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RE: Don't Hear Nothin'



Bill,

I noted you said you were looking on 123.1 MHz, and assuming your convertor
translates this to 2401.1 MHz, you will not hear the beacon.  The beacon
with no doppler offset is at 2401.323 MHz.  If your convertor xtal is dead
on frequency (most are not) then you want to tune 123.312-to-123.330 MHz to
find the beacon.  Doppler can shift the beacon as much as 25 KHz above or
below the published frequency.  Most everyone getting started on AO-40 has
to first find out where their convertor frequency is.  It can easily by off
100 KHz high or low.  Best way to check is with a signal source on 2400 MHz
(see where that tunes on 122.xxx).  If it is off then you have to mentally
add or subtract that to know where to tune.  You say you you used a freq
source so maybe you have done this already.

Of course high squint may make the signal too weak to detect as well.
Knowing for sure you are pointed dead on the satellite is another thing to
check.  Being off even a few degrees makes huge difference at this
frequency as the dish is very narrow beamwidth.  Best way to check your
pointing system is to point at the sun (so the shaddow of the feed is
exactly centered in the dish) [DON'T LOOK AT THE SUN FOR THIS].  Now
compare the readout of your rotator system with what NOVA has for the sun.
If it is off more than 3 -degrees adjust the rotator until it reads out
correctly.

Oh be  careful not to transmit into the Drake with the FT-847 it will still
make "shhhhhhh" but no signal ;-)  If you have a signal source then it is
easy to check.  The preamp should raise the signal level by 10 dB when it
is used.  Without a signal you should hear a definite rise in background
noise when you power on the preamp.  If not then the preamp is broke :-(

After checking all this I think you will find the beacon (with patience).  

GL,
Ed - AL7EB

At 01:51 PM 4/23/03 -0400, Bowman, Greg wrote:
>
>I see squint calcs are around 43 degrees for the time period for Houston,
>you probably won't hear anything.
>
>Greg
>N4EN
>-----Original Message-----
>From: William P Gravett [mailto:wgravett@juno.com]
>Sent: Wednesday, April 23, 2003 1:07 PM
>To: amsat-bb@AMSAT.Org
>Subject: [amsat-bb] Don't Hear Nothin'
>
>
>Well, I am showing my ignorance probably but I am sitting here with my
>N3IYR pointed at where NOVA with the latest Keps says AO40 ought to be,
>my computer synced to wwv, a new DEMI ULN pre amp I just built (and
>checked out with a 2.4 gig signal source) an unmodified DRAKE 2880 with
>13.8 vdc going to it , and  all I hear is sssshhhhhhhhhhhhhhhhhhhhhhhh at
>123.1 MHz with my FT847. GMT is about 1700, AZ at 123, el at 40.3
>Is(are) there something(s) I don't know and should?????Please help>
>Thanks 73
>
>Bill, W5PGZ, (AO40 neophyte)
>
>________________________________________________________________
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