I am about 40 yards from the main power lines coming through my property and the transformer that feeds my house. I have been using RG8X coax and it is OK but I still have a lot of RF noise coming in. I am using a My Antenna Choke (CMC-154-3K 1-54MHz) 5 beads on the coax coming in. I would like to purchase some better coax. In this situation would the LMR-400 be worth the add expense over the RG8X and a better choise?
LMR-400 Coax
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prcguy
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The MyAntennas RF choke is very good and will strip off a lot of common mode junk riding on the shield of the coax both from the antenna into the house and noise from inside the house reaching the antenna traveling on the shield. That still leaves the antenna hanging out there picking up noise and better shielding probably won't do anything to reduce noise.
Another way to look at it is, even cheap coax at HF will probably have at least 40dB of shielding and that's a 10,000:1 ratio. Your antenna has little noise rejection because its designed to work at HF, so adding another 10dB or even 40dB of effective shielding is nothing compared to noise the antenna picks up.
KF0NYL
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Have you checked with a hand held radio to see how noisy the transformer is?
If the transformer is the source of your noise then contact your electric company. Most will make any necessary repairs to fix noisy transformers.
Switching coax and/or adding more toroids or ferrite beads won't help if the noise is getting picked up by the antenna itself.
If the transformer is the source of your noise then contact your electric company. Most will make any necessary repairs to fix noisy transformers.
Switching coax and/or adding more toroids or ferrite beads won't help if the noise is getting picked up by the antenna itself.
OP - What antenna are you using? How is it configured?
I'm using the same MyAntennas choke at the feed point of my OCF inverted V. This antenna runs parallel to some very high voltage lines spanning tower to tower that's just closer to the antenna than the antenna is to the front of my house. It reduced my noise by 2dB on 20m and slightly less or more on other bands. The antenna apex is around 37' and the legs go down to 6' AGL.
I also tried an additional RF choke just a few feet from the radio, but it did not make a difference on my setup. Still, that 2dB reduction was massive. Anyways, when it rains I can pick up a slight pulse I presume is coming from the high voltage lines. I hear the same when underneath the lines...when they're wet. If you ever stand underneath you can see them constantly moving. Still, that noise is negligible and does not really interfere.
Before I even setup that antenna, I walked around my property using an old transistor radio. I adjusted the angle of the antenna as I tested. I set it for AM and tuned it between radio stations. Along the fence in my backyard, near the power line, has the least amount of RF noise. I have enjoyed talking around the world with that OCF inverted V configuration for over a decade.
I'm using the same MyAntennas choke at the feed point of my OCF inverted V. This antenna runs parallel to some very high voltage lines spanning tower to tower that's just closer to the antenna than the antenna is to the front of my house. It reduced my noise by 2dB on 20m and slightly less or more on other bands. The antenna apex is around 37' and the legs go down to 6' AGL.
I also tried an additional RF choke just a few feet from the radio, but it did not make a difference on my setup. Still, that 2dB reduction was massive. Anyways, when it rains I can pick up a slight pulse I presume is coming from the high voltage lines. I hear the same when underneath the lines...when they're wet. If you ever stand underneath you can see them constantly moving. Still, that noise is negligible and does not really interfere.
Before I even setup that antenna, I walked around my property using an old transistor radio. I adjusted the angle of the antenna as I tested. I set it for AM and tuned it between radio stations. Along the fence in my backyard, near the power line, has the least amount of RF noise. I have enjoyed talking around the world with that OCF inverted V configuration for over a decade.
I believe the transformer is arcing pretty bad. I get a load popping every second or 2. It gets way worse about dark and goes on after I go to bed. It is a lot better durning the day. I probably should call the power company. My radio snaps about every second and goes from about 3 to 7 on the S-meter. It seems a lot better on 10 meters but the lower you go in the band the worse it gets. 40 and 80 meters is pretty bad.
A thought just accrued to me that it sounds like and electric fence. Snap snap snap with the same cadence. I have and electric fence that protects my bee hives from the bears. It is probably 150 yards from the antenna. I will have to unplug it tomorrow and see if that is it. Can't leave it off or Yogi will eat all my honey!
I am 2 antennas. Really testing 2 antennas. I am trying to get an idea which will be the best to use from my RV when I leave for Arizona. One is the Chameleon 17' whip and one is an 88" end fed wire antenna. The whip is mounted on a 20' pole and the end fed is 35 feet high at the wire end and goes down to 6 AGL at the unun
I would use the end fed. If you don't use 80 meters you could shorten that wire around 25% to 68'. It should give you 40, 20, 15 and 10 meters. You may or may not need to fold it back slightly to tune things in. As your geographic location changes, as well as the weather (wet), you might need to adjust. Experiment!
- An antenna analyzer is very helpful.
- An antenna analyzer is very helpful.
An old technique that works absolutely GREAT! Even with a tiny SA, I still occasionally grab the old AM radio. I don't know old habits are heard to break.
Error Correction: I intended to type 2 S units and not 2dB. Yes, 2 S units is significant.
Ya that's quite a bit!!
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