Oh no! Knock on the door from neighbour whilst txing on SSB

[G7IVJ]

Gents (and any ladies?)

Thanks for any help in advance.

Name is Simon, located in Surrey - in a very residential area with houses all around me.

This afternoon was enjoying a 4m AM contact using the moxon rectangle (horizontally polarised) operating 50watts and: Ding dong. "hello mate, I live up the road and I can hear you perfectly through my PC speakers". He explained he works from home and is in front of his PC most of the day. He went on to tell me he has had this problem many times and decided now to contact me about it.

I took his phone number and explained we need to do some tests.
So I hurried back into the shack - scratched my head a bit and phoned him up and asked him to sit infront of his PC.

Tests I carried out:

Plugged into the vertical - tried 60watts AM, SSB and FM - all fine no interference.

Back to the beam: FM 60 watts was fine! (horizontally polarized)
SSB of course was about 50% as loud as he could hear me on AM on the beam. Dropped output power to about half and he said it didnt make much difference on AM or SSB

The beam of course is pointed north east - directly at his house which is not surprising. His house is about 100 foot away from the beam.

He is not my direct neighbour - and I havent had complaints from direct neighbours but that doesnt mean much.

Ok - so next test I tried was installing a high power low pass 4m filter between the amplifier and the antenna at the shack end - this is commercially made by cross country wireless and lucky I had one at hand - unfortunately this did not fix the problem, he could still hear it as well on AM and SSB with the moxon.

So - I dont mind losing AM on the beam - there are not many AM operators anyway, and the ones there are operate vertcially so I am happy to use AM via the vertical which as proved doesnt cause him any problems.

But I dont want to lose directional 4m SSB. So, before suggesting to him to install some ferrite filters on his external PC speakers, I would prefer to - if it seems likely to make changes my end to resolve - and to avoid similar problems with other neighbours when I am pointing at them.

I could point the beam in an opposite direction and use it only there, although he will still get some 'off the back of the beam' and baring in mind when I reduced the TX pwr by half he told me it made no difference. And pointing away from him, will only point at someone else who may well knock on the door.

So I am thinking:

1) Not txing on the beam with AM (thats fine - was just me being lazy and not connecting the vertical when I heard someone calling and hapenned to have the moxon connected) so no problem to only do AM thru the vertical in future.

2) Changing the 4m moxon rectangle purchased from Vine to a 4 or 5 element 70mhz beam for SSB... Can anyone tell me if this will help - ie somehow stop the interference to the neighbour(s) that my moxon rectangle is causing ? Interestingly, Vine the antenna manufacturer sells a coax choke balun which is installed at the base of it.

3) Increasing the height of the beam. It is currently only 25 foot off the ground - and whichever direction the beam is at its pointing at someones house. I have had problems with council - (from the neighbours complaining of aerials HI) so how much height would I have to go to to get the signal over his house ? Could 5 foot extra make all the difference ?

I am hoping (somehow) changing the moxon rectangle to a traditional beam on 4m could help - and maybe adding a few feet - upto ten feet I guess I could get away with - could that fix it ?

I know sometimes the only way is to try - but that could cost me deerly and still not fix the problem...

Any thoughts please gentlemen ?

As a last resort - I could change the moxon from horizontally mounted to vertical and use as a directional FM antenna - which would open up FM a bit for me. But this begs a question. The vertical antenna I am using is a Sirio CX-468 - what sort of gain would the moxon have over the vertical - on other words would I see a real difference on the moxon vertically polarised over the Sirio ? (both antennas are mounted at same height - but on different masts)

Anything I could do that I havent mentioned ?

Other than the HF wire, all my other antennas are vertical and I dont seem to cause any problems - or if I do they havent been bought to my attention.

I know the easy answer is to add ferrite filters on his speaker cables connected to his powered external PC speakers but that only masks the problem and wont stop the same thing happening to another neighbour when I am beaming in their direction

Thanks for any help

Simon G7IVJ

Ps, why couldnt my parents have lived in USA and I live on a huge bit of land with no neightbours LOL

[G7IVJ]

The moxon is a 'super moxon' as shown on www.vinecom.co.uk under VHF/UHF antennas, then select 4m

[GW8ASD]

I assume you have a choke on yours?
If you don't then, as far as I'm aware, you should.
You don't need to buy on. Just give Ron a bell and ask him how many turns, etc. on his and wind one.
Just in case there is RF coming down the feeder.
As you have to beam at the house, this is not likely to be the problem.

It's probable that the loudspeakers on the PC, powered ones I assume, have cables that are resonant at 4M and are horizontal.

FM, obviously, will not be demodulated as it is a constant carrier level.
AM, and SSB, since they are amplitude modulated will be detected by the input circuit of the powered LS and produce audio.

No amount of messing at your end will fix it if that is the case.

The fault is on the powered speakers which are doing something they should not.
I've a similar problem here with 400W at 6M, when I point at the shack.
Ferrites cured it.

Any work you do at his end, ferrites etc, is fixing the problem, not masking it.
They are powered speakers, not a radio receiver.

It's possible that just re-arranging the wires at his end might make a difference.

Going for a Yagi with a narrower beamwidth might make it that the effect is over less of an angle as might raising it but I'd go for the ferrites and moving/changing the length of the cable.

Just explain to him that it is a common design problem and they should not act like a radio receiver.
Do you get anything in speakers on your PC?

Cheers

Tony

[PA5DD]

You could consider buying your neighbor a set of these:

http://www.westmountainradio.com/produc ... d=COM_spkr

73 Uffe PA5DD

[GW8IZR]

Yep - dont be affraid of taking some initiative and trying the better speakers that Uffe has linked too. We spend lots of time / effort / money building our stations and if we find its all wasted as we can't use the station due to TVI then 40USD would be a cheap solution. It doesn't involve you having to modify a neighbours asset. If it solves the problem any further complaints can be directed at the link.....

[M0SAT]

Hi Simon

Measure his speaker wire.... I've measured 3 different makes of PC speakers and they all have almost perfectly 70Mhz resonant lengths of wire from the plug to the speakers!

Ferrites or those great speakers that Uffe found may be the only answer.

I have a 4 ele Jaybeam on the deck waiting for my mast to go up over the next month or so. You are welcome to borrow that for further tests without having to shell out for new antennas if that will help.

MB7FM now back on by the way so will be listening out on there if you want to chat.

73 de Dave

[G3PTU]

The problem is your neighbours - speakers are NOT radio receivers. The set up he has is at fault, not you. If he has just bought the things, the Shop has to fix it.
That is the nasty fact for him, however if you want to be cooperative, fettite on the speaker leads, if they are amplified horrors at the speaker end if its a seperate amplifer job at the other end.
Do same to mains lead.
The problem Might be that its getting into the Computoer itself. But these things sometimes just will not be fixable. Do not modify anyuthing - he will hold responacable for ever more.
My advice is do not buy him anything, you will end up buying him and nieghbours a new Kettle, Cat, everything. Dangerous road to go down.
Keep to the letter of the law, If you are Squweeky clean - it's his problem.
Be warned.
If required get Offcom in to help - he pays
David G3PTU

[GW3XJQ]

I agree with the last response and from experience many years ago when I had a similar problem with a cheap and very nasty "Hi Fi" system with long speaker leads piping music around a shop.

I took the job on and fixed it with ferrite rings but that was a mistake as I was then branded as the culprit and cause of the problem and of course the word got around and anyone suffering any sort of noise or intereference on any electronic device or receiver assumed it was my fault.

Just be careful not to accept the blame for the probable shortcomings of the PC and powered speakers. Suggest they at first take the problem to the firm that sold the equipment and only as a last resort and in the interests of your continued enjoyment of the hobby show them that a simple cure could be to fit some ferrite on the speaker leads and that they are cheap and easy to fit.

Assuming the problem can be shown to be resolved then you could leave them fitted and I would ask them to pay for them at cost.

73 and good luck, let us know how you get on,

Martin

[OZ2M]

Hi

I have had a similar problem a number of times.

PC speakers are like FM receivers were 20 years ago. I.e. no proper RF decoupling anywhere.

I have solved all my cases with a handful of 1 nF across all inputs directly on the amplifier IC(s).

If your neighbour does not allow you to do this bring a set of your own that is properly decoupled. Show the neighbour that these work. Then either do it on his speakers og give him yours.

Investment: a pair of speakers, 2 EUR in capacitors, 1 hour labour.

Problem solved.

While you are at it buy an extra set and keep them ready for the next neighbour.

73
Bo, OZ2M - Looking for DX? Try VUSHF DX-peditions www.rudius.net/dxp

[GW8IZR]

Hold on here, the man suffering the problem has put up with the interference for a while and eventually he’s bothered to contact the OP to try and resolve the issue. He seems like he’s cooperating and is behaving like a sensible bloke who with care will see reason.

I’ve witnessed a TVI complaint degenerate into a huge mess, it resulted in bricks through the windows and eventually the amateur who was at “faultâ€

[GW3XJQ]

Wonderful solution to the problem.

Please tell us more about the practicalities and based on your obvious personal experience and sucess in this area of our hobby.

I would not personally know which products to go out and buy, there's a minefiield of equipment out there nowadays.

Would one purchase various items on approval for example and return them for refund if they didn't work?

I have an interest in this modern approach as I been fortunate to live far from "civilisation" for 30 years, but that is set to change this summer with a housing development within 50 metres of the property.

73 Martin

[GW8IZR]

[quote="GW3XJQ"]Wonderful solution to the problem.

Please tell us more about the practicalities and based on your obvious personal experience and sucess in this area of our hobby.

I would not personally know which products to go out and buy, there's a minefiield of equipment out there nowadays.

Would one purchase various items on approval for example and return them for refund if they didn't work?

I have an interest in this modern approach as I been fortunate to live far from "civilisation" for 30 years, but that is set to change this summer with a housing development within 50 metres of the property.

73 Martin[/quote]

Yes I think it is a wonderful solution, I have worked this way for thirty odd years and never had an unresolved issue.

To answer your first question Martin, the OP could follow the link in a previous post which directed the OP to a source of computer speakers with excellent immunity.

In terms of personal experience, well yes I do have rather a lot of experience in resolving RFI issues professionally. By applying a sensible engineering approach to interference reports and helping neighbours optimise their TV/ HIFI and home electronics I have been able to operate VQRO on most bands with no complaints.

Using opportunities such as the recent digital switchover was an ideal chance to discuss TV reception with neighbours, Just taking five minutes to help them with their installations picked up a few defective antennas and badly made connectors.

Making sure they have good reception to start with is key to improving victim immunity.

I want to enjoy my hobby and be able to run QRO when and where I like, I think that's worth investing a few hours with my neighbours.

Hey, what do I know maybe its better to just close the door and board up the windows :-/

[GW8IZR]

GW3XJQ wrote : I have an interest in this modern approach as I been fortunate to live far from "civilisation" for 30 years, but that is set to change this summer with a housing development within 50 metres of the property.

Apologies Martin, I forgot to add that without doubt your biggest issue here is the increased interference TO your station from this new development.

Modern electronic equipment newly installed tends to be very immune to start with so you are very unlikely to cause a problem.

I fear you are more likely to suffer an increase in noise levels at your station, If you are interested in weak signal DX that's going to be much harder to deal with.

[GW3XJQ]

All noted Paul, I will just have to wait and see what happens when these new executive style houses are built and hope that I can still enjoy my life long hobby.

My comments were based on personal experiences some 35 +years ago and I realise things are different in modern times. I used to get involved with RFI and TVI complaints as and when and I generally managed to resolve the problems with various filters and chokes etc. TV reception in one village where I lived was terrible and most people (including myself) used mast head pre amps.

But even after much work on the problem and when I thought all was well and I was on good terms with neighbors someone had to complain to the PO radio regulatory department as it was then and I was visited by two of their engineers and closed down. My equipment (10 Watts max) was returned to the dealer for checking and was found to be working well within specification, even so I never received any form of apology or even a letter telling me I could resume transmitting. The problem was simply down to the fact that the area was outside any recognised TV service area.

What I have described was the "pleasant" nature of the problem, what also had to be suffered from members of the community was verbal abuse and even threats from an individual of serious physical harm and which necessitated a report to the police. So much for amateur radio and trying to be helpful to your fellow citizens! Then there was the speaker leads problem.

So you see why I will if matters similar to this develop in the future, be very reluctant to get directly involved with complainants and would never admit to any personal responsibility for fixing a fault with their equipment. I am now more fortunate to be able to check my own equipment and not use it it if I feel it is at fault and the cause of interference to others.

If I do start to suffer from intereference from my new neighbors then I will refer the matter to OfCom for investigation and in a similar fashion politely inform them that they should do likewise if they wish to complain about my amateur radio station.

73 Martin

[GW8IZR]

For every dispute resolved amicably there will be others that take a more sinister turn and clearly judgement is important. My advice to try a set of the known good PC speakers would be more of a challenge if the victim was a 54" wall mounted plasma TV.

But a similar principle applies, If you can show the neighbour that you can watch any channel on your own TV when running any power, band or mode that you may use without needing filters or modifications its certainly a big help. if your own house is in order and as many of your neighbours as you can be on good terms with, the better your chances in the event of an issue.

The operating environment matters a great deal too, some urban environments have people packed so close together that it would be an unreasonable expectation to set up a 2m EME station amongst them. Running an appropriate power / ERP for the location is crucial to managing problems. Just 'cos it says 26dbw on the licence doesn't mean we have a right to do that in all locations.

I ran a successful 70cm EME setup from my previous home, the local authority then built an old persons accommodation block right at my moonrise window. There was absolutely no point in trying to operate my station from there anymore, sure I could have fixed every single issue but the cost and effort would have been greater than the cost of moving house. Up until the move I could still use some bands without problems so that's what i did.

Some time ago there was a relaxation in the requirement for keeping a log, I believe that is a big mistake as the evidence in the log is so helpful when tracing patterns in an interferer. In the licence it says something about keeping spurious emissions to as low as the current state of the art and recording the results of tests from time to time. I wonder how many log books today have entries in them detailing the tests we make?

TVI used to be a much more challenging issue for us, of course Martin you and I recall a time when 10W home brew kit and wire antennas were more or less the norm, combine that with TV's that had abysmal immunity and it was a hopeless situation. I don't think many amateurs run such low power these days, 100W radios are more or less common and many of us run much more power, thankfully most modern TV's have pretty good immunity. The TV industry has had to improve its equipment as there are so many RF sources now that have the potential to cause problems. The PC and to some extent HiFi audio world has a way to go yet.

Back to the PC loudspeakers, they are as Bo rightly said pretty much the same as the old TV's - with poor immunity, I have a set here at work which suffer badly with interference from mobile phones running a few tens of mW when in the same room. I sometimes use them as a demonstration piece.


WRT your housing development, during the current recession many builders are only erecting affordable accommodation. This type of property seems to attract certain concessions from the local authority which makes it attractive for the developer. One such concession seems to be solar energy generation, solar panels with invertors and control systems. I'm keen to see or hear about any issues relating to such installations.

Anyway this has rambled on long enough, just one thought.

I was quite shocked to hear someone talking about the amateur that died, this was just some bloke with a hobby that couldn't sort out a problem - the conversation went along the lines of being glad he was dead and he was due for a "good hiding" This wasn't some inner city housing estate. These were just people living in an average street, clearly things had got way out of hand.