Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dh06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 8DDB438000087; Wed, 30 May 2012 02:54:38 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1SZclh-0006TC-J1 for rs_out_1@blacksheep.org; Wed, 30 May 2012 07:52:29 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1SZclg-0006T3-Ve for rsgb_lf_group@blacksheep.org; Wed, 30 May 2012 07:52:28 +0100 Received: from out1.ip01ir2.opaltelecom.net ([62.24.128.237]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1SZcle-0004iP-WE for rsgb_lf_group@blacksheep.org; Wed, 30 May 2012 07:52:27 +0100 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AgEFAHnCxU9cHY6N/2dsb2JhbABEgkWDBZ9Wjn+BCIIXAQEFCBszLgUFAwMRBAEBKwICORYIBhMICYd+plGSbYsFhDAyYAONO5dPgmE X-IronPort-AV: E=Sophos;i="4.75,683,1330905600"; d="scan'208,217";a="392791251" Received: from host-92-29-142-141.as13285.net (HELO malHP) ([92.29.142.141]) by out1.ip01ir2.opaltelecom.net with SMTP; 30 May 2012 07:52:24 +0100 Message-ID: <8BAB8ED842A244BBBEEF6CBF623C37A4@malHP> From: "mal hamilton" To: References: <8BE4322932454ABBAF36917E7F0B7293@uwePC> <4FC53EA6.1060003@iup.uni-heidelberg.de> In-Reply-To: <4FC53EA6.1060003@iup.uni-heidelberg.de> Date: Wed, 30 May 2012 07:52:22 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 15.4.3555.308 X-MimeOLE: Produced By Microsoft MimeOLE V15.4.3555.308 X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Hi uwe es MF I built a class E pa for 500 a few years ago and it worked well and was reliable. The tuning at the frequency of interest is critical but easy if you follow the correct procedure for tuning a class E pa. I also built class D pa for 137 and used it for years without problems. I now use Decca amplifiers which are Bridge Fet designs with series resonant PA circuits, in my case matched to 50 ohms. for 500 Khz make L 20uH and C 5nF these are the nearest standard values available, adjust L for resonance. If you copy the Decca circuit it will work extremely well and run trouble free. 73 es gl de Mal/g3kev [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [62.24.128.237 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 13abe497adcf17a4e25c5e2a2ff79111 Subject: LF: Re: 475 kc Exiter Content-Type: multipart/alternative; boundary="----=_NextPart_000_0033_01CD3E39.25650D90" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.7 required=5.0 tests=HTML_20_30,HTML_FONT_BIG, HTML_MESSAGE,MISSING_OUTLOOK_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 x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:458242400:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d411a4fc5c42d1ea3 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. ------=_NextPart_000_0033_01CD3E39.25650D90 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi uwe es MF I built a class E pa for 500 a few years ago and it worked well and was = reliable. The tuning at the frequency of interest is critical but easy = if you follow the correct procedure for tuning a class E pa. I also = built class D pa for 137 and used it for years without problems. I now use Decca amplifiers which are Bridge Fet designs with series = resonant PA circuits, in my case matched to 50 ohms. for 500 Khz make L 20uH and C 5nF these are the nearest standard values = available, adjust L for resonance.=20 If you copy the Decca circuit it will work extremely well and run = trouble free. 73 es gl de Mal/g3kev From: Stefan Sch=C3=A4fer=20 Sent: Tuesday, May 29, 2012 10:24 PM To: rsgb_lf_group@blacksheep.org=20 Subject: Re: LF: 475 kc Exiter Sorry Uwe, missed to answer in all the trouble... I didn't know that a JUMA TX is available for "500". Well, the version for 137 kHz is fine but i think 60W is not really = enough for a ordinary LF amateur antenna. But on MF, 60W may be just = right if one want to strictly stay below the limitation of 1W. Do you know how the PA is designed? I'm just experimenting with a class D PA for MF but am surprised about = the "problems". I.e. i thought it is easier to build. The output C of = the FETs cause a heavy oscillation when the FET is OFF. So actually i = would prefer a class E which does not have this problem. A class E would = be really no problem, regarding the design. But i intend to use it for = various experiments, also with /p antennas, just for playing arround. = Here, a class E is not recommended at all since it needs a very accurate = match to Z=3DR=3D50 Ohm. Otherwise the efficiency is decreasing = dramatically, up to blowing up the FET... 73, Stefan/DK7FC Am 27.05.2012 09:39, schrieb Uwe Wensauer:=20 What do You think about the JUMA TX500 TransmitterI In my eyes a small Rig with 60 Watt and built in Converter. By the way, have a look at the filters in use =E2=80=93 easy to built = an duplicate Uwe, dk1kq ------=_NextPart_000_0033_01CD3E39.25650D90 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hi uwe es MF
I built a class E pa for 500 a few years ago and it = worked=20 well and was reliable.  The tuning at the frequency of interest is = critical=20 but easy if you follow the correct procedure for tuning a class E pa. I = also=20 built class D pa for 137 and used it for years without = problems.
I now use Decca amplifiers which are Bridge Fet = designs with=20 series resonant PA circuits, in my case matched to 50 ohms.
for 500 Khz make L 20uH and C 5nF these are = the  nearest=20 standard values available, adjust L for resonance.
If you copy the Decca circuit it will work extremely = well and=20 run trouble free.
73 es gl de Mal/g3kev
 
 
 
From: Stefan = Sch=C3=A4fer
Sent: Tuesday, May 29, 2012 10:24 PM
Subject: Re: LF: 475 kc Exiter
 
Sorry=20 Uwe, missed to answer in all the trouble...

I didn't know that a = JUMA TX=20 is available for "500".

Well, the version for 137 kHz is fine but = i think=20 60W is not really enough for a ordinary LF amateur antenna. But on MF, = 60W may=20 be just right if one want to strictly stay below the limitation of = 1W.

Do=20 you know how the PA is designed?

I'm just experimenting with a = class D PA=20 for MF but am surprised about the "problems". I.e. i thought it is = easier to=20 build. The output C of the FETs cause a heavy oscillation when the FET = is OFF.=20 So actually i would prefer a class E which does not have this problem. A = class E=20 would be really no problem, regarding the design. But i intend to use it = for=20 various experiments, also with /p antennas, just for playing arround. = Here, a=20 class E is not recommended at all since it needs a very accurate match = to Z=3DR=3D50=20 Ohm. Otherwise the efficiency is decreasing dramatically, up to blowing = up the=20 FET...

73, Stefan/DK7FC

Am 27.05.2012 09:39, schrieb Uwe = Wensauer:=20
What do You think about the JUMA TX500 TransmitterI
 
In my eyes a  small Rig with 60 Watt and built in = Converter.
 
By the way, have a look at the filters in use =E2=80=93 easy to = built an=20 duplicate
 
Uwe, = dk1kq
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