Return-Path: Received: from rly-dc06.mx.aol.com (rly-dc06.mail.aol.com [172.19.136.35]) by air-dc08.mail.aol.com (v126.13) with ESMTP id MAILINDC082-b2c4b2791f9dc; Tue, 15 Dec 2009 08:41:40 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-dc06.mx.aol.com (v125.7) with ESMTP id MAILRELAYINDC068-b2c4b2791f9dc; Tue, 15 Dec 2009 08:41:14 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NKXbU-0004I4-0A for rs_out_1@blacksheep.org; Tue, 15 Dec 2009 13:38:16 +0000 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NKXbT-0004Hv-Bd for rsgb_lf_group@blacksheep.org; Tue, 15 Dec 2009 13:38:15 +0000 Received: from out1.ip02ir2.opaltelecom.net ([62.24.128.238]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NKXd7-0003iW-Rd for rsgb_lf_group@blacksheep.org; Tue, 15 Dec 2009 13:40:00 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AukLABIgJ0tUDUcY/2dsb2JhbACCKIhzwnWKAYQrBIFi X-IronPort-AV: E=Sophos;i="4.47,400,1257120000"; d="scan'208,217";a="215019605" Received: from host-84-13-71-24.opaltelecom.net (HELO xphd97xgq27nyf) ([84.13.71.24]) by out1.ip02ir2.opaltelecom.net with SMTP; 15 Dec 2009 13:39:51 +0000 Message-ID: <000b01ca7d8c$12e01810$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" To: References: <38A51B74B884D74083D7950AD0DD85E828AC77@File-Server-HST.hst.e-technik.tu-darmstadt.de> Date: Tue, 15 Dec 2009 13:39:49 -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,HTML_MESSAGE=0.001 Subject: Re: AW: LF: "Gain" between qrss3 and qrss10? Content-Type: multipart/alternative; boundary="----=_NextPart_000_0008_01CA7D8C.129D69C0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.3 required=5.0 tests=HTML_50_60, HTML_FONTCOLOR_UNKNOWN,HTML_MESSAGE 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-IP: 193.82.116.20 ------=_NextPart_000_0008_01CA7D8C.129D69C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable 10 K/watts is a nice starting power to start a fire with a small broom= stick antenna, be daring and go for 20 K/watts for more spectacular re= sults like the Northern Lights G3KEV ----- Original Message -----=20 From: Stefan Sch=E4fer=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Tuesday, December 15, 2009 12:44 PM Subject: AW: AW: LF: "Gain" between qrss3 and qrss10? Mni tnx Rik for your answer! No, you didn't spoil the fun at all ;-) I have some remarks/ideas. The coil losses increase linear with the power but not more than lin= ear. So, 10x the power wouldn't decrease the antenna efficiency (if no= arcing occurs, of course). If we assume an antenna, e.g. in 8m height= with many toploads, then the efficiency will be poor but the capacita= nce will be high and thus the needed L will be small. Therefore we get= a low voltage even with very high power and due to the low efficiency= we will keep the legal limit. So, if one has no possibility to increa= se the antenna height QRO is one choice, especially when the operator= is already in pension and cannot do a qso in qrss10000000000000000000= 000000 any more ;-)=20 It should be possible to run a TX directly of the mains (giving abou= t 330V DC). But for 10kW the PSU current would be 33A, requiring somet= hing like a 60000uF/450V elco, these large HV elco's cost a fortune (a= t QRL we recenty had to replace a 4700uF/450V capacitor, it costed ove= r 200 Euro). And for a Class-D / Class-E amp running of 330V a 900V power FET mig= ht be a bit on the edge for a foolprove TX (but since you are spending= a fortune on elco's you can spend some more money on 1.5kV devices ;-= ) ). Yes, you are right. But i mean i USA, where the voltage is 110V, you= get about 155V and thus the 900V FET would have 6 times more. For a= class e mode PA, 4x the voltage can be reached when SWR is correct(!)= so there would be a goog savety factor. About the Capacitors: You cou= ld reduce the needed C when using a 3 phase system (of the kitchen ove= n ;-) ). Then you would get about 268VDC and therefore a factor 3,35= to the 900V which will be critical for the FETs when SWR is not absol= utely constant 1:1, so better using a IXFH24N100 ;-) Really nice, that conversation! Tnx! 73, Stefan / DK7FC ------=_NextPart_000_0008_01CA7D8C.129D69C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
10 K/watts is a nice starting power= to start a fire=20 with a small broomstick antenna, be daring and go for 20 K/watts for= more=20 spectacular results like the Northern Lights
G3KEV
 
----- Original Message -----
Sent: Tuesday, December 15,= 2009 12:44=20 PM
Subject: AW: AW: LF: "Gain"= between qrss3=20 and qrss10?

Mni tnx Rik for=20 your answer!

 

No, you didn=92t=20 spoil the fun at all ;-)

 

I have some=20 remarks/ideas.

The coil losses=20 increase linear with the power but not more than linear. So, 10x the= power=20 wouldn=92t decrease the antenna efficiency (if no arcing occurs, of= course). If=20 we assume an antenna, e.g. in 8m height with many toploads, then the= =20 efficiency will be poor but the capacitance will be high and thus th= e needed L=20 will be small. Therefore we get a low voltage even with very high po= wer and=20 due to the low efficiency we will keep the legal limit. So, if one= has no=20 possibility to increase the antenna height QRO is one choice, especi= ally when=20 the operator is already in pension and cannot do a qso in=20 qrss10000000000000000000000000 any more ;-)

 

 

 

 

Yes, you are right.=20 But i mean i = USA, where the voltage=20 is 110V, you get about 155V and thus the 900V FET would have 6 times= more. For=20 a class e mode PA, 4x the voltage can be reached when SWR is correct= (!) so=20 there would be a goog savety factor. About the Capacitors: You could= reduce=20 the needed C when using a 3 phase system (of the kitchen oven ;-) ).= Then you=20 would get about 268VDC and therefore a factor 3,35 to the 900V which= will be=20 critical for the FETs when SWR is not absolutely constant 1:1, so be= tter using=20 a=20 IXFH24N100  ;-)

 

Really nice, that=20 conversation! Tnx!

 

73, Stefan /=20 DK7FC

 

 

 

 

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