[amsat-bb] Re: rotator questions

[i8cvs]

Hi Nigel, G8IFF/W8IFF

You are right

Aiming the antenna for maximum receiver Sun noise is the best method
because the antenna pattern can be affected by some squint angle and not
be perfectly aligned with the boom but receiving Noise from the Sun in
2 meters and 70 cm implies a very high antenna gain and a very low overall
receiving Noise Figure with a very low Antenna temperature.

By the way at microwave such as 2400 MHz it is possible to receive the Sun
Noise using a modest dish diameter even when the Sun activity is low as
actually with around 67 sfu at 2800 MHz (10.7 cm)

See here:

http://www.swpc.noaa.gov/ftpdir/indices/DSD.txt

I use this method with my 1.2 meter dish 27 dBi at 2400 MHz and an overall
receiving Noise Figure of 1 dB equivalent to a Noise Temperature of 75
kelvin

With the above dish and receiver I actually get a Sun Noise of about 3.5 dB
of (S+N)/N wich is easily readible on the S meter or better using an AC
Voltmeter connected to the audio output of receiver.

Using a tracking program and aiming the dish for maximum Sun Noise
it is possible to calibrate the AZ and EL angle of the control box for the
through reference Sun position in the sky.

In addition repeating time to time the above procedure and knowing the
actual Sun's sfu it is possible to monitor the state of healt of our
receiving system.

By the way without an HEO satellite using 2400 MHz the above procedure
is as well a little and interesting Radioastronomy exercise.

Best 73" de

i8CVS Domenico

----- Original Message -----
From: "Nigel Gunn G8IFF/W8IFF" <nigel at ngunn.net>
To: "Greg D." <ko6th_greg at hotmail.com>
Cc: <amsat-bb at amsat.org>; <n0jy at lavabit.com>
Sent: Thursday, August 13, 2009 2:17 PM
Subject: [amsat-bb] Re: rotator questions


> How about aiming for maximum receiver noise? That should be even more
accurate.
>
> Greg Wrote:      and then adjust the antenna so the shadow falls directly
down the antenna boom.
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