Return-Path: Received: (qmail 27487 invoked from network); 22 Sep 2003 17:06:01 -0000 Received: from unknown (HELO netmail00.services.quay.plus.net) (212.159.14.218) by mailstore with SMTP; 22 Sep 2003 17:06:01 -0000 Received: (qmail 21849 invoked from network); 22 Sep 2003 17:06:00 -0000 Received: from post.thorcom.com (193.82.116.70) by netmail00.services.quay.plus.net with SMTP; 22 Sep 2003 17:06:00 -0000 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1A1U7A-0004fn-38 for rsgb_lf_group-outgoing@blacksheep.org; Mon, 22 Sep 2003 18:04:44 +0100 Received: from [194.73.73.92] (helo=carbon.btinternet.com) by post.thorcom.com with esmtp (Exim 4.14) id 1A1U75-0004fe-Vq for rsgb_lf_group@blacksheep.org; Mon, 22 Sep 2003 18:04:40 +0100 Received: from host213-122-107-102.in-addr.btopenworld.com ([213.122.107.102] helo=Main) by carbon.btinternet.com with smtp (Exim 3.22 #23) id 1A1U74-0003Ln-00 for rsgb_lf_group@blacksheep.org; Mon, 22 Sep 2003 18:04:39 +0100 Message-ID: <001301c3812b$8fe2fb20$6507a8c0@Main> From: "Alan Melia" To: rsgb_lf_group@blacksheep.org References: <000701c3811e$7ac5ef20$3704210a@Hugh> Date: Mon, 22 Sep 2003 17:23:25 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: LF: Re: Pot cores Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=-1.5 required=5.0tests=ORIGINAL_MESSAGE,QUOTED_EMAIL_TEXT,REFERENCESversion=2.55 X-Spam-Checker-Version: SpamAssassin 2.55 (1.174.2.19-2003-05-19-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 Hi Hugh, just a thought, but old fashioned telephone engineers used to use coils for loading lines (the ubiquitous 88mH comes from this era) For outside use they were often sealed in an iron pot filled with wax (or pitch) to keep the water out. I seem to remember comments about putting "pots" in the line, but this is really before my time and probably dates back to a long time before ferrite was available. I was not on that side anyway. Maybe a real telephone engineer might have some thoughts. Generally the so-called "pot" cores totally enclose the bobbin (like a "pot"??), though this is not quite the case with the RM design cores which are "X" shaped. My 1972 Mullard Passive Components catalogue shows series of pictures that distinguish RM cores, from Pot cores, which totally enclose the bobbin. I suspect the "X" cores allow the bobbin to be wound and the coil ends terminated on the pins before the enclosing ferrite was installed. This probably made for a better production flow. The pot core is a bit more fiddly to deal with as it the bobbin must be installed with flying leads which then need to be soldered to the carrier pins. Of course the Navy might have a different explanation, but then they used to define their capacitance in "jars" and measure it in centimetres !! Cheers de Alan G3NYK alan.melia@btinternet.com ----- Original Message ----- From: "Hugh M0WYE" To: Sent: 22 September 2003 16:30 Subject: LF: Pot cores > Hi Group > While pondering a filter design and playing with a pot core type inductor... > RM6 / RM10 etc. > I wondered: "Why is it called a pot core - it doesn't look much like a pot > ?" > Anyone know how the pot-core got it's name ? > Silly, I know, but one does like to know these things ... > 73 > Hugh M0WYE > > >