 1m
 
Did you try to use a bettery for testing the effect on the QRM?
Yes. Using the battery there was no difference, once the gro= und loop was removed. I did also used a simple way to notice the noise, whi= ch is to
route the soundcard to the speakers. Then you can clearly he= ar the hum of the QRM noises and the clicks which should be QRN
 
= PS: There are a number of settings you could improve in this wideband spect= rogram. If you send me your usr file i would send you one back with some changes, if you like.

That will be fine ! File is here
 
Also it may be worth to start a sec= ond spectrogram now, centered on 8270 Hz. It could run in 424 uHz
 
Is not in the grabber, but I'm running a 283uHz with the 119= 04 Alpha. It is slow enought to see the improvement when the ground loop wa= s removed
last sunday. And it also shows the shutdown of the Alphas wh= ich happened yesterday ;-)
 
The 32uHz instance in 8270 has been also running for some ti= me. You can also see the noise improvement here
 
If I get the time, will test the probe in a different place.= Not so high but mounted in a totally isolated (PVC) pole
Will try also a twisted pair instead of the coax
 
Will keep you updated
 
73 de Luis
EA5DOM
 
--_000_579355A36AEE9D4FA555C45D556003AB8FDDBABFservigilantvigi_--