August 2007 - AMSAT-BB - mailman.amsat.org

Re: ICOM 910H
by Scott Townley 09 Aug '07

09 Aug '07

The RX specifications are SSB/CW 0.11uV for 10dB S/N ...if the noise bandwidth is around 3kHz then that's a 3dB noise figure FM 0.18uV for 12dB SINAD ...if the noise bandwidth is around 5kHz then that's a 3.4dB noise figure -- Scott Townley NX7U Gilbert, AZ DM43di ---- ubong ukommi <uukommi(a)yahoo.com> wrote: > Hello, > Please could you help me with the Noise figue of the receiver 910H. I want to use it for a link budget analysis. > > I have tried available sources but no solution. > Thanks. > > Ubong (M3UIU) > > > --------------------------------- > Take the Internet to Go: Yahoo!Go puts the Internet in your pocket: mail, news, photos & more. > _______________________________________________ > Sent via AMSAT-BB(a)amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

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STS118
by morsesat＠optonline.net 09 Aug '07

09 Aug '07

Hi all, Just a note from one of the ANS editors--Just saw the shuttle launch live. Extremely exciting. Glad I attended to see what my tax money supports. The live video and audio is nothing to be dismissed. Congrats to the STS118 Team. 73, Dee, NB2F NJ AMSAT co-ordinator ans part time ANS editor.

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Re: 2 ghz antenna question
by k0vty＠juno.com 09 Aug '07

09 Aug '07

Hi Chris I have had a 15 mile one way , 2 gHz, 3 foot, 100 mw, RF link for my ISP for 7 years now, and it has never given me a problem. A 50 foot run of LMR 400 is used here. My grid dish has 23 dbi gain. A Cisco model 350 is in my computer. I will assume for the moment my experiences somehow fit your situation and might be useful to you. I use a telescoping Radio Shack mast to mount a vertically polarized Grid dish. The mast is mounted on a lower roof level , using an upper roof peak bracket to stabilize the mast. It is a good solid mounting. The antenna is looking down a water shed that falls away at 3 foot per mile. That clear all the trees. Trees are a real bad attn on 2.4 gHz The grid dish is mounted vertically ( dish rods in the vertical plane) because the ISP uses that polarization. If I were to consider using two dishes I would test two dishes side by side. Diversity reception ( using two receivers ) of two stacked vertically might cancel some signal when mama nature does her tricks. Where as what ever trick mama nature has in store should remain the same for two antennas side by side. The effective aperture of a dish is the physical size of the dish so the distance between is not as critical. Where as the above and below mounting has to do with how mama moves the signal vertically over time. I hope this has provided some food for thought Joe K0VTY ================== On Wed, 08 Aug 2007 16:56:02 -0700 Chris Huber <cahuber(a)ucdavis.edu> writes: > Hello, > > I know this is off subject, I am looking for ideas on stacking 2 > antennas. > I am doing a 25 mile WiFi link on 2 GHz using 1 3 foot grid dish > with > horizontal polarity. I have a power divider and a second dish that I > > want to mount directly above the first antenna. > > Is the vertical spacing critical? Is there any advantage over close > > spacing, ie. increase gain or wide spacing to give better path fade > > protection. > > Thanks for your time. > > Chris N6ICW > _______________________________________________ > Sent via AMSAT-BB(a)amsat.org. Opinions expressed are those of the > author. > Not an AMSAT-NA member? Join now to support the amateur satellite > program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > >

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Re: 2 ghz antenna question
by Chris Huber 09 Aug '07

09 Aug '07

Scott, Thanks for the information. The antennas would be stacked on the same mast and would be easy to put the edges next to each other.I was not aware of interferometer and its effects. Thanks for the heads up. That would have been frustrating to figure out. Chris N6ICW Scott Townley wrote: > Chris, > It depends... :-) > Wide spacing (presumably to gain path diversity) only is effective > post-detector...meaning, you need two RX paths and you "choose" the > best demodulated path. If you wide-space at RF (using your power > divider) you get an interferometer which is most definitely what you > *don't* want. > > Although IIRC in commercial installations the diversity antenna can be > RF-combined with the main antenna through a 10dB coupler (with the > diversity being -10dB). That keeps the interferometer effects down > while limiting the path fades to near 10dB max...but I'm working from > memory on that one. > > For arraying the dishes ("close spacing") you should put them nearly > edge-to-edge (no more than about 6 or 7 inches apart at the rims). > There are several mechanical issues however: first, the dishes must > be co-aligned very well (a 3' dish at 2GHz will have a beamwidth of > around 5 degrees, so the two antennas have to point in azimuth *and* > elevation within 2.5deg of each other, or you will have gained > nothing). Second, the antennas together will need to be pointed twice > as accurately as before. And stay that way in the wind. > > At 16:56 2007-08-08, you wrote: >> Hello, >> >> I know this is off subject, I am looking for ideas on stacking 2 >> antennas. >> I am doing a 25 mile WiFi link on 2 GHz using 1 3 foot grid dish with >> horizontal polarity. I have a power divider and a second dish that I >> want to mount directly above the first antenna. >> >> Is the vertical spacing critical? Is there any advantage over close >> spacing, ie. increase gain or wide spacing to give better path fade >> protection. >> >> Thanks for your time. >> >> Chris N6ICW >> _______________________________________________ >> Sent via AMSAT-BB(a)amsat.org. Opinions expressed are those of the author. >> Not an AMSAT-NA member? Join now to support the amateur satellite >> program! >> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > > Scott Townley NX7U > Gilbert, AZ DM43di > http://members.cox.net/nx7u > >

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2 ghz antenna question
by Chris Huber 09 Aug '07

09 Aug '07

Hello, I know this is off subject, I am looking for ideas on stacking 2 antennas. I am doing a 25 mile WiFi link on 2 GHz using 1 3 foot grid dish with horizontal polarity. I have a power divider and a second dish that I want to mount directly above the first antenna. Is the vertical spacing critical? Is there any advantage over close spacing, ie. increase gain or wide spacing to give better path fade protection. Thanks for your time. Chris N6ICW

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Re: 2 ghz antenna question
by Chris Huber 08 Aug '07

08 Aug '07

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Video on YouTube
by Howard Long 08 Aug '07

08 Aug '07

Folks I uploaded a video on YouTube that you may be interested in showing last weekend's QSO with astronaut Clay Anderson: http://www.youtube.com/watch?v=1swyCCTbP1w Howard G6LVB

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The AA2TX Parasitic Lindeblad
by john heath 08 Aug '07

08 Aug '07

Hi Guys, Interesting thread I built a Parasitic Lindenblad using Tony's excellent design. I made some modifications to the hub and arms to suit materials easily available in England. The elements were measued very carefully and exactly to Tony's dimensions. The parasitic version was much easier to build than the traditional version with 4 folded dipoles. Results - Used on receive with a pre-amp (The G0MRF low noise design built from a kit) LO-19 CW beacon at about 700mW was solid copy right down to the horizon. For a more extreme test I tried one of the 80mW cubesats. I could copy the CW beacon at 3200km range and 1 degree elevation. If you build one I am sure you will be pleased with the results. It's very neat looking and scored 10 out of 10 on the XYL test. 73 John G7HIA

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Re: ARRL dual moxon turnstyle project questions
by Reicher, James 08 Aug '07

08 Aug '07

Scott, 1. I would recommend using standard connectors and teeing them rather than soldering to a lug. You'll find that if you want to move the array for portable work, it will be easier to set up and take down. 2. Although I'm no expert, I wouldn't think you'd even need the same length feedline, although it couldn't hurt. 3. LB gives the dimensions in inches, but try converting them to millimeters. Just multiply by 25.4 millimeters to the inch. I'd round to the nearest 1/2 mm and cut as close as possible. Then, that ".49 inches" dimension becomes 12.5 mm. 4. You could always use duct tape... they use it on the shuttle and ISS! BTW, the 70cm version calls for #12 AWG wire, not #14. 73 de N8AU, Jim in Raymore, MO Light travels faster than sound... This is why some people appear bright until you hear them speak. Date: Tue, 31 Jul 2007 07:08:16 -0700 (PDT) From: Scott Wilson <s.wilson(a)yahoo.com> Subject: [amsat-bb] ARRL dual moxon turnstyle project questions To: amsat-bb(a)amsat.org Message-ID: <862339.97515.qm(a)web31810.mail.mud.yahoo.com> Content-Type: text/plain; charset=iso-8859-1 I'm working on building the ARRL dual moxon antennas, but the article isn't very detailed where I'd like it to be and a little over detailed in some places I wish it weren't. If you want to look, this is the URL (http://www.arrl.org/members-only/tis/info/pdf/0108038.pdf) 1. What are acceptable ways to terminate the paralled 75 ohm matching sections? I'm thinking now I'll just terminate them to a couple of ring terminals attached to the mast rather than terminating each one with a bnc and teeing them. 2. How do I feed the 70cm and 2m with the same feedline? should I just tee a 50 ohm line to two equal length 50 ohm sections? 3. This is more of a comment... I'm wagering the uhf version doesn't work at all... measurements are given to the hundreth of an inch - and then you solder a big ring lug to the end of it! 4. Are there any other good techniques for setting the distance between the reflector and driver besides heat shrink? The 70cm antenna is using #14 galvanized wire, and I can't think of anything small enough to hold them in place well. I found that the 3/16 rod for the 2m moxon will work great with 1/4" nylon tubing. Thanks for any feedback - I'll probably have more questions.. I'm sitting here with a half-made 70cm turnstyle, and am about to start on the 2m version. Whew - I'm beginning to think that a $1000 investment in rotators and antennae isn't such a bad idea after all! Scott Wilson NW2S

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ICOM 910H
by ubong ukommi 08 Aug '07

08 Aug '07

Hello, Please could you help me with the Noise figue of the receiver 910H. I want to use it for a link budget analysis. I have tried available sources but no solution. Thanks. Ubong (M3UIU) --------------------------------- Take the Internet to Go: Yahoo!Go puts the Internet in your pocket: mail, news, photos & more.

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