Outdoor Antenna Performace Calcs

Discussion in 'Tuners' started by Whitehall, Jan 20, 2006.

  1. Bobby D.

    Bobby D. Active Member

    Messages:
    314
    Don't forget the 200 ft tower :banana:

    Rule of thumb - Every time you quadruple your antenna height, you double your reception distance.

    Bobby D.
     
    Last edited: May 26, 2010
  2. Lineman73

    Lineman73 New Member

    Messages:
    5
    I have a scanner antenna I was given. It has a long run of cable with an end that looks like the type you plug into rear of car radio. My question, if I put this on my TV tower can I run it indoors and use it for FM radio? If yes, the end does not match my receiver, just cut it off?

    If the answer is no, is it just not ideal or would it be better than nothing since I have it?
     
  3. perryinva

    perryinva IS it vintage????

    Messages:
    2,175
    Location:
    Richmond, VA
  4. ng0k

    ng0k Active Member

    Messages:
    392
    Location:
    Omaha, NE
    The assumption that a vertical is better than a horizontal isn't valid. It depends on the FM broadcast stations transmitting antenna polarization. If they transmit vertically polarized then a vertical works better and vice versa. Many stations transmit circular polarization to accomodate both car radios and rooftop yagis and log periodics.

    The antenna you are looking at is a 1/2 wave vertical dipole that should work well. A ground plane vertical around 30 inches tall with a couple of radials the same length would work well too. Google a "2 meter ground plane antenna" to get an idea about what I'm talking about. It would be a bit easier to deploy and have less interaction with the coaxial cable. In either case create an RF choke by coiling 5 turns of the coax 5 inches in diameter as close to the connection to the antenna as you can.

    RG-60 is good enough.
     
  5. Tullman

    Tullman Well-Known Member

    Messages:
    565
    Well...As we all know APS antennas are out of business. From what I saw on another thread, Magnum Dynalab is producing something similar to the APS 13, but for $350. BTW, I have had my APS -13 up for several years and it has survived NE winters, and a tropical storm this summer.

    http://www.magnumdynalab.com/fmantenna-md10.htm
     
    Last edited: Jan 16, 2012
  6. brian222

    brian222 AK Subscriber Subscriber

    Messages:
    1,379
    Location:
    Redford Township, Mi
    Outdoor FM antenna...worth it?

    Living in a large metro area with many FM stations and pretty good signal strength, is an outdoor rig going to do much more? Using indoor setup now.
     
  7. "you pays ya money and takes ya chnces.....

    What constitutes a "Big City" is a relative term..... ( snob that I am). In my earlier posts, I made clear where my former home was "geographically" located:

    25-35 air miles from my roof top of 35 feet where my APS-13 was mounted. 10 miles off the beach on the South Shore of "LONG Island" 360 degrees of rotational ability: The south...Ocean and the New Jersey shore line ( Philadelphia Included). To the West Midtown Manhattan Including Line of sight to both the former World Trade Center and the Empire State Building. To the North, across the Long Island Sound:Connecticut and Rhode Island ( Massachusetts sometimes).

    I used the following "Fully Aligned" Tuners: In order of sound quality....Sansui T-9900, Sansui T-919, Kenwood KT-917, Kenwood 600T and Mac 78 and Sony STJ-75. (The Sony with a good signal has an "Absolutely" "Black Background!) and, The only exception in this list.....

    The rest fall in the sequence as written.... Over time I used several brands of RG-6 and RG-6 quad.... For the most part, Quad primarily cuts down, Machine, Generator and electrical interference.... Save your money and buy BELDEN RG-6 and leave it at that.

    So, I hope this addresses your issue simply and financially.....

    Ps. My Kenwood KT-917 with original box, manuals, tech schematics, rack handles are available to the right interested party.:thmbsp:......
     
  8. R390a

    R390a AK Member Subscriber

    Messages:
    179
    Location:
    Texas
    Very interesting thread! My question for this group is: Do you folks have a favorite site to obtain hardware to build these homemade antennas described on Beezley's website above? I would be especially interested in the insulators used on the square tubing booms. I would like to find new ones because most weathered ones are too brittle to be reused. I have bought some round and square aluminum tubing previously but just haven't found great sources.

    I am interested in Beezley's 20' boom High-Performance 88-92 MHz Yagi. I can already see that it would be much more expensive than the similar manufactured antennas, however, it would be an interesting build and very suitable for my area.

    I didn't want to derail the thread but seeing that Beezley offered no homemade build parts sources, I though the answers would be beneficial to this group. Best Regards
     
  9. FauxHall

    FauxHall Super Member

    Messages:
    1,445
    Re Brian222,

    A large direction antenna on a rotator offers an opportunity to eliminate adjacent channel interference and reduce multipath. Both are problems in urban, built-up areas. Multipath is also an issue in hilly areas.

    The FCC will license broadcasters on adjacent channels is they meet criteria of power, elevation, and direction/distance. This usually works but interference is still possible.

    For example, here in the southern end of San Francisco Bay, my favorite station is 91.5 on top of a mountain, Loma Prieta, just south of me, maybe 6 miles, at 200 watts. Another station I like is on 91.7 broadcasting from Mount Sutro in the center of San Francisco at 1900 watts, maybe 50 miles away.

    These two should be far enough apart that they don't interfere yet the do sometimes at the mid-point. I can get either clearly by swinging my large directional antenna in the right direction and adjusting my tuning appropriately.
     
    Last edited: Jun 17, 2013
  10. The insulators are hydraulic pipe clamps made by Stauff; I haven't found an obvious distributor locally for them but possibly some brake shops would use them, especially for big commercial trucks and industrial equipment. Grainger? I see some types for sale on eBay. Don't know who would be the national distributor(s).
     
  11. RxDx

    RxDx Speaker collector Subscriber

    Messages:
    907
    Location:
    Virginia, the colonies
    These people have a few pieces:
    http://www.dxengineering.com/

    I built a 7 element yagi from a large Channel Master tv antenna- more than enough mounting bits from its disassembly. It was far simpler than sourcing new hardware, as you've noted.
     
  12. wanders

    wanders Super Member

    Messages:
    1,335
    Location:
    Northern California
    Been reading up on the subject & would appreciate any thoughts.

    Just acquired a Mcintosh mr-71and am very peased with sound quality on a few lower end stations (r/s interior dipole). Unfortunately, everything else is poor. I live in Chico, CA, about 80 miles north of Sacramento, 150 from east SF area. I have a 2 story flat roof house and could mount something to one of the roof jacks (vent pipes). Because of the compact size and low wind profile, I'm intrigued with that magnum st-2 whip antenna for such an installation. I could probably, safely, put it on a three foot extension without structural concerns.Higher than that, or a bigget antenna, I'd have to do some engineering.

    But, if that's not going to increase reception, it wouldn't be worth the trouble.
     
  13. cocobeli

    cocobeli Member

    Messages:
    52
    Wanders, did you check fmfool.com to see what turns up? Worth a look.
     
  14. wanders

    wanders Super Member

    Messages:
    1,335
    Location:
    Northern California
    Thanks for the suggestions.
     
  15. 59volvo

    59volvo Well-Known Member

    Messages:
    927
    How are KZFR and KCHO?
     
  16. wa2ise

    wa2ise Super Member

    Messages:
    4,289
    Location:
    USA
    When I was a kid around 10 years old, my family never traveled. Never got more than 90 miles from New York City, and I had thought NYC was an average sized American city... :)

    Anyway, many FMs transmit circular polarization, so the scanner vertical antenna should receive enough signal on your local stations. Many car radio antennas are vertical, and radio stations want people in cars to be able to receive them.

    Given a choice between a big antenna and a small antenna with RF amplifier, I'd go with the big antenna without the amp. As RF amps can get overloaded by a strong local station, and you might get intermod products trashing your desired distant station.

    I rarely ever listen to anything below 92MHz. so when I make antennas I use 100MHz as the center frequency.
    Right now I'm trying to get decent AM radio reception, specifically to WMTR Morristown NJ. As they play the music I want.
     
  17. MudSlideSlim

    MudSlideSlim Well-Known Member

    Messages:
    686
    Location:
    San Diego CA
    Years ago I could always get better FM reception in my car then any roof top antenna with a Yamaha T85 tuner. I was after LA FM stations 120 to 150 miles north of San Diego. Go figure.
     
  18. wa2ise

    wa2ise Super Member

    Messages:
    4,289
    Location:
    USA
    The road noise in the car might have covered up background hiss and low level noise. Noise that you could hear more clearly at home. :)
     
  19. mikejennings

    mikejennings Active Member

    Messages:
    334
    Location:
    Lopez Island, WA
    I have two different systems in my front room. I am at a minimum 80 to 100 miles from all the FM broadcast stations [antennas] that I listen to.
    [1] My every morning "getting ready for work" system is also connected to my iMac and is a Marantz SR4023 with just an indoor commercial FM Dipole tacked to the wall behind it. Usually have the Seattle KUOW NPR station tuned for news and commentary and it comes in fine, but…. some weather conditions or "tower work" can degrade the the signal significantly.
    [2] My main system at the other end of the room [vinyl,CD, Tape, Tuner, to a tube integrated amp] has a Sansui TU717. Back when TV went to digital over air [too far away for reception] I repurposed my large TV yagi to FM to the 717. No/Never any degradation in signal unless the Seattle station are "off the air". If I'm going to listen to music broadcast programing the choice of systems is a no brainer.
     
  20. mr clean

    mr clean Active Member

    Messages:
    172

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