[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: S-band receiving requirements



I disagree that these setups won't be "good enough." Good enough for
what? My subjective tests have shown the ability to clearly copy
relatively strong SSB QSO's on the S2 transponder when the U-Rx AGC is
driven to only about 2-3db. What that corresponds to in EIRP I do not
know but it is WAY below the present LEILA threshold. My last telem
graph of U-AGC still showed AGC being pushed to almost 20db suppression
on one occassion.

My S2 downlink consists of:
Unobscured line of site to the satellite & good squint ---->
ARMSTRONG Pointing system ---->
2x3 foot BBQ dish, long axis horizontal ---->
Standard dish dipole feed and splash plate ---->
Standard dish coax to DEM 0.7db LNA ---->
IF only modified Drake 2880 directly (M/M N coupling) on LNA output --->
75' of ancient, cheap RG-58 ---->
Well used TS790A---->
A pair of not so young ears/AO40RCV

With this I can hear the sun vs the sky at 2.5khz ssb bandwith. It
doesn't budge the s-meter but I can definately hear old sol! I copy the
MB telem 100% for any reasonable squint. The final test will be to see
if I can copy my uplink of 20w into my "shorty" LEO 70cm CP antenna.

Maybe my setup isn't "Good Enough" to hear a 5w uplink on an arrow
antenna... but I have a feeling that it will suffice as long as the
gators stay submerged. See you on the bird as soon as I can get my
uplink on line.

Vince Risalvato
KD7AI

----- Original Message -----
From: "Estes Wayne-W10191" <W10191@motorola.com>
To: <amsat-bb@AMSAT.Org>
Sent: Thursday, May 17, 2001 11:04 AM
Subject: [amsat-bb] S-band receiving requirements

much snipped...
> In retrospect, the only thing that mystifies me is why today's
"alligator critics" were SILENT when months of amsat-bb traffic was
dominated by discussions about building helixes, modifying surplus
converters, etc.  One or more of these silent experts should have spoken
up to explain why those setups won't be good enough.  Then for the last
few weeks the experts remained silent when several people reported
modest success hearing the Middle Beacon.  Again, the experts should
have pointed out that we need to hear much weaker signals than the
Middle Beacon.  The "alligator critics" are vocal now, but they were
strangely silent when their advice would have been most helpful.
>


----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home