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[195.171.43.25]) by mx.google.com with ESMTP id o13si3111638wij.21.2014.02.02.12.48.41 for ; Sun, 02 Feb 2014 12:48:42 -0800 (PST) Received-SPF: neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) client-ip=195.171.43.25; Authentication-Results: mx.google.com; spf=neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) smtp.mail=owner-rsgb_lf_group@blacksheep.org Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1WA3I8-0000k8-Ct for rs_out_1@blacksheep.org; Sun, 02 Feb 2014 20:05:20 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1WA3I2-0000jx-AX for rsgb_lf_group@blacksheep.org; Sun, 02 Feb 2014 20:05:14 +0000 Received: from relay2.uni-heidelberg.de ([129.206.210.211]) by relay1.thorcom.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.77) (envelope-from ) id 1WA3Hy-00077e-PC for rsgb_lf_group@blacksheep.org; Sun, 02 Feb 2014 20:05:13 +0000 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay2.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id s12K58VI009069 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Sun, 2 Feb 2014 21:05:08 +0100 Received: from [129.206.22.206] (pc206.iup.uni-heidelberg.de [129.206.22.206]) by freitag.iup.uni-heidelberg.de (8.12.11.20060308/8.11.2) with ESMTP id s12K58oL023087 for ; Sun, 2 Feb 2014 21:05:08 +0100 Message-ID: <52EEA4EF.8070307@iup.uni-heidelberg.de> Date: Sun, 02 Feb 2014 21:05:03 +0100 From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <000f01cf1d9e$700b49e0$0802a8c0@acer> <52EA67D4.3060604@iup.uni-heidelberg.de> <08be01cf1de6$5b817c90$128475b0$@comcast.net> <52EBB90D.6040101@iup.uni-heidelberg.de> <52ED24D7.8030405@iup.uni-heidelberg.de> <2C298FA71DBE4891AD19AFA27DEF513B@White> <52EE42B9.30006@iup.uni-heidelberg.de> <5A61157818CE4049A4ABE989EBD7AE5C@White> <52EE55E2.7020602@iup.uni-heidelberg.de> In-Reply-To: X-Spam-Score: -2.8 (--) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: VLF, That 3rd harmonic is on the 17 km band. Do we have any experiences about local diurnal propagation? Sooner or later there will be misunderstandings and some will say i am transmitting on 17.265 kHz although the TX runs on 5.755 kHz! [...] Content analysis details: (-2.8 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at http://www.dnswl.org/, medium trust [129.206.210.211 listed in list.dnswl.org] -0.5 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 7507df09b4e78494d20ab2aec3aa67b8 Subject: Re: LF: DX VLF experiments in 3HD Content-Type: multipart/alternative; boundary="------------080707000501050103000900" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,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 This is a multi-part message in MIME format. --------------080707000501050103000900 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay2.uni-heidelberg.de id s12K58VI009069 VLF, That 3rd harmonic is on the 17 km band. Do we have any experiences about=20 local diurnal propagation? Sooner or later there will be misunderstandings and some will say i am=20 transmitting on 17.265 kHz although the TX runs on 5.755 kHz! I had a thought about that. 3rd harmonics are generated by all HF=20 amateurs, but we all ignore them. We actually can ignore them if they=20 are well attenuated but that doesn't mean that they do not exist! BTW=20 has someone ever tried to decode a 3HD signal (that name, 3HD, is just=20 for fun, like the Dreamers band, a shortcut for 3rd harmonic detection,=20 reminds on HD quality movies or 3D glasses ;-) ) in OPERA mode? _Example:_ When someone transmits a legal (!) QRO signal of 750W (in DL)=20 on the 160m band using a typical lambda/4 vertical (which is radiating=20 the 3HD signal because there it is lambda 3/4 and thus low impedant=20 too), using a 60 dB attenuating low pass filter, which is quite a good=20 supression, then there should be a 750uW signal on the 53m band, which=20 could be detected in some distance, probably several 10km when using=20 slow modes like OPERA-4 (WSPR will not work so easily here). Receiving=20 this 3HD signal is certainly not absolutely strictly forbidden :-) So=20 actually the amateurs can do legal QRPP tests in slow modes on 53m,=20 can't they? Would you think that it is ethical unjustifiable to try to=20 receive such a signal if it is there anyway and legally generated? _Example2_: PA0WMR is often TXing OP8 on 478.x kHz, making 2000km=20 distance. If someone in say 30 km distance can receive him on 1434 kHz=20 (if there would be no AM BCD stn), close to the decode limit, would=20 something be wrong with this test? I know from WSPR QRP transmissions from DL to VK on 15m with 0.1 W TX=20 power!! So i assume a 3HD signal could be detected in a few 100 km, maybe= ? Below 8.3 kHz there is no TX power limitation and we can certainly=20 assume that no interference is caused to anyone at 3HD, just like in the=20 above example (53m band ( i never tried it)).So why not trying to do=20 tests like these today? The noise floor is much lower there which=20 improves the situation :-) 73, Stefan/DK7FC Am 02.02.2014 18:15, schrieb Markus Vester: > Stefan, > your third harmonic is clearly visible in Holland > http://www.qsl.net/pa1sdb/ > and here > http://www.df6nm.de/vlf/vlfgrabber.htm > Started spot-on 17265 Hz, now another peak is coming up 15 mHz up. > Good luck, > Markus (DF6NM) > > *From:* Stefan Sch=E4fer > *Sent:* Sunday, February 02, 2014 3:27 PM > *To:* rsgb_lf_group@blacksheep.org > *Subject:* Re: LF: DX VLF experiments in 3HD > > Markus, > > I am 16 dB stronger now! > > > Am 02.02.2014 14:52, schrieb Markus Vester: >> So what should be expected here? Scaling the fieldstrength from 1 km=20 >> to 180 km (1/r^3 to lambda/2/pi, 1/r thereafter), the signal should=20 >> be 82 dB weaker here on 5.755, and 63 dB weaker on 17.265 kHz.=20 >> Neglecting ionospheric contributions (not really correct), and=20 >> assuming similar noise levels (though 5.5 kHz is much affected by=20 >> railway QRM here), my SNR in 0.47mHz should theoretically have been >> 35 - 82 + 10 dB =3D -37 dB on 5 kHz and >> 50 - 63 + 10 dB =3D -3 dB on 17 kHz. >> So while a detection on the fundamental seems pretty hopeless, the=20 >> third harmonic should already be getting close. > Yes, the QRN and QRM is much lower in 3HD :-) Why didn't we get this=20 > idea earlier??? > >> What is the inductance of the loading coil? > Ehm , i didn't really measured it, it's just trial and error. > >> Would be interesting to see a picture of the scope trace picked up=20 >> near the antenna ;-) > Looks quite good but could cause misunderstandings... > > The amperemeter in the coil shows 350 mA now! There is some kind of=20 > selfoscillations, audible. Thus i do not rise the power even more.=20 > Have to search, find and fix this problem later. The AC voltage from=20 > the vari-transformer is 110V now, so there is room for at least=20 > another 6 dB. Power is in the range of 100W now. > > I'm going to measure the strength at home now. Hopefully the signal is=20 > audible :-) Yesterday it was still weaker than the mains hum, so far=20 > away from any interferences! > > 73, Stefan > >> Best 73, >> Markus (DF6NM) >> >> *From:* Stefan Sch=E4fer >> *Sent:* Sunday, February 02, 2014 2:06 PM >> *To:* rsgb_lf_group@blacksheep.org >> *Subject:* Re: LF: DX VLF experiments in 3HD >> >> Markus, VLF, >> >> Am 01.02.2014 20:34, schrieb Markus Vester: >>> Stefan, >>> running two 478 =B5Hz "6000" windows centered on 5755 Hz (on the=20 >>> grabber, but much QRM here) and also 17265 Hz (offline) which seems=20 >>> more quiet. So hoping for a long carrier... >> Well, i hope that 16 hours key down were long enough ;-) >> >>> On which of the two frequencies would you expect to radiate more powe= r? >> I don't know. But the harmonic signal is very weak and cannot cause=20 >> interferences for JXN or HWU or SAQ or GBZ... >> >> I've done measurements at home, 950m distance, of that _5.755 kHz_=20 >> transmission and saw that the signal was very weak, see attachment.=20 >> Just 50 dB SNR in 4.5 mHz at 3HD. The TX power was just 15W at the=20 >> end. Also the frequency response of the active antenna + soundcard is=20 >> attached. >> >> The experiments are very interesting here and i like to do the=20 >> measurements. Despite rain the coil was on the top of the building=20 >> and on air. It was just covered by a trash bag. The voltages are very=20 >> small... >> I just hang out a 30cm long wire connected to a probe of the=20 >> oscilloscope and so the voltage waveform of the antenna wire. It=20 >> nearly looks as expected :-) >> >> Now i got another idea. There is a 2.2 uF WIMA MKP-10 capacitor in=20 >> series to the output of the H bridge, just to protect it against=20 >> damage in case of a DC output. Now i've disconnected the antenna and=20 >> tuned for the series resonance of this C and the L of the primary=20 >> winding of the loading coil. The resonance is at 1.77 kHz. This=20 >> allowed me to calculate a much smaller additional series C which=20 >> helps to attenuate unwanted frequency components, i.e. makes the=20 >> spectrum cleaner and provides a lower impedance on the wanted=20 >> frequency :-) >> >> There is really no alternative to that H bride PA which works from 10=20 >> Hz to 100 kHz :-) >> >> in a few minutes i will be on air again for a longer time, hopefully=20 >> with a much stronger signal. >> >> Maybe you can detect something of that 5.755 kHz transmission. >> >> 73,GL, Stefan/DK7FC >> >> >>> BTW Today I have updated SpecLab from version 2.79 b08 to b10 (Jan=20 >>> 26), and it seems that GPS 1-pps sync is finally working well now,=20 >>> even with 42 =B5Hz resolution. >>> Good luck for the test! >>> 73, Markus (DF6NM) >>> >>> *From:* Stefan Sch=E4fer >>> *Sent:* Saturday, February 01, 2014 5:46 PM >>> *To:* rsgb_lf_group@blacksheep.org=20 >>> >>> *Subject:* LF: DXl VLF experiments in 3HD >>> >>> VLF, >>> >>> This evening and night i'm planning to transmit on _*5.755 kHz*_,=20 >>> using the large antenna, the large coil and the large PA :-) >>> I don't know what can be expected and how the system works at that=20 >>> frequency. Actually it is just _a first test for playing arround and=20 >>> doing some measurements_ :-) >>> If some nearby stations want to give it a try, maybe even in *3HD*,=20 >>> then don't hesitate :-) >>> >>> 73, Stefan/DK7FC --------------080707000501050103000900 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit VLF,

That 3rd harmonic is on the 17 km band. Do we have any experiences about local diurnal propagation?

Sooner or later there will be misunderstandings and some will say i am transmitting on 17.265 kHz although the TX runs on 5.755 kHz!

I had a thought about that. 3rd harmonics are generated by all HF amateurs, but we all ignore them. We actually can ignore them if they are well attenuated but that doesn't mean that they do not exist! BTW has someone ever tried to decode a 3HD signal (that name, 3HD, is just for fun, like the Dreamers band, a shortcut for 3rd harmonic detection, reminds on HD quality movies or 3D glasses ;-) ) in OPERA mode?

Example: When someone transmits a legal (!) QRO signal of 750W (in DL) on the 160m band using a typical lambda/4 vertical (which is radiating the 3HD signal because there it is lambda 3/4 and thus low impedant too), using a 60 dB attenuating low pass filter, which is quite a good supression, then there should be a 750uW signal on the 53m band, which could be detected in some distance, probably several 10km when using slow modes like OPERA-4 (WSPR will not work so easily here). Receiving this 3HD signal is certainly not absolutely strictly forbidden :-) So actually the amateurs can do legal QRPP tests in slow modes on 53m, can't they? Would you think that it is ethical unjustifiable to try to receive such a signal if it is there anyway and legally generated?

Example2: PA0WMR is often TXing OP8 on 478.x kHz, making 2000km distance. If someone in say 30 km distance can receive him on 1434 kHz (if there would be no AM BCD stn), close to the decode limit, would something be wrong with this test?

I know from WSPR QRP transmissions from DL to VK on 15m with 0.1 W TX power!! So i assume a 3HD signal could be detected in a few 100 km, maybe?

Below 8.3 kHz there is no TX power limitation and we can certainly assume that no interference is caused to anyone at 3HD, just like in the above example (53m band ( i never tried it)).So why not trying to do tests like these today? The noise floor is much lower there which improves the situation :-)

73, Stefan/DK7FC

Am 02.02.2014 18:15, schrieb Markus Vester:
Stefan,
 
your third harmonic is clearly visible in Holland
and here
 
Started spot-on 17265 Hz, now another peak is coming up 15 mHz up.
 
Good luck,
Markus (DF6NM)
 

Sent: Sunday, February 02, 2014 3:27 PM
Subject: Re: LF: DX VLF experiments in 3HD

Markus,

I am 16 dB stronger now!


Am 02.02.2014 14:52, schrieb Markus Vester:
So what should be expected here? Scaling the fieldstrength from 1 km to 180 km (1/r^3 to lambda/2/pi, 1/r thereafter), the signal should be 82 dB weaker here on 5.755, and 63 dB weaker on 17.265 kHz. Neglecting ionospheric contributions (not really correct), and assuming similar noise levels (though 5.5 kHz is much affected by railway QRM here), my SNR in 0.47mHz should theoretically have been 
 35 - 82 + 10 dB = -37 dB on 5 kHz and
 50 - 63 + 10 dB = -3 dB on 17 kHz.
So while a detection on the fundamental seems pretty hopeless, the third harmonic should already be getting close.
Yes, the QRN and QRM is much lower in 3HD :-) Why didn't we get this idea earlier???

 What is the inductance of the loading coil?
Ehm , i didn't really measured it, it's just trial and error.

Would be interesting to see a picture of the scope trace picked up near the antenna ;-)
Looks quite good but could cause misunderstandings...

The amperemeter in the coil shows 350 mA now! There is some kind of selfoscillations, audible. Thus i do not rise the power even more. Have to search, find and fix this problem later. The AC voltage from the vari-transformer is 110V now, so there is room for at least another 6 dB. Power is in the range of 100W now.

I'm going to measure the strength at home now. Hopefully the signal is audible :-) Yesterday it was still weaker than the mains hum, so far away from any interferences!

73, Stefan

 
Best 73,
Markus (DF6NM)
 

Sent: Sunday, February 02, 2014 2:06 PM
Subject: Re: LF: DX VLF experiments in 3HD

Markus, VLF,

Am 01.02.2014 20:34, schrieb Markus Vester:
Stefan,
 
running two 478 µHz "6000" windows centered on 5755 Hz (on the grabber, but much QRM here) and also 17265 Hz (offline) which seems more quiet. So hoping for a long carrier...
Well, i hope that 16 hours key down were long enough ;-)

On which of the two frequencies would you expect to radiate more power?
I don't know. But the harmonic signal is very weak and cannot cause interferences for JXN or HWU or SAQ or GBZ...

I've done measurements at home, 950m distance, of that 5.755 kHz transmission and saw that the signal was very weak, see attachment. Just 50 dB SNR in 4.5 mHz at 3HD. The TX power was just 15W at the end. Also the frequency response of the active antenna + soundcard is attached.

The experiments are very interesting here and i like to do the measurements. Despite rain the coil was on the top of the building and on air. It was just covered by a trash bag. The voltages are very small...
I just hang out a 30cm long wire connected to a probe of the oscilloscope and so the voltage waveform of the antenna wire. It nearly looks as expected :-)

Now i got another idea. There is a 2.2 uF WIMA MKP-10 capacitor in series to the output of the H bridge, just to protect it against damage in case of a DC output. Now i've disconnected the antenna and tuned for the series resonance of this C and the L of the primary winding of the loading coil. The resonance is at 1.77 kHz. This allowed me to calculate a much smaller additional series C which helps to attenuate unwanted frequency components, i.e. makes the spectrum cleaner and provides a lower impedance on the wanted frequency :-)

There is really no alternative to that H bride PA which works from 10 Hz to 100 kHz :-)

in a few minutes i will be on air again for a longer time, hopefully with a much stronger signal.

Maybe you can detect something of that 5.755 kHz transmission.

73,GL, Stefan/DK7FC


 
BTW Today I have updated SpecLab from version 2.79 b08 to b10 (Jan 26), and it seems that GPS 1-pps sync is finally working well now, even with 42 µHz resolution.
 
Good luck for the test!
 
73, Markus (DF6NM)
 
 
 

Sent: Saturday, February 01, 2014 5:46 PM
Subject: LF: DXl VLF experiments in 3HD

VLF,

This evening and night i'm planning to transmit on 5.755 kHz, using the large antenna, the large coil and the large PA :-)
I don't know what can be expected and how the system works at that frequency. Actually it is just a first test for playing arround and doing some measurements :-)
If some nearby stations want to give it a try, maybe even in 3HD, then don't hesitate :-)

73, Stefan/DK7FC
--------------080707000501050103000900--