I can finally report a sucessful satellite QSO! It took a lot of trial
and error, but I finally found the right combination of a low traffic
pass with a lot of tweaks that have been suggessted after much useful
feedback from the
ASMSAT mail list.
I
know that lots of people have made successful QSOs using an array of
HT's, mobile units, and any number of home made antennas. I started
similarly small, but had a couple of different design goals for
satellite communications.
First, I am somewhat limited by my
pool of equipment - I don't have old radios around or an HT that can be
brought into service. I want to get as much use of what I have, but I
also will need to make investments as they make sense.
Second, I
want to be able to work satellites from my current base which includes
a 75' feedline to the antennas on my roof. While mobile/portable
operation is a goal, I'd like to start with more and pare down for
portable work rather than the other direction.
Lastly, and
perhaps most importantly, I want to engineer a solution that will
produce reliable, repeatable results. As exciting as the first few
contacts are, if I am to use satellites as a reliable means of DX work,
I'd like to remove as much of the luck from the equation as possible.
Don't
take my example as any sort of assertion that I think this is the best
way, or even how anyone else should follow my lead! I just wanted to
share what I got to work and the results.
The antenna is a
Cushcraft 2m/440cm 3 element yagi mounted about 50' above ground and
15' above the roof of my apartment. It is mounted to a simple
light-duty TV rotator. The bands have different feed points and
elements but share a boom.
Each antenna is connected to an SSB
preamp through 3 feet of 9913. The 2m is using 75' of RG-8X and the
70cm feedline is 75' of RG-213. The 2m antenna is driven by an IC-V8000
and the 70cm with the IC-7000.
I am currently limited by the
antenna in a couple of ways. First is that I have no elevation control
and the antenna to mast mount is fixed at 90 degrees. This means that I
can work satellites as low as 7 degrees, but seem to lose them around
20 degrees elevation. Unfortunately, this also means that I am unable
to take advantage of higher elevation passes which would have a lower
path loss. I had also intended to run full-duplex mode and used the two
different transceivers. Unfortunately, since the two bands share a
boom, they interact heavily and the 2m transmission completely
overloads the front-end of the IC-7000.
In keeping with my goals
of making reliable communications, I'm going to make a few more
attempts making only a couple of tweaks to the setup above. Ultimately,
though, I will move to some antennas like the Gulf Alpha
70CM-8ELSat and
2M-5ELSat
at about a 20 degree elevation on an 8' cross boom. I will replace the
6m beam for now since it will most likely be a while before that band
sees any propagation more than the hour or so a month that I catch.
Many thanks to the AMSAT-BB list, Gary WA2AQH, and the
SatComm Net hosted by the
MBARC . If you're in the area and want to join in, it's every other Thursday at 20h00 on the KC2DAA repeater (144.225 pl 100.0)