Return-Path: Received: (qmail 18225 invoked from network); 29 Jan 2000 20:09:58 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by grants.core.plus.net.uk with SMTP; 29 Jan 2000 20:09:58 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.02 #1) id 12Ee4e-00034E-00 for rsgb_lf_group-outgoing@blacksheep.org; Sat, 29 Jan 2000 20:02:24 +0000 Received: from mta3-rme.xtra.co.nz ([203.96.92.13]) by post.thorcom.com with esmtp (Exim 3.02 #1) id 12Ee4d-000346-00 for rsgb_lf_group@blacksheep.org; Sat, 29 Jan 2000 20:02:23 +0000 Received: from [202.27.181.210] by mta3-rme.xtra.co.nz (InterMail v4.01.01.00 201-229-111) with SMTP id <20000129200159.LAQV3144.mta3-rme@[202.27.181.210]> for ; Sun, 30 Jan 2000 09:01:59 +1300 X-Priority: 3 X-MSMail-Priority: Normal Message-ID: <389346D5.4D3B@xtra.co.nz> Date: Sun, 30 Jan 2000 09:00:21 +1300 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 From: "vernall" X-Mailer: Mozilla 3.01C-XTRA (Win95; I) MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org Subject: Re: LF: 8 kHz loading coil References: <000d01bf6a31$3bf336c0$975b97d4@win95.swipnet.se> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Christer Andersson wrote: > > Hello (V)LF experimenters, > > I have an idea of resonating my existing vertical on 8 kHz. > Is there a practical way to construct a 600 mH loading coil, withstanding 3-4 A and high voltage? > Any *large* toroids on the market?' > > /Christer > sm6pxj How about using salvaged cores from television line output transformers? I can confirm they work well at 180 kHz, even they were intended for LOPT use around 15 kHz. If required, use several cores side by side to get a higher power rating (as do several ZLs). I would also recommend a moderate air gap to assist with linear performance. Thin cardboard about the same type as a QSL card is a starting point for gapping cores :) Regards, Bob ZL2CA