Where's AO-92???

Discussion in 'Satellite and Space Communications' started by K6LCS, May 28, 2018.

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  1. AI6DO

    AI6DO Ham Member QRZ Page

    By the way, I misspoke a bit earlier. I can adjust the VFO A knob easily in either direction with just my left thumb. Don't need the forefinger for that, even if it could reach.


    73, Ryan AI6DO
     
    WD9EWK likes this.
  2. WD9EWK

    WD9EWK Ham Member QRZ Page

    Hi!

    Not too long ago, I ordered an antenna analyzer from Amazon that covers from 140 MHz to 2.7 GHz. I didn't have anything that covered above 450 MHz, and really wanted something that covered the 1.2 GHz band. This little box does a decent job, and appears to be in line with the readings in the 2m and 70cm bands from the Comet analyzer I have.

    When I checked my 10-element eBay 1.2 GHz Yagi with this analyzer, I saw that the SWR was surprisingly good. I put this antenna on the handle for my Elk log periodic:

    Antennas_with_analyzer.jpg

    Here is the reading of the antenna at 1267.330 MHz, the low end of the range I use when working AO-92's L/V mode:

    1.jpg

    At 1267.360 MHz:

    2.jpg

    And at 1267.390 MHz:

    3.jpg

    Looks pretty good.

    This antenna has been an improvement over the small 5-element Yagi I originally used when working AO-92 L/V. I haven't used that smaller Yagi in some time, since I am happy with the performance of this Yagi I purchased from eBay.

    Someone mentioned on Twitter that they are using this antenna for SOTA work. In the USA, the national FM simplex frequency for the 1.2 GHz band is at 1294.500 MHz. While holding the 1.2 GHz Yagi, I checked its SWR on that frequency:


    4.jpg


    5.jpg

    A bit higher at 1294 MHz compared to 1267 MHz in the satellite subband. Still an option for an antenna, especially improving on duckie antennas found on HTs.

    73!
     
    Last edited: Aug 5, 2019
    AK5B, KS1G, N4QX and 3 others like this.
  3. KE8AKW

    KE8AKW Ham Member QRZ Page

    Yes Patrick, I recently ordered that analyzer after seeing a few people on twitter using it for checking their new L-Band antennas. I ordered one last month for our antenna refurbishment project. I got to say it works great despite being only $150. For those wondering its a AAI N1201SA. I think it definitely beats out the RigExpert which costs almost $1k. In our antenna refurbishment project, we put a 45el Loop Yagi to start getting into L band. While we don't have a radio quite yet for L Band use, we have a friend who will sell us a Kenwood TM-942 for a great price which has 1.2ghz with 10W of TX power. Only drawback of this radio is I believe it only has 10khz tuning steps which will prevent me from getting in some portions of the pass, but it should allow me to make a few good Qsos. This should work good as a temporary L Band radio, until we can afford something like a 9700. I hope to be fully back on the air with the new antennas by the end of next week. Looking forward to it!

    73,
     
  4. K3RLD

    K3RLD Ham Member QRZ Page

    Doesn't go to L band, but RTL-SDR.com just had a post today on the NanoVNA. It's about $70 on amazon and getting great reviews. 50kHz to 900MHz only, though.
     
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  5. WD9EWK

    WD9EWK Ham Member QRZ Page

    Hi!

    Earlier this week, I was able to work AO-92's L/V mode with a different radio for the 1.2 GHz uplink. I recently acquired a Kenwood TM-541A 1.2 GHz FM mobile radio. The TM-541A transmits at 1 or 10 watts, and can encode the 67.0 Hz tone to keep AO-92's downlink active. Its smallest tuning step is 10 kHz. I still used the same two-antenna setup as I have been using for a while - a 10-element 1.2 GHz Yagi I bought from eBay, and an Elk 2m/70cm log periodic - along with a Kenwood TH-D74 HT to hear and record the 2m downlink.

    These photos show my setup from last Wednesday (25 March), in front of my house:

    TM-541_TH-D74_Yagi_Elk.jpg

    TM-541_TH-D74-closeup.jpg

    Compared to the Alinco DJ-G7T I have been using for the 1.2 GHz uplink, the Kenwood TM-541A brings a tradeoff with the increased transmit power. It is nice to have the 10W transmit power, but that comes with the larger tuning steps on the TM-541A (10 kHz) compared to the DJ-G7T (5 kHz). The higher transmit power helps AO-92's AFC hear me when I'm not precisely on the uplink frequency at more points in the pass. Even with 10W, there are still times where the uplink frequency falls between the 10 kHz tuning steps on the TM-541A, and I have to wait a little bit before AO-92 hears me again. With less transmit power from HTs like the Alinco DJ-G7T, tuning is more important when working AO-92 L/V. (With that said, there have been some AO-92 L/V passes that I have worked when transmitting only 300mW from my DJ-G7T!)

    I posted recordings of the two AO-92 L/V passes I worked on 25 March with the TM-541A/TH-D74 combination to my Dropbox space. The recordings start at 1730 UTC for one pass covering most of the continental USA, and at 1904 UTC for the other pass that covered the western USA.

    I don't have a small battery that would let me be more portable when using the TM-541A right now. The specifications show that the TM-541A draws 6 amps when transmitting at 10W, so I don't need a battery as large as I might use with other FM mobile radios for higher transmit power levels. This is where the setup with two HTs like my DJ-G7T and TH-D74 has an advantage, or when I worked AO-92 L/V full-duplex with just the DJ-G7T (something I wrote about earlier in this thread). For now, I'll use the TM-541A at times when I am operating from home, but I could take it into the field to places where I would use a 2m/70cm FM mobile radio for other satellites.

    73!
     
    Last edited: Mar 28, 2020
    KA2CZU, KS1G, WE4B and 3 others like this.
  6. WD9EWK

    WD9EWK Ham Member QRZ Page

    Hi!

    Another week, and more AO-92 L/V passes. I had a couple of high passes in the past 24 hours, one on Tuesday (31 March) evening, and one this (Wednesday, 1 April) morning. Once AO-92 is up from the horizon a few degrees, I am able to get through using the TM-541A transmitting on 1267.330 MHz. I tried 1267.320 MHz early in the pass, to see if that made any difference. It did not. It is possible that the larger tuning step meant I could not get in early, where I might have had success if I could have transmitted on 1267.325 MHz using 5 kHz tuning steps. Or, with even smaller 2.5 kHz tuning steps, 1267.3275 MHz.

    During these two passes - the Tuesday evening pass was up to 48 degrees maximum elevation, and the Wednesday morning pass was up to 63 degrees - I had no problems getting through in the middle part of the pass. Especially near the midpoint of the pass, I was able to keep my signals going through the satellite. Later in the pass last night, I ended up transmitting on 1267.390 MHz and was still getting through when the elevation was down to 7 or 8 degrees. At one point this morning, I did go to low power - for the TM-541A, 1W - and was able to get through.

    You can hear the audio from these two passes - one from Tuesday evening, just after 0500 UTC; and the other from just after 1800 UTC this morning - from my http://dropbox.wd9ewk.net/ Dropbox space. These recordings came from the same TH-D74 and Elk antenna I used last week, illustrated earlier in this thread.

    Until next week... 73!
     
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  7. WD9EWK

    WD9EWK Ham Member QRZ Page

    Hi!

    I had 4 workable AO-92 L/V passes this week - 2 rather high passes, and 2 lower passes. I made QSOs on 3 of the 4 passes, only talking to myself on the late-evening pass around 11.15pm Pacific time (0615 UTC) on 14 April. I'm still using the TM-541A as my uplink radio, getting more comfortable with the 10 kHz tuning steps on this radio, compared to the 5 kHz steps I have on my DJ-G7T.

    Of these 4 passes, the lowest pass of this week's AO-92 L/V activation here in central Arizona was on this (Wednesday, 15 April) afternoon around 1920 UTC. This pass only went up to a maximum elevation of 6.7 degrees to the west.

    20200415-1920UTC07-AO92_pass_prediction-DM43bl.jpg


    I have worked this type of pass using the DJ-G7T previously, where my tuning was absolutely critical to get a 1-watt signal through the satellite. With the 10W transmitter power from the TM-541A, I was able to get through in the middle part of the pass. At times, I certainly sounded louder today than I would have with a 1-watt signal. I found that when I was getting through today, I was transmitting on one of only 3 tuning steps - 1267.350, 1267.360, and 1267.370 MHz. Thanks to Alan WA6DNR for being on that pass. We were the only ones there.

    From the curb outside my house, I have a good view to the west and northwest. Few trees, and only the rooftops keeping me from being able to work down to the horizon.

    20200415-WD9EWK_AO92_LV_station_looking_west.jpg

    Since the TM-541 is only being used as a transmitter, and the 67.0 Hz tone remains set in VFO mode as the uplink frequency changes during passes, I only need to use the hand mic once the radio is powered on. PTT on the side of the mic, and the up/down tuning buttons on the top of the mic. I don't have to touch the radio, unless I want to change my transmitter power level. The TH-D74 HT is clipped to my pants pocket, with the volume cranked up, and the HT records the downlink audio. This has not caused audio feedback when I have used either the TM-541A or DJ-G7T (holding the DJ-G7T like a hand mic when transmitting, and not with a speaker/mic).

    Until next week...

    73!
     
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  8. WD9EWK

    WD9EWK Ham Member QRZ Page

    Hi!

    It's been a little bit since I added to this thread. I'm still working the AO-92 L/V passes. On a pass last night (around 0430 UTC Wednesday, 6 May), I heard only one other station - Kyle K0KN in Kansas. We chatted across a few minutes during that pass. This morning, one very high pass at 1800 UTC. More showed up - Bob W7LRD near Seattle, Alan WA6DNR near San Francisco, Ron N8RO in Texas, and my neighbor Chris K7TAB in the Phoenix area.

    Last night, I found I could get through AO-92 using low power (1W) from the TM-541A mobile radio. Doesn't work all the time, with the larger 10 kHz tuning steps on that radio compared to my DJ-G7T, but 1W still works for AO-92 L/V. I am able to get into AO-92 at lower elevations earlier in passes with the mobile radio, and the additional power makes the larger tuning steps less of an issue.

    73!
     
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  9. WE4B

    WE4B Ham Member QRZ Page

    Sadly... wherever AO-92 may be or what mode it may be... it’s dying. Many people are asking why? No real answers. It’s obvious the batteries have failed and there seems to be a software bug. Did we learn anything from the death of this satellite?

    This one was kind of special to me. My daughter did a science fair project using it and won first place. It did help promote STEM. Sadly, it will soon just be another piece of orbiting space junk until gravity takes its toll on it.

    RIP.
     
  10. N6MST

    N6MST Ham Member QRZ Page

    While the battery situation doesn't look so great, I just worked 4 hams from Minnesota to California on AO-92 a few minutes ago. Don't bury her just yet :)
     
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