Set up base station, bleeding the neighbors

[buickid]

Hey there. Just put up my Sirio Vector 4000 yesterday, with a 100ft run of LMR400 under the house to the radio, an old Cobra 139XLR (Also tried the Galaxy 979 from my mobile with similar results). Anyway, after about 15 minutes of ragchew with a buddy (fantastic TX and RX I might add), my neighbor came a knocking. He was pretty cool headed about it, but wasn't too thrilled that I was coming in loud and clear over his computer speakers and clock radio (when it was on). Turns out he holds some ham license, but hasn't been active in a while.

Anyway, we did a few tests, I put an old Johnson LPF inline, with no improvement, and also tried swapping out the 979, which I know doesn't have a clipped mod limiter or any of that (stock radio, tuned up by DTB). Neither showed any improvement on his end. The problem is probably exacerbated by the fact that the antenna is on the side of the property next to his house, and virtually parallel to his house. I didn't want to go too high on the mast to avoid poking the already huge antenna super high in the air.

Any ideas on cutting down the RFI? I know computer speakers are pretty notorious for being susceptible to RF, and it seems interesting that I was coming through his clock radio, tuned to a FM station. Hes a nice guy and I would hate to keep bleeding his electronics. If I can't find an acceptable solution, I might have a like-new antenna for sale soon.

 

[RT2020]

I was bleeding on my own computer speakers and I just put ferrite beads on my coax and it took care of the problem.

 

[Robb]

If he is a Ham and working with you; then he might know about putting bypass capacitors on those troubled speakers. Add toroids on the power cables for those devices too.

It could be that the fundamental freq is too strong. IOW; you are just too close to him and that result is unavoidable. But it should be fixed with the caps and toroids. Keep that LPF inline too.

 

[buickid]

I was bleeding on my own computer speakers and I just put ferrite beads on my coax and it took care of the problem.

Thanks for the advice! The snap on beads would work right? I assume I put it on the radio end of the coax?

If he is a Ham and working with you; then he might know about putting bypass capacitors on those troubled speakers. Add toroids on the power cables for those devices too.

It could be that the fundamental freq is too strong. IOW; you are just too close to him and that result is unavoidable. But it should be fixed with the caps and toroids. Keep that LPF inline too.

Thanks also for the advice. I told him that my radios were pretty much stock and that it was just RF overloading the electronics rather than splattering occurring. He was a little against ferrites and mentioned that he'd rather not have the spectral impurities, but I guess without a spectrum analyzer, no one can really say whether its me splattering, or inadequately shielded electronics. He mentioned back in the 70's, he would trip GFCIs and put some bypass caps in his circuit breakers heh. The ferrite beads and toroids serve the same purposes right? I think I might go buy a couple and take them over to him today. I plan to leave the LPF in there.

 

[Marconi]

Hey buickid, humor me a little.

Take the filter out of line and add a 9' foot jumper or as close as you can to your feed line, and let me know if that helps your RFI issue. This is just a test idea from another thread, where no body really tested the idea about common mode currents. I doubt it will work, but I would like someone to test the idea.

I have estimated that your antenna is about 18' feet high to the feed point. If this is height is wrong, then let me know and I'll fix my Eznec model of the Vector.

 

[buickid]

Hey buickid, humor me a little.

Take the filter out of line and add a 9' foot jumper or as close as you can to your feed line, and let me know if that helps your RFI issue. This is just a test idea from another thread, where no body really tested the idea about common mode currents. I doubt it will work, but I would like someone to test the idea.

I have estimated that your antenna is about 18' feet high to the feed point. If this is wrong, then let me know and I'll fix my Eznec model of the Vector.

Hey there, I would love to try that out, but I am fresh out of coax... I have a 6' LMR400 jumper that I could take out of the mobile, or a 3' LMR400, but no SO239-SO239 couplers. The antenna is at about the top of a 10' mast, buried about 1.5' deep. The problem is, there is a tree next to the antenna on the neighbor's side, as well as my house and theirs, both within 27' or so.

 

[Marconi]

Hey there, I would love to try that out, but I am fresh out of coax... I have a 6' LMR400 jumper that I could take out of the mobile, or a 3' LMR400, but no SO239-SO239 couplers. The antenna is at about the top of a 10' mast, buried about 1.5' deep. The problem is, there is a tree next to the antenna on the neighbor's side, as well as my house and theirs, both within 27' or so.

Wow, IMO and real world experience that is pretty low for a working antenna. But, the old Vector design is noted to be less effected by stuff around it so it can work in moderately confined areas, but not that low, unless it was in a flat medow with nothing around maybe.

I tested my Sigma4 sitting on the ground and it worked, but the signals were severely attenuated, because the houses around are all about 18' feet to the peaks, so the signals from the bottom of the antenna, where most are generated, were blocked somewhat.

In my case I didn't have any mast at all as the feed point was only 1' foot from the Earth, and it acted really bad with electronics nearby. All I was doing was testing the match.

This is strictly a proximity problem, and it is unfair to think you can fix it without raising the antenna higher. Homer talked about this very subject in another thread working in the antenna section as we speak.

It wouldn't even do any good to bother trying the jumper idea if your antenna is on a 8.5' mast. IMO there is nothing that will stop your interference with your antenna being that low. The RF is coming straight from the antenna itself and is broadcasting directly into the neighbor's house and everything else around the area.

That is not really giving the antenna a chance to work near its best either.

Good luck though.

 

[Highland Ranger]

I had the opposite happen. Antenna 8 feet off ground no rfi, 20 feet up and rfi.

Sent from my Nexus 7 using Tapatalk HD

 

[BOOTY MONSTER]

why don't you stick the antenna on the side of the house above the peak of the roof line ? you can also try a coax choke at the feedpoint of the antenna to help reduce CMC's on your feedline ..... if their present .

 

[Lil'Yeshua]

The neighbor mentioned spurious emissions. Anything related to the radios you're using,how they're tuned?

 

[M0GVZ]

8 turns of RG58 on a FT240-61 toriod placed as close to the antenna feedpoint as possible should solve all your problems.

DO NOT tape or tie wrap the coax to the mounting pole after the choke or you've just defeated the whole object of putting in a RF choke.

 

[Shockwave]

You're neighbor is wrong thinking this has anything to do with spectral purity or harmonics. Ask him what frequency the PC speaker is working on that has any harmonic relation to CB? The problem is direct RFI and will only be cured by installing ferrite beads on the wires of the clock radio and PC speakers. The TVI filter also does nothing at all because the interference has nothing to do with harmonics.

 

[buickid]

Hmm, thanks fellas, I will reassess my options. Perhaps a base station isn't in the cards at the moment. I'll take a few ferrite beads over to my neighbor and see if they help at all. Gotta finish tying my ground rod into the mast too. I will post updates as the situation evolves!

 

[Mudfoot]

If he is a Ham and working with you; then he might know about putting bypass capacitors on those troubled speakers. Add toroids on the power cables for those devices too.

It could be that the fundamental freq is too strong. IOW; you are just too close to him and that result is unavoidable. But it should be fixed with the caps and toroids. Keep that LPF inline too.

My guess is that this guy thinks ferrite beads are cheap jewelry and toroids are from straining to hard.

Give the guy some split beads for his Odd Lots speakers and a choke or toroid for his junky clock radio.

 

[N5IT]

Hmm, thanks fellas, I will reassess my options. Perhaps a base station isn't in the cards at the moment. I'll take a few ferrite beads over to my neighbor and see if they help at all. Gotta finish tying my ground rod into the mast too. I will post updates as the situation evolves!

It would certainly be a good idea to make your antenna pole or tower ground a priority issue. This is not only good standard radio practice, but it can make a big difference in the magnitude of surge current that can occur and enter your home in the event of a lighting strike. Trust me, I've been down that road and the scenery wasn't pretty.

In dealing with your RFI issue, you may want to try to purchase several different varieties of clamp-on ferrites, unless the type of ferrite material is specified. Although length and cross-sectional area of the ferrite is also a factor, the material type will primarily determine the amount of attenuation of the rf currents in your neighbors speaker and power cables etc. Type 43 is a more commonly available material that would likely work satisfactorily at 27 MHz, but type 61 would be more effective.

You may also use larger round toroids as others have suggested. The advantage here, is that you can place several turns of wire or cable through them to achieve a much greater impedance to the rf currents. What ever type you end up with to combat the RFI, having some options will give you a better chance of resolving the issues the first time around. It might be a good idea to make a choke balun for the feed point of your antenna first, as the British ham operator mentioned in a previous post. That could solve the problem without having to deal with the neighbors equipment. Good Luck!