Preamps

Discussion in 'Satellite and Space Communications' started by NG1I, Mar 10, 2020.

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  1. K4BAD

    K4BAD Ham Member QRZ Page

    Just took my first shot at RS-44...Using ICOM -9700 and tripod mounted Elk beam.
    Did hear my signal coming back from the satellite...pretty weak.No contacts.
    Maybe ,I’m just meant to be a FM sat.guy....Hi
     
    WE4B likes this.
  2. G0KDT

    G0KDT Ham Member QRZ Page

    A nugget of info - clearly another learning exercise as in 'how to calibrate the uplink frequencies'. That was 'finding your dits' in the old days and working from there, but with cat control in SatPC32 over-riding tweaks the process is far from clear. Would you care to expand on that if you use SatPC32?

    Roy - :D:confused: I think I have more than enough kit, some body may also be rude enough to chip in and say 'yeah, all the gear and no idea'... well I do have the idea too, but like I've said the Amsat community is 'dead' unless it lives in the dark underworld of Facebook and I'm gettin' older by the day and starting to forget where I was and who I am (I Jest)o_O, may be... thank goodness there are some kind people on this forum who are tad more up-todate than I am with the newer software. I just wonder how many simply don't get off the starting line for the complexity before even hitting buggy software, poor documentation etc. etc. I'm sure I could have continued on AO-91 today if I hadn't missed the pass when I switched to manual VFO mode. Clearly as Dave says, the calibration is off for linear sats and I need to learn how to do that.... in the course of a single pass... maybe not!
     
    AK5B likes this.
  3. KB1PVH

    KB1PVH XML Subscriber QRZ Page

  4. W5SAT

    W5SAT Ham Member QRZ Page

    It just so happens, I was helping another ham recently with his uplink calibration. I'll add on with a few more words and visuals:

    Uplink Calibration in SatPC32

    After making sure your RIT and/or XIT (if your radio has XIT) are all zeroed out when you are talking on a linear satellite, you can then click the Upl. Calibr. Hz buttons in the CAT window to tweak your uplink frequency. Once you sound good to yourself on your downlink, you can permanently store those settings in the Doppler.sqf file by clicking on Change/Store Data File then clicking on Uplink Calibration on the window that pops up.

    This needs to be done once for each linear satellite. The next time you operate that satellite, you should be right on frequency.

    upload_2020-5-21_17-18-48.png
     
    KC8T and G0KDT like this.
  5. G0KDT

    G0KDT Ham Member QRZ Page

    Hi Bradley,

    Thank you. I will have a go when I next get a chance. I also went searching and found a youtube that was done recently, it wasn't entirely clear as the op was talking to others and not fully clarified to me.

    I think the problem, for me at least, is having it all in my head together at once and not getting in a 'which button now?' muddle in the pressure of the moment when the bird is passing over. Then ideally I need a good pass for each bird to do it to max the sigs and time.

    Thank you very much for the help.:cool::D
     
  6. KA9JLM

    KA9JLM Ham Member QRZ Page

    RF detection for switching never really works all that well, Unless you run low power.

    RF keying is best left for 11 meters where 5 watts keys your 2 kW amp. :rolleyes:
     
    AK5B likes this.
  7. KC8T

    KC8T XML Subscriber QRZ Page

    I have a newbie question regarding frequency control with SatPC32.
    I've had successful, yet difficult QSOs on both CAS-4A, and CAS-4B. (1 each) The reason for the difficulty as reported by the ham at the other end of the QSO was that my frequency was jumping all over the place. Indeed, it seemed to be. It appeared as though the software was correcting the transmit frequency in the wrong direction. I would tune to hear myself, and then my transmitted signal would start sliding up the band. The beacon, however, was rock solid on the waterfall, which tells me the software is tuning the receiver, just fine. I suspect I have something set wrong. Here is the line from the doppler file:
    CAS-4A,145870.0,435220.0,USB,LSB,REV,0,0,XPDR 145.86-.88
    What should I do to troubleshoot/fix this?
    Tom
    KC8T



     
  8. G0KDT

    G0KDT Ham Member QRZ Page

    I'll second the advice on vfo calibration for linear Sats. I don't program any memories in the 9700 but let SatPC do the tuning. It is a bit fiddly to attain and subject to how well you can hear yourself which has a bearing on other things in your setup like antennas, preamps etc.

    I try to use about 5w tx power into the antenna so I'm not over loading the sat rx.

    I don't think my antennas are that great for sat work as both are horizontal due to the temporary nature of my operating setup. I have also found that 2m up to 70cms down is a lot harder to get really good rx. (with 5 ele 2m and 8 ele 70cms dual antenna). Brads advice. Above was invaluable.
     
  9. KC8T

    KC8T XML Subscriber QRZ Page

    Thank you Brad. I read that post/advice previously, but I wanted to make sure it applied to my situation. I will try this on the next reachable satellite. I watched a Youtube video giving most of that advice, but left out the recommendation to change/store etc. 73
     
  10. KC8T

    KC8T XML Subscriber QRZ Page

    Thanks. I'll be ordering an appropriate antenna near the end of this month. I was very surprised when I was able to complete a couple of QSOs on my low cost vertical. I'm hoping by the time the new antenna and feedline arrives, I'll be sufficiently skilled in SatPC32 use.
     

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