Return-Path: Received: (qmail 31764 invoked from network); 5 Apr 2003 15:27:09 -0000 Received: from netmail02.services.quay.plus.net (212.159.14.221) by mailstore with SMTP; 5 Apr 2003 15:27:09 -0000 Received: (qmail 2905 invoked by uid 10001); 5 Apr 2003 15:20:29 -0000 Received: from post.thorcom.com (193.82.116.70) by netmail02.services.quay.plus.net with SMTP; 5 Apr 2003 15:20:29 -0000 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.14) id 191pS6-00083M-68 for rsgb_lf_group-outgoing@blacksheep.org; Sat, 05 Apr 2003 16:19:30 +0100 Received: from [212.1.130.143] (helo=smtp-1.visp.telinco.net) by post.thorcom.com with esmtp (Exim 4.14) id 191pS1-00083D-6l for rsgb_lf_group@blacksheep.org; Sat, 05 Apr 2003 16:19:25 +0100 Received: from [80.225.93.153] (helo=RSGB613192) by smtp-1.visp.telinco.net with smtp (Exim 3.36 #1) id 191pS0-0001hj-00 for rsgb_lf_group@blacksheep.org; Sat, 05 Apr 2003 16:19:24 +0100 Message-ID: <004001c2fb86$ac5a8c80$545de150@RSGB613192> From: "Andy Talbot" To: rsgb_lf_group@blacksheep.org References: <3.0.5.32.20030401044655.007f7b20@pop.vianw.pt><001a01c2f7c3$800834a0$92e086d4@erica><000501c2f7a3$1f8d9ea0$07d2fc3e@ian><003101c2f7b3$1954f500$cbe8fc3e@l8p8y6> <5.1.0.14.0.20030405094933.01f693d0@POP3.freeler.nl> Date: Sat, 5 Apr 2003 16:18:09 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2615.200 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: Re: LF: Loading coils and Decca 5501 screening Content-Type: text/html; charset=windows-1252 X-Spam-Status: No, hits=-5.4 required=5.0tests=HTML_20_30,HTML_MESSAGE,REFERENCESversion=2.51 X-Spam-Checker-Version: SpamAssassin 2.51 (1.174.2.5-2003-03-20-exp) X-SA-Exim-Scanned: Yes Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rsgb_lf_group-outgoing@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false Content-transfer-encoding: 8bit

Yes, QEX December 2002. The tank coil was located about 30mm away from the perforated steel casing and when the Tx was running at the 700W level the casing immediately above the coil reached over 100deg. (the reast of the PA was quite cool). A sheet of soft aluminium of > 1mm thickness interspersed between the coil and the casing solved that problem, and the Q of teh tank rose a bit. The AL has to have a thickness of a few skin depths to be worthwhile, so 0.5 to 1mm. Al foil is barely good enough at a few tens of microns thickness, and might suggest why some people find lining an otherwise lossey cabin with it to be not very effective.

Andy G4JNT

I think that was G4JNT's off-line TX using circuit techniques from the Decca design. As I recall, When Andy initially put the TX in a steel case, the casing around the tank coil got very hot due to eddy current heating. The problem was overcome by placing aluminium sheeting between the coil and the steel casing.

That is correct. Andy published his design in QEX.

73, Dick,