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RE: Help with L1 uplink on AO-40



The tri-band patch is designed to circular but I have made no particular
measurements to see if it really is. When the squint is between 10 and 20
degrees I get a usable signal with 10 watts out of the radio (about 6 or 7
at antenna). Lower than 10 degrees and I have to turn down the power to not
overload the bird. When the squint is 3 or 4 I usually use 2 or 3 watts out
of the radio and I can get a return a few db stronger than the beacon if I
go full 10 watts.

When the squint is less than about 15 degrees I hear the noise floor at
about 5 db over the ambient noise. I have an MFJ step attenuator on order
and when it gets here I will be able to make more accurate measurements.

I have been off of the bird for the last 2 nights because we have HIGH winds
in so Cal and I have my dish tied down. Winds are supposed to end tonight so
I can get back on.

> -----Original Message-----
> From: Edward R. Cole [mailto:al7eb@ptialaska.net]
> Sent: Sunday, January 05, 2003 3:52 PM
> To: gary@ridepix.com; Amsat-Bb
> Subject: RE: [amsat-bb] Help with L1 uplink on AO-40
>
>
> Gary
>
> Interesting to hear this for L1 which I have no experience.  Your 12-foot
> dish is providing around 32-dBi gain (is the Tri-feed circular or linear
> polarity?) so this multiplies your power by 1585 to get an EiRP = 3170w.
> Is the 2w measured at the dish or radio end of the 75-foot run of
> coax?  If
> at the radio end, then the EiRP will be around 2000w (10w would
> give EiRP =
> 10,000w).
>
> The reason I find this interesting is that is very close to my
> estimate for
> "good" uplinking to AO-40 on mode-L.  My experience was with L2
> over a year
> ago using 9.5w at a 45-element loop-yagi (20 dBi-linear pol) which was
> marginal (EiRP= 950w).
>
> My current plan is 14w at a 28 dBi dish (8-foot) for max EiRP = 8800w!
> Always can turn down the juice!
>
> I bet you hear AO-40 nicely with the big dish!
>
> 73, Ed - AL7EB
>
> At 09:41 AM 1/5/2003 -0800, Gary Gonnella wrote:
> >I was on L band last night around 4:00 to 5:30 UTC I was working
> L1 with no
> >problems. I have a 12 foot dish with a tri-band patch feed and feeding it
> >with an IC-910H at about 10 watts through 75 feet of LMR600. At this time
> >the squint was about 18 degrees and decreasing to 12 or so. The L band
> >appears to be more sensitive to squint than U band and I need to run 10
> >watts down to about 10 degrees, then it decreases it until I
> only need about
> >2 watts below 5 degrees. Hope this helps.
> >
> >Gary Gonnella W6RYO
> >gary@w6ryo.com
> >http://www.w6ryo.com
> >
> >
> >> -----Original Message-----
> >> From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org]On
> >> Behalf Of Joe Steinmetz
> >> Sent: Saturday, January 04, 2003 10:32 PM
> >> To: amsat-bb@AMSAT.Org
> >> Subject: [amsat-bb] Help with L1 uplink on AO-40
> >>
> >>
> >> Hello,
> >>
> >> I am debugging my ground station for AO-40 and was wondering if
> >> someone who
> >> might have been using the L1 uplink tonight could tell me how
> well it was
> >> working? I was just barely able to hear myself on the
> downlink, however I
> >> could hear the beacon and many others well above my signal level. I am
> >> assuming that my receive setup is OK since I could hear myself (in the
> >> noise) and others (well above the noise) and the beacon (very strong).
> >>
> >> At the time of my experiment (1/5/03 05:00 - 06:00 UTC) the
> >> squint was about
> >> 12 degrees (assuming I set Nova up correctly).
> >>
> >> I am thinking that I have a serious uplink problem. I have two
> >> 12-turn-helix
> >> (RHCP) phased for approx 17dBic of gain, with about 60 feet of LMR-400
> >> ultra-flex and a SSB 80watt amp feeding the system. I am
> loosing 3.4dB in
> >> the cable run and according to my directional wattmeter I am
> >> getting 2 watts
> >> reflected. Could something be wrong in the phasing that wouldn't
> >> show up as
> >> a reflected energy? I am thinking of swapping the phased helix out and
> >> replacing it with a 22 element yagi just to help isolate the problem.
> >>
> >> I only plan on running enough power to get my signal 8dB below
> the beacon,
> >> but right now, I am way below that.
> >>
> >> How much power are others using for their L band uplinks? And
> what antenna
> >> (and gain) are you using?
> >>
> >> Any thoughts?
> >>
> >> Joe
> >> k6sat
> >> ----
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> >> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> >
> >----
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> >

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