VE6AB Mobile Ops
Working AO-85
With the recent launch of AO-85 by Amsat NA, I was anxious to check out this new low earth orbit (LEO) satellite.
With the keps downloaded to my smartphone running AmsatDroid, it was just a matter of programing the frequencies in memory on my Kenwood D710A that I use for uplinking from my mobile, and also programing the downlink frequency in to memory on my Yaesu VX-8R that I would be using for downlinking on this day.
Due to the fact that I spend a lot of time in my mobile, I have my mobile set up for working the various LEO's that are available during the course of the day.
When a satellite is about to rise on my horizon, I am able to be prepared for the pass in less that one minute once I have pulled over to the side of the road.
I have my satellite receive module in ready to be placed on the steering wheel and once the antenna is connected up, I'm good to go.
With AO-85 the uplink frequency is 435.180mHz with a 67.0 Hz tone (with Doppler frequencies programed in as well), and the downlink frequency is 145.980mHz.
My first pass of AO-85 was a 30 degree pass on the western horizon at 6am local, and I thought it might be a good pass to work with less activity at that time of the morning.
Interestingly enough I basicly had the satellite to myself, as when AO-85 came up from the NW, and although I though I might hear Alaskan stations working AO-85, I didn't get to work any.
Well I was right, as I could hear a club station identyfing, but the operator was not hearing on their end as I made several calls.
I knew they should have been hearing me, as with a full duplex setup on my end, I was hearing myself almost full-quieting on the down-link when I made my call with my callsign and grid-square.
Soon there-after I heard another station running tests, as the operator was doing this "hello...test...1...2...3...test" but he wasn't hearing his downlink or me for whatever reason, although I continued to hear myself full quieting on the downlink.
Still it was a good first pass of AO-85 for me, as I was able to get a feel for the characteristics of this new satellite.
Doppler corrections were a none issue on this pass with the pass being a 30 degree pass. I expect the Doppler to be more prevalent with a straight on overhead pass, but still very manageable through manual corrections.
When it came time to select one of my 3 element 2 meter yagi's to use for the downlink from AO-85, I decided to try out my take-down tape-measure yagi http://www.jerryclement.ca/MachineShop/Antenna-Werks/i-kMTjrMV/0/XL/2014-09-073-XL.jpg although if required I had my Arrow available as well as another home-brewed yagi that possibly could be better choices.
In the end I was very pleased with my TDY, as I was able to hear myself on the downlink frequency with ease, and mostly full quieting after AO-85 had reached a elevation of 5 degrees on AOS, without the use of a receive preamp.
With a preamp on receive, I expect to hear this bird flat on the horizon at AOS (acquisition of signal) and LOS (loss of signal) with my TDY.
The best part of using my take-down yagi while working LEO's from my mobile is the fact that the tape-measure elements allow me to leave it assembled ready for use, and the flexibility of the elements allow me to push it through the open window without any damage occurring to the elements, and once I am finished with the pass, pulling the yagi back inside through the open window.
I also found it easy to compensate for polarization as the satellite spins with a slight twist of the wrist, and part of this was due to the fact that my TDY weight's only a 3rd of what my Arrow 3 element yagi weighs, therefore making it very easy to manipulate when making adjustments for polarization changes.
In case you were wondering what I use for an uplink antenna with my Kenwood D710A, that would be the dual band Larsen 2/70K antenna mounted on the cowl of my mobile.
On the 10 through 30 degree passes that I worked over several days, I was using 35 watts of power, as a vertical antenna is not nearly as efficient as a directional antenna when uplinking to the satellite, especially cowl mounted, and not centered on the roof (garaged at night).
I have to say that I am pleased with this new bird that Amsat NA has put in to orbit, and I look forward t0 many years of working through this fine new satellite.
Give it a try, you'll like it.
Click on the photo for a closer look.....
