Return-Path: X-Spam-DCC: paranoid 1290; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-0.7 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_MESSAGE,RATWARE_GECKO_BUILD,SPF_PASS autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id u3NGusGr019642 for ; Sat, 23 Apr 2016 18:56:55 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1au0m2-0005U2-LV for rs_out_1@blacksheep.org; Sat, 23 Apr 2016 17:51:14 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1au0m2-0005Tt-7y for rsgb_lf_group@blacksheep.org; Sat, 23 Apr 2016 17:51:14 +0100 Received: from mout01.posteo.de ([185.67.36.65]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1au0m0-0002xH-2k for rsgb_lf_group@blacksheep.org; Sat, 23 Apr 2016 17:51:13 +0100 Received: from dovecot03.posteo.de (dovecot03.posteo.de [172.16.0.13]) by mout01.posteo.de (Postfix) with ESMTPS id 20570209C5 for ; Sat, 23 Apr 2016 18:51:11 +0200 (CEST) Received: from mail.posteo.de (localhost [127.0.0.1]) by dovecot03.posteo.de (Postfix) with ESMTPSA id 3qsdmH0K5Rz5vN3 for ; Sat, 23 Apr 2016 18:51:11 +0200 (CEST) Message-ID: <571BA7FE.6080601@posteo.de> Date: Sat, 23 Apr 2016 18:51:10 +0200 From: DK7FC User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <57101A93.9050904@posteo.de> <8D364FDC57083E1-13C0-757EEB@webmail-vm186.sysops.aol.com> <5710A5DD.7040300@abelian.org> <5710BCBA.60901@posteo.de> <5711387D.7070600@abelian.org> <57134ADA.1020309@abelian.org> <5713EABF.70601@abelian.org> <5713EE10.3000008@posteo.de> In-Reply-To: <5713EE10.3000008@posteo.de> X-Scan-Signature: f1498eebf16822c5ea85527a90413169 Subject: Re: LF: TXing on VLF again, my first homemade linear PA! :-) Content-Type: multipart/alternative; boundary="------------020709000404080700010306" 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-Scanned-By: MIMEDefang 2.56 on 10.1.3.11 Status: O X-Status: X-Keywords: X-UID: 7811 This is a multi-part message in MIME format. --------------020709000404080700010306 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi all, Since about 16 UTC i'm transmitting on 8270.00500 Hz again. The antenna current is about 200 mA. It is a first test over a longer time with my new PA. I have been off the air for a few days now becuase i destroyed my audio amp that i used as a VLF PA. Somehow i started to like the idea of a clean sine wave coming from the PA. Low pass filters are hard to design for VLF, you know. Since i don't like buying and since i didn't find another one in the trash, i 'had to' (actually /wanted/) to build my own. It is a class-AB PA now running at 20V DC using 2x IRFP064N against ground. Opposite phase drive signals are generated by a small blue ferrite core with 20 quadfilar turns. On the primary side, 2 of these 4 windings are in series. On the scope, the signal looks quite good. The 3rd harmonic is at about -20 dBc, certainly improvable. But it's just version 0.2 now ;-) A large ferrite core is used to up-transform the voltage to about 220V rms for this power level (i'm not spot on the resonance), also providing galvanic decoupling. A photo can be found at https://dl.dropboxusercontent.com/u/19882028/VLF/20160423_184046.jpg https://dl.dropboxusercontent.com/u/19882028/VLF/20160423_184059.jpg The PA consumes 3.6A at 20V DC now. Improvements will follow... The signal will stay on air for a few hours now. 73, Stefan --------------020709000404080700010306 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi all,

Since about 16 UTC i'm transmitting on 8270.00500 Hz again. The antenna current is about 200 mA. It is a first test over a longer time with my new PA.

I have been off the air for a few days now becuase i destroyed my audio amp that i used as a VLF PA. Somehow i started to like the idea of a clean sine wave coming from the PA. Low pass filters are hard to design for VLF, you know. Since i don't like buying and since i didn't find another one in the trash, i 'had to' (actually wanted) to build my own. It is a class-AB PA now running at 20V DC using 2x IRFP064N against ground. Opposite phase drive signals are generated by a small blue ferrite core with 20 quadfilar turns. On the primary side, 2 of these 4 windings are in series. On the scope, the signal looks quite good. The 3rd harmonic is at about -20 dBc, certainly improvable. But it's just version 0.2 now ;-)
A large ferrite core is used to up-transform the voltage to about 220V rms for this power level (i'm not spot on the resonance), also providing galvanic decoupling.

A photo can be found at
https://dl.dropboxusercontent.com/u/19882028/VLF/20160423_184046.jpg
https://dl.dropboxusercontent.com/u/19882028/VLF/20160423_184059.jpg

The PA consumes 3.6A at 20V DC now. Improvements will follow...

The signal will stay on air for a few hours now.

73, Stefan
--------------020709000404080700010306--