Return-Path: Received: (qmail 16163 invoked from network); 26 Jan 2001 13:08:43 -0000 Received: from unknown (HELO warrior-inbound.servers.plus.net) (212.159.14.227) by extortion.plus.net with SMTP; 26 Jan 2001 13:08:43 -0000 Received: (qmail 9535 invoked from network); 26 Jan 2001 12:34:51 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by warrior with SMTP; 26 Jan 2001 12:34:51 -0000 Content-Transfer-Encoding: 8bit Received: from majordom by post.thorcom.com with local (Exim 3.16 #1) id 14M7ze-0003MC-00 for rsgb_lf_group-outgoing@blacksheep.org; Fri, 26 Jan 2001 12:28:42 +0000 Received: from bob.dera.gov.uk ([192.5.29.90]) by post.thorcom.com with esmtp (Exim 3.16 #1) id 14M7zd-0003M7-00 for rsgb_lf_group@blacksheep.org; Fri, 26 Jan 2001 12:28:41 +0000 X-Priority: 3 X-MSMail-Priority: Normal Received: by bob.dera.gov.uk; (8.8.8/1.3/10May95) id MAA31414; Fri, 26 Jan 2001 12:29:58 GMT Received: (qmail 2777 invoked from network); 26 Jan 2001 13:21:57 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from gauntlet.mail.dera.gov.uk (172.16.9.10) by baton.dera.gov.uk with SMTP; 26 Jan 2001 13:21:57 -0000 Received: by gauntlet.mail.dera.gov.uk; id NAA28270; Fri, 26 Jan 2001 13:13:07 GMT Received: from unknown(10.71.64.31) by gauntlet.mail.dera.gov.uk via smap (3.2) id xma028152; Fri, 26 Jan 01 13:12:46 GMT Received: from FRN-MAIL-3.dera.gov.uk (unverified) by mailguard.dera.gov.uk (Content Technologies SMTPRS 4.1.5) with ESMTP id for ; Fri, 26 Jan 2001 12:31:32 +0000 Received: by frn-mail-3.dera.gov.uk with Internet Mail Service (5.5.2650.21) id ; Fri, 26 Jan 2001 12:27:57 -0000 Message-ID: <65AECDF1F89AD411900400508BFC869F0D7568@pdw-mail-1.dera.gov.uk> From: "Talbot Andrew" To: rsgb_lf_group@blacksheep.org Subject: LF: RE: RE: VA3LK seen in ON Date: Fri, 26 Jan 2001 12:28:11 -0000 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2650.21) Content-Type: text/plain; charset=iso-8859-1; format=flowed Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: > -----Original Message----- > PA must be linear. Is this a though requirement for the > present crop of PAs > around ? How much would this requirement be of obstacle to > the adoption > of such a scheme (which could also be FEC corrected...). TNX > 73 Alberto With the present designs a real killer ! Switching transmitters achieve well over 90% efficiency, and a conventional linear design would have 78% absolute maximum, more like 50% in reality. With kW outputs, that's a lot of heat to get rid of. The efficiency issue is why so many commercial LF transmissions use constant amplitude MSK now, having changed over from bandwidth hungry FSK. PSK, to be social, needs amplitude tailoring otherwise this would be the mode of choice. We can get away with using PSK without any complaints as we are using very low data rates, so the sidebands are not a serious problem, but there all the same. Hence my proposal for two sequential tones for a (tongue in cheek) visual human decoded system. Or a slowed down narrowband version of Piccolo. Isn't is about time some more LF operators tried BPSK - I've no one to listen out for ! But we'll have to find a new frequency, Larry is established on 137.79 now. Andy G4JNT -- The Information contained in this E-Mail and any subsequent correspondence is private and is intended solely for the intended recipient(s). For those other than the recipient any disclosure, copying, distribution, or any action taken or omitted to be taken in reliance on such information is prohibited and may be unlawful.