R: [amsat-bb] UO-11 Beacon

["i8cvs" <domenico.i8cvs@xxxxxx>]

Hi  Ken,

The nominal UO-11 beacon frequency is 2401.505 MHz  at TCA or time of
closest approach.

At AOS or aquisition of  signal you must look and tune approximately 50 KHz
higher  in frequency for Doppler i.e. at 2401.555 MHz

At LOS or lost of signal  the frequency  will appear approximately 50 KHz
lover for Doppler  i.e. at 2401.455 MHz

In total the rate of chage of  frequency for Doppler is about 100 KHz in a
pass and you have to tune the carrier continuosly at a rate of about  6
KHz/min at TCA

Try to tune your IF  from around  145.555 MHz  at AOS to 145.455 MHz at LOS
because in a LEO satellite the frequency  is always higher than nominal for
Doppler as soon you get the aquisition of  signal  i.e. + 50 KHz in this
case.

The UO-11 beacon is very strong and it is a very good reference to evaluate
the S band receiver performance time to time.

73 de i8CVS Domenico

----- Original Message -----
From: ken durham <kendurham@home.com>
To: <amsat-bb@AMSAT.Org>
Sent: Wednesday, July 04, 2001 10:55 PM
Subject: [amsat-bb] UO-11 Beacon


> Well, using the UO-11 beacon for a signal source doesn't work for me
either. It just went
> nearly overhead and I couldn't hear anything
> near 2401.500. Guess the system isn't near good enough for AO-40
> yet. Got a .7dB NF primp ordered from Down East Microwave. Maybe
> this will help enough. Maybe a helical feed on the BBQ dish might
> give some improvement too. At this point, I don't know how far
> the LO is off in the Drake downconverter. The IF is at 145 MHZ for
> 2401 MHZ input and the NF is supposed to be tested at 3 dB. Don't
> have a way to calibrate either one. Wonder if there is a local HAM
> who could xmt on 2400?
> Ken K5MBV Garland, TX
>
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