Re: [amsat-bb] AO-40 Transponder Question

[Wayne Estes W9AE <w9ae@xxxxxxxxxxxxx>]

Eric Christensen wrote:

I see on the schedule for AO-40 that the current mode of operation is 430MHz up and 2.4GHz down.  Is the transponder ever set for 2.4 up and down?  I am trying to put together a portable radio set for AO-40 that would use a single small parabolic antenna and a radio set that could be used when I'm out and about in the world.


Wayne replies:

AO40 has a 2.4 GHz uplink that has been successfully tested.  But it's not practical to use because 2.4 GHz is the only functional/practical downlink.  The satellite must have uplink and downlink on separate bands.

For portable AO40 operation you have two main options:

1. Use a single dish for both 2401 MHz downlink and 1296 MHz uplink.  This typically requires a 4-foot dish to have enough gain for the 1296 MHz uplink.  A fairly compact portable setup is possible if you can get your hands on one of the rare 4-foot Inmarsat umbrella dishes.  You can see a photo of F6CBC operating portable in French Guiana in the "Satellite DX" column in the Nov/Dec 2003 AMSAT Journal.

2. Use a small dish for 2401 Mhz downlink and a small yagi for 435 MHz uplink.  My AO40 portable setup uses a 2-foot dish for the 2401 downlink and a 7x7 yagi for the 435 MHz uplink.  I'll send you a photo in a separate email.  KO4MA has done successful portable operation with an 18-inch DSS dish.  Most people think reception is inadequate with such a small dish, though.

Wayne Estes W9AE
Mundelein, IL, USA
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