RF Grounding

Discussion in 'General Technical Questions and Answers' started by NL0H, Apr 15, 2019.

ad: L-HROutlet
ad: l-rl
ad: MessiPaoloni-1
ad: Left-3
ad: Subscribe
ad: K5AB-Elect-1
ad: Left-2
ad: L-MFJ
  1. NL0H

    NL0H Ham Member QRZ Page

    I am looking for suggestions for a simple and effective (if possible) grounding system.
    I have always had troubles with a good ground. My previous station location on ledge, yes even above ground rock. My current shack is located on permafrost tundra.
    My transmissions are now bleeding into the FM broadcast station at the same location.
    Any suggestions are greatly appreciated!

    Henry
    N1HEN/KL7
     
  2. W9XMT

    W9XMT Ham Member QRZ Page

    Just to note that such local interference can result from the high radiated fields generated by a transmit system, regardless of how good an r-f ground is connected to it.
     
  3. NL0H

    NL0H Ham Member QRZ Page

    That is one thing I have been thinking.... I am still hoping I can solve the problem and stay on the air.

    Henry
    N1HEN/KL7
     
  4. W9XMT

    W9XMT Ham Member QRZ Page

    This may include modifying the shielding/grounding of the devices experiencing interference from your transmit system.

    Are you using balanced antennas, such as center-fed dipoles? If so and they are fed through coax transmission lines, are there provisions installed to reduce the common-mode current that otherwise will flow along the outer surface of the coax shield (which by itself produces radiation)?
     
  5. WB5WPA

    WB5WPA Ham Member QRZ Page

    Is this from a 7 Watt Chinese 2 meter HT or from an HF base station at 1,000 Watts on 80 meters or 10 meters? A little context and we might get a better idea of the 'players' involved. :)
     
  6. K4SAV

    K4SAV Ham Member QRZ Page

    Also

    You have an FM broadcast station located at the same place as your ham antenna (whatever that may be)? Are you the engineer for the FM station?

    Jerry, K4SAV
     
  7. AA5MT

    AA5MT Ham Member QRZ Page

    If at the same location, can you not tap into the station ground?

    Very likely, even with a good ground, you are creating rfi through your feedline. Are you using a choke balun at the feedpoint?

    Tom
     
  8. NL0H

    NL0H Ham Member QRZ Page

    Well... I reckon I did leave out quite a lot of information. Right now I am using 100w on 20m. The antenna is a roof mounted 20m vertical that is coax feed mounted perhaps 30ft from the tower. I had also connected a longer wire to the vertical so as to use 40m. The antenna system needs to be improved.
    No, I’m not the engineer! I work in the studio as programmer/DJ. My shack and the studio/transmitter are at a distance from each other although the same building.
    I have so far found one ground and at different part of the building. Not sure what it is for as it comes out of the snow and is mounted to one of the foundations pillars (size of a well casing). It may be for the electrical service which is nearby that grounding location. I did not find a ground wire directly from the electrical service but it could be because it is buried in rock hard snow. There may be other grounding locations; however, most things are boxed in and insulated plus buried in ice/snow.

    Thank you,
    Henry
    N1HEN/KL7
     
  9. K6BSU

    K6BSU Ham Member QRZ Page

    My station grounding system consists of copper braid which connects to an existing outdoor ground rod. Length of the braided cable is about 15 ft. I'm not sure it does any real good, because it should be shorter. I didn't have any RFI problems before, so maybe the ground cable serves as an additional safety feature for a possible ground fault.
     
  10. K4SAV

    K4SAV Ham Member QRZ Page

    What are you using for radials for the vertical? Hope you have some.

    If you don't have a choke on the feedline at the antenna, you need one to keep the currents off the feedline. The only other thing that could make a difference is to move your antenna further away from the commercial station. A "ground" wire is very unlikely' to solve the problem. It may make a difference, could be a little better, or a little worse. I put my money on the worse.

    Likely it is because of some poor shielding on some of the audio lines inside the commercial station that allows the radiated signal to be picked up. If that is the case, the station engineer will have to solve that problem at the station.

    Jerry, K4SAV
     

Share This Page