Hello Jim,

I routinely get the downlink quite well using an 8 element 70 cm yagi, with a pre-amp at the antenna, fixed elevation, tracking in AZ . The digital transmission is currently about 500 mW, but you need a good S/N ratio to decode the data, even if your modem locks on to the clock.

The AMSAT Digital Guide has a very good description from actual experiments by Mike, N1JEZ on what is need in a 1.2 GHz uplink signal for digital operation on AO-51. GO-32 also has a 1.2 GHz uplink, but it has also needs more signal than you are delivering.

The downlink reception is pretty easily and inexpensively corrected. I am not sure how the increase in TX delay time to a second will help your uplink as you didn't mention an amplifier needed to switch in.

A good deal of the enjoyment for many of us is the challenge of getting operations on the satellites and the multiple modes they present. I am sure the digital guide would be of assistance to you.

73, Gould, WA4SXM

--- Original Message ----- From: "James Denneny" 57JNDenneny@comcast.net To: amsat-bb@amsat.org Sent: Wednesday, April 09, 2008 3:16 PM Subject: [amsat-bb] AO-51 Mode L/U

I have had no luck uplinking on Mode L. I even followed a suggestion to increase TX delay to 999 ms and tail time to 100 ms to give the bird extra time to grab me. However, 10w from my 910H on 23cm with a single twisted helix 1.2G antenna does not cut the mustard. I also have had very limited success on the 70cm downlink grabbing the DIR. All in all - a bust.

Jim

K7EG

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