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Content preview: Hi Warren, I use variable PA supply volts & can take power level to exactly what level I require. 73, Gary - G4WGT. ----- Original Message ----- From: Warren Ziegler To: rsgb_lf_group Cc: James Moritz Sent: Saturday, December 15, 2012 10:46 PM Subject: Re: LF: Re: M0BMU mods to the G0MRF PA [...] Content analysis details: (-0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [212.74.100.53 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (g4wgt[at]tiscali.co.uk) -0.0 SPF_HELO_PASS SPF: HELO matches SPF record -0.0 SPF_PASS SPF: sender matches SPF record -0.0 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: cd79e98bb57cf38a756c15469b5a993e Subject: Re: LF: Re: M0BMU mods to the G0MRF PA Content-Type: multipart/alternative; boundary="----=_NextPart_000_001B_01CDDB7E.4E820B00" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_30_40,HTML_MESSAGE, MISSING_OUTLOOK_NAME autolearn=no version=2.63 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-aol-global-disposition: G x-aol-sid: 3039ac1d60cc50cdad446d50 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. ------=_NextPart_000_001B_01CDDB7E.4E820B00 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Warren, I use variable PA supply volts & can take power level to exactly what = level I require. 73, Gary - G4WGT. ----- Original Message -----=20 From: Warren Ziegler=20 To: rsgb_lf_group=20 Cc: James Moritz=20 Sent: Saturday, December 15, 2012 10:46 PM Subject: Re: LF: Re: M0BMU mods to the G0MRF PA 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 = 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 --=20 73 Warren K2ORS WD2XGJ=20 WD2XSH/23 WE2XEB/2 WE2XGR/1 =20 ------=_NextPart_000_001B_01CDDB7E.4E820B00 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Warren,
 
I use variable PA supply volts & = can take power=20 level to exactly what level I require.
 
73, Gary - G4WGT.
----- Original Message -----
From:=20 Warren = Ziegler=20
Sent: Saturday, December 15, = 2012 10:46=20 PM
Subject: Re: LF: Re: M0BMU mods = to the=20 G0MRF PA

Jim,
      One further question,  can I tap the = secondary=20 per the original G0MRF design so as to have lower power outputs = available by=20 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,=20 but...
The multi-stranded winding was mainly used because it is = much more=20 flexible
and so easier to wind onto the core. I used a salvaged = LOPT core=20 as if it
were a toroid core, i.e. fixing the two core halves = together=20 before
threading the wire through the aperture repeatedly to = produce the=20 winding.
Producing a compact, even winding that lay snugly on the = core=20 using solid
wire was difficult because of the stiffness of the = wire. It=20 is desireable to
make the windings as compact as possible with = the=20 minimum amount of space
between the turns in order to reduce the = leakage=20 inductance of the
transformer as much as possible. This raises = the=20 self-resonant frequency of
the transformer and reduces the amount = of RC=20 damping needed to produce a
sensible drain waveform. The multiple = strands=20 do probably give some
reduction in losses at 137k, but I expect = only=20 marginally.

Cheers, Jim Moritz
73 de=20 M0BMU





--
73 Warren K2ORS
        =  =20       WD2XGJ
          =  =20     WD2XSH/23
            =  =20   WE2XEB/2
              =  =20 WE2XGR/1

 
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