[amsat-bb] AO-51 Mode L/S Mobile (thanks, guys)

K5OE k5oe at aol.com
Sat Nov 20 16:28:19 PST 2010

Working satellites has always been a blast, especially when pushing the envelope in either technology, skill, or simply practicality.  I was eager to work mode L/S mobile, not having worked that mode since I was in Darwin, NT (VK8OE, 1995)... and then I had a small dish and a TS-2000 in my SUV.  It was easy, as I had full duplex, but there was nobody to talk to since the bird was mostly over the Indian Ocean!

Now 5 years later and I am back in South Texas and missing that thrill from a "you can't do that" challenge.  In my truck I have an FT-100.  This rig worked mode V/S easily this past summer when I was visiting the US (I was P29OE then).  The 2.4 gHz downlink was with an old 10-turn helix (my very first mode-S antenna, used to listen to Oscar-11), a TSI 3731 downconverter to 2 m and a Hamtronics 10 m downconverter.  This arrangement allowed me to use the 2 m uplink from the FT-100, albeit in split mode (not full duplex).  This mode was loud and easy.  N5UXT, Angelo, was my first V/S contact, followed by N5AFV, Allen.

Mode L/S required a little more hardware.  I used an old MML trippler (varacter diode) I bought on ebay in the 90's for about $20.  My uplink on 422.902 with about 10 W out didn't work well yesterday into my 2m/70cm vertical, so today I changed it out for a old (everything I have is old) home brew dual-band patch feed leftover from an AO-40 antenna (that same 18" DSS dish I took to Australia).  Even though the downlink and uplink are both LHCP, they worked well enough on today's western pass of 20 degrees (from EL29) to make contact with K4YYL, AK5V, and N5UXT (again!).  Thanks, guys.  I know I was off frequency as I was guessing at the uplink frequency based on the downlink Doppler, dividing it in half then dividing that by 3... and all the while changing and hanging my arm out the truck window with a handful of gear!  I appreciate you guys coming back to me.  It's good to be home in Texas, it's good to work a satellite, and it's great to have such a frequncy agile bird to play with!  I can't wait to get the shack set up this winter (the ARRL 10 m contest is just around the corner).

Jerry, K5OE

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