M2 Satpack 1 for Novice Sat Work

Discussion in 'Satellite and Space Communications' started by K7CFO, Sep 18, 2021.

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  1. K7CFO

    K7CFO Ham Member QRZ Page

    Howdy Sat Friends,

    First a story or skip to the end (bold) for my question.

    I had a friend over the other day that couldn't believe we could talk to the ISS (which I've never done before) so I yanked my IC-9700 out of my shack, downloaded MacDoppler, dug out a yagi antenna, and we made a partial/muddy contact on the ISS FM repeater. It wasn't the best but I was just happy I got through, sorta like keying up the repeater for the first time when you figure out what a PL is (har har).

    After the contact, I decided to put the IC-9700 into a portable case with power supply for easy easy deployment. I really don't want to mess around with rotators or get too complicated here, just looking for something that "mostly works"

    Question #1 - Can I reliably use the M2 Satpack 1 without an elevation rotator? I'm assuming I can catch birds that have a high enough elevation and just will realize shorter QSO's.

    Question #2 - Any suggestions on how to make the M2 Satpack 1 a bit more portable? I'll be using an SUV for deployment (has a roof rack) and I was thinking the roof rack (if I confirm it is really all metal) would be an excellent reflector and thus wouldn't need the reflectors on the M2 Satpack (just the egg beaters).

    Question #3 - How does polarity work on the egg beaters, I think they are fixed right hand out of the box? Do I need to worry about that much?
     
  2. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    We repeatedly get these questions about omni antennas and basic setups. I encourage you to spend some time reading previous threads in the sat-forum.

    -Omni antennas like Eggbeaters and Turnstiles are really not great for modern conditions of LEO, low power cubesats. Twenty plus years ago they were adequate for higher orbit, larger satellites.

    -Randomly removing parts from antennas is unlikely to yield good results. Particularly at VHF+ fractions of an inch changes in any component will upset the performance.

    -As discussed in other threads, a Fixed elevation Yagi(s), on a TV Azimuth rotor is an excellent beginning setup. Math shows that +85% of satellite passes will be covered by a fixed elevation of 15-20 degrees. High elevation passes are less common, however they quickly transit through those small window of angles.
    Read This:
    http://aprs.org/LEO-tracking.html


    -Omni (or any antenna polarization)... for basic - medium level complexity, you just have to pick a polarization and live through the fades and peaks. Using omnidirectional polarization trades off for never having strong peaks, or really weak fades.

    Motto of amateur antennas "You Can't Have It All!". :)

    Jump in and get excited! b.

    http://k3rrr.com/attic-amsat-antenn...table-computer-controlled-yagi-attic-antenna/

    http://rsgb.org/main/files/2012/07/satellites_radcom_mar07.pdf
     
    K4BAD, KS1G and KB1PVH like this.
  3. K7WDO

    K7WDO Ham Member QRZ Page

    I wouldn't recommend the satpack (eggbeaters), either. It's an expensive setup that doesn't offer much performance on the current crop of active satellites and if it was sitting on the roof a vehicle, I'd worry about the wires getting bent out of shape over time.

    The M2 LEO-pack (436CP16/2MCP8A) which is the same price offers way batter performance if you were looking at something for a fixed installation. For portable, the Elk & Arrow antennas have been popular with users on the forum here for use out in the field. Even M2's 2M-440XP-SS would be a better pick over the eggbeaters. Just use a camera tripod if you want to free up an arm to run the radio. Yes, you have to aim them, but they're going to hear the satellites far better than an omnidirectional antenna would.
     
    K4BAD likes this.
  4. KS1G

    KS1G Ham Member QRZ Page

    For portable ops, get a split-boom Arrow (diplexer not needed w 9700 but may be useful in other situations). Optional - various "improvements" for hand-held (modified booms/grips, drill out boom ("Lid Stik"), Carbon Fiber boom (VE3HLS), use of a diplexer as a LPF on 2M for 3rd harmonic (Mode V/U sats), or tripod mounts. Great article by AC9O in latest AMSAT Journal on his setup, and many posts here and in the amsat-bb email archives.
     
    K4BAD likes this.
  5. K7CFO

    K7CFO Ham Member QRZ Page

    Well I def made a mistake then. Since I already have the Arrow Antenna I'll just skip the duplexer and feed the 2m/70cm lines into the 9700. Can you recommend a rotator that will work with MacDoppler nicely in the <$600 price range?
     
  6. K7CFO

    K7CFO Ham Member QRZ Page

    wow great links thank you!!!
     
  7. KB1PVH

    KB1PVH XML Subscriber QRZ Page

    L

    You can find the YAESU G5400 and G5500 used between $400-600 and then you would need an interface board to connect the rotor to the computer to allow it to be controlled by software.
     
  8. VE4MM

    VE4MM Ham Member QRZ Page

    I have a M2 Sat Pack fixed at 45 degrees. I had a M2 10' boom 2M and 440 dual polarity fixed at 45 degrees. I have 3000 QSO's in 2 years and almost 400 grids. Can work almost every active satellite including A07 Mode A. At the cottage I have a G5500 and moved the 10' boom antenna to there this summer.
     
    KA0HCP likes this.
  9. KS1G

    KS1G Ham Member QRZ Page

    IMO, for a rotator for an Arrow that works with MacDoppler and in your 1st post, mentioned easy deployment; therefore: "None." Reasoning: Polarization varies across the pass for all the currently available satellites (possible exception of ISS because the platform is stabilized and strong downlink provides a lot of margin). Arrow and Elk users twist the antenna in real-time to match the polarization of the downlink signal. (Maybe the uplink as well, YMMV). No rotator system can accomplish that. Home stations get around this limitation by using higher-gain and often circularly polarized antennas; they give up some max gain most of the time in return for better handling of polarization fading (and I can still hear near drop-outs sometimes, need to get the polarization reversing switch connected). A remotely mounted Arrow will be in one fixed polarization; it will work well sometimes and be miserable at others. There are some YouTube videos illustrating this behavior. Rotators add significant complexity - 2 more control cables usually, the interface box, power (bring a small 12V-110V inverter) and you have to align everything at least close enough that the software can trim out errors (like you used Magnetic North instead of True North).

    [Aside - my "heavy" demo or Field Day setup uses rotators and computers so I can just sit in the tent and make QSOs, do demos, and ensure reliable easy QSOs. I also have help setting up and tearing down and it can still take an hour plus for each. My portable setup fits in the trunk of my small car, can be left partially assembled, be set up in minutes almost anywhere, everything runs off 12V DC, and works very well.]

    I know of some hams who have mounted a pair of Arrows cabled to either produce circular polarization, or with the antennas oriented so one is Vertical/Horizontal and the other Horizontal/Vertical, and use antenna switch and or remote relays to switch antennas for the best signal.

    If you still want rotators and computer control, your best shot will be a functioning G5400 or G5500 as suggested above. Be aware the position-sensing potentiometers are known to degrade/fail in older units, but are replaceable. The ERC-M (sold in US by Vibroplex) and the FoxDelta ST-2 are good candidates and not as $$ as the Yaesu interface. The CSN Technologies SAT controller is designed for the 9700 and G5500 (or 5400) and eliminates need for a computer and separate interface (you control it via web browser on a phone or tablet); it would be my choice for a portable station due to size and simplicity. You can also homebrew (several plans out there using Ardiuno boards, etc.). No experience with Mac-anything in the shack, but they should be controllable by macDoppler and easy enough to check and see what others are doing. There was a small 12V-based system (Precision Rotation??) that ceased production about a year or so ago; videos from the AMSAT Dayton booth pre-Covid should show it in action. Not cheap but more portable than the Yaesu. The SATNOGs organization has plans for building computer controlled rotators for small antennas that would handle something Arrow-size, and there is a group in Australia selling kits for something similar. If you are OK with azimuth only (esp if you can adjust the elevation angle for each pass), you can reduce the cost considerably, and the ERC-M I know is fine controlling az only. If you can live with manual control; a common practice up until the G5400 & interfaces became available was one (az) or two (az/el) small TV rotators and a plate to cross-mount; use one for az and the sideways mounted one for elevation. There may be plans out there for getting one to work with computer control.

    I'd start using what you have - you have ALL you need for an excellent portable station. Hope this helps.
     
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  10. N4UFO

    N4UFO Ham Member QRZ Page

    EDIT: This is the TLDR version of what KS1G just said. <DOH!>

    I'm confused. You want to go portable & without a rotator, yet...

    Is there a problem with just holding the antenna? Or are you talking about two different things? If you are just talking going portable, using a handheld antenna SO simplifies things. No PC, no stand, no powering it all, AND you can easily adjust for polarity fades when pointing by hand.

    Walmart 1613 #2.JPG em95jr.jpg P7200015.JPG
     
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