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	<E349A726890B44AEAF5FE010B8B34281@JimPC>
Date: Sat, 15 Dec 2012 17:46:41 -0500
Message-ID: <CAMFjj73UdzOx3W6XJT1_BFN3Sf=GGg_sEr7hd8rfc0p+vs_L8w@mail.gmail.com>
From: Warren Ziegler <wd2xgj@gmail.com>
To: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Cc: James Moritz <james.moritz@btopenworld.com>
Subject: Re: LF: Re: M0BMU mods to the G0MRF PA
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Jim,
      One further question,  can I tap the secondary per the original G0MRF
design so as to have lower power outputs available by switching taps?

Tnx & 73 Warren



On Sat, Dec 15, 2012 at 3:55 PM, James Moritz
<james.moritz@btopenworld.com>wrote:

> Dear Warren, LF Group,
>
> It's a long time ago now, but...
> The multi-stranded winding was mainly used because it is much more flexible
> and so easier to wind onto the core. I used a salvaged LOPT core as if it
> were a toroid core, i.e. fixing the two core halves together before
> threading the wire through the aperture repeatedly to produce the winding.
> Producing a compact, even winding that lay snugly on the core using solid
> wire was difficult because of the stiffness of the wire. It is desireable
> to
> make the windings as compact as possible with the minimum amount of space
> between the turns in order to reduce the leakage inductance of the
> transformer as much as possible. This raises the self-resonant frequency of
> the transformer and reduces the amount of RC damping needed to produce a
> sensible drain waveform. The multiple strands do probably give some
> reduction in losses at 137k, but I expect only marginally.
>
> Cheers, Jim Moritz
> 73 de M0BMU
>
>
>


-- 
73 Warren K2ORS
                WD2XGJ
                WD2XSH/23
                WE2XEB/2
                WE2XGR/1

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Jim,<div>=A0 =A0 =A0 One further question, =A0can I tap the secondary per t=
he original G0MRF design so as to have lower power outputs available by swi=
tching taps?</div><div><br></div><div>Tnx &amp; 73 Warren</div><div><br></d=
iv><div class=3D"gmail_extra">
<br><br><div class=3D"gmail_quote">On Sat, Dec 15, 2012 at 3:55 PM, James M=
oritz <span dir=3D"ltr">&lt;<a href=3D"mailto:james.moritz@btopenworld.com"=
 target=3D"_blank">james.moritz@btopenworld.com</a>&gt;</span> wrote:<br><b=
lockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px =
#ccc solid;padding-left:1ex">
Dear Warren, LF Group,<br>
<br>
It&#39;s a long time ago now, but...<br>
The multi-stranded winding was mainly used because it is much more flexible=
<br>
and so easier to wind onto the core. I used a salvaged LOPT core as if it<b=
r>
were a toroid core, i.e. fixing the two core halves together before<br>
threading the wire through the aperture repeatedly to produce the winding.<=
br>
Producing a compact, even winding that lay snugly on the core using solid<b=
r>
wire was difficult because of the stiffness of the wire. It is desireable t=
o<br>
make the windings as compact as possible with the minimum amount of space<b=
r>
between the turns in order to reduce the leakage inductance of the<br>
transformer as much as possible. This raises the self-resonant frequency of=
<br>
the transformer and reduces the amount of RC damping needed to produce a<br=
>
sensible drain waveform. The multiple strands do probably give some<br>
reduction in losses at 137k, but I expect only marginally.<br>
<br>
Cheers, Jim Moritz<br>
73 de M0BMU<br>
<br>
<br>
</blockquote></div><br><br clear=3D"all"><div><br></div>-- <br>73 Warren K2=
ORS<br>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XGJ <br>=A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 WD2XSH/23<br>=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XEB/2<br>=A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 WE2XGR/1<br><br>=A0<br>
</div>

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