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Content preview: Andy Your method too lossy and complicated, interaction etc Use one coil for each band and switch between them for the desired Band G3KEV On 28 Jun 2018, at 20:32, Andy Talbot wrote: [...] 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 [62.24.135.69 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 MIME_QP_LONG_LINE RAW: Quoted-printable line longer than 76 chars 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: da9a90c67b7e22f6718c156d8d99c1a4 Subject: Re: LF: Can I match 2 frequencies with one loading coil? Content-Type: multipart/alternative; boundary=Apple-Mail-A345271D-812D-4F76-BE13-17E595C4F25B Content-Transfer-Encoding: 7bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_20_30, HTML_FONTCOLOR_UNSAFE,HTML_MESSAGE 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 --Apple-Mail-A345271D-812D-4F76-BE13-17E595C4F25B Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Andy Your method too lossy and complicated, interaction etc Use one coil for each band and switch between them for the desired=20 Band=20 G3KEV On 28 Jun 2018, at 20:32, Andy Talbot wrote: Try this, but you'll have to adjust iteratively: Bands referred to as LF and MF First make your LF loading coil so it resonates the antenna as it stands. = Now make an MF loading coil. The problem is that t=3Dwhen both are connect= ed to the antenna teh lower value MF one shunts teh LF. So add series C to t= he MF one to make a series tuned circuit, increasing the L to keep the syste= m at resonance. The net effect now, at LF will be an increased value of X s= hunting it. As your additional C reduces and L increases, the residual at L= F across the LF coil goes up. Now adjust teh LF colil to bring it to reso= nance, then go back and redo the MF L or C. Iterating between teh two until= they both go. I'ts a complicated setup, with two frequencies and three variables to play w= ith - so an infinite set of values to end up with, but if I were doing it, I= 'd make up a spreadsheet and play around with values until a workable soluti= on that resonated both antennas was found and looked OK. Once resonated you= can bring them to a match if needed. But on Rx just resonating them ought= to suffice Or use a circuit analysis prog. =20 Andy www.g4jnt.com > On 28 June 2018 at 20:04, Chris Wilson wrote: >=20 >=20 > Hello Mal, >=20 > Thanks Mal and Stefan, but Mal, I want to listen to and decode both bands > at the same time on 2 different receivers, sharing the one antenna. I > tried shorting out the loading coil but LF reception is much poorer. > Not sure how much of an effect no loading coil has at MF ,but suspect > a loading coil to resonate would be pretty helpful? >=20 > Thursday, June 28, 2018, 7:55:55 PM, you wrote: >=20 > > I use aircore loading and matching > > Use 2 coils and SW between them for desired band > > G3KEV >=20 >=20 >=20 >=20 >=20 >=20 >=20 > --=20 > Best regards, > Chris mailto:dead.fets@gmail.com >=20 >=20 --Apple-Mail-A345271D-812D-4F76-BE13-17E595C4F25B Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Andy
Your method t= oo lossy and complicated, interaction etc
Use one coil for each ba= nd and switch  between them for the desired 
Band <= /div>
G3KEV


On 28 Jun 2018, at 20:32, Andy T= albot <andy.g4jnt@gmail.com&g= t; wrote:

Try this, but you'll have to ad= just iteratively:
Bands referred to as LF and MF

First make your LF loading coil so it resonates the antenna as it stands.&= nbsp;   Now make an MF loading coil.  The problem is that t=3Dwhen= both are connected to the antenna teh lower value MF one shunts teh LF.&nbs= p; So add series C to the MF one to make a series tuned circuit, increasing t= he L to keep the system at resonance.   The net effect now, at LF w= ill be an increased value of X shunting it.  As your additional C reduc= es and L increases, the residual at LF across the LF coil goes up.  &nb= sp; Now adjust teh LF colil to bring it to resonance, then go back and redo t= he MF L or C.  Iterating between teh two until they both go.
=
I'ts a complicated setup, with two frequencies and three vari= ables to play with - so an infinite set of values to end up with, but if I w= ere doing it, I'd make up a spreadsheet and play around with values until a w= orkable solution that resonated both antennas was found and looked OK. = Once resonated you can bring them to a match if needed.   But on R= x just resonating them ought to suffice

Or use a ci= rcuit analysis prog.     


On 28 June 2018 at 20:04, Chris Wilson <dead= .fets@gmail.com> wrote:


Hello Mal,

Thanks Mal and Stefan, but Mal, I want to listen to and decode both bands at the same time on 2 different receivers, sharing the one antenna. I
tried  shorting out the loading coil but LF reception is much poorer. Not  sure how much of an effect no loading coil has at MF ,but suspect<= br> a loading coil to resonate would be pretty helpful?

Thursday, June 28, 2018, 7:55:55 PM, you wrote:

> I use aircore loading and matching
> Use 2 coils and SW between them for desired band
> G3KEV







--
Best regards,
 Chris                  &n= bsp;         mailto:dead.fets@gmail.com



= --Apple-Mail-A345271D-812D-4F76-BE13-17E595C4F25B--