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Par OA-144 - What's the realistic distance I can reach with this thing?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KN4DQE, Jan 10, 2020.

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  1. KN4DQE

    KN4DQE Ham Member QRZ Page

    I have a vertical triband (2m/70cm/23cm) antenna on my roof that can reach about 50-60 miles with at 50 watts. Since I've recently acquired an IC-9700, and now have 100 watts to play with, I'd like to try out SSB. The vertical just won't cut it though, so I am looking at a PAR OA-144. It's nice and compact, and won't raise any issues with the HOA if I mount it on the existing vertical pole on my roof.

    However, since it's basically a no gain antenna, what sort of distance should I expect out of this thing? The radio puts out 100 watts, and I am running 7/8" heliax to my existing antenna - so realistically I should be getting about 80-90 watts out to the antenna.

    Thanks
     
  2. NH7RO

    NH7RO Ham Member QRZ Page

    About 400 miles or even more when propagation is cooperating (sporadic E multiple hops, tropspheric ducting, meteor scatter, etc.).

    Without those enhancements a lot depends on your terrain but I say out to 75-100 miles or so.

    The higher the better as you do actually get some ground gain when used horizontally. They are great for monitoring beacons, too.

    VHF weak signal stuff can be a real blast; I'm toying with the idea of getting a 9700 for satellite stuff, too.

    Have fun!

    73,

    Jeff (I've had 6m, 2m and 70cm PAR OA units in the past---all good omnis! Stack two or more for more gain...)
     
    Last edited: Jan 10, 2020
  3. KN4DQE

    KN4DQE Ham Member QRZ Page

    Wow that's pretty impressive, considering the cost and size! I really want to try out SSB (as well as Sat) since I got this radio. I may get one to play with and see what it can do!
     
  4. NH7RO

    NH7RO Ham Member QRZ Page

    Three things to remember when delving into weak signal operating; height above ground (don't worry about feedline length when most of your coax is going upwards instead of outwards), patience (listen a lot on the recognized call frequencies like 144.200 (2m ssb) 432.100 (70cm ssb), 1296.100 (23cm ssb) and realize that a lot of the time the bands will be quiet (but not necessarily dead as many assume).

    "Get used to listening to the frying pan" as we say... When I lived in KH6 and regularly worked 6m dx into South America, VK/ZL and the Far East I had rigged up a baby monitor in the shack and the portable monitor on my belt so I could hear stations calling CQ out in my garden or downstairs. My wife even helped out sometimes by yelling out on the balcony, "Honey, I'm hearing voices!" (Good xyl!).
    I think I worked ZD7VC that way and my running back upstairs paid off. F2 was in effect at the time and 6m was pretty hot back in Cycle 23.

    2m is almost as exciting sometimes but the dx will be much less distant unless you are running legal limit with long boom stacked Yagis, of course---I don't want to get your hopes up too much, hi hi! You'll still have fun during contests and Es openings---and possibly plenty of across-the-Gulf tropo ducting, too.

    Catching brief openings requires the patience to listen a lot and calling CQ on a quiet band can also bring results (if everyone is listening then no qsos will happen---feel free to try your luck and throw out some CQs, too.)

    Propagation is the third big key to all of it coming together for fun times.
    Nothing significant happens without some kind of propagation on VHF---but the good news is that it is somewhat less dependent on the current solar cycle (unlike HF). Sporadic E happens mostly in mid-summer and mid-winter but can occur anytime.

    The January VHF Contest would be an excellent time to check out your new system; I've linked it below along with an interesting Rover site below it for further inspiration.


    http://www.arrl.org/january-vhf

    https://www.k5nd.net/2019/12/arrl-january-2020-vhf-contest-rover-route/

    Hope this helps!

    73,

    Jeff NH7RO/W5 EL18 (rare grid)
     
  5. N1LOU

    N1LOU XML Subscriber QRZ Page

    Around here in the northeast there are a number of folks that rag chew on 2M SSB. The game is all about highly directional antennas and power. These folks regulary make contacts up and down the eastern seaboard daily regardless of propagation. IIRC, there was one guy in CT who would talk to another in Virgina on a regular basis. They were running 13 and 26 element yagis and such. When I first got my 857D I tried to communicate with them on a vertical ground plane and the guy in CT, 35 miles away, could barely hear me. When I went to a horizontally oriented circular loop antenna, I could barely reach guys with a beam say 100 miles away or so. If you want an omni antenna with some gain, look at stacking 4 of those loops vertically. You will have to figure out the correct spacing and phasing requirements, but that will be your best bet without a rotor. Theoretically you will get 5db of gain from stacking 4 loops
     
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I think it will get out millions and millions of miles, since 2m is such a high frequency the signal goes right through the ionosphere and keeps going.

    Ever time you transmit on 2m, your signal is reaching the moon, about a quarter million miles away. To hear the reflection, you'd just need to run a few million Watts.:)

    Realistically, based on my 53 years or so of 2m weak-signal work (all CW at first, now SSB also since about 1970), I'd agree "height above ground" is important unless you happen to live on a mountaintop with a clear and very long horizon. Most SSB ops on 2m, unless mobile, use beams, and some enthusiasts use really big sets of beams up very high, along with kilowatts and good low-noise preamps and stuff; as such, working "them" can be pretty easy even if they're a few hundred miles away. Working another station using an OA-144 at a low height (20-30 feet) and 100W will restrict working radius to something much less, usually.

    Looks like you're in Florida, which is really "flat" with no mountains in any direction for a very long distance, and that's pretty good for VHF. Shouldn't take much enhancement to get into AL and southern GA, maybe the Bahamas if anyone's on. Activity peaks during the VHF contests, and your timing is good for the January VHF Sweepstakes.
     
  7. KN4DQE

    KN4DQE Ham Member QRZ Page

    Thanks for the feedback. I like the stacking idea. I'll have to look into that
     
  8. WA3GWK

    WA3GWK XML Subscriber QRZ Page

    There are quite a few stations down there in central FL on 2 meter SSB. I'm able to work stations with a 7 ele beam and 100 watts down there from EM60 (AL) when there is a bit of enhancement. As WIK says, it's flat down there and you can work the northern and western gulf coast over water. Good luck, will look for you when the band is open down there.
     
  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Stacked omni antennas like the OA-144 work fine, but remember they must be separated properly (as well as phased/divided properly) to actually work.

    In the case of an OA-144 or similar "0 dBd" antenna, spacing between bays is about 1/2 wavelength, or 40 inches at 144 MHz; so to stack four of them, which is a good setup, requires at least ten feet of vertical mast space, using all of it; so wherever the "lower" OA-144 is, the "uppermost" one needs to be 10' higher, on the same mast, in the same orientation.

    If you can do that, it's a pretty good idea. Making a coaxial power divider/phasing-matching harness out of coax is pretty easy and doesn't cost much.
     
  10. KN4DQE

    KN4DQE Ham Member QRZ Page

    I may only try and stay with 2, since I am limited to space. I need to try and place the top one just below or at the crest of my roof line, since I don't want it visible from the road, otherwise it will cause issues with the HOA. I realize it's not the most ideal place to put it, but I have to be stealth. I am going to use LMR-600, which should give me about 75 watts at the antenna.
     

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