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

R: get a clue...

----- Original Message -----
From: Lee <lee-fl@cfl.rr.com>
To: <amsat-bb@AMSAT.Org>
Sent: Tuesday, December 17, 2002 4:07 AM
Subject: Re: [amsat-bb] get a clue...

> There are several things which I believe contribute to this problem.
> 1.  In some cases it is an attempt to compensate for a simple lack of
> receive sensitivity.  Stations hearing the excessively strong L-band
> don't realize how marginal their receive set up is.

Lee and Kevin,

Many stations using L-band uplink are really at the same level or constantly
stronger than the beacon by 6 dB or more all the time as i can see on my
panoramic receiver wich is constantly connected to the IF of my 2400 MHz
downconverter and they are strong not because those stations hearing
excessive strong L-band signals are using marginal receiver sensitivity but
because those L-band signals are strong in reality including sometime my

Excessive strong L-band signals are possible because LEILA do not operate
for the L-band uplink and actually i can increase my L-band power to any
level i like and i can be as many dB over the beacon i  decide without the
intervention of LEILA

The problem is that many radio operators in the passband instead to
disregard those stations using very high level downlink through the L-band
congratulates instead with those L-band operators for their strong signals
and they are happy to make QSO hearing strong signals so that the pile-up
over a 6 dB or more signal over the beacon is higly populated and
continuously operating particularly when the moon is not in range for some
EME operators.

Remember that if a signal is at the level or more than the beacon this
signal is coming from the L-band uplink because LEILA do not operate in it.
and is not coming from the U-band.

> 2. The L-band rx AGC does not restrict users of this band to the
> MB-10db signal level.  As a result some stations attempt to achieve the
> excessive levels using the 70cm uplink resulting in decreased U-Rx
> sensitivity.

Stations using excessive 70 cm uplink power cannot achieve the same
excessive level of those using L-band because LEILA put  a notch and
the siren to the U-band offending signals for level just 8 dB belove the
beacon. If i use the U-band uplink i cannot desense the U-band receiver and
i cannot desense the L-band receiver at all because of the above LEILA

Normally my 70 cm and 23 cm TX are ON all the time and some time i prefere
to use the U-band uplink but as soon LEILA get a notch on me i can switch
immediately to the L-band and i can continue to discusse with my friends
even with a stronger signal over the LEILA siren using the L-band uplink !

> 3.  The U-rx AGC has been driven so high for so long that everyone now
> considers it normal to run 4 to 8 times the recommended 100w EIRP.

If i run 4 or 8 times more power than the recommended power for the
U-band, LEILA put a notch on me and i get the siren on,so that
i cannot desense the transponder using U-band but i can easily desense the
transponder for everybody using the L-band because LEILA do not operate in

Without LEILA for the L-band the actual EIRP depends only by a decision
of the L-band  operator but for the U-band operator is LEILA that decides.

The difference existing between the limitation using high power on U-band
because of LEILA intervention and the freedom of using any power in L-band
without any limitation by LEILA make the operation of the AO40 transponder
impartial because the users become divided in to two different categories
Those that are limited by a good  impartial roule and those that are only
limited by their roules.

> Take a look at some AO-40 AGC data downloaded from the archive for this
> month.
> http://home.cfl.rr.com/lmclamb/ao40agc1202.html

A test of desensing  was made by G3WDG, DJ1KM, 4X1AS and my self some monts
ago and this indicates that using U-band the SSB is mostly affected by LEILA
and that CW or a steady carriers like SSTV are  less affected  by LEILA for

 > Lee-KU4OS

Lee and Kevin

I cannot understand why i should have the freedom to overload and desense
everybody in the passband using the L-band and i cannot do the same using
the U-band because of LEILA and i cannot understand why LEILA is not
operating  for the L-band or cannot be switched time to time between the
U-band and the L-band in a more balanced operating democracy.

Technical problems or what  ?

73" de i8CVS Domenico

 ----- Original Message -----
> From: "kevin schuchmann" <kschuchm@pacbell.net>
> To: <amsat-bb@AMSAT.Org>
> Sent: Saturday, December 14, 2002 16:55 PM
> Subject: [amsat-bb] get a clue...
> > Hi All,
> >    could people please get a clue on AO40?  everyone has run too much
> power
> > at one time or another
> > including myself... but I try not to... yet there are stations that are
> > always way too loud... pass after pass... I'm talking beacon level
> >
> > GET A CLUE!!! tune down and look at the beacon, I don't care what your
> setup
> > is... it doesn't matter..
> > but look at that beacon... see where it is on your meter??? be under it
> > at least a couple s units....
> >
> >  and another thing,everyone loves to praise cw, how it can get through
> when
> > ssb wont cut it.... then how come so many cw stations are beacon
> > DUH!!!
> >
> > I'm sure that a lot of people have seen this behavior and have seen the
> > results... agc clamping the passband... and splatter and  images on the
> > passband....
> >
> > If you only get the beacon a s unit or two above your noise guess
> > you need to fix your receive and probably shouldn't be on the sat till
> > fix that....
> >
> > ok rant mode off... shields up!!
> >
> > Kevin
> > WA6FWF
> >
> >
> >
> >
> >
> >
> > ----
> > 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.
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org

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