My UHF TV antenna

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by VE3JCJ, Jun 28, 2015.

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  1. VE3JCJ

    VE3JCJ Ham Member QRZ Page

    Hi Ed: That was my original set up and there is even a website that suggests it works that way. I also do realize that even a combiner, as a reversed splitter will still attenuate in either direction by 3.5 db. The one you suggested is the most common sense approach, but it doesn't work that way even though it should. Yet when I do the one antenna direct to the preamp it's an awesome signal with lots of stations. But I still want to run two different antennas 180 degrees apart.
    I found channel master support not very helpful. I also found the antenna manufacture equally not very helpful. They don't want to get involved with simple designs. I think it's because they hire some of these guys that don't have an extremely little RF background. (minimal at best)
     
  2. N3DT

    N3DT Ham Member QRZ Page

    VE3JCJ,

    I don't know if you're having antenna problems or feed line issues. That said, let me tell what I did and works for me. I live about 50 miles as the crow flies from DC with 2 ridges between. I put up a home made dual bay Hoverman (http://www.digitalhome.ca/ota/superantenna/) which works better than any TV UHF antenna I've seen. I use a CM7778 (I think) right at the antenna and it transforms the 300 to 75 ohm coax plus there's about 20dB amplification in it. The antenna is about 50' pulled up in an oak tree. I've got about 60' of quad RG6 into my radio room where I have a small 10dB amp and send it to the TV from there. I can receive all Digital UHF channels from DC fine most of the time and Charlottsville off the back all the time. Once in a while DC just drops out because I'm really past where I should be able to rx TV signals, but I get it most of the time.

    That's my antenna on the 3rd page of the link made from chicken wire, pvc and #6 copper wire. I painted it black before I installed it. No other commercial antenna I tried would work at all at my place and I made it for about $30. If you have feed line loss that's too much, try RG11 which is available on evilbay for very reasonable loot with connectors. Next time I bring mine down I'm switching to RG11. Only thing I watch is WETA, PBS. I would never pay to watch such insipid commercial TV.
     
  3. NC5P

    NC5P Ham Member QRZ Page

    I would suggest getting the most gain in antenna and use very low loss coax, like CATV hard line. You can get shorter runs and the adapters to F at surplus places. Avoid amps as much as possible, they will overload and mix up everything they pass into total junk. They do work OK in some places where there's not much RF around. Many people go overboard amplifying everything. If just one signal in the whole passband (50-700MHz) is strong enough to cause compression in the amp everything will get trashed.
     
  4. VE3JCJ

    VE3JCJ Ham Member QRZ Page

    Back to my second question. Please bare with me.
    Now that I find my first 8bay works great facing due east with only a preamp and that I found a combiner does not work, in my case.
    I'd like to run a second 8 bay and hopefully a second 7778 preamp for the opposite direction facing due west. My one main 8 bay now picks up 30 stations with the preamp, and without a combiner, no issue. Hence is why I'd like to run a second 8 bay for the opposite direction.

    I just bought a second 8 bay today, used, but I'll be going over it to clean connections and do this and that. Like any good ham would do I will buy the odd used item and quickly check it over for major breaks or damage. This one only had slight surface corrosion
    I found my existing new preamp works better than not so I am very please with its performance.

    There will be a couple of different configurations I'll be trying with the two 8 bays and maybe try that new combiner again.
     
  5. KP4SX

    KP4SX Premium Subscriber QRZ Page

    Although these antennas generally have a very narrow pattern, if the signals have any strength at all you can experience 180 degree phase cancellation because they are being picked up on the other antenna. You may have to monkey with coax lengths, etc.

    I tried some combining schemes from my location that didn't seem to work out well all across the band.
     
  6. K4EJQ

    K4EJQ Ham Member QRZ Page

    Hello Folks: I worked in the TV broadcast biz for 35 years. I decided to get out BEFORE TV went Digital. We are in a mountainous section of the country and I had that gut feeling that the feces were gonna hit the fan as soon as digital was implemented. Well, I have to admit...those that get a "clean" OTA TV signal ( NO GHOSTS/NOISE )...HAVE A BEAUTIFUL PIX/SOUND.....SOMETIMES. That's another topic.
    I enjoy TV DXing along with my VHF/UHF/Microwave hamming. I purchased a mid-sized Upper VHF/UHF Yagi and installed it atop a 60 ft tower. Fed it with Andrew 7/8 inch 50 ohm cable to minimize loss accepting the " impedance bump" /loss. To make a long story short, I decided to add a pre-amp to increase range/reliability. I finally decided on a model that was reasonably priced that offered very low noise figure and moderate gain. When I added it to the system I got LESS stations ! I'd seen this problem before : front-end overload from local TV and FM stations line of sight with my receiving antenna. I retuned a commercially built "high-pass" filter to delete vhf chs 2 through 6 as well as the FM band, aircraft frequencies, and the 2 and 6 meter ham and commercial two-way/ pager bands. That solved the problem-got many more UHF and VHF digital channels on a more consistent basis. I use good quality RG-6 cables through the home for distribution. Your mileage may vary---enjoy the ride!! Bunky, K4EJQ
     
  7. W9GB

    W9GB Ham Member QRZ Page

    Your Combiner/Splitter problem (not passing injected DC) is NOT a new issue -- many have a Diode internally.
    Winegard, at one time, (as well as Jerrold, Finco, Channel Master) made a Combiner/Splitter for your usage (passing DC voltage). I remember the 1960s MATV catalogs, before widespread CATV roll-outs, that were targeted for urban apartment and high-rise buildings. All the pieces were there to build your own TV system.

    There was a special VHF/UHF antenna (may have been Finco design) manufactured in 1960s for the IL/WI border communities ... that were 1/2-way between Chicago and Milwaukee (almost 180 degrees from transmitter sites). Strange bird, with DE in middle and directors at both ends.

    When I drive through Kenosha, WI to go to Chester Electronics on South Sheridan Road, I see some of those old OTA antennas on some homes in the neighborhood.
    http://www.chesterelectronics.com

    =====
    BTW, I found that the Hoverman design by Antenna Craft G-1483 (also sold by Radio Shack) was a very good UHF antenna.
    http://www.dtvusaforum.com/antenna-r-d/18735-vintage-antennacraft-g1483-hoverman-antenna.html
    Surprisingly, at times outperforming the old ChannelMaster 4228 / 4251 parabolic dishes and Winegard deep-fringe UHF yagi in my 1970s tests.
    http://www.kvhf.com
     
    Last edited: Jul 31, 2015
  8. KA0GKT

    KA0GKT Ham Member QRZ Page

    Before I would go with a preamp, I'd add antenna gain. The Winegard HD-8800 is a decent antenna which can be stacked with some 450 Ohm window line for an additional 3 dB gain. Minimize your losses by using a good quality coaxial cable RG-11u would be a good bet; that said, you have four VHF High Band (channels 7 through 13) stations which should be receivable they are on channels 7,CIII-DT; 9,CFTO-DT; 10, CKVR-DT and 12,CHEX-DT. They are all in different directions, so either plan on cut-channel antennas or bite the bullet and buy a rotor.

    Bon Chance!
     
  9. W9GB

    W9GB Ham Member QRZ Page

    Here is the Finco FM Antenna by Finney Company of Bedford, Ohio -- that featured that classic 180 degree,
    figure-8 (like dipole) reception pattern. The Kenosha, WI television (VHF) antennas were same style, with longer elements.
    http://www.kvhf.com/flyers/FincoFM.jpg

    ======
    Instructables has DIY Build of a Gray-Hoverman antenna
    http://www.instructables.com/id/Gray-Hoverman-TV-Antenna-Final-Assembly/

    image.jpg
    DIY Build Blueprint
    Double Bay GRAY HOVERMAN Colinear Narod Antenna for High-VHF and UHF
    http://www.user.dccnet.com/jonleblanc/Canada_TV_Stations/Gray-Hoverman/DBGH_VHF_hi_Antenna.pdf
     
    Last edited: Jul 31, 2015
  10. VE3JCJ

    VE3JCJ Ham Member QRZ Page

    1) If I may be so bold to ask, what mistakes do you think you made and what cures do you think you found.
    2) I said I'll be mounting mine 180 degrees. It will most likely be 180 degrees but one 8 bay may be lower than the other one purely for installation ease on my part finger tip access to hardware.
    3) Also, I do understand keeping both feeds to the combiner equal lengths but how long is too long and how short might be too short?
    4) I guess now I should be looking for a combiner that can pass DC (no diodes). Hmmm, price just went up for fewer parts (jk):eek:
    5) if one antenna reflector is physically touching the other antenna reflector would that be a help or a hindrance? BTW the top of one antenna to be (how close) to the bottom of the other?

    All my cable and connectors are industry standard from CATV as are all my connectors. There's no fine braided wire touch the center core anywhere.

    we've been running a heat wave lately. Just today things cooled down a wee tad.
    I'm sure my signal strength will perk up during colder weather...right?
     

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