[amsat-bb] Re: bird to bird fun

SV1BSX sv1bsx at yahoo.gr
Thu Aug 28 12:34:00 PDT 2008

Hi Domenico, Bob & all

it's a nice idea but I am thinking also that, the relay between AO-7 & FO-29
needs UHF Uplink and UHF Downlink as well !
Therefore, we need two UHF systems (TX-RX) working simultaneously
for Full-Duplex operation.
And even if the AO-7 Uplink is 3.7 MHZ lower than FO-29 downlink,
we need two antennas in the same band  and probably
a repeater-style  *Hi-Q duplexer* in order to avoid the desense.
Or just a UHF antenna and a circulator dr Domenico ?
Difficult components for the most of us!

However, it's a great challenge. For example @ 18:30 UTC the overlap took 
place between
the 2 footprints  over W.Asia.  From E.Canada, Atlantic Ocean,  Europe, Asia 
E.Siberia it was  possible a QSO... !

Amazing distance for LEOs !  Can you imagine that ?!?!?

Yes, I know..  it's difficult, yes.   But a great-great challenge for the 
hibernal months !
And the AO-7 is working 24/7 for the next months - out of eclipse.
Great opportunity !

73 de Mak, SV1BSX

----- Original Message ----- 
From: "i8cvs" <domenico.i8cvs at tin.it>
To: <w7lrd at comcast.net>; "AMSAT-BB" <AMSAT-BB at amsat.org>
Sent: Thursday, August 28, 2008 5:03 PM
Subject: [amsat-bb] Re: bird to bird fun

> ----- Original Message -----
> From: <w7lrd at comcast.net>
> To: "AMSAT-BB" <AMSAT-BB at amsat.org>
> Sent: Thursday, August 28, 2008 12:07 AM
> Subject: [amsat-bb] bird to bird fun
>> Hello All
>> Here's an interesting endeavor.  The downlink on AO-7 mode B is 145.950
>> which is the uplink for FO-29.  So you could hear yourself (or anyone
>> else on the FO-29 downlink at 435.850, when both are in view.   I think
>> there was something like this back in the days of the RS birds.  Why
>> bother?
>> Well we have to do something to keep our interest going while waiting for
>> the next HEO.  Plus it's fun.
>> 73 Bob W7LRD
>> Seattle
>> --
>> "if this were easy, everyone would be doing it"
> Hi Bob, W7LRD
> Since OSCAR-7 mode B and FO-29 mode-J have both inverting transponders
> using
> SSB it happens that to be received as usually in USB over the FO-29
> downlink
> we must transmit as well USB into the OSCAR-7 uplink.
> Since the noise translated by OSCAR-7 mode-B is very high probably a try
> on
> CW will be convenient.
> As Rick WA4NVM pointed out with OSCAR-7 mode-B and OSCAR-8 mode-J
> it was a common practice.
> 73" de
> i8CVS Domenico
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