Return-Path: Received: from mtain-dl01.r1000.mx.aol.com (mtain-dl01.r1000.mx.aol.com [172.29.74.207]) by air-dc01.mail.aol.com (v129.10) with ESMTP id MAILINDC012-86254da84bbc201; Fri, 15 Apr 2011 09:44:28 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dl01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 1232438000114; Fri, 15 Apr 2011 09:44:25 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QAjIt-0001nG-8b for rs_out_1@blacksheep.org; Fri, 15 Apr 2011 14:43:19 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QAjIs-0001n7-O8 for rsgb_lf_group@blacksheep.org; Fri, 15 Apr 2011 14:43:18 +0100 Received: from cavuit01.kulnet.kuleuven.be ([134.58.240.43]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QAjIq-0008HA-3F for rsgb_lf_group@blacksheep.org; Fri, 15 Apr 2011 14:43:18 +0100 Received: from smtps01.kuleuven.be (smtpshost01.kulnet.kuleuven.be [134.58.240.74]) by cavuit01.kulnet.kuleuven.be (Postfix) with ESMTP id AA53B7B8053 for ; Fri, 15 Apr 2011 15:43:07 +0200 (CEST) Received: from ICTS-S-HUB-N1.luna.kuleuven.be (icts-s-hub-n1.luna.kuleuven.be [10.112.9.11]) by smtps01.kuleuven.be (Postfix) with ESMTP id 7049031E705 for ; Fri, 15 Apr 2011 15:43:07 +0200 (CEST) Received: from ICTS-S-EXC2-CA.luna.kuleuven.be ([10.112.11.13]) by ICTS-S-HUB-N1.luna.kuleuven.be ([10.112.9.11]) with mapi; Fri, 15 Apr 2011 15:43:07 +0200 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: "rsgb_lf_group@blacksheep.org" Date: Fri, 15 Apr 2011 15:38:39 +0200 Thread-Topic: LF: RE: VLF - vertical probe measurements Thread-Index: Acv7cHIxtvXYFR7tRp6Hoc1eO9+2XQAAfu6N Message-ID: References: ,<79966.50780.qm@web28516.mail.ukl.yahoo.com> In-Reply-To: <79966.50780.qm@web28516.mail.ukl.yahoo.com> Accept-Language: nl-NL, nl-BE Content-Language: nl-BE X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: nl-NL, nl-BE MIME-Version: 1.0 X-KULeuven-Information: Katholieke Universiteit Leuven X-KULeuven-Scanned: Found to be clean X-KULeuven-Envelope-From: rik.strobbe@fys.kuleuven.be X-Spam-Score: 0.1 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,HTML_TAG_EXIST_TBODY=0.126 Subject: RE: LF: RE: VLF - vertical probe measurements Content-Type: multipart/alternative; boundary="_000_BF4A524700075746A6467658DFC7102C88B4A7886DICTSSEXC2CAlu_" 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, HTML_TAG_EXISTS_TBODY,TO_ADDRESS_EQ_REAL 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-sid: 3039ac1d4acf4da84bb866bf X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --_000_BF4A524700075746A6467658DFC7102C88B4A7886DICTSSEXC2CAlu_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Chris, Since you alter the drive level I do assume the PA is linear. At lower input (and thus output) power the efficiency will drop, due to th= e bias current (ultimately at zero input level the efficiency will be 0%). Can you measure the output current of the PA ? That would give a better in= dication of the output power. 73, Rik ON7YD - OR7T ________________________________ Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.or= g] namens Chris Osborn [g3xiz@yahoo.co.uk] Verzonden: vrijdag 15 april 2011 15:22 Aan: rsgb_lf_group@blacksheep.org Onderwerp: Re: LF: RE: VLF - vertical probe measurements Hello Stefan / Rik, Thanks for the response. I adjust the PA current by varying the drive level to the FET's so the PA= supply voltage stays constant. I should have made that clear. 73 Chris G3XIZ --- On Fri, 15/4/11, Rik Strobbe wrote: From: Rik Strobbe Subject: LF: RE: VLF - vertical probe measurements To: "rsgb_lf_group@blacksheep.org" Date: Friday, 15 April, 2011, 14:11 Hello Chris, maybe a stupid question (wouldn't be my first one): how do you alter the= PA current ? If you change the PA current by changing the PA voltage then the output po= wer will change more or less with the square of tht PA current (P =3D UxI= and you change both U and I), what would result in a linear behaviour bet= ween PA current and probe voltage. 73, Rik ON7YD - OR7T ________________________________ Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.or= g] namens Chris Osborn [g3xiz@yahoo.co.uk] Verzonden: vrijdag 15 april 2011 14:40 Aan: LF Group Onderwerp: LF: VLF - vertical probe measurements LF, Acting on advice I have installed a whip aerial (probe) on top of a mast= at the boundary of my property. This is in order to monitor my VLF transmissions and to provide a referenc= e level for any system improvements. I noticed that the probe's pick-up voltage is directly proportional to my= PA's supply current. Assuming that the PA efficiency doesn't change drastically with current th= en would I be correct in assuming that the probe's voltage is directly pro= portional to the radiated power? I was expecting a square law relationship . . 73 Chris G3XIZ --_000_BF4A524700075746A6467658DFC7102C88B4A7886DICTSSEXC2CAlu_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Chris,
 
Since you alter the drive level I do= assume the PA is linear.
At lower input (and thus output) pow= er the efficiency will drop, due to the bias current (ultim= ately at zero input level the efficiency will be 0%).
Can you measure the output current= of the PA ? That would give a better indication of the output power.
 
73, Rik  ON7YD - OR7T
 
Van: owner-rsgb_= lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Chris= Osborn [g3xiz@yahoo.co.uk]
Verzonden: vrijdag 15 april 2011 15:22
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: RE: VLF - vertical probe measurements

Hello Stefan / Rik,
 
Thanks for the response.
 
I adjust the PA current by varying the drive level to the FET's= so the PA supply voltage stays constant.
I should have made that clear.
 
73 Chris G3XIZ

--- On Fri, 15/4/11, Rik Strobbe <Rik.Strobbe@fys.kuleuven.be>= wrote:

From: Rik Strobbe <Rik.Strobbe@fys.kuleuven.be>
Subject: LF: RE: VLF - vertical probe measurements
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.= org>
Date: Friday, 15 April, 2011, 14:11

Hello Chris,
 
maybe a stupid question (wouldn't be= my first one): how do you alter the PA current ?
If you change the PA current by chan= ging the PA voltage then the output power will change more or less wi= th the square of tht PA current (P =3D UxI and you change both U and I),= what would result in a linear behaviour between PA current and probe voltage.
 
73, Rik  ON7YD - OR7T
 
Van: owner-rsgb_= lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Chris= Osborn [g3xiz@yahoo.co.uk]
Verzonden: vrijdag 15 april 2011 14:40
Aan: LF Group
Onderwerp: LF: VLF - vertical probe measurements

LF,
 
Acting on advice I have installed a whip aerial (probe) on top= of a mast at the boundary of my property.
This is in order to monitor my VLF transmissions and to provide a ref= erence level for any system improvements.
 
I noticed that the probe's pick-up voltage is directly proportional= to my PA's supply current.
Assuming that the PA efficiency doesn't change drastically with curre= nt then would I be correct in assuming that the probe's voltage is directly proportional to the radiated power?
 
I was expecting a square law relationship . .
 
73
Chris G3XIZ
--_000_BF4A524700075746A6467658DFC7102C88B4A7886DICTSSEXC2CAlu_--