>I have tried to send APRS spots over AO-51 using my >TM-D700 and ... the ...exercise has not been very satisfying. >...on 435.300 I hear voices faintly. When I switch to >435.150 I hear nothing. When I listen on my base >satellite rig / antennas... the S-meter registers S5 or better >and I can distinctly hear the 9600 baud packet burst. Yes, but remember, that your UPLINK from your APRS mobile has an over 22 dB better link than the very weak downlink. That is, your chance of hitting it is 150* times better than hearing it which is exactly why the mission of this mode for mobiles with mobile antennas is to be heard, and for a few sat-gate ground stations then to hear those digipeats and to feed them through the global APRS internet linked system to all of the various APRS data engines. That is, an AMSAT amateur radio position reporting and email input system for mobiles anywhere on the planet. Remember that from the front panel of a D700 or D7 you can send an email to anyone anywhere... if you can be heard. The ECHO digipeater brings that capability everywhere on earth at least a few times a day. Of course, portable stations with ARROW or other gain antennas can use the system two-way station-to-station such as for messaging out of an area with no other services. But this takes both sides of the coin. We need sufficient sat-gates feeding the internet to make sure that a packet sent from an HT actually gets into the system. * Why is the upolink 22 dB (150 times) stronger? SImple.