Satellite operation with an HT test

  One of the more interesting and fun aspects of satellite operation is operating the analog FM satellites portable, while on vacation or on travel for work. I’ve operated this way for many years. It is always fun to operate from a historical site, lighthouse, special event, marine mobile, or from a rare grid, etc. The group of operators on the FM bird’s are a friendly group, and through short contact’s over a period of time you will make many new friend’s. I have made many friends, who I would then visit with in my travels. New sat ops usually start out on the FM birds.  There are presently 3 FM bird’s that are in an operational state. SO-50 is on every day, AO-27 due to be turned back on soon, and SO-41 that is turned on occasionally. A new FM bird ECHO, is scheduled to be launched by AMSAT/NA in March 2004. To amateur’s wishing to try FM satellite operation there is a wealth of information on the AMSAT/NA site www.amsat.org. There you will find information on tracking software, to find out when you will be in the satellites footprint, and Spacecraft information, that would contain the operating frequencies and operational status of the various amateur birds. To help in choosing an HT that will be used for satellite communications I tested 4 of the more popular HT’s used for satellite operation. I’m not saying that you have to use one of these Radio’s compared here, these are just some of the more popular ones used. On 8/21/2002 on the 10:07 EST pass of UO-14 I tested 4 HT's. Following is the results of that informal test. Participants were KB2M, K3TL,and KB2QRM. Here is picture of the 'test range' (in front of HRO, in New Castle, Delaware) left to right KB2M, K3TL. Picture by KB2QRM.

http://www.qsl.net/kb2m/ht%20test.jpg

Antennas used were Premier AL-800's, my favorite travel antenna for the FM sats. We had three on hand so we rotated an HT every minute or so during the pass. Not much of a difference was heard during the pass until about 2 minutes before LOS. Here is the order of finish...

1. Kenwood D7AG. advertised Sensitivity is <.18mv. At one minute to LOS this was the only HT still receiving the downlink! A clear winner.

2.  Yaesu VX7R. Advertised Sensitivity is <.18mv. Seemed a tad better then the VX5R.

3. Yaesu VX5R.  Advertised Sensitivity is <.16mv. If we did this again the VX5R might be second.
4. Kenwood TH-F6A. Advertised Sensitivity is <.13mv . A clear loser in this test, last to pickup the bird, first to drop out. But not by as much as the D7's ability to rx better.

 We were located in an urban area, but noticed no inter-mod. Also we were aware (and tested) the differences between the A an B sides of the radio's. Although we didn't notice any difference between main and sub on the VX7R. My prior experience with inter-mod with the F6 put it in last place, it's performance on receive was just a bit less then the Yaesu's. But once again the D7 was easily the winner. This has been said on the AMSAT SIG before, the D7A has great RX.
 Another plus for the Kenwood D7A is it’s ability to digipeat APRS messages using it’s internal 1200/9600 baud TNC with built-in APRS software. The APRS land based infrastructure is capable of receiving short EMAIL formatted messages off of UO22, NA-44, and the ISS. This a accomplished via an Amateur station called a satgate. A satgate simply receives the APRS formatted message and gates it to the internet, for farther routing in real-time. I’ve sent EMAIL messages with my D7A from way offshore while fishing. Well beyond the range of the current terrestrial Cell phone system, or amateur repeater system. The D7A can of course be replaced with a radio, TNC(or soundcard software), and a laptop. Either of these VHF/UHF band based system’s has also proved to be a nice backup for the HF based WINLINK2000 EMAIL system.
 Also worth mentioning is the Arrow Antenna, used by more serious FM bird ops for better receive and transmit capabilities http://www.arrowantennas.com/. Need any more help getting started with portable satellite operations? Contact your local AMSAT coordinator www.amsat.org/amsat/fieldops . 

73 Jeff kb2m