For your first part, if they are fixed polarity, I would recommend crossed polarization as it helps prevent killing your downlink with your own uplink. This is particularly true for Mode V/U operation where that third harmonic can be particularly troublesome.
For your second question, that one can be debated forever. The official "One True Rule" is to adjust both uplink and downlink to maintain the same frequency at the satellite. That is fine IF everyone in the conversation is using computer frequency control. If you are manually correcting for doppler, it's almost impossible. Therefore, the alternative rule is to tune the higher frequency. In reality, it will somewhat depend on what the other person is doling or is capable of. Personally I never used computerized frequency control - mainly as a limitation of my Yaesu FT-736 which only has one way CAT control. I found it to be an absolute pain in the backsides to attempt to dial around looking for conversations from the computer
Jim Walls K6CCC
-----Original Message----- From: "NA1SA Loon" [email protected] Sent: Monday, January 7, 2019 06:34 To: "AMSAT-BB" [email protected] Subject: [amsat-bb] Antenna and Doppler Question
Greetings,
I recently purchased an FT-857D with hopes of working some linear birds. I know it's not the prime radio for the task, but I'm on a budget and would like to remain happily married, although she understands and supports my love for this hobby. The antennas are a rotatable array, each fixed 20 degree elevation, consisting of a Diamond A144S5 for 145mhz and a Diamond A144S10 for 435mhz. The antennas are currently mounted 2 meter horizontal, 70cm vertical. I have had success using this configuration, knowing full well I will not have the coverage I would as if I had circularly polarized antennas for each band (again, budget and marital status come to mind). My thought behind this was if I'm using my Arrow, the 2 meter and 70cm elements are 90 deg to each other and it works, for both FM and SSB birds (seen it on YouTube). Question is, would it be beneficial to put them (a) both horizontal, (b) both vertical, or leave it like I currently have them? Again, I know there is no correct answer due to a tumbling satellite and changing polarity, I just haven't had time to experiment with different configurations, and thought maybe someone has and found that one configuration may have been more consistent than the other.
Now for the linear bird question... I have an Icom IC-746PRO that I use to listen to, or for, the downlink frequency. I was told to set the uplink frequency and DO NOT touch it, just tune the downlink frequency. Running CAT control (OmniRig with PstRotator), it is constantly updating both uplink and downlink frequencies for doppler. I thought that was the whole purpose of running CAT control with a doppler updating program, to keep you on frequency, or close anyways. This area of the satellite world is all new to me. I never had the chance to observe some work a linear bird to get an idea on how to do it properly. I certainly do not expect to carry a QSO throughout pass, I'm just seeking to explore another avenue of this hobby and to have fun making a contact or two on a good pass. Like I said this all new to me and I'm just seeking good advice and some positive guidance to be successful.
Thanks,
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