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 w9SDRwSe012302 for ; Sun, 28 Oct 2018 14:28:06 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1gGkv9-0007p3-6F for rs_out_1@blacksheep.org; Sun, 28 Oct 2018 13:15:59 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1gGkv5-0007ou-VF for rsgb_lf_group@blacksheep.org; Sun, 28 Oct 2018 13:15:55 +0000 Received: from out2-22.antispamcloud.com ([185.201.17.22]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91_59-0488984) (envelope-from ) id 1gGkv3-0006SQ-8Y for rsgb_lf_group@blacksheep.org; Sun, 28 Oct 2018 13:15:54 +0000 Received: from 132.178.216.87.static.jazztel.es ([87.216.178.132] helo=servigilant.vigilant.es) by mx105.antispamcloud.com with esmtpsa (TLSv1:ECDHE-RSA-AES128-SHA:128) (Exim 4.89) (envelope-from ) id 1gGkuw-0000IJ-SZ for rsgb_lf_group@blacksheep.org; Sun, 28 Oct 2018 14:15:50 +0100 Received: from servigilant.vigilant.local ([fe80::c40d:8140:d722:5448]) by servigilant.vigilant.local ([fe80::c40d:8140:d722:5448%13]) with mapi id 14.03.0123.003; Sun, 28 Oct 2018 14:15:37 +0100 From: =?iso-8859-1?Q?VIGILANT_Luis_Fern=E1ndez?= To: "rsgb_lf_group@blacksheep.org" Thread-Topic: Antenna resistance (Re: LF: EbNaut Autodecoder 137490 Hz: EA5DOM received) Thread-Index: AQHUbkNjR4wTiw30h0e0VbyJADSpj6U0neXI Date: Sun, 28 Oct 2018 13:15:36 +0000 Message-ID: <6DB8451D7F3D3947A5918808A59621EA086800C1@servigilant.vigilant.local> References: <462455091.17510919.1540678881904.ref@mail.yahoo.com>,<462455091.17510919.1540678881904@mail.yahoo.com> In-Reply-To: <462455091.17510919.1540678881904@mail.yahoo.com> Accept-Language: es-ES, en-US Content-Language: es-ES X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [144.178.130.163] MIME-Version: 1.0 X-Originating-IP: 87.216.178.132 X-MailAssure-Domain: vigilant.es X-MailAssure-Username: smtpsolarwinds Authentication-Results: antispamcloud.com; auth=pass (login) smtp.auth=smtpsolarwinds@vigilant.es X-MailAssure-Outgoing-Class: ham X-MailAssure-Outgoing-Evidence: Combined (0.26) X-Recommended-Action: accept X-Filter-ID: EX5BVjFpneJeBchSMxfU5jDaXY482qtUG5/wLVmdG3h602E9L7XzfQH6nu9C/Fh9KJzpNe6xgvOx q3u0UDjvOw5j2C7YKailx2Uop+U2Gs8m9etQhNgzEtWqBtUXOJSHVTGbEWWnE2yTxqfzAQugcZzY BPmtD1NlfRqK+POuWZ5IeZjZv1oz6oWKgngYgisMJ0bZP3eYDXxLY7bneVfI6dcam2SxBi2gl3tH FIoPtzsf0wQn+qGFwFhnrZWr3AIwIkRInETzFeWnWEMjTrypoJbF8Ivvzp41zJACSToCpX36qyHr byaR4ePUKnm2FKDCDD2gT2inkFvv0JWjnb/IrPOCuoaV6DYsC3dGdIrLGqrW8aZxLG7Y0pk1ZN1X bEZoeGCH+SJjE48GzCqfGD0ud53+zxpzqXnGGiQ01PlGSKsJi5lucXozcAWJZZIdG3Z2NDwiAPJ6 Kw+cgKFzaOFmsJFVgpT1b21uZVckGp0ccOZ1/atoPPXpgcY5OL20mhCuJgQWcrs8q+WcXVXZDcW5 0nQA4NuQg1+/HGgfT4I9ZhrTiEw2ui8TVPldBCj8jBAT53fcGYa1TFd19zW4fvyg/zNyzzGpc26/ TNtBmFllDzu+r8564J4UcaAj3COWkYMPEq/3gpfDhw/6RJBwn4n3MznjzDI/k4qfLUUHhFnEa/pq 8v2adr3xIBXCBg0CnYzHqhP5Vx9mYbtLHtnDO0U0zCYrtIwlafnLqYYQk954CU09b3leuW1nwm9V qgLZsi1SxgbXfobrH7q6EdEeDH4qlUuAWi2g3/gaJEQTE6LAVcVy2DNwOgV373pfDhBQ21OdYUOm 5fvWMXipQ+V80TIqPZuLmUbMjhg0DEd+zPjh9/C5AciD3r534W8yYMyVxKqoC8tHbhwU9bRJ9YQQ 0RkXryJZl3Me5gJDDv4NyBpsS9g2kPAiQKyAqeIr3zn0QFnWVgW9/bktU41htiJ8fk7NkHONYiYO dpvlUyaOFS6YnjEmPP4IsIGmW4/5Ep1RHXEb9jihx+Za/cV70jOJzN2r4A== X-Report-Abuse-To: spam@quarantine3.antispamcloud.com X-Spam-Score: 0.3 (/) 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: Hi Markus, LF The pipe contains presurized water for the fire extinguish system. Is a "wet colum" system. Pipe segments are connected with big brass links. Should be a good enought current conductor. Down in the basement it connects with a pressure pump and a water reservoir tank, linked to the water grid system [...] Content analysis details: (0.3 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [185.201.17.22 listed in list.dnswl.org] 1.0 SPF_SOFTFAIL SPF: sender does not match SPF record (softfail) 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 197e3b57b6f6f3314687a7b82bb93a83 Subject: Re: Antenna resistance (Re: LF: EbNaut Autodecoder 137490 Hz: EA5DOM received) Content-Type: multipart/alternative; boundary="_000_6DB8451D7F3D3947A5918808A59621EA086800C1servigilantvigi_" 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, TO_ADDRESS_EQ_REAL 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 --_000_6DB8451D7F3D3947A5918808A59621EA086800C1servigilantvigi_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Markus, LF The pipe contains presurized water for the fire extinguish system. Is a "we= t colum" system. Pipe segments are connected with big brass links. Should be a good enought current conduc= tor. Down in the basement it connects with a pressure pump and a water reservoir tank, linked to the wat= er grid system Will have to check the ground connections of all this stuff when possible. = Not easy But after all, we are all doing all this "not easy" things because it is no= t easy to work low bands, right? ;-) Tested mains ground connection too and it helps a lot, but still depends on= rain. Access to the ground line at the lifts engines room on top building is complicated too, as I have no acc= ess there because of a AMHPS (Anti Mad Ham Protection System) hi, hi Installing my own ground line may be an option, but using light cable. As I= can only support the 80m cable at the top end, so weight must be low. Finally may be the best way to go 73 de Luis EA5DOM ________________________________ De: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org]= en nombre de Markus Vester [markusvester@aol.com] Enviado: domingo, 28 de octubre de 2018 0:21 Para: rsgb_lf_group@blacksheep.org Asunto: Re: Antenna resistance (Re: LF: EbNaut Autodecoder 137490 Hz: EA5DO= M received) > Something gets wet in the basement and the pipe gets a better connection = to ground, or at least to the water grid pipes, which finally run undergrou= nd Ah that must be the reason! That drain pipe is obviously not continuous met= al but inrterropted by some insulating joints or plastic sections, which ar= e more or less bypassed by a water film or flow when it rains. Could you try to use another ground connection which is continuous all the = way down? E.g. external lightning protection conductors, or even the protec= tive earth in your appartment? Best 73, Markus -----Urspr=FCngliche Mitteilung----- Von: VIGILANT Luis Fern=E1ndez An: rsgb_lf_group@blacksheep.org Verschickt: Sa, 27. Okt 2018 23:17 Betreff: Re: Antenna resistance (Re: LF: EbNaut Autodecoder 137490 Hz: EA5D= OM received) Hi All, LF Interesting topic. Also happens in MF but in LF it gets more critical. Must= be a nightmare at VLF :( As Marco explained, our setup is not the usual at ground level in a propert= y plot. And in my case ther ground is 80m away down from the feed point, coil and capacitive topload. Measured with the antenna analyzer I can see a drop in the impedance module= when all gets wet by rain It is not only an increase of RF current. Today I measured resistance from = the ground side of the feed point trought the pipe to building basement and then returning via the water grid= connecting the other side of the multimeter to a water pipe in my house: 4 Ohm measured early morning when it started with soft rain. At noon we had= stronger rain and in the afternoon I measured again. It dropped to 2 Ohm. Big difference. Something gets wet i= n the basement and the pipe gets a better connection to ground, or at least to the water grid pipes, which f= inally run underground The top of the antenna is dismantled during storms, so can't measure impeda= nce with the analyzer right now but bet it is now well under 30 Ohm and would drain a few amps Other intringuin detail. When it is dry and impedance rises to >100 Ohm the= only way to hardly reach 1A RF is to detune the antenna. I have to set the resonant peak at 138Khz and the= n at 137,5 get even higher impedance and high SWR, but the antenna current rises and so the radiated signal. All= this at the cost of more amps consumed by the PA and higer voltage at antenna feed. Running the antenna a= t the optimum resonance makes almost no RF current, even considering that this is the minimum impedance p= oint. About the LPF, this is really the only part of the Ropex PA still in use. T= his is a link to the schematic with the LPF https://www.dropbox.com/s/ejn5stuz7vban7u/Ropex%20Schematic.JPG?dl=3D0 Have not tried without LPF. The analyzer measurements are made directly to = antenna. But may be a good idea to make them with the LPF inserted and see what happens 73 de Luis EA5DOM ________________________________ De: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org]= en nombre de marcocadeddu@tin.it [marcocadeddu@tin.it] Enviado: s=E1bado, 27 de octubre de 2018 18:12 Para: rsgb_lf_group@blacksheep.org Asunto: R: Antenna resistance (Re: LF: EbNaut Autodecoder 137490 Hz: EA5DOM= received) Hi Paul, Luis, Markus, LF let me join the topic ;-) the antenna location of Luis is something else of your Markus and Paul and = much similar to mine: roof based antennas with elevated ground (in my case)= and vertical ground (the water pipe) for Luis. Anyway also in my case the serie resistance of my antenna increases with ra= in (almost doubles). But.. Luis, probably assumes the lower impedance basing on the higher curre= nt. Luis, what kind of LPF have you adopted? Now I have a T filter with no shunting cap at the input and impedance incre= ases with rain both with and without LPF, but if I remember correctly, when= in the past I had an PI LPF with shunting input and output caps the impeda= nce in my shack was transformed from the transmission line and LPF giving l= ower impedance by rain. Could be an explication? By the way, just for fate it's raining also here and I made some measuremen= t when dry again will repeat ;-) Have a funny weekend LF Marco IK1HSS ----Messaggio originale---- Da: paul@n1bug.com Data: 27-ott-2018 12.34 A: Ogg: Antenna resistance (Re: LF: EbNaut Autodecoder 137490 Hz: EA5DOM recei= ved) Hi Luis, Markus, LF This is a very interesting topic for me too. My antenna resistance is very high, usually more than 100 ohms. I think there may be a few reasons. There are trees near the antenna which I presume to be lossy. My antenna ground system is not tied into the house ground, in order to minimize 120 Hz sidebands on my transmitted signal. When I tie the grounds together the level of these sidebands increases almost 20 dB. Also my RX antenna is more noisy when the TX antenna ground and house ground are tied together. I suppose this is because more noise is radiated from the TX antenna, then picked up by the RX antenna which has its own small, isolated ground. Rain has no effect on the antenna resistance, but temperature does. During summer there is little change, just minor variations. But as the temperature drops and begins to approach freezing, resistance begins to get lower. There is a big drop right around freezing or few degrees below, but resistance continues to drop with even lower temperatures, reaching minimum on the coldest winter nights. Last winter I saw it reach 40 ohms a few times. :) I am no expert but I guess the trees are partly responsible for the high resistance and the drop with freezing temperature? Anyway I can run enough power to reach calculated 1W EIRP and it's enough to be heard across that little pond. :) But here is a related question: I have calculated my EIRP to be one watt using the measured resistance, antenna parameters and current. But does this calculation include all the losses in trees? If I had the proper equipment to make field strength measurements at a distance, would I find that my EIRP is less than one watt due to the tree losses? 73, Paul N1BUG On 10/27/18 5:45 AM, Markus Vester wrote: > Hi Luis, > >> Impedance drops a lot after rain > > This seems unusual. I have exactly the opposite effect here: > Series resistance at 137 kHz is normally around 20 ohms > (including 5 ohms for the coil). When it rains it get worse up to > about 40 ohms, whereas best times are cold and dry winter days > with ~15 ohms when the trees are solidly frozen. So I presume > that the major contribution to my resistance are > capacitively-coupled losses in vegetation and other nearfield > environment. The ground connection itself (the "house earth" > which is connected to electric grid PE, and also pipe systems for > water supply and distict heating) seems to have a low resistance. > > > My only explanation for lower wet resistance would be if one were > using a separate radial system in the garden, whose connection to > ground might be better when the lawn is soaked. But I don't think > this applies to your setup at all. > > Best 73, Markus > > Von: VIGILANT Luis Fern=E1ndez > > I'm struggling > here with the antenna. Most of the time impedance rises and I > hardly run 1A RF current > > Rainy weekend here. > Impedance drops a lot after rain. Let's see how much current can > drainLast time I could see almost 4A RF. --_000_6DB8451D7F3D3947A5918808A59621EA086800C1servigilantvigi_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Markus, LF

The pipe contains presurized water for the fire extinguish system. Is = a "wet colum" system. Pipe segments
are connected with big brass links. Should be a good enought current c= onductor. Down in the basement it
connects with a pressure pump and a water reservoir tank, linked to th= e water grid system

Will have to check the ground connections of all this stuff when possi= ble. Not easy
But after all, we are all doing = all this "not easy" things because it is not easy to work low ban= ds, right? ;-)

Tested mains ground connection too and it helps a lot, but still depen= ds on rain. Access to the ground line at
the lifts engines room on top building is complicated too, as I have n= o access there because of a AMHPS 
(Anti Mad Ham Protection System) hi, hi

Installing my own ground line may be an option, but using light cable.= As I can only support the 80m cable
at the top end, so weight must be low. Finally may be the best way to = go

73 de Luis
EA5DOM

De: owner-rsgb_lf_group@blacksheep.org [o= wner-rsgb_lf_group@blacksheep.org] en nombre de Markus Vester [markusvester= @aol.com]
Enviado: domingo, 28 de octubre de 2018 0:21
Para: rsgb_lf_group@blacksheep.org
Asunto: Re: Antenna resistance (Re: LF: EbNaut Autodecoder 137490 Hz= : EA5DOM received)

> Something gets wet in the basement and the pipe gets a better connecti= on to ground, or at least to the water grid pipes, which finally run underg= round

Ah that must be the reason! That drain pipe is obviously not continuou= s metal but inrterropted by some insulating joints or plastic sec= tions, which are more or less bypassed by a water film or fl= ow when it rains.

Could you try to use another ground connection which is continuous all the = way down? E.g. external lightning protection conductors, or even the protec= tive earth in your appartment?

Best 73,
Markus

-----Urspr=FCngliche Mitteilung-----
Von: VIGILANT Luis Fern=E1ndez <luis@vigilant.es>
An: rsgb_lf_group@blacksheep.org <rsgb_lf_group@blacksheep.org>
Verschickt: Sa, 27. Okt 2018 23:17
Betreff: Re: Antenna resistance (Re: LF: EbNaut Autodecoder 137490 Hz: EA5D= OM received)

Hi All, LF

Interesting topic. Also happens in MF but in LF it gets more critical.= Must be a nightmare at VLF :(

As Marco explained, our setup is not the usual at ground level in a pr= operty plot. And in my case ther ground
is 80m away down from the feed point, coil and capacitive topload.

Measured with the antenna analyzer I can see a drop in the impedance m= odule when all gets wet by rain
It is not only an increase of RF current. Today I measured resistance = from the ground side of the feed point
trought the pipe to building basement and then returning via the water= grid connecting the other side of the
multimeter to a water pipe in my house:

4 Ohm measured early morning when it started with soft rain. At noon w= e had stronger rain and in the afternoon
I measured again. It dropped to 2 Ohm. Big difference. Something gets = wet in the basement and the pipe gets
a better connection to ground, or at least to the water grid pipes, wh= ich finally run underground

The top of the antenna is dismantled during storms, so can't measure i= mpedance with the analyzer right now
but bet it is now well under 30 Ohm and would drain a few amps

Other intringuin detail. When it is dry and impedance rises to >100= Ohm the only way to hardly reach 1A RF
is to detune the antenna. I have to set the resonant peak at 138Khz an= d then at 137,5 get even higher impedance
and high SWR, but the antenna current rises and so the radiated signal= . All this at the cost of more amps
consumed by the PA and higer voltage at antenna feed. Running the ante= nna at the optimum resonance makes
almost no RF current, even considering that this is the minimum impeda= nce point. 

About the LPF, this is really the only part of the Ropex PA still in u= se. This is a link to the schematic with the LPF

Have not tried without LPF. The analyzer measurements are made directl= y to antenna. But may be a good idea to
make them with the LPF inserted and see what happens

73 de Luis
EA5DOM

De: owner-rsgb_lf_group@blacksheep.org = [owner-rsgb_lf_group@blacksheep.org] en nombre de marcocadeddu@tin.it [marcocadeddu@tin.it]
Enviado: s=E1bado, 27 de octubre de 2018 18:12
Para: rsgb_lf_group@blacksheep.org
Asunto: R: Antenna resistance (Re: LF: EbNaut Autodecoder 137490 Hz:= EA5DOM received)

Hi Paul, Luis, Markus, LF

let me join the topic ;-)
the antenna location of Luis is something else of your Markus and Paul and = much similar to mine: roof based antennas with elevated ground (in my case)= and vertical ground (the water pipe) for Luis.
Anyway also in my case the serie resistance of my antenna increases with ra= in (almost doubles).
But.. Luis, probably assumes the lower impedance basing on the higher curre= nt.
Luis, what kind of LPF have you adopted?
Now I have a T filter with no shunting cap at the input and impedance incre= ases with rain both with and without LPF, but if I remember correctly, when= in the past I had an PI LPF with shunting input and output caps the impeda= nce in my shack was transformed from the transmission line and LPF giving lower impedance by rain.

Could be an explication?

By the way, just for fate it's raining also here and I made some measuremen= t when dry again will repeat ;-)

Have a funny weekend LF

Marco IK1HSS
 

----Messaggio originale----
Da: paul@n1bug.com
Data: 27-ott-2018 12.34
A: <rsgb_lf_group@blacksheep.org>
Ogg: Antenna resistance (Re: LF: EbNaut Autodecoder 137490 Hz: EA5DOM recei= ved)

Hi Luis, Markus, LF

This is a very interesting topic for me too.

My antenna resistance is very high, usually more than 100 ohms. I
think there may be a few reasons. There are trees near the antenna
which I presume to be lossy. My antenna ground system is not tied
into the house ground, in order to minimize 120 Hz sidebands on my
transmitted signal. When I tie the grounds together the level of
these sidebands increases almost 20 dB. Also my RX antenna is more
noisy when the TX antenna ground and house ground are tied together.
I suppose this is because more noise is radiated from the TX
antenna, then picked up by the RX antenna which has its own small,
isolated ground.

Rain has no effect on the antenna resistance, but temperature does.
During summer there is little change, just minor variations. But as
the temperature drops and begins to approach freezing, resistance
begins to get lower. There is a big drop right around freezing or
few degrees below, but resistance continues to drop with even lower
temperatures, reaching minimum on the coldest winter nights. Last
winter I saw it reach 40 ohms a few times. :)

I am no expert but I guess the trees are partly responsible for the
high resistance and the drop with freezing temperature?

Anyway I can run enough power to reach calculated 1W EIRP and it's
enough to be heard across that little pond. :)

But here is a related question: I have calculated my EIRP to be one
watt using the measured resistance, antenna parameters and current.
But does this calculation include all the losses in trees? If I had
the proper equipment to make field strength measurements at a
distance, would I find that my EIRP is less than one watt due to the
tree losses?

73,
Paul N1BUG



On 10/27/18 5:45 AM, Markus Vester wrote:
> Hi Luis,
>
>> Impedance drops a lot after rain
>
> This seems unusual. I have exactly the opposite effect here:
> Series resistance at 137 kHz is normally around 20 ohms
> (including 5 ohms for the coil). When it rains it get worse up to
> about 40 ohms, whereas best times are cold and dry winter days
> with ~15 ohms when the trees are solidly frozen. So I presume
> that the major contribution to my resistance are
> capacitively-coupled losses in vegetation and other nearfield
> environment. The ground connection itself (the "house earth"=
> which is connected to electric grid PE, and also pipe systems for
> water supply and distict heating) seems to have a low resistance.
>
>
> My only explanation for lower wet resistance would be if one were
> using a separate radial system in the garden, whose connection to
> ground might be better when the lawn is soaked. But I don't think
> this applies to your setup at all.
>
> Best 73, Markus
>
> Von: VIGILANT Luis Fern=E1ndez
>
> I'm struggling
> here with the antenna. Most of the time impedance rises and I
> hardly run 1A RF current
>
> Rainy weekend here.
> Impedance drops a lot after rain. Let's see how much current can
> drainLast time I could see almost 4A RF.



--_000_6DB8451D7F3D3947A5918808A59621EA086800C1servigilantvigi_--