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From: Chris Osborn <g3xizchris@gmail.com>
Date: Sat, 17 Jun 2017 13:26:21 +0100
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To: LF Group <rsgb_lf_group@blacksheep.org>
Subject: Re: LF: WSPR problems
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Hi Stefan,

Many thanks for the prompt reply.
I shall do as you suggest and hopefully cure the problem.

73
Chris

On Sat, Jun 17, 2017 at 12:57 PM, DK7FC <selberdenken@posteo.de> wrote:

> Hi Chris,
>
> Try a 1:1 RF ferrite decoupling trasformer, right behind the PA. Maybe
> also on the PA input. Try to use a battery for the PA, just for one WSPR
> sequence, to see if that solves the problem. If it does, then use common
> mode chokes in the PA supply cable. Avoid ground loops. Use shielded
> circuits only.
>
> 73, Stefan
>
>
> Am 17.06.2017 13:20, schrieb Chris Osborn:
>
>> GA LF,
>>
>> I have a recurring problem with my home made LF WSPR TX  :-
>>
>> As the PC's audio signal shuts down (after the nominal 2 minute
>> transmission time) it picks up RF  -  this is fed back to the TX input
>> causing several seconds of instability.
>>
>> Has anyone else had this trouble and/or knows of a simple solution?
>>
>> I've tried putting ferrite rings around the PC's input and output cables
>> which solved the problem for a while.
>>
>> In desperation I'm considering adding a monostable to ground the TX input
>> for a few seconds after the PC's AF shuts down, but this will be a last
>> resort.
>>
>> Any useful advice or comments would be most welcome.
>>
>> 73
>> Chris (G3XIZ)
>>
>
>

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<div dir=3D"ltr"><div><div><div>Hi Stefan,<br><br></div>Many thanks for the=
 prompt reply.<br></div>I shall do as you suggest and hopefully cure the pr=
oblem.<br><br>73<br></div>Chris<br></div><div class=3D"gmail_extra"><br><di=
v class=3D"gmail_quote">On Sat, Jun 17, 2017 at 12:57 PM, DK7FC <span dir=
=3D"ltr">&lt;<a href=3D"mailto:selberdenken@posteo.de" target=3D"_blank">se=
lberdenken@posteo.de</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_qu=
ote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex=
">Hi Chris,<br>
<br>
Try a 1:1 RF ferrite decoupling trasformer, right behind the PA. Maybe also=
 on the PA input. Try to use a battery for the PA, just for one WSPR sequen=
ce, to see if that solves the problem. If it does, then use common mode cho=
kes in the PA supply cable. Avoid ground loops. Use shielded circuits only.=
<br>
<br>
73, Stefan<div class=3D"HOEnZb"><div class=3D"h5"><br>
<br>
Am 17.06.2017 13:20, schrieb Chris Osborn:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">
GA LF,<br>
<br>
I have a recurring problem with my home made LF WSPR TX=C2=A0 :-<br>
<br>
As the PC&#39;s audio signal shuts down (after the nominal 2 minute=C2=A0 t=
ransmission time) it picks up RF=C2=A0 -=C2=A0 this is fed back to the TX i=
nput causing several seconds of instability.<br>
<br>
Has anyone else had this trouble and/or knows of a simple solution?<br>
<br>
I&#39;ve tried putting ferrite rings around the PC&#39;s input and output c=
ables which solved the problem for a while.<br>
<br>
In desperation I&#39;m considering adding a monostable to ground the TX inp=
ut for a few seconds after the PC&#39;s AF shuts down, but this will be a l=
ast resort.<br>
<br>
Any useful advice or comments would be most welcome.<br>
<br>
73<br>
Chris (G3XIZ)<br>
</blockquote>
<br>
</div></div></blockquote></div><br></div>

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