Return-Path: <owner-rsgb_lf_group@blacksheep.org> Received: (qmail 29116 invoked from network); 1 Sep 2002 20:55:43 -0000 Received: from warrior.services.quay.plus.net (212.159.14.227) by mailstore with SMTP; 1 Sep 2002 20:55:43 -0000 Received: (qmail 29082 invoked from network); 1 Sep 2002 20:56:03 -0000 Received: from post.thorcom.com (193.82.116.70) by warrior.services.quay.plus.net with SMTP; 1 Sep 2002 20:56:03 -0000 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.10) id 17lbkm-00083j-00 for rsgb_lf_group-outgoing@blacksheep.org; Sun, 01 Sep 2002 21:55:28 +0100 Received: from [130.244.199.132] (helo=fep04-svc.swip.net) by post.thorcom.com with esmtp (Exim 4.10) id 17lbkm-00083Z-00 for rsgb_lf_group@blacksheep.org; Sun, 01 Sep 2002 21:55:28 +0100 Received: from oemcomputer ([213.101.36.173]) by fep04-svc.swip.net with SMTP id <20020901205520.BZEX20297.fep04-svc.swip.net@oemcomputer> for <rsgb_lf_group@blacksheep.org>; Sun, 1 Sep 2002 22:55:20 +0200 Message-ID: <003001c251f9$ed27a4a0$ad2465d5@oemcomputer> From: "Johan Bodin" <sm6lkm.jbeab@swipnet.se> To: rsgb_lf_group@blacksheep.org References: <000001c24c38$ea026420$f976073e@main> <002001c2513c$a9f3a5c0$4bdf7ad5@j1r9b7> <001f01c24bf7$599c0e40$4e6152d5@it> Date: Sun, 1 Sep 2002 22:55:35 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: LF: Re: Re: Re: E-field antennas Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=-0.7 required=5.0tests=DEAR_SOMEBODYversion=2.31 Sender: <owner-rsgb_lf_group@blacksheep.org> Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Dear All, Giulio Scaroni wrote: > So i'm planning to made an Amrad antenna, i have send a request at > Crystalonics for high current FET. Has anyone tried a small power MOSFET as input stage in an active antenna? I am thinking of BS170, 2N7000 and similar transistors. They have a very high forward transconductance (hundreds of mA/V) and should make a very "stiff" source follower. They are easy to find and are cheap too. The input capacitance is higher than that of J-FETs (in the order of 30pF) but it can be compensated by a longer whip/wire. The drain-gate capacitance is also high but I guess that a cascode circuit can be used to minimise the effects of Mr Miller... Since they are "enhancement mode FETs", they require some bias voltage to start condicting but that's no problem. The big question is noise...? 73 Johan SM6LKM