X-GM-THRID: 1214483372695040095 X-Gmail-Labels: rsgb lf X-Gmail-Received: 2264a115e71ee9a8f765f0c59002c3c9c641ab3a Delivered-To: daveyxm@gmail.com Received: by 10.64.250.20 with SMTP id x20cs932766qbh; Thu, 14 Sep 2006 05:43:01 -0700 (PDT) Received: by 10.48.254.10 with SMTP id b10mr12035450nfi; Thu, 14 Sep 2006 05:43:01 -0700 (PDT) Return-Path: Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mx.gmail.com with ESMTP id g1si19255727nfe.2006.09.14.05.42.59; Thu, 14 Sep 2006 05:43:01 -0700 (PDT) Received-SPF: neutral (gmail.com: 193.82.116.20 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1GNqUG-0001BN-C7 for rs_out_1@blacksheep.org; Thu, 14 Sep 2006 13:38:36 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1GNqUF-0001BE-Vp for rsgb_lf_group@blacksheep.org; Thu, 14 Sep 2006 13:38:35 +0100 Received: from imo-m26.mx.aol.com ([64.12.137.7]) by relay1.thorcom.net with esmtp (Exim 4.62) (envelope-from ) id 1GNqUC-00057l-03 for rsgb_lf_group@blacksheep.org; Thu, 14 Sep 2006 13:38:35 +0100 Received: from G0MRF@aol.com by imo-m26.mx.aol.com (mail_out_v38_r7.6.) id l.c37.2b65642 (39952) for ; Thu, 14 Sep 2006 08:34:39 -0400 (EDT) From: G0MRF@aol.com Message-ID: Date: Thu, 14 Sep 2006 08:34:39 EDT To: rsgb_lf_group@blacksheep.org MIME-Version: 1.0 X-Mailer: 9.0 SE for Windows sub 5014 X-Spam-Flag: NO X-Spam-Score: -0.4 (/) X-Spam-Report: autolearn=disabled,AWL=-0.706,HTML_50_60=0.095,HTML_MESSAGE=0.001,NO_REAL_NAME=0.178 Subject: Re: LF: RF Ferrite - off topic for LF and Micro waves Content-Type: multipart/alternative; boundary="-----------------------------1158237279" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.2 required=5.0 tests=HTML_30_40,HTML_FONTCOLOR_BLUE, HTML_MESSAGE,NO_REAL_NAME 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 Status: O X-Status: X-Keywords: X-UID: 4312 -------------------------------1158237279 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 14/09/2006 08:10:00 GMT Standard Time, ACTALBOT@mail.dstl.gov.uk writes: The PA uses an MRF 141G Mosfet device rated for 300 Watts out with 14dB gain. The circuit itself is quite simple - see the data sheet for teh MRF141G - and would have been finished a long time ago but for the output transformer. Andy G4JNT Andy. I've used the transformers from the Granberg application note for the MRF151G for comms relays on band 2. This transformer arrangement appears very efficient and did not need the recommended ferrite sections. I would suggest you try the 25 ohm coax line transformers but make them just a little larger then Granberg suggests. Another method is to use two sections of RG58 or its PTFE equivalent in parallel to get the correct 25 Ohm impedance. These are not quite so efficient as the semi rigid but are still OK. I don't have a spare semi rigid transformer, but I'll bring one of the commercial ones produced by Communications Concepts in the USA on Sunday. You may be able to create an easy way to duplicate it. _Communication-Concepts_ (http://www.communication-concepts.com/) Regards David 'MRF -------------------------------1158237279 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

In a message dated 14/09/2006 08:10:00 GMT Standard Time,=20 ACTALBOT@mail.dstl.gov.uk writes:

The PA uses an MRF 141G Mosfet device rated for= 300=20 Watts out with 14dB gain. The circuit itself=20 is quite simple - see the data sheet for teh MRF141G - and woul= d=20 have been finished a long time ago but for the output=20 transformer.

Andy =20 G4JNT

Andy.

I've used the transformers from the Granberg application note for=20= the=20 MRF151G for comms relays on band 2. This transformer=20 arrangement appears very efficient and did not need the recommended fer= rite=20 sections. I would suggest you try the 25 ohm coax line transformers bu= t=20 make them just a little larger then Granberg suggests.

Another method is to use two sections of RG58 or its PTFE equivalent in= =20 parallel to get the correct 25 Ohm impedance. These are not quite so efficie= nt=20 as the semi rigid but are still OK.

I don't have a spare semi rigid transformer, but I'll bring one of the=20 commercial ones produced by Communications Concepts in the USA on Sunday. Yo= u=20 may be able to create an easy way to duplicate it.

Communication-Concep= ts=20

Regards

David 'MRF

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