The Balloon has APRS on it, so it is telling us where it is. We have GPS, so we know where we are and our heading, a PIC processor takes those two inputs, does the 3D math and points the AZ/EL mount. Again, the dish will be an open-wire grid with nearly 1" spacing and have little drag.
Will have to power the Yaesu mount from a 115v AC inverter because they are AC motors.. Bob, WB4APR > I'm trying to visualize you driving (bouncing) down the freeway at 70 mph with a square yard of curved (airfoil!) metal sitting at odd angles to the air flow, trying to aim it at a target you may not be able to see clearly, which is also moving at some rate in another direction, with an accuracy of +/- a half dozen degrees (which is what you get with a dish that size). I had a hard enough time aiming my 30 inch BBQ grill at AO-40, from my nearly stationary house (this is California, after all), with up to date KEPS, a rotor system calibrated earlier against the position of the Sun, NBS-sync'd clock on a Linux PC, and so forth. Even if you mount the dish inside a camper minivan with a fiberglass roof (think mobile Radome), I don't see how this is going to work. I've seen you do amazing things, but what are you thinking? The best use of the dish would probably be to catch the balloon payload as it falls from the sky... Greg KO6TH > From: bruni...@usna.edu > To: k...@aol.com; amsat-bb@amsat.org > Date: Wed, 4 Jan 2012 17:54:02 -0500 > Subject: [amsat-bb] Re: Looking for a G3RUH dish > > > Regarding your Cu wire dish... you might look at > > the Tek Sharp dishes as an easier alternative to "rolling your own." > > We are after absolute minimum wind drag. I don't think the Tek dish would > survive accurate tracking while driving along the interstate at 70 PMPH to > catch a balloon. And we want it to be a good 3' by 4' dish... Need the > gain for the tiny wifi video link... > > Bob > > > > I picked one up on ebay about a year ago and put it in my attic... waiting > for amsat-dl :-) > > http://www.plumdragon.com/teksharp/hr_AO-40_products.htm > > Drew, > I have a spare PF dish about 60 cm, but it is steel, not aluminum like the > G3RUH. I used it on AO-40 for 24 GHz. Let me know off-list if you want it. > > 73, > Jerry, K5OE > > ---- previous message ---- > You probably have one of the K5GNA "BBQ" dishes. The G3RUH is a solid round > spun dish. > > 73, Drew > > -----Original Message----- > >From: Bob Bruninga <bruni...@usna.edu> > >Sent: Jan 3, 2012 2:19 PM > >To: 'Andrew Glasbrenner' <glasbren...@mindspring.com>, 'amsat-bb' > ><amsat-bb@amsat.org> > >Subject: RE: [amsat-bb] Looking for a G3RUH dish > > > >> I'm looking for one of the 60cm G3RUH dishes > > > >Got one, (but not available). > > > >Questions: I measured reflector grid separation as .88 inches which works > >out to be about 0.18 wavelength. I always thought the grid had to be > >tighter than 0.1 inches to be an effective "surface". > > > >Maybe the difference with almost double the spacing is not that > significant? > >(especially for a steel one which would be quite heavy. > > > >Reason I am asking is that I also need another S band dish (at 70 MPH on > the > >roof of a tracking van) and we are thinking about building one by using an > >old solid 6' TVRO dish as a form and laying in copper wire and soldering it > >to copper straps. With all that labor, I'd not want to get the spacing > >wrong. > > > >Bob, Wb4APR > > > > _______________________________________________ > Sent via AMSAT-BB@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 > > _______________________________________________ > Sent via AMSAT-BB@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 _______________________________________________ Sent via AMSAT-BB@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
