Rick,
In your original post, you said " I have no decoding packets whatsoever either from ARISS or terrestrial on 144.390." Since RX is in fact working, the most likely transmission problem with the Flex is that compared with traditional rigs, there is considerable latency, or delay, between the audio input and transmission. The result is that the transmitter cuts off before the full packet is sent. Fortunately there is a parameter, TXtail, which will keep the transmitter keyed for a period after the audio is sent. Somewhere in Soundmodem, probably the Modem tab, IIRC. Try setting it for 500 ms or so, and see if that helps. It solved my problem. After you get it working, you can cut that back a bit, if desired. How much is a complicated function of sampling rates, buffer sizes, etc.
Another issue is deviation. Too much is much worse than too little. I find that setting VAC at -14 gives me 3 KHz deviation.
73s,
Alan WA4SCA
<-----Original Message----- <From: Richard Lawn [mailto:rjlawn@gmail.com] <Sent: Tuesday, February 28, 2017 17:01 PM <To: Alan Biddle wa4sca@gmail.com <Subject: RE:ARISS Packet < <Decoding for me either at ARISS downlink freq or 144.390 isn't the problem. I <seem to have no luck getting any confirmation packets back at 144.390 and I <should think using WIDE I should at least see my own packets echoed back. <Nothing..... < < <Rick, W2JAZ