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Re: Re: AO-40 AGC study,please read it!




Even though I plan on using a BUD next spring myself, the problem with the 
reasoning you stated below is that not everyone
can have or desires to use a BUD on AO-40.

I suspect 1m dish owners are hearing "well enough" with reasonably low 
squints but the BBQ dishes have always been marginal.  During higher 
squints, the 1m dishes are marginal and so on...  I started with a 4' prime 
focus dish and a patch feed and then tried a BBQ... The BBQ was not even 
close.   The 4' was good except for the worst conditions.  But a 10' would 
have probably salvaged the worst conditions....

I think we need to let everyone know that BBQ's are really only okay as a 
receving setup when the sat is at very low squints....and that
no, really, bigger is better.  Period.   It wouldn't have been if the 
satellite was 3-axis stabilized with the high gain transponder working  
because after a certain point increases in SNR don't help.

But in the current case with AO-40, we have to often overcome a weaker 
transponder (lower antenna gain on the sat) and high squints on occasion.

Nevertheless, the point remains that it does not  really matter what your 
receiving setup is.  You need to be 10-12 dB below the beacon not to be an 
alligator and many stations aren't.  If the beacon is only S1-S1.5 above the 
noise, then SSB should be out for your station.  Don't even try it!  But 
then again if you save a S-3 to S-5 beacon signal then you should be able to 
get >10 db SNR and it starts to be okay for SSB use.  If the beacon is S-3, 
then you should only peak at more or less S1.5 etc.  If everyone would 
calibrate themselves like this, then differences in attenna gain vs. squint 
angle for the uplink/downlink will be compensated for etc.  And recalibrate 
yourself periodically too.
At least between QSOs...

The thing is I bet a lot of those people know they are running too much 
power and are doing it anyway..... :O(

Fred W0FMS


>From: "John Wilcox / NS1Z" <ns1z@gwi.net>
>Reply-To: "John Wilcox / NS1Z" <ns1z@gwi.net>
>To: <kgschaffrath@beckman.com>, <amsat-bb@amsat.org>
>Subject: Re: [amsat-bb] Re: AO-40 AGC study,please read it!
>Date: Thu, 16 Jan 2003 16:57:59 -0500
>
>I'm a little fuzzy here: Why would a QRP evening each week work any better
>than the current instructions to operate at 2 "S" units below the beacon? 
>It
>would still require user cooperation, wouldn't it?
>
>With my new antenna setup I can hear much better than I did previously 
>using
>the 1 meter dish. AO-40's beacon is consistently 7 to 9 S units above the
>noise now. I call stations using my L band uplink of 10 watts and get no
>replies or worse, comments that I must have power problems as my signal is
>real weak into the satellite!
>
>The real truth is that the other station is having difficulty hearing me,
>not that my signal is weak. I can see my L band signal at about 5 S units
>above my noise floor (10 watts into 70 feet of LDF4-50 to a Directive
>Systems 55 el loop yagi). The stations I try to call are at least another
>couple of S units above me. Most are just slightly less than the beacon, 
>but
>not by the recommended amount. Some are equal or stronger than the beacon
>signal. I know this because I switch between VFOs on my ICOM 746 which I 
>use
>for my down converter IF. One VFO is on the QSO, the other is on the 
>beacon.
>
>I have found that most users who have heard Leila admonishing them on their
>poor operating practices state that "Leila is not for me! It must be 
>working
>improperly again" (or words to that effect). Ask not for whom the bell
>(Leila) tolls, it tolls for thee...
>
>How are they to be convinced that their receive system is still "marginal"
>at best and in real need of improvement if they want to really work this
>bird as suggested by control operators? I know that in my case, I didn't
>believe the improvements suggested by W0LMD on his website, that were
>achievable with the larger dish.
>
>It's probably like they say, "Nothing worse than a reformed (put your
>favority here!)". Education is still needed for the operators on this bird.
>
>I'm falling off the soapbox now...
>
>----- Original Message -----
>From: <kgschaffrath@beckman.com>
>To: <amsat-bb@AMSAT.Org>
>Sent: Thursday, January 16, 2003 2:10 PM
>Subject: [amsat-bb] Re: AO-40 AGC study,please read it!
>
>
> > A QRP evening a week would be great! I have also been able to copy 
>myself
> > at less then 1/2 watt on the uplink. Lately the Over use of power on the
>uplink
> > has been so brazen that i have been recording signals on my spectrum
>analyzer
> > and 'tagging' them with callsigns,  So before we have to start a web 
>page
>hall
> > of shame
> > maybe some of you guys, (you know darn well who you are) will start to 
>get
>a
> > little reasonable
> > with your uplink power levels.
> >
> > 73,
> > Keith N6ORS
> >
> >
> >
> >
> > ----
> > Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> >
>----
>Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
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