Radio interference

[Bouleversee]

I have radios dotted around the house, some of them dating from before the digital switchover, and I have noticed that for some time now when I switch on the one on my bedside table if my phone is in the recharge socket or I switch the bedside lamp on, I get loud interference. Today, my window cleaner came and when he put his metal ladder up over the double glazed kitchen window, the radio on the windowsill, which I had on fairly high, made a horrendous noise which disappeared as soon as he removed the ladder.

Can anyone explain what is happening here, whether there is anything I can do to prevent it (other than the obvious separation of the items) and whether the problem would not occur with new digital radios. It's only the bedroom one which is a nuisance as I often want the radio and lamp on at the same time at this time of year.

[swill453]

There hasn't been a digital switchover for radio yet, it's not expected for some years if ever. DAB digital radio runs in parallel with all the old FM (and other) channels.

If this (the bedroom radio issue) is something that has only started fairly recently then it could have become faulty. Does it have one of these trailing aerial wires? If so make sure it's fully extended, and away from other electrical equipment.

The chances are a new FM radio wouldn't have the problem, and a new DAB one definitely wouldn't.

For the kitchen radio issue with the ladder, that's not surprising for an FM radio, I wouldn't worry about it. Or buy a new DAB one...

Scott.

[Urbandreamer]

I fear that you need a new radio.

What is happening is that part of the reciever circuit is responding to radio waves of a different frequncy that the intended one. Your CF or LED light is emmiting some as is your mobile phone charger* and the windocleaners mobile phone.

When I got my first mobile phone I was ammused to note that if I put it near my computer monitor the picture went fuzzy every minuit or so as the phone checked in with the cell.

Digital radios, which may or may not be DAB, can have better frequency descrimination. Though to be fair there are constraints upon some frequencies.
DAB actually uses digital modulation which avoids cross talk issues. Alternatively you could use the internet to listen to the radio. In which case a £20 or £25 echo dot might be a solution.

*My phone charger is that bad and my phone that sensitive that If I touch the screen it sees lots of phantom screen presses while charging. The screen pickup must be by the charging port and the swiched mode power suply sending a lot of harmonics down the USB cable.

[Bouleversee]

Thanks for responses.

Swill 453: It has a metal telescopic aerial which is fully extended, though a bit floppy at the base so I rest it against the wall. Works fine if I don't have the lamp on or the phone on the charger. I can avoid the latter but I do need a lamp on at the same time as the radio sometimes to avoid having to get out of bed to switch off the overhead lights and have 3 lights on when one will do fine. I'll get a DAB at some point.

Urbandreamer: Very interesting, albeit some of it over my head. So I guess it must be since I put an LED bulb in the bedside lamp. Well, that's easily remedied as I still have a few of the old variety or I could use my tablet to listen to the radio which in fact I do sometimes when I need the light on in bed. I sometimes listen to music while reading. The only problem with that is remembering to charge it up sufficiently beforehand or falling asleep with it on, which leads me to another question: does one use more electricity to listen to radio programmes or watch TV on a tablet battery than one would use if listening/watching on radio/tv sets? I suppose there might actually be a saving re TV as sets are so much bigger than tablets. No idea what an echo dot is but will look up.

[Urbandreamer]

, which leads me to another question: does one use more electricity to listen to radio programmes or watch TV on a tablet battery than one would use if listening/watching on radio/tv sets? I suppose there might actually be a saving re TV as sets are so much bigger than tablets. No idea what an echo dot is but will look up.

And while we are at it, how long is a piece of string?

Light takes huge amounts of energy when compaired to sound, so the TV will definatly take more. Anything digital will take more than most analoge circuits. You will find that DAB radios don't last too long on battery power. Higher sound quality, louder or with the ability to play louder analoge will take more power than lower quality or quieter stuff.

At the extreme you can actually listen to some radio stations with just a special ear piece, lots of wire and a bit of rock. The power for crystal sets comes from the radio waves themselves.
https://www.amazon.co.uk/Halsall-Scienc ... B00098Q1BA

A echo dot is like the StarTreck computer. Once set up you say Alexa play radio 4 and it does. Or so I have been told.
https://www.amazon.co.uk/Amazon-Echo-Do ... s=echo+dot

[kiloran]

Many/most electrical items such as TVs, computers, phone chargers and LED light bulbs contain what is known as a Switched Mode Power Supply (SMPS), which converts the mains voltage of 240v to a level more suitable for small electrical items. An inherent characteristic of an SMPS is that it generates radio waves that can cause interference to radios, TVs and other items. A well-designed SMPS incorporates components which suppress the emission of these radio waves (not completely, but to an acceptable level). There are standards which define the acceptable level of these emissions, but not all items meet these required standards, especially dubious imports of cheap chargers.

Getting a new radio may help if your current radio is receiving signals outside the normal frequency range, but it may may little difference if your charger, etc, is generating radio waves similar to the frequency of your radio broadcast.
If your bedside lamp has an LED or compact fluorescent bulb, try changing it for another well-known brand. Or, even better, use an old filament bulb if you can find one.

Try to move the mains leads of the lamp and the charger away from the radio.

If your radio is set to listen to, say, Radio 4 on medium wave, try it with Radio 4 on FM. Or vice-versa

Hope this helps

--kiloran

[Bouleversee]

So far I've switched to an old bulb and the interference has stopped so the switch to LED caused the interference from the lamp. I can charge the phone when I am not using the radio so problem solved. Thanks to all.

[UncleEbenezer]

So far I've switched to an old bulb and the interference has stopped so the switch to LED caused the interference from the lamp. I can charge the phone when I am not using the radio so problem solved. Thanks to all.

I have no problem with LEDs, though other things - including my own body - can cause lots of interference if in the wrong (relative) place.

Your LED may have a dodgy transformer causing trouble.

Or perhaps your problem is pure coincidence, and will recur when the weather changes again.

[AleisterCrowley]

have no problem with LEDs, though other things - including my own body - can cause lots of interference if in the wrong (relative) place.
usually down to multipath propagation - where two or more signals reach the antenna via reflected paths. Sometimes the interference is destructive, and moving the reflector(s) -your body, or a ladder- alters the situation

[Bouleversee]

So you think it could have been the ladder rather than his mobile phone as someone else suggested?

[AleisterCrowley]

Yes, more than likely.
Moving the antenna, or the whole radio often helps. Kitchen table?
I had a little Sony portable in my bathroom, which worked fine when I was in the bath, but not when I was standing up!

[Bouleversee]

I don't need to have that radio on when the window cleaner is here. I was just curious to find out why and so was he. Next time he comes, I'll ask him to leave his mobile phone in the van or I'll hold it for him some distance away while he goes up the ladder as an experiment. It's all very strange; the one in my conservatory only works when I put it on the floor though there is nothing else near it that could cause problems unless the plants are giving off bad vibes.

[UncleEbenezer]

I had a little Sony portable in my bathroom, which worked fine when I was in the bath, but not when I was standing up!

At your old place or since moving?

Maybe there's a moral in that. Standing up (other than walking) should never be more than a very transient state.

[AleisterCrowley]

The old place. I'm happy standing at a bar. Otherwise seated, or horizontal is preferable. Reduces joint strain..

[XFool]

I have radios dotted around the house, some of them dating from before the digital switchover, and I have noticed that for some time now when I switch on the one on my bedside table if my phone is in the recharge socket or I switch the bedside lamp on, I get loud interference. Today, my window cleaner came and when he put his metal ladder up over the double glazed kitchen window, the radio on the windowsill, which I had on fairly high, made a horrendous noise which disappeared as soon as he removed the ladder.

You haven't made entirely clear whether the windowsill radio is DAB or AM/FM (in which case on AM or FM). Also, what exactly was the nature of the "horrendous noise"?

IMO most likely explanation for both DAB and FM was that his metal ladder interfered with the RF signal (by screening or re-radiating). This could cancel out and reduce the signal at the radio aerial. The results vary; a reduced RF signal on DAB would cause the sound to become horribly 'bubbly' and or garbled. On FM, time delays in multipath reception (via ladder plus direct signal) can cause horrible sibilant distortion to the sound.

[ten0rman]

It has a metal telescopic aerial which is fully extended, though a bit floppy at the base so I rest it against the wall.

Unless I've missed it, no-one seems to have picked up on the above comment. Could it be something as simple as the aerial fixing, possibly a screw, having come loose resulting in a very poor connection and hence weak signal. Might I suggest trying to tighten it by rotating the base section of the aerial in a clockwise direction and see what happens. Ifthe aerial becomes tighter, then that may possibly be the problem.

ten0rman

[Bouleversee]

I have radios dotted around the house, some of them dating from before the digital switchover, and I have noticed that for some time now when I switch on the one on my bedside table if my phone is in the recharge socket or I switch the bedside lamp on, I get loud interference. Today, my window cleaner came and when he put his metal ladder up over the double glazed kitchen window, the radio on the windowsill, which I had on fairly high, made a horrendous noise which disappeared as soon as he removed the ladder.

You haven't made entirely clear whether the windowsill radio is DAB or AM/FM (in which case on AM or FM). Also, what exactly was the nature of the "horrendous noise"?

IMO most likely explanation for both DAB and FM was that his metal ladder interfered with the RF signal (by screening or re-radiating). This could cancel out and reduce the signal at the radio aerial. The results vary; a reduced RF signal on DAB would cause the sound to become horribly 'bubbly' and or garbled. On FM, time delays in multipath reception (via ladder plus direct signal) can cause horrible sibilant distortion to the sound.

I thought I had made it clear that they were not DAB. Both are switched to FM. I don't know how to describe the noise other than as interference which completely drowned out the programme. It wasn't a high pitched squeak or a buzz, more a rasping crackle.
Incidentally, they are not battery operated so moving them away from the plug sockets is not an option.

[XFool]

You haven't made entirely clear whether the windowsill radio is DAB or AM/FM (in which case on AM or FM). Also, what exactly was the nature of the "horrendous noise"?

IMO most likely explanation for both DAB and FM was that his metal ladder interfered with the RF signal (by screening or re-radiating). This could cancel out and reduce the signal at the radio aerial. The results vary; a reduced RF signal on DAB would cause the sound to become horribly 'bubbly' and or garbled. On FM, time delays in multipath reception (via ladder plus direct signal) can cause horrible sibilant distortion to the sound.

I thought I had made it clear that they were not DAB. Both are switched to FM. I don't know how to describe the noise other than as interference which completely drowned out the programme. It wasn't a high pitched squeak or a buzz, more a rasping crackle.

Sounds like bog standard FM multipath reception problems! Presumably caused by the metal ladder reflecting the VHF signal.

https://www.bbc.co.uk/rd/publications/whitepaper184

[pochisoldi]

Incidentally, they are not battery operated so moving them away from the plug sockets is not an option.

My plan of attack would be as follows:

1) See if I can tune into the same station on a different frequency
- Usually works for the likes of Radio 1-4 or Classic FM, but some BBC local radio stations have alternate frequencies.

2) Play with the antenna
[*] Make sure the antenna isn't touching anything metalic, then move the antenna.
[*] If the antenna is not completely vertical, make sure it's vertical
[*] If the antenna is vertical, move it so it's horizontal
[*] Reduce the length of the antenna - slide in one section - might make the antenna less likely to pickup interference, whilst maintaining the ability to pickup the wanted FM signal

3) Find the source of the interference
a) Unplug any chargers/TVs etc fed from the same socket
If the interference goes away, you have found its source.

b) Use a battery powered radio with a similar sized antenna in the same location and see if the type of interference is still present. (unplug the mains radio when you do this)

If the interference goes away, then it's either a fault with the radio (replace the radio), or more likely that the interference is being introduced via the mains cable.

If the interference can be traced to one item, then fit a "clip-on ferrite choke" (Google is your friend: search for "clip on ferrite choke mains cable" without the quotes) onto the appliance end of the mains cable of the offending piece of kit. (Stop the "noisy" appliance broadcasting via the mains wiring)

If the interference can't be traced to a one item, then fit the the clip-on choke on the appliance end of the radio mains cable (stop the "noise" from entering the radio).

In my experience most radio interference comes from "plug in ethernet extenders", or noise from charging mobile phones (e.g. charging my Samsung from 10% battery in a holder 6" from the car radio) However this tends to affect LW or MW.

My last resort would be to switch to DAB, but I would only do that if I could get DAB solid reception, and a radio that I could live with.

PochiSoldi

[Bouleversee]

Thanks, Pochisoldi, but changing the lightbulb has solved the problem for the time being.
How would I know if I can get solid DAB reception prior to buying one? I did have a couple of Pure battery/mains operated radios but they didn't last long.