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Before I finally get a chance to fire up my AL-80B....

Discussion in 'Amateur Radio Amplifiers' started by KN4DQE, Nov 26, 2018.

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  1. KN4DQE

    KN4DQE Ham Member QRZ Page

    So I bought a used AL-80B almost two months ago. I was trying to get the amp up and running but ran into a snag. I and my lucky neighbors have Eton breakers installed in our homes. Our neighborhood was built around 2014. I got to about 200 watts out and I kept tripping my AFCI breakers (as well as my neighbors in my immediate vicinity). Fast forward to now. Working with Eaton, they are replacing breakers in my neighbors panels this week! The breakers that they sent me seem to work, but who knows what will happen once I reach about 800-900 watts output.

    However, this got me thinking. What other things could be impacted by the amp? I've heard a few stories on here, but anyone care to share their experiences and things to look out for, so as to not piss off the neighbors?
     
  2. KO6WB

    KO6WB Premium Subscriber QRZ Page

    Powered speakers used on computers, cordless phones, home surround sound systems and other electronic devices. You could also affect smoke alarms and/or CO detectors.
    Most all of these could have been rectified with proper engineering design and almost never has to do with your transmissions.
    The problem becomes exasperated by proximity. Close is bad.
    Some of these can be resolved by either replacement or using external devices to control the extent by which the transmissions are reduced in severity. The consumer devices respond quite well to added ferrite cores to any leads coming into and out of the device that is affected.
    One thing to remember, it's almost never your fault. You are there and they are there. All you're doing is exposing a fault in their devices.
    I doubt they'll see it that way though. Diplomacy goes well in handling these problems. You may actually get a chance to see the devices affected and you can make advances for the needed steps to alleviate the problem. This also gives you the opportunity to show your neighbors that none of the similar devices in your home are affected. Give advice but try not to do the actual work. This can cascade into further problems that might occur at a latter date. So, hands off.
    So, if your neighbors do not allow access to their devices, then try to get them to tell you about them.
    Sometimes, you just have to bite the bullet and locate a replacement device. This needs to be of the neighbors liking so ask a lot of questions. Also, the replacement unit should be one that is known to be resistant to your transmissions.
    This can get expensive but if you want to keep the peace, then these are good steps to take.

    Hope this helps
    73
    Gary
     
    Last edited: Nov 26, 2018
  3. KN4DQE

    KN4DQE Ham Member QRZ Page

    Thanks, good advice! I'm honestly hoping that I don't run into these issues. We shall see what happens!
     
  4. W1QJ

    W1QJ Ham Member QRZ Page

    I might add that the FCC offers a free pamphlet (or at least they did) which is written in plain English so just about anyone can understand it, outlining RFI problems as it relates to hams. This pamphlet CLEARLY states "the law" as it pertains to this. It outlines the fact that most consumer devices are at fault and makes them aware of the part 15 disclaimer that ALL devices come with. It clearly states that cooperation with the ham is essential and if it is proven that there has been n cooperation on their part that the FCC will not get involved in any action against the ham. It might not be a bad idea to obtain this if you see that cooperation on their part is breaking down. On another note, Many of the NEWER AFCI breakers are much better and have been RFI free. I do believe QST did an article on this a few years back and made some recommendations on the breakers that are the best in the RF environment. That may be something to check into because they do call out specific brands that work well. Clearly the first ones made were really bad.
     
    WA7PRC likes this.
  5. AI3V

    AI3V Ham Member QRZ Page

    Op, you didn't mention just what kind of antenna you have.

    But if you use any sort of indoor antenna,or any "no counterpoise" outdoor antenna,

    Then I bet the interference IS your fault.

    Likewise if your outdoor dipole is too close to your neighbors house.

    You have actually MEASURED the rf field strength at the site of the interference?

    Rege
     
  6. KN4DQE

    KN4DQE Ham Member QRZ Page

    I'm using a Hustler 6BTV with ground radials. It's behind my house about 30-40 feet, in a treeline. I need to obtain a forkf strength meter yet, so have not yet measured it.
     
  7. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Ham grade field strength meters are almost exclusively relative strength meters and not calibrated to any absolute scale. IOW, all you'll be able to measure is that there is signal but not whether that signal exceeds safety limits at a defined distance from your antenna. This is after all a transmit antenna and it's purpose is to radiate a signal so a relative field strength measurement will just tell you that it is in fact radiating a signal.

    It is possible to buy absolute field strength meters that come with specific calibrated antenna elements but these are very expensive devices and not typically used by hams and not really necessary. As long as you adhere to the RF exposure limits for uncontrolled environments at your neighbor's property line or on any public spaces and ideally also adhere to the controlled environment limits on your own property (and adhere to transmit power limits out of your amp) then you're meeting the RF radiation limits requirements. More information can be found on these limits and how to estimate them in the ARRL Handbook or on the ARRL or FCC websites.

    Based on your description of a vertical (with radials, so presumably limited common mode radiation off the feed line coax) located 30 to 40 feet back from the house it's all but impossible that you're exceeding the RF exposure limits for either controlled or uncontrolled environments. The ARRL Handbook lists examples of antenna measurements including an 80m vertical driven with 800 watts of RF that is below the exposure limit when measured only 0.5 meters from the base of the antenna. If you have 30 or more feet between your antenna and your home and presumably something like that to the neighbor's home your field strength is going to be well below the published limits as in a couple to few orders of magnitude below those limits.

    It's quite possible that your signal stays below all the published RF exposure limits and your neighbors still experience RFI to overly sensitive consumer devices. At that point it becomes a diplomatic problem of how to keep the neighborhood happy even if you're not technically at fault. I ran into some of that when I started running an amp at this QTH a number of years ago and helped my next door neighbor with some clamp on ferrite chokes on the speaker lines of his stereo which resolved the problem.
     
  8. KN4DQE

    KN4DQE Ham Member QRZ Page

    Thanks for the insight. I will still check out the calculator just to ensure that all loose ends are tied up. I am hoping I don't end up with the horror stories that I've read here of crazy folks coming to my door with a shotgun, blaming me for their TV reception sucking, lol.
     
  9. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    On HF even at 1 kW you have to be quite close to a 0 dB gain antenna to have proximity that would exceed the FCC guidelines for even an uncontrolled environment.

    I wouldn't worry at all about that.

    Getting into TVs is quite rare nowadays, but getting into sound systems and (landline) telephones is a bit more common. Crappy consumer electronics is still crappy consumer electronics, but the old days of "TVI" are long behind us, at least everywhere I've lived since the 1980s.
     
  10. AI3V

    AI3V Ham Member QRZ Page

    So if this was a ordinary size Marconi, your house would actually be INSIDE the antenna.


    Expecting your, or any other electronic gear to operate interference free 30 feet (1/8 wavelength!!) from a 800 watt transmitter is wishful thinking.

    Good luck, your going to need it.

    Rege
     

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