Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-df01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 96E9C3800010F for ; Thu, 29 Sep 2011 15:06:34 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1R9LQ6-0004ib-Bu for rs_out_1@blacksheep.org; Thu, 29 Sep 2011 19:33:18 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1R9LQ5-0004iS-Vo for rsgb_lf_group@blacksheep.org; Thu, 29 Sep 2011 19:33:17 +0100 Received: from out1.ip01ir2.opaltelecom.net ([62.24.128.237]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1R9LQ3-0008Hh-FU for rsgb_lf_group@blacksheep.org; Thu, 29 Sep 2011 19:33:17 +0100 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AucAAAG5hE5cHYT4/2dsb2JhbABBiSCPcEOOQXiBTgUBAQQBCAEBA0kCExMGAQEDBQIBAxEEAQEKJRQBBBoGFggGEwoBAgIBAYdpAroNhxMEh0KdTg X-IronPort-AV: E=Sophos;i="4.68,462,1312153200"; d="scan'208";a="366922674" Received: from host-92-29-132-248.as13285.net (HELO xphd97xgq27nyf) ([92.29.132.248]) by out1.ip01ir2.opaltelecom.net with SMTP; 29 Sep 2011 19:33:09 +0100 Message-ID: <007701cc7ed6$3c8ff430$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" To: References: <002801cc7e08$6e9ec9c0$0401a8c0@xphd97xgq27nyf> <4E839D14.5080105@telus.net> <002f01cc7e84$49295490$0401a8c0@xphd97xgq27nyf> <004901cc7ebd$3d0db910$0401a8c0@xphd97xgq27nyf> <4E849D17.3030607@telus.net> Date: Thu, 29 Sep 2011 18:33:08 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: Wilkinson combiner Content-Type: text/plain; charset="iso-8859-1" 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=0.0 required=5.0 tests=none 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 x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:479123936:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d40d54e84c1ba43d0 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Not so long ago some expert on here said I was optimistic about my erp and divide by 2. I have been worried ever since !!!!!!!!!!! g3kev ----- Original Message ----- From: "James Moritz" To: Sent: Thursday, September 29, 2011 6:06 PM Subject: Re: LF: Wilkinson combiner > Dear Mal, Scott, LF Group, > > The Decca design does not only use a combining transformer (effectively > connecting the 3 PA module outputs in parallel). Each PA module has a "guard > circuit" RF current limiter that protects the individual PA in the event of > a low-impedance antenna fault, or a fault in one of the other PAs. The Decca > design concept provides a measure of redundancy - if one PA fails, a new > module can be "hot swapped" while the other two continue to produce some > output. This isn't really needed for an amateur radio TX - with the bigger > SMPS MOSFETs available today, it is easier and cheaper to design and build a > single large PA. > > But with a large antenna as you often describe, a high power PA really > shouldn't be necessary - 100 - 200W should be plenty to reach 1W ERP. If it > really takes so much power, perhaps you really need to investigate why your > antenna efficiency is so dismal before running up your electricity bill! > > Cheers, Jim Moritz > 73 de M0BMU > >