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[195.171.43.25]) by mx.google.com with ESMTP id j47si11279385eeg.18.2013.07.09.05.52.02 for ; Tue, 09 Jul 2013 05:52:03 -0700 (PDT) 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 1UwWs4-0003RE-4L for rs_out_1@blacksheep.org; Tue, 09 Jul 2013 13:18:16 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1UwWs2-0003R5-Sj for rsgb_lf_group@blacksheep.org; Tue, 09 Jul 2013 13:18:14 +0100 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 1UwWs0-0001IQ-2m for rsgb_lf_group@blacksheep.org; Tue, 09 Jul 2013 13:18:13 +0100 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 r69CIBQY029564 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Tue, 9 Jul 2013 14:18:11 +0200 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 r69CIA7J023224 for ; Tue, 9 Jul 2013 14:18:10 +0200 Message-ID: <51DBFF7D.9050807@iup.uni-heidelberg.de> Date: Tue, 09 Jul 2013 14:18:05 +0200 From: =?UTF-8?B?U3RlZmFuIFNjaMOkZmVy?= 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: <51D498BD.3050007@iup.uni-heidelberg.de> <005b01ce798a$b0476600$6d01a8c0@DELL4> <20130706131640.GG5246@cs.utwente.nl> <7D6B8CBB38964C9C82487F5D0F3648FC@FMVXD1232> <20130707203537.GA30691@cs.utwente.nl> <51DA00C8.6000600@iup.uni-heidelberg.de> <51DA0212.8020808@iup.uni-heidelberg.de> <51DA03CE.6020508@iup.uni-heidelberg.de> <51DA1680.6030602@iup.uni-heidelberg.de> <51DB6CB3.2080708@iup.uni-heidelberg.de> <001601ce7c95$f235b360$6401a8c0@JAYDELL> In-Reply-To: <001601ce7c95$f235b360$6401a8c0@JAYDELL> X-Spam-Score: -2.6 (--) 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: Hi Jay, Thanks for the suggestion. Well, i also had some thoughts on the balance issue. The battery is mounted to the dipole half that is connected to source of the FET. The battery itselfe should have this potential as well. So it's just the geometry that slightly deforms the symmetry, maybe. [...] Content analysis details: (-2.6 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] -0.3 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 170d09a2454389e326e0caea8d7379f3 Subject: Re: LF: Re: MiniWhip antenna, fiber optic Content-Type: multipart/alternative; boundary="------------070103090306030707090200" 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 Status: O X-Status: X-Keywords: X-UID: 2802 This is a multi-part message in MIME format. --------------070103090306030707090200 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay2.uni-heidelberg.de id r69CIBQY029564 Hi Jay, Thanks for the suggestion. Well, i also had some thoughts on the balance issue. The battery is=20 mounted to the dipole half that is connected to source of the FET. The=20 battery itselfe should have this potential as well. So it's just the=20 geometry that slightly deforms the symmetry, maybe. I thought about using a tube with a higher diameter so i can mount the=20 batteries _inside_ the dipole half connected to source. This would then=20 allow a maximum of symmetry. Last night i didn't find a suitable tube.=20 And i thought that the construction does not need a perfect symmetry for=20 first tests as it is completely floating. At least i can do some measurements of 630m signals in the far field and=20 in daytime and in an open field. I can test different heights above=20 ground, horizontally and vertically. In each position i can use a=20 separate ground (3 short eath rods and a wire) and connect this to one=20 of the halfs, just to show the difference in the levels. Later it will be interesting to do the test on the top of the institute,=20 i.e. with a noisy ground! Will the S/N suffer from the ground=20 connection? I assume yes! And that would mean that this concept is worth=20 to build and use daily! To my surprise it appears that the dynamic range and noise performance=20 is much better than i thought. But i'm still not sure if i will see the=20 (daytime) natural background noise with this construction. It's quite warm outside now and i will see if i can do some first=20 experiments today as long as there is no skywave... 73, Stefan/DK7FC Am 09.07.2013 13:17, schrieb jrusgrove@comcast.net: > Stefan > Suggestion ... in the interest of better dipole balance mount=20 > battery so that it isn't taped to one half of the dipole. Suspect=20 > it's quite easy to upset the balance on such a short antenna. > Jay W1VD WD2XNS WE2XGR/2 > > ----- Original Message ----- > *From:* Stefan Sch=C3=A4fer > *To:* rsgb_lf_group@blacksheep.org > > *Sent:* Monday, July 08, 2013 9:51 PM > *Subject:* Re: LF: Re: MiniWhip antenna, fiber optic > > Hi all, > > Today i just made some changes on the antenna. Now the dipole legs > are aluminium foil on a plastic tube. Length is 30 cm (29cm on the > side where the battery is connected, GND of the circuit) and > diameter is 18mm. The forward current of the TX LED is about 15 > mA. Some working point optimisations were done so the gain is a > bit higher (not only due to the increased electrode capacity). I > know, the signal voltage does NOT rise linearly with the capacity > of the electrodes (thinking about the voltage between 2 parallel > plates of a capacitor which is put in an external electrical > field) but it allows to realise a RC lowpassfilter in a next step. > New antenna: > https://dl.dropboxusercontent.com/u/19882028/LF/20130709_033824.jpg > I can now do some /p experiments in the far field (for my local > 630m transmissions) in a location without trees, houses.... > > 73, Stefan/DK7FC > > > Am 08.07.2013 03:31, schrieb Stefan Sch=C3=A4fer: >> Hi all, >> >> Well, somehow i didn't want to stop, so i now built the RX too: >> https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC_fiber%20opti= c%20active%20dipole_RX.jpg >> I made some changes in the RX schematic, using a J310 instead of >> the BF862 but the principle schematic is the same. The working >> points look as expected. BTW that electrical/optic/electrical >> converter must be quite wide in the transferred frequency range, >> i guess starting from a few 100 Hz to a few 100 kHz. >> >> When connecting the BNC output to the scope, the noise shown from >> the scope does not change. When switching on the active probe >> there is some noise visible in the range of 2 ms/div. The probe >> stands in the lab where many noise sources can be expected. >> >> And suddenly!!! : It was 1:06 UTC. I am transmitting WSPR-2 each >> 6 minutes on 630m, from the same building, in some 10m distance. >> *Suddenly there was a 472 kHz signal on the scope*, although the >> antenna can't work :-) The short dipole is completely floating. >> See another photo where the floating antenna is placed on a >> (isolating and low coupling capacity to sourroundings) cardboard: >> https://dl.dropboxusercontent.com/u/19882028/LF/Signal%21.jpg >> >> When switching off the active antenna, the signal disappears >> completely on the scope, of course! >> >> When coming closer with my hand to one of the legs of the dipole >> or the battery, the signal rises, as expected. I think we can >> agree that this antenna IS floating!! >> >> So far for now. It's 3:26 AM and i think i should take some sleep >> :-) Looking forward to the tomorrows experiments. Let me know if >> you have suggestions for experiments! >> >> 73, GN, Stefan/DK7FC >> >> >> Am 08.07.2013 02:11, schrieb Stefan Sch=C3=A4fer: >>> 3rd: >>> https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC_fiber%20opt= ic%20active%20dipole_TX3.jpg >>> >>> The optic cable is 9m long. >>> >>> Am 08.07.2013 02:04, schrieb Stefan Sch=C3=A4fer: >>>> another image of the TX: >>>> https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC_fiber%20op= tic%20active%20dipole_TX2.jpg >>>> >>>> Am 08.07.2013 01:59, schrieb Stefan Sch=C3=A4fer: >>>>> Hi all, >>>>> >>>>> OK, although it can't work (do you remember?!) i built an >>>>> active antenna with battery supply and fiber optic output. The >>>>> active part is a BF862 >>>>> . >>>>> The circuit is quite simple: >>>>> https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC_fiber%20o= ptic%20active%20dipole%20schematic.jpg >>>>> It is a first idea for the schematic. Maybe i will change it >>>>> later so that the gate is shifted to 9V/2. Just for first >>>>> experiments. In various tests with the BF862 i found that it >>>>> was necessary to add a ferrite bead directly in front of the >>>>> gate to prevent VHF oscillations of the JFET. >>>>> >>>>> The TX is already working: >>>>> https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC_fiber%20o= ptic%20active%20dipole_TX.jpg >>>>> Yes yes yes, it is not truely symmetric and the capacity at >>>>> source must be a bit larger than that of the leg connected to >>>>> gate. Anyway it will be useful for some basic and interesting >>>>> experiments. >>>>> >>>>> RX is ready tomorrow. >>>>> >>>>> 73, Stefan/DK7FC > --------------070103090306030707090200 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay2.uni-heidelberg.de id r69CIBQY029564 Hi Jay,

Thanks for the suggestion.

Well, i also had some thoughts on the balance issue. The battery is mounted to the dipole half that is connected to source of the FET. The battery itselfe should have this potential as well. So it's just the geometry that slightly deforms the symmetry, maybe.

I thought about using a tube with a higher diameter so i can mount the batteries inside the dipole half connected to source. This would then allow a maximum of symmetry. Last night i didn't find a suitable tube. And i thought that the construction does not need a perfect symmetry for first tests as it is completely floating.

At least i can do some measurements of 630m signals in the far field and in daytime and in an open field. I can test different heights above ground, horizontally and vertically. In each position i can use a separate ground (3 short eath rods and a wire) and connect this to one of the halfs, just to show the difference in the levels.

Later it will be interesting to do the test on the top of the institute, i.e. with a noisy ground! Will the S/N suffer from the ground connection? I assume yes! And that would mean that this concept is worth to build and use daily!

To my surprise it appears that the dynamic range and noise performance is much better than i thought. But i'm still not sure if i will see the (daytime) natural background noise with this construction.

It's quite warm outside now and i will see if i can do some first experiments today as long as there is no skywave...

73, Stefan/DK7FC


Am 09.07.2013 13:17, schrieb jrusgrove@comcast.net:
Stefan
=C2=A0
Suggestion ... in the interest of better dipole balance mount battery=C2=A0so that it isn't taped to one ha= lf of the dipole. Suspect it's=C2=A0quite easy to upset the balance on such = a short antenna.
=C2=A0
Jay W1VD=C2=A0 WD2XNS=C2=A0 WE2XGR= /2=C2=A0
----- Original Message -----
Sent: Monday, July 08, 2013 9:51 PM
Subject: Re: LF: Re: MiniWhip antenna, fiber optic

Hi all,

Today i just made some changes on the antenna. Now the dipole legs are aluminium foil on a plastic tube. Length is 30 cm (29cm on the side where the battery is connected, GND of the circuit) and diameter is 18mm. The forward current of the TX LED is about 15 mA. Some working point optimisations were done so the gain is a bit higher (not only due to the increased electrode capacity). I know, the signal voltage does NOT rise linearly with the capacity of the electrodes (thinking about the voltage between 2 parallel plates of a capacitor which is put in an external electrical field) but it allows to realise a RC lowpassfilter in a next step.
New antenna: https://dl.dropboxusercontent.com/u/19882028/LF/20130709_033824.jpg<= /a>
I can now do some /p experiments in the far field (for my local 630m transmissions) in a location without trees, houses....

73, Stefan/DK7FC


Am 08.07.2013 03:31, schrieb Stefan Sch=C3=A4fer:
Hi all,

Well, somehow i didn't want to stop, so i now built the RX too: https://dl.dropboxusercontent.com/u/19882028/LF= /DK7FC_fiber%20optic%20active%20dipole_RX.jpg I made some changes in the RX schematic, using a J310 instead of the BF862 but the principle schematic is the same. The working points look as expected. BTW that electrical/optic/electrical converter must be quite wide in the transferred frequency range, i guess starting from a few 100 Hz to a few 100 kHz.

When connecting the BNC output to the scope, the noise shown from the scope does not change. When switching on the active probe there is some noise visible in the range of 2 ms/div. The probe stands in the lab where many noise sources can be expected.

And suddenly!!! : It was 1:06 UTC. I am transmitting WSPR-2 each 6 minutes on 630m, from the same building, in some 10m distance. Suddenl= y there was a 472 kHz signal on the scope, although the antenna can't work :-) The short dipole is completely floating. See another photo where the floating antenna is placed on a (isolating and low coupling capacity to sourroundings) cardboard: https://dl.dropboxusercontent.com/u/19882028/LF= /Signal%21.jpg

When switching off the active antenna, the signal disappears completely on the scope, of course!

When coming closer with my hand to one of the legs of the dipole or the battery, the signal rises, as expected. I think we can agree that this antenna IS floating!!

So far for now. It's 3:26 AM and i think i should take some sleep :-) Looking forward to the tomorrows experiments. Let me know if you have suggestions for experiments!

73, GN, Stefan/DK7FC


Am 08.07.2013 02:11, schrieb Stefan Sch=C3=A4fer:
3rd: https://dl.dropboxusercontent.com/u/19882028/LF= /DK7FC_fiber%20optic%20active%20dipole_TX3.jpg

The optic cable is 9m long.

Am 08.07.2013 02:04, schrieb Stefan Sch=C3=A4fer:
another image of the TX: https://dl.dropboxusercontent.com/u/19882028/LF= /DK7FC_fiber%20optic%20active%20dipole_TX2.jpg

Am 08.07.2013 01:59, schrieb Stefan Sch=C3=A4fer:
Hi all,

OK, although it can't work (do you remember?!) i built an active antenna with battery supply and fiber optic output. The active part is a BF862. The circuit is quite simple: https://dl.dropboxusercontent.com/u/19882028/LF= /DK7FC_fiber%20optic%20active%20dipole%20schematic.jpg It is a first idea for the schematic. Maybe i will change it later so that the gate is shifted to 9V/2. Just for first experiments. In various tests with the BF862 i found that it was necessary to add a ferrite bead directly in front of the gate to prevent VHF oscillations of the JFET.

The TX is already working: https://dl.dropboxusercontent.com/u/19882028/LF= /DK7FC_fiber%20optic%20active%20dipole_TX.jpg
Yes yes yes, it is not truely symmetric and the capacity at source must be a bit larger than that of the leg connected to gate. Anyway it will be useful for some basic and interesting experiments.

RX is ready tomorrow.

73, Stefan/DK7FC
--------------070103090306030707090200--