Low VHF interference

Discussion in 'Over the Air TV By RabbitEars.Info' started by freeisforme, Feb 22, 2017.

  1. how far can interference travel from outside power lines and still cause interference on low VHF rf channel 2?
     
  2. It will depend a lot on how strong the interference is, how strong is the antenna reception, what direction is the interference coming from compared to the broadcast signal. Is the cable shielded or is it flat lead that has no shielding.
     
  3. Unshielded Twin lead Cut to 98.5 inches
     
  4. Get a balun and run coax.
     
    K9SAT and Claude Greiner like this.
  5. Got the balun connected to the twin lead then rg6 25ft to the tv. No amp or splitter. I have a noisey pole about 200ft away on a AM radio.
     
  6. Electrical interference can transmit for miles on low VHF.

    Coax has been around for 50 years and is fairly cheap, there's NO reason to run 300 ohm flatlead anymore.

    Unless the flatlead IS your antenna??

    If you know for a FACT a particular pole is noisy, report it to your local power company. They will repair whatever is causing this. They don't want arcing or noise anymore than you do.
     
    navychop likes this.
  7. Would a moderator please combine his 2 threads to give a complete picture of his question.
     
  8. I am using the twin lead as a simple folded dipole tv antenna. Is there a better radio or radio antenna to find other poles? Marine VHF radio? Don't have it but can borrow. I don't mind building a antenna. As always, cheap or free is best.
     
  9. I looked at your other thread. KJWP is only 9.36KW in broadcast power. That's not much, and if you are further than about 25 miles away, it's a problem. With your issues, you will first have to contact the local power company to fix the noisy power pole. You never gave any details such as how far away you are from it, and any terrain issues. IMO you will then need to have a directional low-band VHF OUTDOOR antenna, up as high as you can get it.

    This will need to be installed with grounded coax, preferably quad-shield. Do not attempt to use any sort of amplifier for this.
     
  10. 1/2 wave length for ch 2 is 103.8 inches with a frequency of 54-60 MHz.
    In his other post he gives a zip code that puts him at 55 miles using a unity gain home made antenna in a 1 edge area located in his attic for more signal loss. I would call that an impossible dream even with a low VHF antenna mounted outside. He also guessed he is 22 ft above ground.
     
  11. i divided by the center frequency. I used 300 * 0.95 / 57=5 meter. 39.37 inches in a meter. divided by 2 equals 98.4. i made it 98.5. users.wfu.edu/matthews/misc/dipole
     
  12. If you want thoughtful answers, you need to give us all the key parameters. Don't make us bludgeon the information out of you.

    In TV reception, the most helpful of tools is probably the table you get when you enter your address into tvfool.com.

    A simple dipole may work, but as boba points out, it has to be "tuned" to the correct frequency and more importantly, be of the appropriate impedance.
     
    primestar31 likes this.
  13. I agree with boba and you a 100% of course i dont have any antenna testing knowledge. i just center cut the antenna and assumed it would work OK when center cut. Most web sights uses the center frequency for a tv antenna. If not what would you use? 54 MHz or 57 MHz for a tv antenna real/rf channel 2? what velocity factor would you use? i read different numbers other then 0.95. then how would i test the impedance? SWR meter? back to interference. with nothing more then a AM/FM radio what else could i use to find the noise from less noise utility poles?
     
  14. This is why it is important to illustrate what you're working with. The tvfool table is the tool that we need to tell you if it is even possible to accomplish your goal with a simple antenna such as you propose. Real TV antennas use not only dipoles but reflectors and other gain (and rejection) aids.
     
  15. what numbers would you use to find the length of the antenna? btw zip 08087
     
  16. with nothing more then a AM/FM radio what else could i use ( build or buy, ) to find the noise from utility poles?
     
  17. #17 boba, Feb 23, 2017
    Last edited: Feb 23, 2017
    103.8 inches is the length for the antenna for CH.2 that broadcasts at 54-60 MHz. The power pole is probably not your reception problem you just don't have enough signal from the broadcast tower. At 55 miles in a 1 edge environment you have very little chance of getting a usable signal.

    Mediasonic Homeworx makes a small all channel antenna on ebay for $29 with shipping it would have a much better chance of working than your home construction.but I doubt it would work.
    Winegard has a HD8200U sold by Solid Signal for $119.99 plus shipping that might work but it isn't cheap.
     
    navychop likes this.
  18. Read this thread at TvFool: http://forum.tvfool.com/showthread.php?t=15701

    See post #3, but most of the thread is real good.
     
  19. why do you use 54 MHz and not 57 MHz? I have / had both of the antennas. i have the hd8200u setup in my yard but my neighbors were making fun of me, asking me do i know what year it is. lol. So i took it down. Had the antenna 8ft up KJWP and WPVI kinda worked 50% of the time and pixelated the rest but watchable. The mediasonic my brother took was from amazon 20$, different brand, same size work good, KJWP and WPVI kinda can in as good as the Winegard at the same height. This was the antenna the showed me that WPVI had to be a vertical antenna in my attic. Made a twin lead for WPVI too and its works fine about 95+% of the time. Now i had KJWP at 25% + - 10 in my attic and this is why i believe i can make it work in the attic once the noise issue if fixed. and now fix the antenna length.
     
  20. great read, have any more links? if i make the tape measure yagi can i use rg6, and how would i connect it a AM radio? or would a marine VHF radio work better?