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Date: Thu, 12 Jan 2012 18:02:48 +0100
From: wolf_dl4yhf <dl4yhf@freenet.de>
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Subject: Re: LF: Tuning inductance for 137kHz receive.
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Hi Martin,

build a really big former from the "brickwork" used for Renato's monster 
VLF induction coil ?

 From http://www.vlf.it/romero3/ics101.html :

 > Ferrite blocks are readily available worldwide from large 
distributors of electronic components
 > such as RS-Components. The cost of each ferrite block is 
approximately EUR 20.00.
 > The blocks are assembled together using a bicomponent glue.

73,
   Wolf DL4YHF .


Am 12.01.2012 12:02, schrieb Martin Evans:
> Morning, Pete.
>
> Thanks for this.
>
> Yes, this is what I should do. My problem is that I get carried away -  I
> begin by thinking of making a variometer - then I decide that it *must* be
> the biggest one ever - so I search for a *huge* former - which I can't
> find - and so it goes.
>
> Pathetic really.
>
> Maybe my resolution for 2012 should be to stop daydreaming and actually *do*
> something!
>
> Martin  GW3UCJ.
>
> ########################################
>
> Just make a variometer two inductors one inside the other like piston and
> cylinder and adjust in and out to resonance (I think this design is the
> simplest form of variometer mechanically). I use a couple of plastic paint
> buckets, mine are 200mm diameter. 3mH looks about right for the antenna
> described but fine inductance adjustment is necessary and it is best to get
> as high a 'Q' as you can. The band is very narrow and 'Q' helps reduce out
> of band high power signals. I am in fact describing my TX setup the primary
> inductor is a large 600mm diameter coil tapped. All my inductors are air
> cored.
>
> For RX you can tune the inductor with a large variable capacitor strapped
> across because there are no flash over issues. It is quite simple to make
> these tuning coils from scratch a lot of wire though, but I would recommend
> it.
>
> Try Rick Strobbe ON7YD's site highly recommended
> http://www.strobbe.eu/on7yd/136ant/#Introduction
>
> Hope this helps.
>
> 73 es GL Pete M0FMT IO91UX
>
>
>
>


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    Hi Martin,<br>
    <br>
    build a really big former from the "brickwork" used for Renato's
    monster VLF induction coil ?<br>
    <br>
    From <a class="moz-txt-link-freetext" href="http://www.vlf.it/romero3/ics101.html">http://www.vlf.it/romero3/ics101.html</a> :<br>
    <br>
    <font face="Tahoma">&gt; Ferrite blocks are readily available
      worldwide from
      large distributors of electronic components <br>
      &gt; such as RS-Components. The
      cost of each ferrite block is approximately &#8364; 20.00. <br>
      &gt; The blocks are
      assembled together using a bicomponent glue.</font><br>
    <br>
    73,<br>
    &nbsp; Wolf DL4YHF .<br>
    <br>
    <br>
    Am 12.01.2012 12:02, schrieb Martin Evans:
    <blockquote cite="mid:00e101ccd119$b7755790$ae01a8c0@youry0mkaz8jaq"
      type="cite">
      <pre wrap="">Morning, Pete.

Thanks for this.

Yes, this is what I should do. My problem is that I get carried away -  I
begin by thinking of making a variometer - then I decide that it *must* be
the biggest one ever - so I search for a *huge* former - which I can't
find - and so it goes.

Pathetic really.

Maybe my resolution for 2012 should be to stop daydreaming and actually *do*
something!

Martin  GW3UCJ.

########################################

Just make a variometer two inductors one inside the other like piston and
cylinder and adjust in and out to resonance (I think this design is the
simplest form of variometer mechanically). I use a couple of plastic paint
buckets, mine are 200mm diameter. 3mH looks about right for the antenna
described but fine inductance adjustment is necessary and it is best to get
as high a 'Q' as you can. The band is very narrow and 'Q' helps reduce out
of band high power signals. I am in fact describing my TX setup the primary
inductor is a large 600mm diameter coil tapped. All my inductors are air
cored.

For RX you can tune the inductor with a large variable capacitor strapped
across because there are no flash over issues. It is quite simple to make
these tuning coils from scratch a lot of wire though, but I would recommend
it.

Try Rick Strobbe ON7YD's site highly recommended
<a class="moz-txt-link-freetext" href="http://www.strobbe.eu/on7yd/136ant/#Introduction">http://www.strobbe.eu/on7yd/136ant/#Introduction</a>

Hope this helps.

73 es GL Pete M0FMT IO91UX




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