Shortwave radio interference

[chriswaz]

My neighboor is a shortwave radio guy, but not a very helpful or friendly person. His shortwave radio transmissions (I think they range from 2-30 Mhz) can interfer with my viewing. I've read about high pass filters (i.e. universal-radio.com/catalog/hamacc/2914.html) that would seem to filter out these transmissions from the signal, but I'm not sure if they would cause other problems for my directv or ota signal.

Is there an issue filtering these high Mhz ranges (0-52MHz) for Directv (either SD or HD) signals?

I've already got Quad Shield cable and that doesn't prevent the interference. If these filters won't work, is there something else I can do to keep the signal free of this interference?

Thanks.

[Earl Bonovich]

A pair of wire cutters, and a ski mask?

Sorry.... I really don't know.... for this one you may want to go over to AVSForums

[litzdog911]

Tell us more about how your DirecTV Receiver(s) is connected to your TV. Ham or CB radio frequencies really should not interfere with satellite signals, but they can couple into the TV's RF tuners. So using an RF coax connection between the DirecTV Receiver and TV over Ch3 or Ch4 is a bad idea. Using an SVideo or composite video connection will be better.

Here's an easy way to see where the CB/Ham radio signals are coupling into your system ....
Disconnect the satellite coax from your DirecTV Receiver. Do you still the inteference? If so, you know it's NOT coupling in from the satellite coax.

[chriswaz]

I'm 99% sure that it's coming through the Satillete Coax because it will show up in DVR recordings (SD-DVR40), so I can replay the interference over and over again.

My Setup is:
Satellite -> Multi Switch -> Sat Receiver DVR (all using Quad Shield Coax)
From the Sat Receiver to AV Receiver using S-Video
AV Receiver to the TV using S-Video

Unfortunetly (and fortunetly) shortwave transmissions tend to be short. This means that the interference comes and goes which makes it hard to troubleshoot, but most of the time the interference isn't there. On occassion though, he'll be transmitting a lot, and in those cases I can have 15-20 minutes of interference (usually on the video, not the audio); when I'm home I just go over and tell him to stop, but when I'm out there is nothing worse than coming home to find my recorded show is hard or impossible to watch.

This has been going on for a while, but seems to have gotten worse over the past month or so. A few months back they tried to sell their house and move, so I thought that the situation would just go away, but the house is off the market so now I'm looking for a real solution.

I did some reading and it sounds like the newest Directv AT9 dish will use 250MHz - 2150MHz, so putting a 0-50 Mhz filter should be ok.

I'll probably just go to Radio Shack this weekend, buy a couple and see what happens. Worse case I can always return them if they totally prevent usability. The worst situation is that it's not coming through the cable, but that my proximity to the transmitter (probably 30 feet away), is allowing interference into the actual components themselves. I have no idea how to adjust for that, or if there is some sort of FCC regulation that I can shut him down with.

[litzdog911]

You'll need to make sure that those Low Pass Filters also pass DC, or the switching signals will be blocked. Let us know how you make out.

[boba]

Your probably barking up the wrong tree. Standard D* broadcasting uses 950-1450 Mhz and the new AT9 will use 250-2150 all well above the 50 MHZ filter you are writing about. The only time you should see interference is when he is transmitting and if his equipment is meeting FCC specs. you shouldn't see any interference.

[paulman182]

"My neighboor is a shortwave radio guy, but not a very helpful or friendly person. His shortwave radio transmissions (I think they range from 2-30 Mhz) can interfer with my viewing. I've read about high pass filters (i.e. universal-radio.com/catalog/hamacc/2914.html) that would seem to filter out these transmissions from the signal, but I'm not sure if they would cause other problems for my directv or ota signal."

I am also a shortwave radio guy, and I compliment you on your reasonable approach to the problem.

Many people do not realize that the problem could be either on the receiving end, transmitting end, or both. You do realize this and are looking for a solution, instead of pointing fingers, and I compliment you for that.

I would first ask if your system is well grounded? Sometimes signals can ride in on the ground connection if it is too long or simply not connected.

Then I would recommend you go to www.arrl.org and search for advice from the American Radio Relay League, the national association of radio amateurs. They will also be impressed that you are making an effort to solve this from your end. I am sure there are links on that website, or email addresses, that will help you out.

Also, do you know for a fact that your neighbor is a licensed radio amateur, or could he be an illegal CB operator? CB equipment operating off-frequency or with too much power would be far more likely to interfere with a neighbor, and much harder to fix.

Good luck!

[Cap'n Preshoot]

I think I would first attempt to find out of the neighbor is a bona-fide, FCC-licensed Amateur Radio Operator (HAM radio) or is an unlicensed CB radio operator.

The FCC-Licensed HAM operator can legally use up to 1000 watts (2000w peak envelope power). By contrast, the CB radio operator cannot operate with more than 5 watts.

A legally-operating 5-watt CB transmitter will not under ordinary circumstances, cause any interference. However, many CB operators flagrantly violate this power restriction.

If the neighbor says he is a licensed HAM radio operator, I would ask to see his license. If he's genuine HAM operator he'll be proud to show it to you. Make note of his callsign, then look him up at http://www.qrz.com to see if the info he gave you matches. Most HAM operators are decent folk and do not want to interfere with your TV viewing any more than you want them to. Maybe let him know what your viewing hours are or when you'll be taping something and ask him if he would mind observe "quiet hours" during those times.

On the other hand, if he is a CB operator or answers in a deceptive manner I would turn him in to the nearest United States District Attorney at my first opportunity. Don't bother with the FCC. The US Attorney's office will deal with him.

[Earl Bonovich]

I'm 99% sure that it's coming through the Satillete Coax because it will show up in DVR recordings (SD-DVR40), so I can replay the interference over and over again.


What kind of interference are you seeing?

As it being a digital signal, you would brakeups... not ghosting or lines.

[carl6]

You might also try putting some type of filtering on the power cord going into your tivo. I think it is more likely that is where the interference is getting to you.

Due to the significant difference in his transmitting frequency and the satellite frequencies, it makes me doubt that is where the interference is coming from.

Carl
also a ham

[Cap'n Preshoot]

You might also try putting some type of filtering on the power cord going into your tivo. I think it is more likely that is where the interference is getting to you.

Due to the significant difference in his transmitting frequency and the satellite frequencies, it makes me doubt that is where the interference is coming from.

Carl
also a ham

I'm inclined to agree with Carl6.
Likely it's brute force interference that getting into the power line.
Go into someplace that sells computer networking equipment and cables. See if they have any media filters. These are split ferrite cores that you can snap-over the power cord as near to the appliance (TIVO) as possible. Also put one on the TV power cord and over the coax cable where it attaches to the STB.

In the old days we could go into a TV repair shop and talk the guy out of an old flyback transformer, cut the windings off of it then wrap the TV power cord through it 3 or 4 wraps.

[bobnielsen]

i'm seeing zero problems with my ham equipment (running up to 600 watts) getting into my DirecTV setup, although I have had a few occasions where it got into the input lead of my subwoofer (a split-core ferrite filter from Radio Shack took care of this).

[chriswaz]

Thanks for the great advice. I'll get some ferrite cores as well and see if they and/or the hi pass filters improve the situation.

The interference does not appear to be digital, but rather the whole screen gets horizontal lines that move up and down.

The system is well grounded. Everything goes through a surge protector which has a three prong plug to the wall. The house is less than 5 years old, so I know the wiring is ok (and just be sure I bought and tested with an inexpesive line tester), so the grounding is solid. Thanks for that link, I'll definetly look through both of those sites. I haven't had a lot of luck talking with him, but once I try a few things on my side, if that doesn't work I'll try again.

I hadn't thought about the power cord, but anything is possible. The Ferrite Core/Beads sound like they could really help with that. Do I need to worry about the other wiring like the Component, RCA or S-Video? Not there yet, but what about HDMI? I assume the optical are ones are okay.

Looks like I have some shopping to do this weekend. Thanks so much for all your advice.

[chriswaz]

i'm seeing zero problems with my ham equipment (running up to 600 watts) getting into my DirecTV setup, although I have had a few occasions where it got into the input lead of my subwoofer (a split-core ferrite filter from Radio Shack took care of this).

I assume you're equipment is operating within specs. Could it cause interferences if it was not operating properly?

[Earl Bonovich]

The interference does not appear to be digital, but rather the whole screen gets horizontal lines that move up and down.


One thing to try to narrow it down....

Take your DVR... over to a friends house... far far away from the HAM..
And see if the interference is still there.

Then you will know if it is from the incomming signal, or something with your DVR -to- TV connections.

Do you see the interference when say using a DVD Player or (gulp) VCR ?

[bobnielsen]

I assume you're equipment is operating within specs. Could it cause interferences if it was not operating properly?

It might, but there are so many possibilities it is hard to tell. A lot of devices just aren't designed to work in the presence of strong r.f. fields.

[N5XZS]

Cap'n Preshoot,

1 and half little errors are listed here........:hurah:

1000 watts wrong, it's 1500 watts PEP, and as for CB radio 4 watts for AM mode and one you did not mention is 12 watts SSB mode.:)

Just a little clear up on informations FCC"s rules on radio hobbies!

9-20-06

[Cap'n Preshoot]

Cap'n Preshoot,

1 and half little errors are listed here........:hurah:

1000 watts wrong, it's 1500 watts PEP, and as for CB radio 4 watts for AM mode and one you did not mention is 12 watts SSB mode.:)

Just a little clear up on informations FCC"s rules on radio hobbies!

9-20-06


Well, picking nits a little, but thanks all the same. 12w SSb is PEP, and that's before 'Soda Pop' has the area X-spurt and screwdriver mechanic install a switch for him to bypass the ALC. Sounds like heck & splatters beyond description but it will sure make the wattmeter jump esp. when there's an amp attached.

Wouldn't you agree though that under normal circumstances that it would be somewhat unusual for a legally operating Citizen's Band transceiver to be causing the severity of interference as the original poster is experiencing?

On the off-chance the cause turns out to be CB and he cannot get relief by trying to be nice and all else fails, then fighting fire with fire is sometimes necessary. A very effective method requires only an 18 kv neon sign transformer, spark plug and couple of 9' pieces of wire strung together between a couple of clothes poles. As dangerous as it sounds this lashup has been known to paralize it's share of 27 Mhz receivers for several hundred feet in all directions. When his S-meter is buried by the buzz he sure won't be doing much transmitting. Maybe put a timer on it to come on every evening during prime time. Maybe add a motorized cam-operated switch (old washing machine or dishwasher timer) to pulse it at odd intervals. Not serious, just thinking out loud....

[kenglish]

But, you'll be interfering with everything from DC-to-light, and then someone will call the cops on you!

[kenglish]

I would suggest trying some large ferrite cores, or a real honest-to-goodness RF Filter on the power cords that feed all of your A-V stuff.....you'll need to filter off the signal that is riding along on the AC cords in to each piece of gear that is connected together (otherwise, it's like fixing only one hole in a boat!).

A well-filtered plug strip might work for everything, if you have all the individual cords coiled up fairly short. Otherwise, they might act like small antennas, too.

In addition, a ferrite core should be used on each RF cable, such as from the dish and TV antenna.

The ARRL usually has people in each area who are experienced in troubleshooting this sort of thing. You could call or e-mail them and ask if they have a Technical Specialist in RFI (Radio-Frequency Interference) in your area. It would be helpful if the "Ham" next door would contact them as well. Also, you can find some good info on the ARRL website, by using their search engine, looking for "TVI". A Google or similar search engine may help as well....although the ARRL search will be more in line with ham radio frequencies and their "fixes".

[luv2fly3]

Wow, as a Ham Radio operator, I surely hope my neighbors are like you! I agree with all that's been suggested relating to going after your power source as a potential for the interference. I'd go after that before worrying too much about the signal from your dish given the frequencies used by Hams. I'd also agree you should check your grounding. I know my D* installer did a less than stellar job making sure my grounding was done properly. I had to redo it and make sure all the connections were tight.

I do commend you however on your patience and working through the problem, rather then using the "wire cutter and ski mask" approach!! As a ham operator, I'd sure help out if you were my neighbor and the problem seemed to come from my transmissions regardless of if the problem was truely on my end or yours.

Good luck.

Lars
(K8LEC)

[Igor]

Thanks for the great advice. I'll get some ferrite cores as well and see if they and/or the hi pass filters improve the situation.

The interference does not appear to be digital, but rather the whole screen gets horizontal lines that move up and down.

The system is well grounded. Everything goes through a surge protector which has a three prong plug to the wall. The house is less than 5 years old, so I know the wiring is ok (and just be sure I bought and tested with an inexpesive line tester), so the grounding is solid. Thanks for that link, I'll definetly look through both of those sites. I haven't had a lot of luck talking with him, but once I try a few things on my side, if that doesn't work I'll try again.

I hadn't thought about the power cord, but anything is possible. The Ferrite Core/Beads sound like they could really help with that. Do I need to worry about the other wiring like the Component, RCA or S-Video? Not there yet, but what about HDMI? I assume the optical are ones are okay.

Looks like I have some shopping to do this weekend. Thanks so much for all your advice.

Interesting issue:
1) Interference into D* digital signal would create blackouts (loss of lock) or macroblocking. This is not the case.
2) D* DVRs record the digital signal, there isn't any digital-to-analog-to-digital
3) You say that the DVR records the interference.

If you had a standalone DVR connected to a D* receiver, the interference could cause the issue you are describing. But given that this is not the case :confused:

My guess is to analyze the grounding scheme and filter the powerline.

[Cap'n Preshoot]

But, you'll be interfering with everything from DC-to-light

Well yes and no. The 2 two 9' lengths of wire between the output terminals of the transformer and the spark plug, should prolly be 18 feet each stead of 9 and arranged in sort of a small rhombic fashion with the spark plug end favoring the general direction of our "target". This length of wire would serve to concentrate most of the resulting wideband 'noise' between 24~30 Mhz. Granted it's going to be detectable from "DC to Light" but not for any significant distance and certainly no worse than an old Diathermy machine with raw AC on the plates. A few of the quackropractors still have these things tho they were outlawed (Federal) years ago. Unlike diathermy (typ. 1/4 kw) there's no real "power" with this lashup, a couple milliwatts or so and it's not like we chunked the thing high into a tree. I doubt you'd hear it a block away. But for what it's purpose is, I can almost guarantee results. Right next door it'll have his receiver front-end paralized and appear to be so strong he won't be able to DF it. Don't run it all the time, just when you're wanting to watch or record something. The intermittency alone will make it hard to find. :)

Somewhere I heard you can tune the "sweet spot" of the thing somewhat by adjusting the plug gap. Start around .050 and tighten it up from there. Just make sure you remember to shut it off between "adjustments" cuz it'll sure bite! This "idea" came from W2NSD (73 Mag editor) about 30 years ago.

[bobnielsen]

Well yes and no. The 2 two 9' lengths of wire between the output terminals of the transformer and the spark plug, should prolly be 18 feet each stead of 9 and arranged in sort of a small rhombic fashion with the spark plug end favoring the general direction of our "target". This length of wire would serve to concentrate most of the resulting wideband 'noise' between 24~30 Mhz. Granted it's going to be detectable from "DC to Light" but not for any significant distance and certainly no worse than an old Diathermy machine with raw AC on the plates. A few of the quackropractors still have these things tho they were outlawed (Federal) years ago. Unlike diathermy (typ. 1/4 kw) there's no real "power" with this lashup, a couple milliwatts or so and it's not like we chunked the thing high into a tree. I doubt you'd hear it a block away. But for what it's purpose is, I can almost guarantee results. Right next door it'll have his receiver front-end paralized and appear to be so strong he won't be able to DF it. Don't run it all the time, just when you're wanting to watch or record something. The intermittency alone will make it hard to find. :)

Somewhere I heard you can tune the "sweet spot" of the thing somewhat by adjusting the plug gap. Start around .050 and tighten it up from there. Just make sure you remember to shut it off between "adjustments" cuz it'll sure bite! This "idea" came from W2NSD (73 Mag editor) about 30 years ago.

That sounds like Wayne, alright.

[Cap'n Preshoot]

That sounds like Wayne, alright.

Yeah, back then Wayne's disdain for the CB'er was secondary only to his hatred for the IRS. If you were a reader of his rag back when he got audited, you saw how really uncorked the guy could become.