Message-ID: <571CFD33.2070606@posteo.de>
Date: Sun, 24 Apr 2016 19:06:59 +0200
From: DK7FC <selberdenken@posteo.de>
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> <571BA7FE.6080601@posteo.de> <571CFAD6.8000806@mbsks.franken.de>
In-Reply-To: <571CFAD6.8000806@mbsks.franken.de>
Subject: Re: LF: TXing on VLF again, my first homemade linear PA! :-)
Content-Type: multipart/alternative;
 boundary="------------000204090004080704090209"
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Status: O

This is a multi-part message in MIME format.
--------------000204090004080704090209
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit

Hi Roland,

Oh, we quickly need a strict bandplan!!! :-)
Seems there is more activity on VLF then on LF these days, hi.

73, Stefan

Am 24.04.2016 18:56, schrieb Roland Bruestle:
> Hello,
> I'm on 8270Hz with 0.3A as test transmission.  I hope our signal 
> separation is good enough.
> Roland Dl3NDR
>
> Am 23.04.2016 um 18:51 schrieb DK7FC:
>> 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
>

--------------000204090004080704090209
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: 8bit

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
  <meta content="text/html; charset=UTF-8" http-equiv="Content-Type">
</head>
<body bgcolor="#ffffff" text="#000000">
Hi Roland, <br>
<br>
Oh, we quickly need a strict bandplan!!! :-)<br>
Seems there is more activity on VLF then on LF these days, hi.<br>
<br>
73, Stefan<br>
<br>
Am 24.04.2016 18:56, schrieb Roland Bruestle:
<blockquote cite="mid:571CFAD6.8000806@mbsks.franken.de" type="cite">
  <meta content="text/html; charset=UTF-8" http-equiv="Content-Type">
  <div class="moz-cite-prefix">Hello,<br>
I'm on 8270Hz with 0.3A as test transmission.  I hope our signal
separation is good enough.<br>
Roland Dl3NDR<br>
  <br>
Am 23.04.2016 um 18:51 schrieb DK7FC:<br>
  </div>
  <blockquote cite="mid:571BA7FE.6080601@posteo.de" type="cite">
    <meta content="text/html; charset=UTF-8" http-equiv="Content-Type">
Hi all, <br>
    <br>
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.<br>
    <br>
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 <i>wanted</i>) 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 ;-) <br>
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.<br>
    <br>
A photo can be found at <br>
    <a moz-do-not-send="true" class="moz-txt-link-freetext"
 href="https://dl.dropboxusercontent.com/u/19882028/VLF/20160423_184046.jpg">https://dl.dropboxusercontent.com/u/19882028/VLF/20160423_184046.jpg</a><br>
    <a moz-do-not-send="true" class="moz-txt-link-freetext"
 href="https://dl.dropboxusercontent.com/u/19882028/VLF/20160423_184059.jpg">https://dl.dropboxusercontent.com/u/19882028/VLF/20160423_184059.jpg</a><br>
    <br>
The PA consumes 3.6A at 20V DC now. Improvements will follow...<br>
    <br>
The signal will stay on air for a few hours now.<br>
    <br>
73, Stefan<br>
  </blockquote>
  <br>
</blockquote>
</body>
</html>

--------------000204090004080704090209--