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[82.70.254.222]) by smtp.gmail.com with ESMTPSA id 55sm28255537wrw.87.2018.03.08.04.00.04 (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 08 Mar 2018 04:00:05 -0800 (PST) Date: Thu, 8 Mar 2018 12:00:03 +0000 From: Chris Wilson X-Priority: 3 (Normal) Message-ID: <3610102492.20180308120003@gmail.com> To: "rsgb_lf_group@blacksheep.org" CC: dead.fets@gmail.com MIME-Version: 1.0 X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Hello expert LF'ers! The centre toroid of my three toroid LPF heats up on the longer transmissions like WSPR15. I have added a small fan as a crutch (thanks N1BUG!) but I guess that's a crutch for inadequate hardware. I was wondering whether instead of buying a larger toroid, which seem only to be available from the US at high cost, I could wind an air cored coil of similar inductance. But I am unsure whether it would have the required "Q" factor. Your opinions please? Thanks, [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (dead.fets[at]gmail.com) 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: e09cca6d8e44a91eadbdfb3e1b8aec09 Subject: LF: Can an air cored LPF inductor have as high a "Q" as a toroidal wound one? Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=PRIORITY_NO_NAME, TO_ADDRESS_EQ_REAL 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 Hello expert LF'ers! The centre toroid of my three toroid LPF heats up on the longer transmissions like WSPR15. I have added a small fan as a crutch (thanks N1BUG!) but I guess that's a crutch for inadequate hardware. I was wondering whether instead of buying a larger toroid, which seem only to be available from the US at high cost, I could wind an air cored coil of similar inductance. But I am unsure whether it would have the required "Q" factor. Your opinions please? Thanks, Also I am wondering, looking at the Micrometals site, whether the current -2 material can be bettered by using -3 material? http://www.w1vd.com/LPF.pdf and info on frequency range of these cores is at: http://toroids.info/ -- Best regards, Chris mailto:dead.fets@gmail.com