Return-Path: X-Spam-DCC: paranoid 1233; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_50_60,HTML_MESSAGE autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id t5TC0xnD007538 for ; Mon, 29 Jun 2015 14:01:00 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Z9Xgi-0004KH-EA for rs_out_1@blacksheep.org; Mon, 29 Jun 2015 12:57:24 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Z9Xgh-0004K8-Sk for rsgb_lf_group@blacksheep.org; Mon, 29 Jun 2015 12:57:23 +0100 Received: from mail-oi0-f41.google.com ([209.85.218.41]) by relay1.thorcom.net with esmtps (TLSv1.2:AES128-GCM-SHA256:128) (Exim 4.85) (envelope-from ) id 1Z9Xgf-0001oo-2S for rsgb_lf_group@blacksheep.org; Mon, 29 Jun 2015 12:57:22 +0100 Received: by oigb199 with SMTP id b199so116082870oig.3 for ; Mon, 29 Jun 2015 04:57:19 -0700 (PDT) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=qnPOCHDiGECqqBk1sETrUhdiJbN+VXKPingiVRXYK5E=; b=gDSs2oayWAyQxtxNf8nE/98uU7r6wu9KP5tZ8tteEykf+EaGgXXDF7hNt2jWozf4Us aAEk5wWqoh1qOObbuxVA6lM2Rqu1VMYiv1lqrfnjkLmqC9+7kytZmK2ZzOOkle4Lb9DO 4Wd+gvPFX9gD33aFl/m+3ykfcgYFymKDHkQbcjPUALqM4Is46BXayqX1dq+MTTFxdKIe aw45aENUTd7ZLg3ShXS4dZMJU8CxGkuFcYtxvbU40lE47iETscAvAVK2pB0GjxG4N0Kq /k062MkjVtkr7VldieucF5RBalipcUYvg59BenmNCjTnPn39NcXoof9lUIMkEjEZ75Bc dLCQ== MIME-Version: 1.0 X-Received: by 10.202.75.141 with SMTP id y135mr12885694oia.6.1435579038997; Mon, 29 Jun 2015 04:57:18 -0700 (PDT) Received: by 10.60.8.97 with HTTP; Mon, 29 Jun 2015 04:57:18 -0700 (PDT) In-Reply-To: <8D28074F91D01E3-230C-131019@webmail-vm008.sysops.aol.com> References: <8D28074F91D01E3-230C-131019@webmail-vm008.sysops.aol.com> Date: Mon, 29 Jun 2015 07:57:18 -0400 Message-ID: From: Warren Ziegler To: rsgb_lf_group X-Scan-Signature: e46c171071e4381f0f05c7e52ee5e3ee Subject: Re: LF: MF mobile ? Content-Type: multipart/alternative; boundary=001a11c170e6aaa3e70519a6ca44 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-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 3570 --001a11c170e6aaa3e70519a6ca44 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Markus, >I'm only a bit worried about unexpected behavior of modern vehicle electronics. In particular, unappropriate firing of >the airbags could potentially become a nasty surprise. I guess this may be less of a concern in an old Golf Diesel ;-) I've run a kW on 160m mobile, some nice corona discharge from the end of the antenna on damp nights and some dashboard indicator lights would come on when keyed up but no damage or airbag deployment :-) Have you calculated the loading coil L and the self-resonant frequency of the coil? 73 Warren On Mon, Jun 29, 2015 at 7:22 AM, Markus Vester wrote= : > Revisiting the topic... My ERP calculation was erroneous by a factor of > ten (looks like I can no longer do without a calculator). It should be > radiated power =3D 0.0256 * 160 =3D 4 microwatts or -24 dBm > ... which could let me produce a comfortable 21 dB SNR in Stefan's LF > QRSS-60 window - and even mobile QRSS-10 comes within reach. > Scaling from 137 to 475 kHz, we'd be able to achieve 0.6 mW EMRP, which > would probably be good for aural CW up to 50 km over land. > > When driving around with a mobile antenna it will probably anyway need to > be guyed. So we might use the strings partly as a topload, forming a > miniature umbrella antenna with higher current and effective height. > > I'm only a bit worried about unexpected behavior of modern vehicle > electronics. In particular, unappropriate firing of the airbags could > potentially become a nasty surprise. I guess this may be less of a concer= n > in an old Golf Diesel ;-) > > All the best, > Markus (DF6NM) > > -----Urspr=C3=BCngliche Mitteilung----- > Von: Markus Vester > An: rsgb_lf_group > Verschickt: Do, 28 Mai 2015 1:23 am > Betreff: Re: LF: MF mobile ? > > > I bet you have all the formulas in your mind :-) > > Yes Stefan, sure do... this is the kind of stuff I sometimes like to thin= k > about during my bike ride to work - about 70 minutes, twice a day ;-) Ok, > no pocket calculator allowed then... > > A 1.5 m stick would have about 10 pF or -j 120 kohm at 137 kHz. If you're > keen you could probably go up to 20 kV, giving 0.16 A. Effective height > will be around 0.7m, so radiation resistance is 1579ohms*(.7/2200)^2 =3D = 160 > microohms. Thus radiated power =3D 0.0256 * 160 =3D 0.4 microwatt or -34 = dBm. > > Assuming a coil Q of 400, required TX power would be only 0.16^2 * 120k / > 400 =3D 8 watts. If you're not afraid of non-ionizing E-fields you could > probably do that from a bicycle (sic), or walking around with a backpack = ;-) > > At a range of 180 km between us, we'd get a groundwave fieldstrength > of 50-34-45-4 dBuV/m =3D -33 dBuV/m. Assuming a quiet day with of -26 > dBuV/m/Hz background noise, and watching in a "QRSS-60" spectrogram with = 16 > mHz (-18 dBHz) noise bandwidth., the noise floor would be -44 dBuV/m, and > we'd achieve 11 dB SNR. Phew, we've made it.... > > Scaling from LF to MF while maintaining same antenna voltage, current wil= l > be 3.4 times higher, ERP 144 times (ie. 60 uW), and fieldstrength 12 time= s. > > BTW Forget about that parallel capacitor to reduce tuning variation - tha= t > would be just cheating yourself, similar to adding an attenuator after th= e > TX to improve matching. Only the current going into the actual antenna is > the one that's radiating. > > All the best, > Markus > > > *From:* DK7FC > *Sent:* Thursday, May 28, 2015 12:10 AM > *To:* rsgb_lf_group@blacksheep.org > *Subject:* LF: MF mobile ? > > Hmm, i find someone should do a real mobile (mobile-mobile, with a > velocity > 0) experiment. A 1.5 m long CB antenna with a special preparat= ed > feed point should work. And i think that the wire works better with a fix= ed > C in parallel, even if this reduces the efficiency. But it stabilises the > SWR or better said, the voltage on the wire. Corona? Where is the problem > with corona? :-) > Markus, could you calculate the ERP when 10 kV rms is applied to a 1.5m > high antenna on a car roof? I bet you have all the formulas in your mind = :-) > > Maybe the antenna has 10 pF. I remember i have a 470pF/16kV capacitor at > home. So if C =3D 470 pF and f =3D 475 kHz, L =3D 239 uH With 470 pF para= llel to > the antenna, a moving wire (=3D changing C) does not make a significant > effect i think. > 10 kV at 239 uH at 10 kV is 14A. If P =3D 200 W, the losses must be 1 Ohm= ! > With a good RF litz wire, this is possible :-) > > What would be the ERP and possible distance? > > It would be interesting to try that in WSPR / QRSS-60 :-) I would also > drive to someone for making a CW QSO but most likely there is a LOT of QR= M > when driving... > > More ideas? > > 73, Stefan > ... > > . > > > ------------------------------ > [image: Avast logo] > L'absence de virus dans ce courrier =C3=A9lectronique a =C3=A9t=C3=A9 v= =C3=A9rifi=C3=A9e par le > logiciel antivirus Avast. > www.avast.com > > > > --=20 73 Warren K2ORS WD2XGJ WD2XSH/23 WE2XEB/2 WE2XGR/1 --001a11c170e6aaa3e70519a6ca44 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Markus,

>I'm only a bit worried about unexpected behavior=C2= =A0of mode= rn vehicle electronics.= In particular, unappropriate firing of >the airbags could potentially b= ecome a nasty surprise. I guess this may be less of a concern in an old Gol= f Diesel ;-)
=
=C2=A0 = =C2=A0I've run a kW on 160m mobile, some nice corona discharge from the= end of the antenna on damp nights and some dashboard indicator lights woul= d come on when keyed up but no damage or airbag deployment :-)
=

=C2=A0 =C2=A0Have you calculated = the loading coil L and the self-resonant frequency of the coil?

73 Warren




<= div class=3D"gmail_quote">On Mon, Jun 29, 2015 at 7:22 AM, Markus Vester <markusvester@aol.com> wrote:
Revisiting the topic... My ERP calculation was erroneous by a factor = of ten (looks like I can no longer do without a calculator). It should be
=C2=A0radiated power =3D 0.0256 * 160 =3D 4 microwatts or -24 dBm
... which could let me produce a comfortable 21 dB SNR in Stefan's= LF QRSS-60 window - and even mobile QRSS-10 comes within reach.
Scaling from 137 to 475 kHz, we'd be able to achieve 0.6 mW EMRP, = which would probably be good for aural CW up to 50 km over land.
=C2=A0
When driving around with a mobile antenna it will probably anyway need= to be guyed. So we might use the strings partly as a topload, forming a mi= niature umbrella antenna with higher current and effective height.
=C2=A0
I'm only a bit worried about unexpected behavior of modern vehicle= electronics. In particular, unappropriate firing of the airbags could pote= ntially become a nasty surprise. I guess this may be less of a concern in a= n old Golf Diesel ;-)
=C2=A0
All the best,
Markus (DF6NM)
=C2=A0
-----Urspr=C3=BCngliche Mitteilung-----
Von: Markus Vester <markusvester@aol.com>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Do, 28 Mai 2015 1:23 am
Betreff: Re: LF: MF mobile ?

=20
=20
=20
> I bet you have all the formulas in your mind :-)

Yes Stefan, sure do... this is the kind of stuff I sometimes like to think= about during my=C2=A0bike ride to work - about 70 minutes, twice a day ;-= ) Ok, no pocket calculator allowed then...
=20
=C2=A0
=20
A 1.5 m stick would have=C2=A0about=C2= =A010 pF or -j 120 kohm at 137 kHz.=C2=A0If you're keen you could prob= ably go up to 20 kV,=C2=A0giving 0.16 A. Effective height will be=C2=A0aro= und 0.7m, so radiation resistance is 1579ohms*(.7/2200)^2 =3D 160 microohm= s. Thus radiated power =3D 0.0256=C2=A0* 160 =3D 0.4=C2=A0microwatt or -34= dBm.
=20
=C2=A0
=20
Assuming a coil Q of 400, required TX = power would be only 0.16^2 * 120k / 400=C2=A0=3D 8 watts. If you're not afraid of non-ionizing E-fields y= ou=C2=A0could probably do that from a bicycle (sic), or walking around=C2= =A0with a=C2=A0backpack=C2=A0;-)
=20
=C2=A0
=20
At a range of 180 km between us, we= 9;d get=C2=A0a groundwave fieldstrength of=C2=A050-34-45-4 dBuV/m =3D -33 = dBuV/m.=C2=A0Assuming a quiet day with=C2=A0of -26 dBuV/m/Hz background no= ise, and watching=C2=A0in a "QRSS-60" spectrogram with=C2=A016 m= Hz (-18 dBHz)=C2=A0noise bandwidth., the noise floor would be -44 dBuV/m, = and we'd achieve 11 dB SNR. Phew= , we've made it....
=20
=C2=A0
=20
Scaling from LF to MF while maintainin= g=C2=A0same antenna voltage,=C2=A0current will be 3.4 times higher,=C2=A0E= RP 144 times (ie. 60 uW), and fieldstrength 12 times.=C2=A0
=20
=C2=A0
=20
BTW=C2=A0Forget about that=C2=A0parall= el capacitor to reduce tuning variation - that would be just cheating your= self, similar to adding an attenuator after the TX to improve matching.=C2= =A0Only the=C2=A0current going into the actual antenna=C2=A0is the one tha= t's radiating.
=20
=C2=A0
=20
All the best,
=20
Markus
=20
=C2=A0
=20

=20
=20
=20
From: DK7FC
=20
Sent: Thursday, May 28, 2015 12:10 AM
=20 =20
Subject: LF: MF mobile ?
=20

Hmm, i find someone should do a real mobile (mobile-mobile, with a velocit= y > 0) experiment. A 1.5 m long CB antenna with a special preparated fe= ed point should work. And i think that the wire works better with a fixed = C in parallel, even if this reduces the efficiency. But it stabilises the = SWR or better said, the voltage on the wire. Corona? Where is the problem = with corona? :-)
Markus, could you calculate the ERP when 10 kV rms is applied to a 1.5m hi= gh antenna on a car roof? I bet you have all the formulas in your mind :-)=

Maybe the antenna has 10 pF. I remember i have a 470pF/16kV capacitor at h= ome. So if C =3D 470 pF and f =3D 475 kHz, L =3D 239 uH With 470 pF parall= el to the antenna, a moving wire (=3D changing C) does not make a signific= ant effect i think.
10 kV at 239 uH at 10 kV is 14A. If P =3D 200 W, the losses must be 1 Ohm = !
With a good RF litz wire, this is possible :-)

What would be the ERP and possible distance?

It would be interesting to try that in WSPR / QRSS-60 :-) I would also dri= ve to someone for making a CW QSO but most likely there is a LOT of QRM wh= en driving...

More ideas?

73, Stefan
...
=20
.


=20
=
3D"Avast = =20
L'absence de virus dans ce courrier = =C3=A9lectronique a =C3=A9t=C3=A9 v=C3=A9rifi=C3=A9e par le logici= el antivirus Avast.
www.avast.com






--
73 Warr= en K2ORS
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 WD2XGJ =
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 WD2XSH/23
= =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 WE2XEB/2
=C2=A0 = =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 WE2XGR/1

=C2=A0
--001a11c170e6aaa3e70519a6ca44--