Return-Path: X-Spam-DCC: paranoid 1102; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: * X-Spam-Status: No, score=1.7 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, FORGED_MUA_OUTLOOK,HTML_MESSAGE,SPF_PASS autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id u44BYpwH022286 for ; Wed, 4 May 2016 13:34:51 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1axv0D-0006rQ-Gz for rs_out_1@blacksheep.org; Wed, 04 May 2016 12:30:01 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1axv0C-0006rC-Qf for rsgb_lf_group@blacksheep.org; Wed, 04 May 2016 12:30:00 +0100 Received: from rgout0102.bt.lon5.cpcloud.co.uk ([65.20.0.122]) by relay1.thorcom.net with esmtp (Exim 4.87) (envelope-from ) id 1axv0A-0005sD-T2 for rsgb_lf_group@blacksheep.org; Wed, 04 May 2016 12:29:59 +0100 X-OWM-Source-IP: 81.129.183.21 (GB) X-OWM-Env-Sender: alan.melia@btinternet.com X-CTCH-RefID: str=0001.0A090205.5729DD35.00AE,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-Junkmail-Premium-Raw: score=39/50,refid=2.7.2:2016.4.28.172416:17:39.532,ip=81.129.183.21,rules=__HAS_MSGID, __SANE_MSGID, MSGID_32HEX_LC, INVALID_MSGID_NO_FQDN, __MSGID_32HEX, __HAS_FROM, __PHISH_FROM2, __FRAUD_WEBMAIL_FROM, __TO_MALFORMED_2, __TO_NO_NAME, __REFERENCES, __BOUNCE_CHALLENGE_SUBJ, __BOUNCE_NDR_SUBJ_EXEMPT, __SUBJ_ALPHA_END, __MIME_VERSION, __CT, __CTYPE_MULTIPART_ALT, __CTYPE_HAS_BOUNDARY, __CTYPE_MULTIPART, __HAS_X_PRIORITY, __HAS_MSMAIL_PRI, __HAS_X_MAILER, USER_AGENT_OE, __OUTLOOK_MUA_1, __USER_AGENT_MS_GENERIC, __ANY_URI, __HTTPS_URI, __URI_WITH_PATH, LINK_TO_IMAGE, __URI_NO_WWW, __CP_URI_IN_BODY, __STOCK_PHRASE_7, __SUBJ_ALPHA_NEGATE, SUPERLONG_LINE, __MULTIPLE_URI_TEXT, __URI_IN_BODY, __HTML_AHREF_TAG, __HAS_HTML, BODYTEXTP_SIZE_3000_LESS, BODY_SIZE_5000_5999, BODYTEXTH_SIZE_3000_MORE, BODYTEXTH_SIZE_10000_LESS, __MIME_HTML, __TAG_EXISTS_HTML, RDNS_GENERIC_POOLED, __URI_NS, SXL_IP_DYNAMIC[21.183.129.81.fur], HTML_50_70, RDNS_SUSP_GENERIC, __FRAUD_WEBMAIL, __PHISH_FROM, __OUTLOOK_MUA, RDNS_SUSP, FORGED_MUA_OUTLOOK, REFERENCES, BODY_SIZE_7000_LESS X-CTCH-Spam: Unknown Received: from gnat (81.129.183.21) by rgout01.bt.lon5.cpcloud.co.uk (8.6.122.06) (authenticated as alan.melia@btinternet.com) id 57160E1401F93C9B for rsgb_lf_group@blacksheep.org; Wed, 4 May 2016 12:29:57 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=btinternet.com; s=btcpcloud; t=1462361398; bh=mE6FSGRkWv/s/wWMm5jFOh+rZobmCsE5mrUV0D9Ynwc=; h=Message-ID:From:To:References:Subject:Date:MIME-Version:X-Mailer; b=R4Mz7y9E0qxxw8eUbJnH9HMtzMi4CAMQmjb90pAZqnT0s/sCzWbR4yqcoidIbOEiONnxsU3GGwXLkfG8CDNHZ/+IwaJJmn3cAL89QuFZgxBTXLHOo+AWgfaDcmQQAFhrvOAGyFup06+Rt/3Ia5pa7wNFGBcHVjxc4cJX8G2uv04= Message-ID: <45BDA64675F74264A51E9E2E5073D120@gnat> From: "Alan Melia" To: References: <579355A36AEE9D4FA555C45D556003AB53B9701E@servigilant.vigilant.local> Date: Wed, 4 May 2016 12:14:26 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 X-Scan-Signature: b707651713bcd4ad9db4bb0f5d794041 Subject: LF: Re: Vintage RF current meter Content-Type: multipart/alternative; boundary="----=_NextPart_000_001E_01D1A5FE.809E4FB0" 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 2.56 on 10.1.3.11 Status: O X-Status: X-Keywords: X-UID: 7992 This is a multi-part message in MIME format. ------=_NextPart_000_001E_01D1A5FE.809E4FB0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Luis, the range is determined by athe thickness of the heater wire = betweemn the terminals. there is a thermocouple welded to the centre of = this wire and there may be a coil of wire between the t/c and the = movement to set the calibration. You will find the DC resistance quoted = is a function of the range. These style of meters could be found with a = ramge down to 300mA though these are easily damaged. You can make the = range larger as with DC meters by using a shunt, though the calibration = differs from DC levels. I have not tried replacing the heater wire with a finer gauge and re = welding the t/c, but it is possible. A ferrite is easier ....see = http://huprf.com/huprf/rf-current-meter/ Alan G3NYK ----- Original Message -----=20 From: VIGILANT Luis Fern=E1ndez=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Wednesday, May 04, 2016 9:46 AM Subject: LF: Vintage RF current meter Hi xyF Yesterday I got a nice gift from a local friend, Pascual EA5JF :-) = https://dl.dropboxusercontent.com/u/7162072/Fotos%20varias/MF/IMG_2016050= 4_091006.jpg Unfortunately the current range under 1A looks unusable=20 Still not opened to have a look. Seems to use a thermocouple. Is there = any chance to make it more sensible and usable for <1A currents ? 73 de Luis EA5DOM ------=_NextPart_000_001E_01D1A5FE.809E4FB0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Luis, the range is determined by = athe thickness=20 of the heater wire betweemn the terminals. there is a thermocouple = welded to the=20 centre of this wire and there may be a coil of wire between the t/c and = the=20 movement to set the calibration. You will find the DC resistance quoted = is a=20 function of the range. These style of meters could be found with a ramge = down to=20 300mA though these are easily damaged. You can make the range larger as = with DC=20 meters by  using a shunt, though the calibration differs from DC=20 levels.
 
I have not tried replacing the heater = wire with a=20 finer gauge and re welding the t/c, but it is possible.  A ferrite = is=20 easier ....see http://huprf.com/huprf/= rf-current-meter/
 
Alan
G3NYK
----- Original Message -----
From:=20 VIGILANT = Luis=20 Fern=E1ndez
Sent: Wednesday, May 04, 2016 = 9:46=20 AM
Subject: LF: Vintage RF current = meter

Hi=20 xyF
 
Yesterday I got a=20 nice gift from a local friend, Pascual EA5JF :-)
 
https://dl.dropboxusercontent.com/u/7162072/Fotos%2= 0varias/MF/IMG_20160504_091006.jpg
 
Unfortunately the=20 current range under 1A looks unusable 
Still not opened=20 to have a look. Seems to use a thermocouple. Is there any chance to = make=20 it
more = sensible and=20 usable for <1A currents ?
 
73 de Luis
EA5DOM
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