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Re: Simple OMNI receivers for LEO's.



I used a 2m quarter wave on the car with great results when I was on a
trip.  I was able to use AO-51, AO-27 and even SO-50 with no pre-amp
with an HT as long as the elevation was 30 degrees or more.

73 de Pat --- KA9SCF.
Amsat #35741

On 6/17/05, Robert Bruninga <bruninga@usna.edu> wrote:
> Dont forget also that a 1/4 wave 2 meter 19" whip
> over a ground plane about a meter in diameter also
> makes an EXCELLENT UHF 3/4 wave omni antenna
> above about 25 deg.  It has about 7 dBi of
> gain (and the antenna is perfectly dual band, since
> it is 1/4 wave at 2m.).
> 
> THus it works well for ISS and PCSAT, and VO-52 on
> 2 meters above about 15 deg and on the other birds
> above 25 deg, the 7 dBi of gain there and the fact that
> the birds are 6 dB closer makes ALL amateur satellites
> hearable above those angles on nothing but this whip.
> 
> But again, the UHF birds are above those angles only about
> 1/3rd of the time.  But it sure makes for a simple,
> no hassle, no moving parts receive system.  Hooked to
> a TH-D7 HT running satellte tuning software, tuning the
> radio to every satellite that comes into view, you wont
> miss a thing (except the low passes)...
> 
> See the bottom half of this page:
> 
> http://www.ew.usna.edu/~bruninga/astars.html
> 
> Also see the percentage of time that a LEO satellite
> is in view at various angles on:
> 
> http://www.ew.usna.edu/~bruninga/rotator1.html
> 
> And FINALLY, remember that your car with a center
> roof mounted whip and only 10' of coax will always
> hear satellites better than any other omni with 50
> feet of coax in the shack.  AND you can move it
> around blockages.  Satellites from the mobile works
> well...
> 
> de WB4APR, Bob
> 
> >>> "John Henderson" <jah@ec.rr.com> 06/17/05 9:32 AM >>>
> Thanks Bob,
> 
> The most definitive answer I got. I plan to get a preamp for 70cm just
> to give it a try on the listening end. I will most likely build me a
> couple of yagis and forget the omni-dir approach. I was trying to keep
> it simple ( rotors,etc) but I now know you give up too much taking that
> route.
> 
> I have pl259's in the 9913. I plan to switch them out to N's. What is
> the dbm data of the two? I've looked on several websites but didn't find
> the data.
> 
> Really appreciate the FB reply.
> 
> 73,  John
> N4NAB/ FM14lq
> AMSAT # 32411
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