Adding vhf/uhf to my shack for satellites. What's your setup? Coax length and type?

Discussion in 'Satellite and Space Communications' started by KI4WCC, Apr 1, 2021.

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  1. KI4WCC

    KI4WCC Ham Member QRZ Page

    I've had my general about a year. I have been enjoying HF bands immensely. but I'm wanting to switch gears.

    I'm wanting build my own eggbeaters and add an IC-9700 to my shack so I can access the satellites from home instead of waving an arrow antenna around portable. I have an arrow antenna and have used it before in my yard. The 9700, albeit expensive, seems to be the best way to go for a base type setup. I had an FT818 and sold it.... I'd rather not own two of them for duplex satellite ops when the 9700 would be within $250 of the same cost as two of them.

    My shack is setup comfortably in my garage. I like it here, and moving it closer to the rear of my home isn't an option. My current coax is RG-8X for the HF bands, about 125 feet, after snaking out the door and through the landscape. I have a 7300 and a 40m full wave loop. The thought of having to spend another $300-400ish on 2 runs of low loss coax (9913 or similar) alone is giving me second thoughts about the whole thing.

    For those of you working satellites from your home QTH on a semi regular basis - how are you doing it? Eggbeaters? Yagi with rotator? What rig? Are you using low loss coax on long runs?

    Any guidance/ suggestions appreciated.

    Thanks.

    Conn
     
  2. NE3R

    NE3R Ham Member QRZ Page

    You either spend a more on feedline or you have less distance between the antenna and radio. It really depends on how much loss is acceptable to you. Over 100' you really don't want to go with coax under 1/4 inch, especially for 70cm. If you do, at least plan for a couple of half inch runs down the road, leave yourself room, because you will want to upgrade later. For satellite, you aren't going to need a lot of power on 70cm, so, as long as the coax can handle 75 watts, even if you are only getting 25 to the antenna, you'll be fine. Most of your satellite RX will be on 2, which will have less loss, it won't be ideal for the weakest signals, but you can pick up most satellites with the stock bofeng antenna, so. I would just buy once and cry once here though, as long as you keep the water out, the coax will last longer than the radio.
     
    VE4MM likes this.
  3. N1VAU

    N1VAU XML Subscriber QRZ Page

    How about locating the eggbeaters closer to the radio? Garage roof or an evening mount, maybe on a 4x4 post if the location has a good enough sky view?

    Personally I would never try to run VHF/UHF through anything less than LMR-400 "equivalent" for distances longer than 30' in a permanent installation.

    Davis RF makes some more reasonably priced "LMR 400 equivalent" that's pretty good. You should check out at HRO.

    Some hams have had good luck with getting Hardline free from the cable TV companies, might be an option for you. Ask around the commercial radio shops, they might have some used cable or Hardline that's still useful for your purposes.
     
    Last edited: Apr 1, 2021
    VE4MM likes this.
  4. WA9SVD

    WA9SVD Ham Member QRZ Page

    I won't make a specific recommendation, but considering the length you seem to need, you should use something like LMR-400 coax, NOTHING "smaller." There are several variations on that type of coax, made by reputable manufacturers, and you may need (or at least want) the flexible variant, even if it costs a bit more. Remember, it IS a "one-time" (or at least, once in a decade or so, if installed properly) expense. RG-8x just has far too much loss @ VHF/UHF.
     
    VE4MM likes this.
  5. K3RLD

    K3RLD Ham Member QRZ Page

    I'm running two independent lines from my rigs to the M2 Leo Pack. Both are RG-8X (I think... not LMR-240 and definately not 1/2" line). I have mast mounted pre-amps, though.

    I know it's not the best, but it works just fine for me. The runs are only 50ft.
     
  6. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Hardline is always king; LMR-400 is probably next best; 9913 equivalent is good. Fit your price range. For rotators remember you need a flexible portion.

    Masthead preamps provide a few dB boost on receive to overcome feedline losses.

    It has been discussed many times in the AMSAT circles that omnidirectional antennas like the Eggbeater, Lindenblad and Ground Plane are not the best choices for the current generation of LEO, low power satellites, though they are useful for monitoring and listening. Additionally, they are quite expensive compared to basic yagis which can easily be home brewed.

    For low cost and simplicity a much more effective station entry-mid level is a a single yagi or dualband yagi of fixed elevation 15-20 degrees on a manually operated TV rotor or similar. Statistics show that this will provide coverage for about 80% of all satellite passes. It will have both forward gain and noise nulling to the sides. A much better choice, and can probably be put up for the cost of an Eggbeater from one of the reliable antenna manufacturers (circa $300 as I recall). AMSAT-NA as info on this. Google/YT for many examples.

    -Please join AMSAT-NA and support more launches. They have excellent books in their bookstore, as well as a very good dual yagi package.

    https://www.amsat.org/

    Examples:
    http://k3rrr.com/el-cheapo-az-el-satellite-antenna/

    AMSAT Journal Article, Getting Started, 2010
    https://www.amsat.org/wordpress/xtra/Getting Started 3.pdf

    Getting Started (2020 update) Book; by the wonderful Gould Smith-WA4SXM (SK)
    [​IMG]
     
    Last edited: Apr 1, 2021
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  7. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Apparently my report of Gould Smith's passing is greatly exaggerated!

    My apologies and Congratulations! (embarrassed).
     
  8. KD9VV

    KD9VV Ham Member QRZ Page

    For TX to the birds, coax is not overly important. Note I said TX since the birds don't need much signal, especially the linear sats.
    So 15-20 watts squirting to a 10dbi antenna is sufficient. Now RX is another story; which is why most will go the cost effective route of LMR 400. Personally I think hardline is overkill under 100 feet for working sats.
    As others have pointed out, there are other options for this coax other than Times Microwave to save a few bucks.

    "For those of you working satellites from your home QTH on a semi regular basis - how are you doing it? Eggbeaters? Yagi with rotator? What rig? Are you using low loss coax on long runs?"

    This ^^ ^ deserves it's own topic.

    If you want to go all in, you install cross polarized Yagi's with polarization switches.
    Next you want a alt/az rotor.

    Me? I do NOT elevate my antennas, currently running 9ele on 2M and 13ele on 70cm.
    My operating is primarily terrestrial anyway; just dabble with the birds.
    I can work any satellite UNTIL it's elevation goes above 50 degrees. Then I simply wait will it begins to descend on the other side of the pass.
    My qso's are generally about 6-8 mins in length if I ragchew; which BTW most don't..most want your grid and it's (Hi-Goodbye)

    My rig is the IC 9700; LMR400, 75 feet.... if you get a 9700 you will love it, esp for SatOps coupled to satPC32 is almost unbeatable.
    Back in the day tracking doppler was tedious; not any longer; it's almost too easy :)
     
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  9. G0VKT

    G0VKT Ham Member QRZ Page

    Based on what I am attempting to get to work for me, could I make a suggestion that may work?

    Put the receiver at the antenna and eliminate coax Rx losses.

    Use an RSP1A or similar. A Raspberry Pi 4b and virtualHere software. The Pi acts as a server and the PC is the client. Connect the two together with ethernet cable. I use SDRUNO to run the RSP.

    Mine isn't working yet. Lack of time and knowledge! Hopefully this long weekend.

    I can find a link to a video if anyone is interested.

    Paul G0VKT
     
  10. N4UFO

    N4UFO Ham Member QRZ Page

    That's brilliant, Paul... I would have never thought of that!
     

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