Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mb06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 7EF5B380000DD; Sat, 12 May 2012 17:35:10 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1STJxC-0003kp-Ic for rs_out_1@blacksheep.org; Sat, 12 May 2012 22:34:18 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1STJxB-0003kg-J6 for rsgb_lf_group@blacksheep.org; Sat, 12 May 2012 22:34:17 +0100 Received: from cmsout02.mbox.net ([165.212.64.32]) by relay1.thorcom.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.77) (envelope-from ) id 1STJx9-00058I-Am for rsgb_lf_group@blacksheep.org; Sat, 12 May 2012 22:34:16 +0100 Received: from cmsout02.mbox.net (co02-lo [127.0.0.1]) by cmsout02.mbox.net (Postfix) with ESMTP id 113FF1342DF for ; Sat, 12 May 2012 21:34:10 +0000 (GMT) X-USANET-Received: from cmsout02.mbox.net [127.0.0.1] by cmsout02.mbox.net via mtad (C8.MAIN.3.82F) with ESMTP id 227qeLVIH9264M02; Sat, 12 May 2012 21:34:07 -0000 X-USANET-Routed: 3 gwsout-vs Q:bmvirus Received: from imap03.cms.usa.net [165.212.11.3] by cmsout02.mbox.net via smtad (C8.MAIN.3.72B) with ESMTP id XID227qeLVIH1987X02; Sat, 12 May 2012 21:34:07 -0000 X-USANET-Source: 165.212.11.3 IN dibene@usa.net imap03.cms.usa.net X-USANET-MsgId: XID227qeLVIH1987X02 Received: from [127.0.0.1] [151.55.18.228] by imap03.cms.usa.net (ESMTPSA/dibene@usa.net) via mtad (C8.MAIN.3.82G) with ESMTPSA id 675qeLVIg6752M23; Sat, 12 May 2012 21:34:06 -0000 X-USANET-Auth: 151.55.18.228 AUTH dibene@usa.net [127.0.0.1] Message-ID: <4FAED74D.5060507@usa.net> Date: Sat, 12 May 2012 23:34:05 +0200 From: Alberto di Bene User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <96F6DE3827714341B45E5194EA6D7946@AGB> <933D952DE28E4835A61D2B4B6F455CBF@computereebf79> In-Reply-To: X-Enigmail-Version: 1.4.1 X-Antivirus: avast! (VPS 120512-1, 05/12/2012), Outbound message X-Antivirus-Status: Clean Z-USANET-MsgId: XID675qeLVIH6752X23 X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: On 5/12/2012 9:41 PM, Andy Talbot wrote: > A JFET switch is probably the simplest. Uses a P Channel device > like a 2N3820 so it can be controlled with a positive voltage. +V > is device off, 0V is switched on. Which sounds a bit weird to > visualise Used in shunt means a +Ve voltage switching it off gives > RF is on. 0V attenuates RF. Rds(on) is a good few ohms, so needs to > be run in a Hi-Z system. There are no doubt better P-Chan FETs. > > Andy > 'jnt Or maybe the ubiquitous 2N7000 enhancement mosfet... does not conduct with the gate a 0V, but it does when the gate is at +V [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [165.212.64.32 listed in list.dnswl.org] 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 7ab87d4d3ea1d9dcb73a78e83fe4d608 Subject: Re: LF: IEEE488 Content-Type: multipart/alternative; boundary="------------030609050105080002040807" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,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 x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:457422688:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d601a4faed78d783a X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. --------------030609050105080002040807 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit On 5/12/2012 9:41 PM, Andy Talbot wrote: > A JFET switch is probably the simplest. Uses a P Channel device > like a 2N3820 so it can be controlled with a positive voltage. +V > is device off, 0V is switched on. Which sounds a bit weird to > visualise Used in shunt means a +Ve voltage switching it off gives > RF is on. 0V attenuates RF. Rds(on) is a good few ohms, so needs to > be run in a Hi-Z system. There are no doubt better P-Chan FETs. > > Andy > 'jnt Or maybe the ubiquitous 2N7000 enhancement mosfet... does not conduct with the gate a 0V, but it does when the gate is at +V 73 Alberto I2PHD --------------030609050105080002040807 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable On 5/12/2012 9:41 PM, Andy Talbot wrote: 
 A JFET switch is probably the simplest.   Uses a P =
Channel device
like a 2N3820 so it can be controlled with a positive voltage.     +V
is device  off, 0V is switched on.  Which sounds a bit weird to
visualise   Used in shunt means a +Ve voltage switching it off gives
RF is on.  0V attenuates RF.  Rds(on) is a good few ohms, so needs to
be run in a Hi-Z system.  There are no doubt better P-Chan FETs.

Andy
'jnt
Or maybe the ubiquitous 2N7000 enhancement mosfet...=A0 does not conduct with
the gate a 0V,=A0 but it does when the gate is at +V

73=A0 Alberto=A0 I2PHD

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