| Author |
Message |
    
Linx
Junior Member
Username: Linx
Post Number: 30
Registered: 9-2006
| | Posted on Friday, October 20, 2006 - 8:33 pm: | 
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Hi,
I'm having some rf interference problems. I have searched the site and read every thread I could find on this problem.
Like most with high wattage, when I key up, I'm blasting my tv's audio output with interference. I am also interupting one of my neighbor's t.v.'s as well as one of his stereos (which is turned off and still getting the interference). I am looking for a way to stop the interference.
He's a rundown of my equipment:
I have a 41' tall Rohn 25G tower. On top of the tower is a 5' piece of pipe and then on top of the pipe is a I-max 2000 with the ground plane kit. I have one solid piece of coax going from the antenna, down the center of the tower and then to a PolyPhaser lightning arrestor. The PolyPhaser is mounted to the tower (shielded from moisture with a home made aluminum box). The coax then goes into the house from there through the crawl space. The tower and PolyPhaser are both grounded to an 8' copper ground rod, and are grounded with all copper.
The radio is an older President Washington base and a Cobra 148 GTL from my mobile that I transport to and from the truck. There is a Para Dynamics 1000 watt low pass filter on the end of the coax before the coax comes into my amplifier, which is a KLV 1000. The base stations are stock except for the 148 has channels, and both push 2 watts which is changeable at any time thanks to a watt/swr meter that I don't plug up until I use them. The coax I am using is all Astatic/Belden wire and is great quality.
In the morning I am going to go to Radio Shack to try and find a High Pass Filter for the TV and if needed a ferrite or something of that nature.
Besides a stand alone ground system for the amp/radio, can you guys give me some pointers of something I missed? The only other thing I have not done which I didn't feel was nessisary was to run a ground all the way down from the antenna to the grounding rod. I figured it was grounded already since the tower is all steel and connected.
A couple of other guys locally said it was the ground plane kit on the radio that is causing the problem, and a couple said it was the fiberglass antenna in general causing the problem.
I'm lost and don't know what to do.
Thanks for any help.
Rob - linx
CEF# 830
Portland, TN |
1861
Advanced Member
Username: 1861
Post Number: 579
Registered: 2-2004
| | Posted on Friday, October 20, 2006 - 9:06 pm: |
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COULD BE FRONT END OVER LOAD - MY GUESS |
Captian_radio
Member
Username: Captian_radio
Post Number: 63
Registered: 9-2004
| | Posted on Friday, October 20, 2006 - 10:15 pm: |
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Rob you could try something called an rf isolator, it consists of 19 ferrite beads on a small piece of coax mounted inside a piece of abs pipe.They are available through various radio dealers.This isolator is supposed to block any and all rf from traveling back down the shield of your coax.This rf is called the skin effect.I havent used one myself but it might be worth a try, as maybe rf on the outside of your coax could be causing some of this problem.
bob CEF451 |
Linx
Junior Member
Username: Linx
Post Number: 31
Registered: 9-2006
| | Posted on Saturday, October 21, 2006 - 12:09 am: |
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Bob, I've never heard of that! I appreciate the info. Ya learn something new every day.
I hated to start a new thread on something that has been discussed over and over again, but I wanted a thread taylored toward what I have.
I'm heading to the electronics store first thing in the morning, and I'll update! |
Slugo4449
Intermediate Member
Username: Slugo4449
Post Number: 122
Registered: 7-2004
| | Posted on Saturday, October 21, 2006 - 1:11 am: |
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There are many things you can do to uncouple the coax from the antenna so it doesn't radiate.
You can coil up about 6-8 turns of the coax just at the bottom of the antenna. This is called a decoupling loop.
You can add ferrite beads to the coax at the point where it attaches to the antenna. Just what Captain Radio said.
Or you can get a 1:1 balun, sometimes known as decoupling transformers. Make sure you get one with the proper power capabilities.
Did you say this was cable or satalite or just a regular TV antenna that your radio is interfering with?
Running a KW on CB is hard to keep from producing TVI or RFI.
Good luck. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2172
Registered: 9-2004
| | Posted on Saturday, October 21, 2006 - 1:18 am: |
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do not listen to the locals. usually ends up bad.
the paradynamics low pass filter is junk.
you need to buy a good one which will cost over 50.00 new.
definitely need to run a ground wire, solid, 6ga. minimum from the base of the antenna to the ground rod.
the groundplane kit is helping you.
i noticed you said "besides" grounding the equipment. is there a reason you dont want to do this?
it is very important.
if the gear does not have a short path to ground, it can radiate a signal on the house's ground wire.
you need to run a wire shorter than about 6 ft. from each piece of equipment inline to a ground rod that is right outside the shack.
this ground rod needs to be connected to the tower ground rod, and the ground wire from the breaker box needs to be tied in with both grounds.
if the coax you are using is less than 95% shielded, then you should replace it with better coax.
all that being said, if your radios are running clean, and the system is grounded properly, then you are just overloading the cheap electronics that are being interfered with.
the only way around this is to get the antenna further from them.
41 feet is not all that high if your neighbor is only 20 feet from your tower.
also, the KLV amps arent really known for their filtering.
running a good low pass filter after the amp should help.
good luck,
matt |
Linx
Junior Member
Username: Linx
Post Number: 32
Registered: 9-2006
| | Posted on Saturday, October 21, 2006 - 9:00 am: |
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Slugo4449: It's cable TV.
Kid_vicious: I guess I'll run the ground wire from the antenna to the gounding rod next time I lean the tower over. I just figured it was grounded if the base of the tower was well grounded. I didn't want to ground the actual equipment b/c I saw how everyone else had theirs grounded and it not only looks expensive, but I don't have a short distance like that outside the house other than just cutting a hole all the way through the exterior wall. As far as low pass filter, what is a good brand of filter? Also I read where some put them between the amp/radio and also one between amp/atennna. I had a feeling this para dyanamics one was junk.
Therealporkchop: I'm sitting on 2 acres but the house next to me is about 40 ft away. The radio is bone stock other than having the wattage turned down to 2 watts, which I did myself. Nothing in the radio clipped that I noticed.
Thanks for all the input guys/gals. I'm soaking it in and WILL make changes needed. |
Linx
Junior Member
Username: Linx
Post Number: 33
Registered: 9-2006
| | Posted on Saturday, October 21, 2006 - 9:03 am: |
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By the way, all the coax is belden and is 95% or better with capabilities of 3000+ watts (which I'll never run..I'm just trying to run about 200 watts right now!) |
Road_warrior
Senior Member
Username: Road_warrior
Post Number: 1995
Registered: 7-2004
| | Posted on Saturday, October 21, 2006 - 1:46 pm: |
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High pass Tv filters usually only work
if TV is hooked to an antenna.
If you have VCR or anything else in-line
with TV. Unhook everything and use just TV
and see if your still coming through.
Cable TV, make sure all connectors and coax
is good and you have no cable leaks. Wrapping
cable coax around a common mode choke may help.
Satellite TV, check poor grounding of the dish,
loose connections, use good coax from dish,
use quality patch cords.
Maybe you need a better quality low pass
filter after your amp.
Neighbors stereo may need wires shortened as
long wires act as antennas. chokes on the wires.
Start with your CB equipment first as
Kid mentions above. Get that corrected and
go from there. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2174
Registered: 9-2004
| | Posted on Sunday, October 22, 2006 - 6:18 pm: |
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if you get the ferrite chokes, put them on the neighbors speaker wires and power cords first.
long speaker wires and a cheap stereo equals trouble.
you have to decide what your priorities are. this is not computers where everything is modular and looks nice, this is radio, and it involves drilling a few holes here and there.
if you are not willing to drill a hole to ground it; you do not get to run a KLV1000.
it is not expensive to do. take a look in the MEMBERS PICTURES area at TECH808's install.
get some 6ga. solid copper wire, a ground buss bar from home depot, a ground rod, and whatever lugs you want to use for the equipment end.
pound the rod in right outside the shack, as close as possible, must be less than 8 feet to equipment.
attatch wire to rod, drill hole in wall, feed wire through. attatch to buss bar.
attatch short copper wires to bus bar and attatch other ends to equipment case screws, making sure it is attatched to the metal chassis of the equipment. these wires, plus the wire going from the buss bar to the ground rod, must be less than 8 feet long total.
good low pass filters are: Drake and Nye viking.
pretty much any that are offered in ham only catalogs are good ones. they are always more than 50.00
good luck,
matt |
Road_warrior
Senior Member
Username: Road_warrior
Post Number: 1998
Registered: 7-2004
| | Posted on Sunday, October 22, 2006 - 8:32 pm: |
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Read my last few lines in my post Kid.
Road_warrior  |
Chad
Senior Member
Username: Chad
Post Number: 1165
Registered: 11-2004
| | Posted on Sunday, October 22, 2006 - 10:51 pm: |
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200W At 40-sum'....... And the ability to run much more......
That's the problem.
I suspect front end overload and even with the cleanest rigs it will still exist.
Chad |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2178
Registered: 9-2004
| | Posted on Sunday, October 22, 2006 - 11:48 pm: |
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yep, shouldve read before i posted.
hope this all works out for you linx,
matt |
Linx
Junior Member
Username: Linx
Post Number: 35
Registered: 9-2006
| | Posted on Monday, October 23, 2006 - 6:31 am: |
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Thanks for ALL the suggestions. I'm going to buy a second, good quality, low pass filter today and have it mailed in. I'll see if that helps.
Most people don't think you should have to take care of your neighbors, but if it's still a problem, I'll fix their equipment as well.
If it's STILL a problem, then my only solution is proper groundeding, and I will have to ground it right and get over my issue of drilling holes.
I'll keep everyone updated. I bought a little TVI filter from radio shack that screws into the back of the TV, and it helped tremendously on my TV. Running low power, the TVI is non existant, running about half power, it makes a pop sound on the TV from time to time, and running full power I get just minimal bleed over.
My other neighbor is an older gentleman, and he has a satellite mounted so I figured he was using it, but he told me he was using an antenna in his attic. I know it has to be bothering him, but he's so nice he'd never tell me, so I just want to make it right on my end as best as possible, and then in casual talk see if it's effecting him.
Thanks again for all the help. |
Hotwire
Senior Member
Username: Hotwire
Post Number: 1927
Registered: 1-2005
| | Posted on Monday, October 23, 2006 - 9:51 am: |
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Check for leaks in your cable TV feed lines. Like a terminated end not connected to anything or a splitter with extra outputs not being used. Anytime the center conducter is exposed anywhere in your whole cable tv system it will act like an antenna for tvi. |
Tech237
Moderator
Username: Tech237
Post Number: 582
Registered: 4-2004
| | Posted on Monday, October 23, 2006 - 10:50 am: |
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Lin,
Also try raising or moving your antennas. I know neither is easy when you have atower but sometimes it has to be done. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2181
Registered: 9-2004
| | Posted on Monday, October 23, 2006 - 4:52 pm: |
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well linx,
for the neighbor using his roof antenna:
replacing the coax to his antenna would be a big help. its probably really old.
some ferrite on the coax also, and a high pass filter on his TV should really help.
i have offered to do the install if the neighbor would but the materials, and that has worked out well in the past.
matt |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2182
Registered: 9-2004
| | Posted on Monday, October 23, 2006 - 4:57 pm: |
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linx,
i just re read your original post and noticed that you said the low pass filter is going INTO your amp.
while this is a good thing, and is done because most radios are overmodulated and modded, you still need one after the amp to clean up the harmonics the AMP is producing.
try putting that para dynamics filter coming OUT of the amp and see if that helps.
a better setup would be the paradynamics going INTO the amp, and a better one going OUT of the amp.
good luck,
matt |
Linx
Junior Member
Username: Linx
Post Number: 36
Registered: 9-2006
| | Posted on Tuesday, October 24, 2006 - 9:46 am: |
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Hotwire: I've got 2 room with no TV and cable lines going to them. Is there some type of termination system I can get for these 2 rooms?
Kid: The older gentleman next door with the roof antenna has it in his attic. I'm not sure how old it is. I asked him to let me know if it caused any interference, but he has not said anything. I've talked with him multiple times since I put my tower up, and all is well. However, I just figured since it was coming in on my TV then it was probably coming in on his, and he's just being a good neighbor and not saying anything. I don't mind buying all materials and installing them on neighbors equipment. Everyone in talk locally with gets in fights with their neighbors all the time and are always getting the cops called on them making them turn their equipment off, but I'd just rather do the right thing before I have a grudge with my neighbor and get to the point of where those guys are at.
Kid: About the low pass..I had it on the end of my chain between the amp and my polyphaser outside. (all my coax btw is going through my central air/heat duct and then going out one of my foundation vents). We'll definatly try that out! Yesterday morning I ordered a Bencher YA-1 low pass filter which I saw in 2 different HAM magazines. I am going to put it between the amp and anenna, and then put this para dyamics between the amp and radio. I'm like you and am hoping this will work out nicely!
Thanks again for the help guys/gals! I installed a little TV filter on my TV from radio shack, and it worked well for about 2 days and now it's not, lol. It's probably b/c I tweaked out the amp and am running the amp drive higher. I'll keep ya updated. BTW, I asked the guy at radio shack about some ferrites and balun's and he didn't know what I was talking about, lol. Crappy radio shack, I know. Do you think coiling up some coax at the bottom of the tower will do the same as coiling it up at the top? I plan on laying my tower down sooner or later, but I didn't know if it had to be up top for that to work.
73, Rob - linx
CEF# 830 |
Tech237
Moderator
Username: Tech237
Post Number: 586
Registered: 4-2004
| | Posted on Tuesday, October 24, 2006 - 5:19 pm: |
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Linx,
You can get a termination resistor bulti into the F connector. I have several if you need a couple. Check any place that sells TV stuff they should have them. |
Tech237
Moderator
Username: Tech237
Post Number: 587
Registered: 4-2004
| | Posted on Tuesday, October 24, 2006 - 5:21 pm: |
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Linx,
Find a couple of dead computer monitors and use the cores the wires feeding teh thick Ultor lead is wound one. Should work the same. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2192
Registered: 9-2004
| | Posted on Tuesday, October 24, 2006 - 4:39 pm: |
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yep, its gotta be right at the base of the antenna to work right.
go to the members picutres area, and look in CHAD's profile. there you will find some nice pics of the one he built using hot glue, hose clamps, and PVC.
its quite cool, should be easy enough to make your own, and his works quite well.
good luck,
matt
BTW, the bencher is a good one! |
Linx
Junior Member
Username: Linx
Post Number: 40
Registered: 9-2006
| | Posted on Thursday, October 26, 2006 - 6:58 pm: |
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I'm going to maybe build one of those. I put the Bencher YA-1 on the system, and it did help out a lot more than that para dynamics low pass filter. I tried putting the para between the radio and amp, and then the bencher between the amp and antenna, and no matter what I did, I couldn't get it tuned in, so I took the para dyamics one off and I'm starting to get the other tuned in. I am going to try that other idea. I'd rather have no RF interference than anything right now, so I'm willing to try just about anything. I'll check out that dudes pics! |
Chad
Senior Member
Username: Chad
Post Number: 1179
Registered: 11-2004
| | Posted on Friday, October 27, 2006 - 9:30 am: |
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The Balun Helped with RF in the shack but after the tower hit the magic Imax 36' mark it was useless. Down low it helped though.
Me still thinks you have too much RF in too populated of an area 
Chad |
Gator44
Junior Member
Username: Gator44
Post Number: 20
Registered: 1-2007
| | Posted on Wednesday, January 24, 2007 - 8:11 pm: |
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Linx, just went through the same problem myself. my fix..well i did two tasks the same day so i really don't know what actually fixed the TVI problem! 1. I re-grounded everything over again,new wire to an 8' solid copper ground rod(compliments of ms. power co. buddy),and then i made a choke in my cable coax 5 3" wraps and zipped tied prior to entering the tv...wa-la now no more TVI anywhere. It was probably some bad grd. somewhere in my set up, but all is well now. Maybe this will help you.... |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2365
Registered: 9-2004
| | Posted on Friday, January 26, 2007 - 12:16 am: |
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TVI/ phone interference cured!
hi all, wasnt sure where exactly to post this.
hope its ok here.
i have been having issues with one of my neighbors over some interference to their TV and phone.
i found the cure and want to share it with you guys so you can try it if you are having issues.
i bought five snap on ferrite chokes that were the right size for RG8 etc... cable, and snapped them onto the coax coming off of my antenna, right at the feedpoint.
i did a test with the neighbor and all is clear.
NO TVI or phone interference.
i found these on the auction site by searching for
TVI RFI EMI filter.
good luck, and i hope this info helps someone.
matt |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2367
Registered: 9-2004
| | Posted on Wednesday, January 31, 2007 - 10:52 pm: |
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good deal with the TVI cure gator!
the ferrite worked for me, but i like the idea of making a coil out of the cable TV coax.
cool thing about the snap on ferrite beads is that if they dont work on your antenna, you give them to the neighbor and have them put them on the power cords and speaker wires of the equipment you are interfering with.
good info here.
matt |
