67 miles on 50w SSB

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by KK4YWN, Nov 18, 2014.

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  1. KF6A

    KF6A Ham Member QRZ Page

    That's a misconception, unless you're referring to CW EME. With JT65 you can do EME with a relatively modest setup. With two 15ft boom yagis or a single 30ft boom yagi and a 170w-400w brick there are lots of people you can work. And when conditions are favorable you can work stations that size as well.
     
  2. K0RGR

    K0RGR XML Subscriber QRZ Page

    I was talking to a friend in Peoria on 30 meters yesterday, and he said he had done some tests along these lines, with a distant friend using FM on 2 meters, and that he typically saw a 3-6 dB improvement using horizontal antennas on both ends. I suspect it's probably very terrain dependent.
    On the other hand, some people who work aurora suspect that vertical and circular work better than horizontal, so there may be a reason to have both if you're in the region that can use aurora on a frequent basis.

    Honestly, I never really tried this, or paid any attention when it happened randomly. I can work all of our local repeaters with a handheld, regardless of the antenna orientation. But if I want to work the repeater 35 miles away, I need a vertical antenna with some gain. But I'm starting to wonder if I could work those guys on simplex if we were all on horizontal antennas. 6 dB would make my 50 watts sound like 200 watts.
     
  3. KA2BPP

    KA2BPP Premium Subscriber QRZ Page

    ZYT,

    do the LFA's live up to the hype? I am in the process of building 4 9 ele lfa for 2 mtrs to go on a H frame for both terrestrial and EME.
    (actually gathering the aluminum to start building)

    Was just wondering.
    Thanks
    73
     
  4. WA9SVD

    WA9SVD Ham Member QRZ Page

    Congrats, and welcome to the adventure and delight of VHF (and hopefully UHF.) The "cheap yagi" designs are great as starter antennas, and almost "foolproof;" they just WORK. But better yet, plan on making a more dedicated, higher gain antenna, that will last longer outdoors in the weather.

    While not optimum, and the radiation pattern is somewhat unpredictable, the 2M antenna can usually be used on the 70 cm. (Think "third harmonic.")

    You didn't state the height of your antenna, but even 67 miles is actually "small potatoes," although a good accomplishment. With a decent antenna, (a more permanent version) and a few more elements (6 el is considered pretty small @ 2 Meters) at a decent height, you can often find contacts as far as 200 or more miles on a regular basis. (I remember working San Jose, CA from Long Beach, CA on 2 M SSB; I don't know what the other station was using, but our club had a 12 element circular polarized Yagi.and about 35 Watts output power.
    As with any band, the antenna usually makes the greatest contribution to a station's performance, and getting the antenna "out in the clear," away from obstructions, is the most important factor.
     
  5. WA9SVD

    WA9SVD Ham Member QRZ Page

    Circular polarization is often preferable, even if it does lead to a 3dB signal reduction over strictly vertical or horizontal polarization. The real advantage of a CP Yagi antenna is GAIN, with the downside being directionality, almost always requiring a rotator. (Of course, that IS the advantage of a directional antenna.)
    I can marginally access a local repeater about 20 miles away with 35 watts, using a horizontally polarized beam, yet I can easily access the same trepeater with a H-T using a vertical antenna.

    There is a theoretical infinite attenuation between vertical and horizontally polarized signals; in real world, the difference is 20-30 dB. (Since no antenna is perfectly vertically or horizontally polarized, due to mechanical considerations.) But THAT difference of 20-30dB is certainly significant.
    When one gets to modes that are NOT strictly "line of sight," or (at VHF+, where diffraction and more importantly in some cases, reflections come into play) and use the ionospheric propagation, then polarization becomes scrambled, and sometimes variable (thus leading to some "QSB" even at HF frequencies.) so on long range communications (such as E-skip on 6 Meters) polarization can be less of a concern than actual antenna gain.
    Still, most SSB stations on 6 Meters and above, for example, use horizontal polarization. FM operators usually rely upon vertical polarization, as that's most easily achieved in mobile applications, and for that reason, most repeaters are also vertically polarized; they are still working on the "line of sight" principle.
     
  6. WA8ZYT

    WA8ZYT Ham Member QRZ Page

    I am not sure what you mean by hype, but I love mine. I have a 6 element 24' boom on 6 meters and am very pleased with the performance. When I had the 9 element up, I was very pleased with it also. I plan on building a 3 element LFA for 10 meters, next.

    While construction of the loop driven element may seem intimidating to some, it's actually quite easy to do. I used a $5 tubing bender from Harbor Freight to bend the 3/8" tubing, with no problem. Just follow the instructions on the website to avoid wasting a good piece of tubing. It's a whole lot easier than trying to build a gamma match and fooling with getting the match right.

    I procured my element to boom insulators from McMaster Carr. DX Engineering carries them too, which is where I get my tubing from.

    I got the boom materiel from Home Depot for the 2 meter antenna, which cost almost as much as I paid for the single 24' 1.5" square boom from a local metal supply company.
     
  7. KK4YWN

    KK4YWN Ham Member QRZ Page

    Just to keep things in perspective:
    3db is half an s-unit at the reciever.

    20db (if you actually suffer this much) polarization loss is the difference between an s-9 and an s-5. But that loss in the real world is mostly related to ground losses in vertical antennas.

    The vhf world is upside down: reflections come from ground instead of the ionosphere. Ground reflections are very common and do alter the signal polarity.

    But a vertical signal suffers ground absorption while a horizontal signal may experience ground gain.

    Multipath is a pain across the board.
     
  8. WA8ZYT

    WA8ZYT Ham Member QRZ Page

    3 DB MAY be a half S unit or it may be several S units. Depends on the radio. While an S unit is supposed to be 6 DB, very few radios have precision calibrated S meters.
     
  9. KK4YWN

    KK4YWN Ham Member QRZ Page

    I've calibrated my s-meter to 8 places past the decimal. I also replaced the leads with silver coated balanced lines and triple shielding.

    This is the exact same setup used in many episodes of Star Trek.
     
  10. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I like that. "You're S8.30057279" is a good report.

    But if you run out of dilithium crystals, "she's gonna blow, Captain!"
     
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