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How to build a jammer Answered

Hi All,

I'm a new member living in the UK and don't know anything about eletronics.I am looking for some help on how to block my neighbours radio signal-He is a radio ham  and everytime he is transmitting i get the whole conversation through my  radio, hifi and stand alone TV's and anything that has a speaker attached to it-sometimes get lines through my TV.

Hope you can help

Best regards

Tony Mac


It is not clear if he is a Ham Radio operator or a CB radio operator. The latter is often less technically proficient and therefore often less likely to help with the problem. If the transmissions are ALL understandable, then they are probably AM (not SSB - 'single side band' and not CW - 'code') and this might be an indication of type of radio enthusiast next door. Also, if the neighbour says ‘break break’ a lot, then he is probably a CB Radio operator.
What is the person’s call sign? IN GB, if his call starts with:
G (and a number)
GM (and a number)
M (and a number)
MW (and a number)
MI (and a number)
…and other similar prefixes, then he is probably a radio amateur (Ham).
It is not clear who is at fault. Granted the writer above is being interfered with, but it MAY be that the problems are with the writer’s equipment. Manufacturers of equipment have to compete in a global market and cost is the driving force and installing even the simplest RF filters cost money.
My stereo picks up CB radio from passing trucks. I am suspicious that the CB’ers passing by my home are using linear amplifiers (running too much power and using not approved equipment). If this is the case with your neighbour, then my understanding of the law (in most countries) would mean the neighbour is at fault. But even then, I could install filters (chokes and line filters) and I am confident that is it possible to make my stereo RF interference proof with a little bit of work. (This kind of work may need to be done by a professional.)
There are many good publications on this topic of RF interference. Check with the ARRL www.arrl.org/ or the Radio Society of Great Britain http://www.rsgb.org/ (I have not done a search of these sites recently for this topic.)
Another source of information is: http://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/h_sf06086.html This web page is produced by the government agency in Canada who is responsible for the radio spectrum.
Contacting a local Ham Radio club is a good idea. The hams in Great Britain are well organized and most large clubs have an interference committee/group which can help, and may help even if the neighbour is not a ham radio operator. Remember, these committee members are all volunteers.
In general, just because a person is receiving interference does not mean the neighbour is at fault. Investigations by competent persons are required.
Hi to Ross, VE1BHE, who I do not believe I have ever ‘worked’ – not yet anyway.
Paul, VE1AVD.

If I'm not mistaken, a jammer would merely put MORE noise on the air.

Have you talked with the guy about adjusting his equipment to stop interfering with yours?

Yeah your right, so i have not ventured down that route,the relationship between us is strained at times but what miffs me is the attitude of the guy,he does not work,he claims benefits and talks like he owns the land!

I can see that it would be difficult to bring up the subject.

Maybe he doesn't know his conversation is on your equipment. A slightly underhanded approach would be to chat with him about specific details of his conversation. For example: " hey neighbor, hows it going with that(insert detail from his conversation he thinks was private)"

Or you could learn enough about the subject to make a suggestion that would allow you both to be happy. Like blkhawk wrote, maybe if he has the right filter, he can happily talk without messin up your stereo.

He is fully aware of the problems he causes me and other neighbors each time he transmits,He actually thought i had some sort of jammer because he came calling one day with a gizmo in his hand saying i had such a device,which i don't.I don't get the levels i once did, in terms of volume but do get some most nights on my PC if i have the speakers turned on. I have tried OFFcom and they just buried their heads in the sand just like the local council so i'll keep sending the emails and see what can be done,Watch this space!lol

You don't need a jammer, as that places you in the same bracket as the ham operator.

If you can't just talk to him, you need to report him to OfCom.  The interference you are suffering is probably a breach of his licence.

It is Definately against FCC rules fo interfere with anyone locally.....and as Kiteman points out, you'd do better with a "filter" rather then a jammer.

If he is on the proper channels, then he may be upping his power output over the top and some of the resonance is forcing itself onto your equipment.  

Ok thanks Goodhart.

Where can i buy a filter and where do i insert it?Apart from the obvious!


A google search for "inline filters" or low pass inline filters will give you a plethoria a sources

Thanks Goodhart for the excellent advice,totally appreciate your help
Thanks again
Tony Mac

Of course, the first thing you want to do is talk to the fellow about his "arrangement" and power out put.  If he is not reasonable about that, he may indeed be in violation of his license and the link Kiteman supplies would help with that.   If that is not the case, you are on your own to stop the interference.

Frequency filters are available, or if you have background in radio electronics, you can build one -  at this site, there is one for filtering out TV interferences.

 You may find info on what you would need here, at this filter site.  But maybe not.

At the following site, there is an explanation of filters and some circuit diagrams to follow.

There are also KITS available if you are not adventuresome enough to tackle it from schematics and explanation.   And finally, DigiKey has some passive filter kits also (as I would assume Jameco and others have)

And a few more "design" sites.   And a tutorial.

Talking to him is no longer an option as he has took umbrage to me complaining about it-When he first took this hobby on we were on good terms an slowly he has built up his masts around his property,Four in total, the roof one has been up for four years and last year he altered it to a far larger mast than prevoius.I complained to my local council about the size of the new mast but because the previous mast was installed four years previous without any challenge from me he does not require planning permission.He his very knowledgeable on local planning requirments it seems, which rises my suspicion that it was his intension all along.

Thanks again for some good product liks,i'l have a perusal when i get a mo
Best regards

I also have a neighbor who dose the ham radio to make people mad FCC dose nothing for 3 years I need something to send a pulse or somthing to interup his signal Its time for me to interrup him I need Anyons help Thanks all our neighbors

If you're real close, and in the induction fied from the antenna, you get very strong coupling to the transmission - and its not the Ham's fault.


In the USA, it would be his fault. I'td mean either he had equipment that was more powerful then legally allowed by a "local" operator, or it'd mean he was operating outside of the bands he was supposed to.

This simply because it "does" interfere.

From what i can gather in the UK all you have to do is pass an exam and bingo! The have a large lobby group based over here and seem to get their own way a lot-His fall out shall we say reaches neighbours 30 yards away,I've sent an email to people who have supplied his license so just awaiting a response.


This is pretty much true in the USA too, but the problem is, if he "passed the exam" and got a license, he still needs to operate legal equipment at legal power ratings, and he has to do all this "legally". If he is not doing so, he needs to have someone "set him straight". :-)

Just waiting for the people in power to have a word in his shell!

Cant wait!!

In our population densities, its much more likely its the induction field from the antenna. AFAIR, Induction field falls with the 4th power of radiusl, so its neglible pretty quick.

Ok, I just know that if I had a Ham radio, and it interfered with another piece of equipment in the apartment (flat) next door (shared dividing wall), here in the USA....the FCC would be knocking on my door :-)

Its the antenna that's doing the interfering I suspect - the transmitter isn't usually the culprit

Hmmm, I know we have "CB" users that broadcast "more power out" then legally allowed. I assumed that could be accomplished with any similar radio. If "every" speaker is picking it up, it does sound like a strength issue, but this is not my "forte`" so I may be out of my league here ;-)

His speakers aren't picking up, his amplifiers open inputs are. What happens then is caused by non-linearities in the inputs demodulating the incoming RF.


Yeah, I have made more "am radios" in my life then any other type of audio equipment, and only one of them was "on purpose" :-)

I remember as a very cocky 14 year old electronics expert building an intercom for my uncle, which picked up the local radio incredibly well !


My first project in audio, YEARS ago, which I bought from Radio Shack (back when they carried a lot of components) which was built around this chip (or something VERY similar, was an amazingly clear "am recorder", picking up and recording the local station a little better then my own voice which went into the (then) crystal mic I had for the project. :-)

I still have that chip and board (somewhere)  :-) Of course, this was long before I learned about "filters" and harmonics . . .

Here, transmitting equipment is stamped by the FCC as none interfering and that it can not interfere with the normal operation of other equipment. If it does, it is both a radio license breach and "harassment". :-)

We have the same rules, but If you put perfectly FCC or CE compliant transmitters in the same room with an antenna you're still stuffed. FCC approval is granted under approved test conditions. If someone installs it slightly wrongly, its "compliant", but not compliant.

Thanks for your input Steve but you missed out consideraion for the neighbour-this guy is the exception to the norm so why should i need to buy filters! He doesn't work and i think he has a long enough window during the day to play with the it! His hobby has turned into and obsession with it unfortunately!!

Thanks again

Ok, so don't they have similar rules? I'd think it odd that a developed country would allow just anyone to interfere with any piece of equipment like that.

I'm merely saying FCC rules don't apply; not saying they don't have similar rules.

Understood, sorry if I took it the wrong way :-)

Thanks Kiteman but the relationship has deteriorated between us so i think i'll let ofcom deal with him,

I believe that your neighbor needs a filter so you are not bothered by his HAM transmissions. You should have him reported to your national communications agency. In Britain is OFCOM.

OK thanks for your input ,much appreciated.
Best regards

in the USA, such things are a breach of Federal FCC laws. Equipment is not supposed to interfere with others, especially that far from the equipment.

Yes i heard they have better control in the US,shame they don't have the same in the UK,it seems that if you pass the exam you can do as you please with no control what so ever.The range of his transmissions extends to homes fifty meters away, i have written to OFCOM and,my local council and it's like they don't want yo know ,they say we should sort it out between neighbors,well i have tried all that and he still at it 24/7.Grrrrrrrrrrrrr

other than constructing or buying narrow band filters for all your equipment, I don't know what else you can do (if they are unwilling to stop or cut back).



5 years ago

my neighbor bleed thru all the time. we had to unplug the china hutch cause he kept triggering the touch censor light and i think he killed my router. about 2am in bed sleeping and the ceiling fan light magicaly comes one. soo frustrated and beyon talkin anymore

Same here,we have not spoke for over a year and he is still on his radio 24/7. which country are you from?

WOW, that just would not be tolerated here by the FCC

So. Cali and his daughter says he tries to talk to china.... funny but not anymore


5 years ago

Someone needs to be banned... as soon as possible!


6 years ago

As a ham myself, it is good operator practice to help the neighbor out of his problems. If the signal is coming out of your speakers on a Hi Fi system, then get some .01 mf Capacitors and put them accrost the speaker.

If he is a CBer then he may be using too much power.

If he is a Ham, then he might be overdriving his transmitter,


Hi Ross,

I have not had any intereference since i wrote to the licence body in the uk but thanks for taking the time to give me advice.

much appreciated


Hi Guys,me again.

Re:- Update.

I put your very good advice in action and wrote to the radio society (UK) who supply him with his license and things have been very quiet lately.

Strange thing happened last last night though,my house alarm went off twice for no apparent reason and i was thinking if it may have been caused by my neighbour next door ,is it possible for that to happen?

Best regards


Does your system tell you which sensor was tripped?