Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id x5TCGgVN020219 for ; Sat, 29 Jun 2019 14:16:43 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1hhC9f-00053X-Tp for rs_out_1@blacksheep.org; Sat, 29 Jun 2019 13:08:31 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1hhC9Q-00053O-V7 for rsgb_lf_group@blacksheep.org; Sat, 29 Jun 2019 13:08:16 +0100 Received: from smtp3web.tin.it ([212.216.176.237]) by relay1.thorcom.net with esmtp (Exim 4.92) (envelope-from ) id 1hhC9O-0001I1-II for rsgb_lf_group@blacksheep.org; Sat, 29 Jun 2019 13:08:15 +0100 Received: from feu11 (10.192.64.21) by smtp3web.tin.it (8.6.060.43) id 5CCA84590097A893 for rsgb_lf_group@blacksheep.org; Sat, 29 Jun 2019 14:08:12 +0200 Received: from (80.180.70.86) by webmailtin.pc.tim.it; Sat, 29 Jun 2019 14:08:12 +0200 Message-ID: <16ba322c100.marcocadeddu@tin.it> Date: Sat, 29 Jun 2019 14:08:12 +0200 (CEST) From: "marcocadeddu@tin.it" To: Mime-Version: 1.0 X-Originating-IP: 80.180.70.86:1473 X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see @@CONTACT_ADDRESS@@ for details. Content preview: :-D ohhh poor Old Man ! I have to wear glasses to read other way my arms are not long enough ;-) Marco ----Messaggio originale---- Da: 29-giu-2019 10.52 A: Cc: "marcocadeddu@tin.it" Ogg: Re: R: Re: LF: LF daylight test close to the north hemisphere solstice 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 [212.216.176.237 listed in list.dnswl.org] -0.0 RCVD_IN_MSPIKE_H2 RBL: Average reputation (+2) [212.216.176.237 listed in wl.mailspike.net] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (marcocadeddu[at]tin.it) 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 86b6d14137f1f41166b7b27a17921f7a Subject: R: Re: R: Re: LF: LF daylight test close to the north hemisphere solstice Content-Type: multipart/alternative; boundary="----=_Part_48465_2070020.1561810092292" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=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 ------=_Part_48465_2070020.1561810092292 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable :-D ohhh poor Old Man ! I have to wear glasses to read other way my arms are not long enough ;-) Marco ----Messaggio originale---- Da: selberdenken@posteo.de Data: 29-giu-2019 10.52 A: Cc: "marcocadeddu@tin.it" Ogg: Re: R: Re: LF: LF daylight test close to the north hemisphere solstice Hi Marco, Oh, indeed. My old eyes, you know, im now 43 yrs old and still refuse to=20 wear glasses!!! :-( Variations from 30...100 is almost acceptable and it may be the PA=20 design that makes it a real problem. 73, Stefan Am 29.06.2019 10:39, schrieb marcocadeddu@tin.it: > Hi Stefan, Luis > Luis pointed out changes in impedance from 30 to 100 ohms not 1000 ;-) > Leaving this misreading away, you are right Stefan: it should be nice=20 > to know what happen to both reactive and resistive component of the=20 > impedance. > I assume that Luis has still working a variometer thus he can manage=20 > change of reactance with it and change of resistance with an=20 > insulating and matching transformer > > Marco, IK1HSS > > ----Messaggio originale---- > Da: selberdenken@posteo.de > Data: 29-giu-2019 10.21 > A: > Ogg: Re: LF: LF daylight test close to the north hemisphere solstice > > Hi Luis, > > Am 28.06.2019 22:04, schrieb VIGILANT Luis Fern=C3=A1ndez: > > My problem is that the antenna impedance varies a lot with humidity.=20 > This days we have a hot and > > dry weather about 30% moisture. VNA shows an impedance value of just=20 > 30Ohms at resonance > > Previous week having sea moisture with 80% values, which are normal=20 > here over summer, the > > impedance rised to 100Ohm at resonance. Of course, PA works in a=20 > completely different way in both > > cases. > What happens with the reactive part of the impedance? Does it stay > constant or do you have to retune all the time? Then, the relays and > tapped transformer wouldn't help you. > > The best antenna impedance is about 70 Ohm, were I can get 3.2A RF=20 > current with 15A@33V PA current > > Higer impedance causes PA current to rise and RF current drops.=20 > Mosfets also get much hotter > > Low antena impedance produces high RF currents but low PA current=20 > and so, less power > > and higer voltages in the LPF which causes arcs. (LPF is also=20 > pending resize. Is the only part still > > remaining from the old Ropex PA) > > > Hmmmm, hard to belive that it is just the humidity that leads to a > variation from 70 to 1000 Ohm. Maybe it is a bad ground contact at some > point? > > You could do a test: Tune to resonance when the system is at 70 Ohm. > Then run low power, maybe 5W. Run a carrier transmission for some days. > Observe the signal level at your remote site in 7 km distance. Use > SpecLabs plotter and plot the signal level over time. Watch the > variations. When the system changes slowly to 1000 Ohm, the antenna > current will drop and so the signal will be lower. If this happens > slowly, when it starts to rain, then it is ok. But maybe you will find a > sudden jump of the current, then it could be a bad contact somewhere. > You know what i mean? > > > So, I need a matching transformer, but must be variable and remotely=20 > selectable. May be selecting > > taps with a set of relays or any other mechanical selector. What do=20 > you propose for that ? > > > It is all possible but you will need time again! ;-) > > How many turns ? I have a pair of the big blue cores you recommended > > > Which ones? The very big ones? I used 18 turns primary for 50 Ohm. > Calculate the voltage at 50 Ohm and your power level. Then apply this > voltage to the core and the primary winding only, without a load. The > core should stay cool! Or, if you don't have a voltage source, build a > 1:1 (18:18) transformer and apply full power through it and connect a > dummy load. The transformer should stay cool. > If you want to transform from 50 to 1000 Ohm (which is not a good > solution somehow) then the secondary winding needs 18*sqrt(1000/50) =3D 8= 0 > turns. > > I would focus on finding the reason for the heavy changes. I would doubt > that it is just humidity, although i would certainly expect that > humidity has a significant influence in your configuration. > > Relays: I personally would select such one: > https://www.reichelt.de/steck-printrelais-1-co-16-a-12-v-dc-sensitiv-fin-= 40-61-7-12v-p259198.html?&trstct=3Dpos_12 > > 73, Stefan > > 73 de Luis > > EA5DOM > > > > > > ________________________________________ > > De: owner-rsgb_lf_group@blacksheep.org=20 > [owner-rsgb_lf_group@blacksheep.org] en nombre de DK7FC=20 > [selberdenken@posteo.de] > > Enviado: mi=C3=A9rcoles, 5 de junio de 2019 8:16 > > Para: rsgb_lf_group@blacksheep.org > > Asunto: Re: LF: LF daylight test close to the north hemisphere solstice > > > > Hi Luis, > > > > No, i just mean a second transformer between PA and the other > > transformer, into the coax line. A simple 1:1 ferrite transformer. > > Your ground conductors into and arround the building are a part of the > > antenna, obviously causing a high voltage between that ground and your > > shack ground. All you can do is reducing the coupling impedance > > (capacitive) and the electrical field strength. A well dimensioned 1:1 > > transformer will provide a good decoupling and low losses. The improved > > decoupling may change the resonance a bit (because your shack earth is > > less a part of the system taking RF currents), so a retuning is > > required. Hopefully your shack earth is not the dominant part of the > > antenna ground :-) The less it is a part of the ground system, the less > > is the detuning of the antenna when inserting the second transformer. > > > > 73, Stefan > > > > > > > > > ------=_Part_48465_2070020.1561810092292 Content-Type: text/html;charset="UTF-8" Content-Transfer-Encoding: quoted-printable :-D ohhh poor Old Man !
I have to wear glasses to read other way my arms= are not long enough ;-)

Marco

----Messaggio originale----
Da: selberdenken@posteo.de
Data: 29-giu-2= 019 10.52
A: <rsgb_lf_group@blacksheep.org>
Cc: "marcocadeddu@t= in.it"<marcocadeddu@tin.it>
Ogg: Re: R: Re: LF: LF daylight test c= lose to the north hemisphere solstice

Hi Marco,

Oh, indeed. M= y old eyes, you know, im now 43 yrs old and still refuse to
wear glasse= s!!! :-(
Variations from 30...100 is almost acceptable and it may be the= PA
design that makes it a real problem.

73, Stefan


A= m 29.06.2019 10:39, schrieb marcocadeddu@tin.it:
> Hi Stefan, Luis> Luis pointed out changes in impedance from 30 to 100 ohms not 1000 ;-= )
> Leaving this misreading away, you are right Stefan: it should be = nice
> to know what happen to both reactive and resistive component = of the
> impedance.
> I assume that Luis has still working a v= ariometer thus he can manage
> change of reactance with it and chang= e of resistance with an
> insulating and matching transformer
>= ;
> Marco, IK1HSS
>
> ----Messaggio originale----
>= Da: selberdenken@posteo.de
> Data: 29-giu-2019 10.21
> A: <= rsgb_lf_group@blacksheep.org>
> Ogg: Re: LF: LF daylight test clos= e to the north hemisphere solstice
>
> Hi Luis,
>
>= Am 28.06.2019 22:04, schrieb VIGILANT Luis Fern=C3=A1ndez:
> > My= problem is that the antenna impedance varies a lot with humidity.
>= This days we have a hot and
> > dry weather about 30% moisture. V= NA shows an impedance value of just
> 30Ohms at resonance
> &g= t; Previous week having sea moisture with 80% values, which are normal
= > here over summer, the
> > impedance rised to 100Ohm at resona= nce. Of course, PA works in a
> completely different way in both
= > > cases.
> What happens with the reactive part of the impedan= ce? Does it stay
> constant or do you have to retune all the time? Th= en, the relays and
> tapped transformer wouldn't help you.
> &g= t; The best antenna impedance is about 70 Ohm, were I can get 3.2A RF
&= gt; current with 15A@33V PA current
> > Higer impedance causes PA = current to rise and RF current drops.
> Mosfets also get much hotter=
> > Low antena impedance produces high RF currents but low PA cur= rent
> and so, less power
> > and higer voltages in the LPF= which causes arcs. (LPF is also
> pending resize. Is the only part = still
> > remaining from the old Ropex PA)
> >
> Hm= mmm, hard to belive that it is just the humidity that leads to a
> va= riation from 70 to 1000 Ohm. Maybe it is a bad ground contact at some
&g= t; point?
>
> You could do a test: Tune to resonance when the s= ystem is at 70 Ohm.
> Then run low power, maybe 5W. Run a carrier tra= nsmission for some days.
> Observe the signal level at your remote si= te in 7 km distance. Use
> SpecLabs plotter and plot the signal level= over time. Watch the
> variations. When the system changes slowly to= 1000 Ohm, the antenna
> current will drop and so the signal will be = lower. If this happens
> slowly, when it starts to rain, then it is o= k. But maybe you will find a
> sudden jump of the current, then it co= uld be a bad contact somewhere.
> You know what i mean?
>
&g= t; > So, I need a matching transformer, but must be variable and remotel= y
> selectable. May be selecting
> > taps with a set of rel= ays or any other mechanical selector. What do
> you propose for that= ?
> >
> It is all possible but you will need time again! ;-= )
> > How many turns ? I have a pair of the big blue cores you rec= ommended
> >
> Which ones? The very big ones? I used 18 turn= s primary for 50 Ohm.
> Calculate the voltage at 50 Ohm and your powe= r level. Then apply this
> voltage to the core and the primary windin= g only, without a load. The
> core should stay cool! Or, if you don't= have a voltage source, build a
> 1:1 (18:18) transformer and apply f= ull power through it and connect a
> dummy load. The transformer shou= ld stay cool.
> If you want to transform from 50 to 1000 Ohm (which i= s not a good
> solution somehow) then the secondary winding needs 18*= sqrt(1000/50) =3D 80
> turns.
>
> I would focus on findin= g the reason for the heavy changes. I would doubt
> that it is just h= umidity, although i would certainly expect that
> humidity has a sign= ificant influence in your configuration.
>
> Relays: I personal= ly would select such one:
> https://www.reichelt.de/steck-printrelais= -1-co-16-a-12-v-dc-sensitiv-fin-40-61-7-12v-p259198.html?&trstct=3Dpos_= 12
>
> 73, Stefan
> > 73 de Luis
> > EA5DOM> >
> >
> > _____________________________________= ___
> > De: owner-rsgb_lf_group@blacksheep.org
> [owner-rsg= b_lf_group@blacksheep.org] en nombre de DK7FC
> [selberdenken@posteo= .de]
> > Enviado: mi=C3=A9rcoles, 5 de junio de 2019 8:16
> = > Para: rsgb_lf_group@blacksheep.org
> > Asunto: Re: LF: LF day= light test close to the north hemisphere solstice
> >
> >= Hi Luis,
> >
> > No, i just mean a second transformer be= tween PA and the other
> > transformer, into the coax line. A simp= le 1:1 ferrite transformer.
> > Your ground conductors into and ar= round the building are a part of the
> > antenna, obviously causin= g a high voltage between that ground and your
> > shack ground. Al= l you can do is reducing the coupling impedance
> > (capacitive) a= nd the electrical field strength. A well dimensioned 1:1
> > trans= former will provide a good decoupling and low losses. The improved
> = > decoupling may change the resonance a bit (because your shack earth is=
> > less a part of the system taking RF currents), so a retuning = is
> > required. Hopefully your shack earth is not the dominant pa= rt of the
> > antenna ground :-) The less it is a part of the grou= nd system, the less
> > is the detuning of the antenna when insert= ing the second transformer.
> >
> > 73, Stefan
> &g= t;
> >
> >
>
>
>



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