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 Static... White noise... annoying interference? Anybody know how to eliminate???
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 Return to top of page · Post #: 1 · Written at 8:20:52 PM on 30 April 2016.
JamieLee's Gravatar
 Location: Clare, SA
 Member since 27 March 2016
 Member #: 1894
 Postcount: 510

Saturday night, rock'n roll jukebox, seems always that there is anywhere from 5=50 percent interference, which ruins the reception of compromises the sound at best. Our little Peal seems to be the most immune, the bigger louder radio's tend to be more afflicted, but the radiogram, on the odd occasion, I can get wonderful reception, however mostly it's just loud white noise... The little Peal will usually get a really good sound. but is not the loudest radio, however when we want some volume, we are at the mercy of this horrible interference...

Is there a way to minimise it, perhaps amplify the signal, I can get rid of it on the bedroom radiogram (Airvoyce) by rolling off the tone, but wondering how others have overcome this, with distant stations, 100km away, etc.would lengthening the "long wire aerial" help, adding cross wires to it or anything?


 
 Return to top of page · Post #: 2 · Written at 9:06:31 PM on 30 April 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6760

Out of interest, how is the AM reception at your location at that time on a modern radio, such as in your car?


 
 Return to top of page · Post #: 3 · Written at 9:57:55 PM on 30 April 2016.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5385

If you are in a city you have a problem: The "catch 22" with interference is that you have to identify the source, before you attempt to suppress it. That can be quite entertaining.

I am rural based but that does not give automatic immunity. What I have to give you some ideas:

White RF noise on the mains; RF being picked up by 24KV overhead lines. Mains filters fitted;.
The power supply in the refrigerator. supplying LED lights etc;
Fluorescent lighting, including the worse compact fluorescent lights;
One ageing computer;
The switchmode PSU supplying the NBN connection box;
The NBN box itself & it can wipe out an AM radios reception from 15feet+ away.
I took two LED floodlights back to point of purchase as one wiped out AM the other FM;
PSU in a FAX: Fax retired.

Regulators seem to be asleep at the wheel: Maybe the Government could save big money by getting rid of them. NBN Box has been mentioned in a magazine, by other parties doing same thing.


 
 Return to top of page · Post #: 4 · Written at 10:32:43 PM on 30 April 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6760

Jamie's location is given in his profile as Clare, SA, in which case he's 100+ Km from Adelaide and, from what he says, I guess he's trying to hear 5AU or 5RM.

If he's getting hash instead of a signal on his car radio or a modern portable transistor outside the house at that time and location, then it would appear that it's a geographical location reception problem as much as anything else.

If not, then all of the above are the usual suspects, to which I'd add RFI generated by the mains supply itself due to dirty insulators (this is especially the case during prolonged dry spells).

As frequent members might recall, I had a very bad RFI on AM band problem in my workshop that was eventually found to be caused by inadequate earthing on a variable frequency drive controller on the supply fan in the underground garage's ventilation system.


 
 Return to top of page · Post #: 5 · Written at 11:40:51 PM on 30 April 2016.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 2174

A very common cause can be mobile phone chargers or Laptop chargers . I know when my wife has hers plugged in as my radios pick it up in the next room.


 
 Return to top of page · Post #: 6 · Written at 11:45:25 PM on 30 April 2016.
JamieLee's Gravatar
 Location: Clare, SA
 Member since 27 March 2016
 Member #: 1894
 Postcount: 510

GTC, on a modern radio, completely up the shit, no reception at all, or nothing worth a hope in hell of trying to listen to... My Fiance loves her little Peal kitchen radio, because she can now listen to her favourite AM stations, whereas she has bought various transistor radio's over the past 18yrs to be completely disappointed, yet the little Peal, adequate but not super loud is clear and a good performer, the old eclipse is a gem too.
Marcc I am rural, Port Pirie 5CS or 1323 (5AD) Adelaide, both a whisker over 100km away from Clare, but it makes sense, that some device it the culprit as some nights my reception is munted by a loud 50Hz buzz which sometimes cuts in and out or is totally absent or everpresent, or just a WWwwsssssssshhhh of white noise... So maybe a bad earth? It seems to abate over time, as now after persisting for some hours, reception has become clear!


 
 Return to top of page · Post #: 7 · Written at 12:05:33 AM on 1 May 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6760

on a modern radio, completely up the shit, no reception at all, or nothing worth a hope in hell of trying to listen to

The AM receivers in modern radios are usually nowhere near as sensitive as they were back in the 1980's and earlier, that's for sure. These days radio chip manufacturers put more effort into FM reception. However, what you say seems to indicate that you are in a challenging reception area to start with and need a sensitive receiver.

I have a fantastic DX AM radio made by C Crane in the USA. When I'm outdoors, and away from residential hash, it easily pulls in distant stations at night on its internal ferrite antenna alone. For instance I can receive 4VL Charleville which is 955Km as the crow flies from Sydney.

https://lordshopping.com/siteadmin/images/products/_all_category_photos/c/c_crane/CCRANE-EP-03.jpg

It seems to abate over time, as now after persisting for some hours, reception has become clear!

Interesting. In that case, the source of the RFI appears to be local to you and may be related to machinery or a process.

Are you anywhere near an industrial area?

To acquit your own residence, what you could try is briefly turning off everything in the house except the radio. If you have a number of power and light circuits in your place, then isolating each circuit in turn via the breaker or fuse can speed up that process.


 
 Return to top of page · Post #: 8 · Written at 12:52:26 AM on 1 May 2016.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 2174

Could it possibly be your off peak hot water system. Or a solar system if you have one.


 
 Return to top of page · Post #: 9 · Written at 12:59:50 AM on 1 May 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6760

Solar system inverters are notorious for RFI, but shouldn't be an issue after sunset.


 
 Return to top of page · Post #: 10 · Written at 1:17:02 AM on 1 May 2016.
JamieLee's Gravatar
 Location: Clare, SA
 Member since 27 March 2016
 Member #: 1894
 Postcount: 510

Not sure, but I will investigate! The masters Apprentices in a bowl of amplified rice bubbles is somewhat disconcerting! However, two other places in Clare where I have stayed have much better reception, however we are under the shadow of "Neagles Rock", a large hill immediately to our west, perhaps physically blocking signal? Suddenly reception has gone pear shaped at 12:20 am, cutting in and out... It seems my radio's are very sensitive, at night a myriad more stations, I get Victoria, Wimmera, Melbourne and Sydney stations, I normally couldn't hope to receive during daytime, although they peter out to rice bubbles and Ssshhhhh within seconds or minutes, but the stations I usually get clearly seem to be competing with a bunch of other stations vying for the same place on my dial, interfering with the one I am listening to, causing patchy intermittent interference! I'm guessing this just goes with the territory..


 
 Return to top of page · Post #: 11 · Written at 1:28:21 AM on 1 May 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6760

The nature of medium wave AM is that during the day the ground signal is strongest, so that means good reception of close-by stations only. However after sunset AM signals are bounced between earth and the ionosphere and very long distance reception is possible under favourable conditions, but this does mean that stations which are transmitting on the same or close frequencies will tend to be received together.

High quality AM receivers excel in two characteristics: sensitivity and selectivity. The first is how well they can hear; the second is their ability to fine tune to a given signal.

Adding a good aerial can be a two-edged sword: the radio can hear better but it hears everything better -- including interference.

Hills tend to block FM more than AM, because FM transmission is line-of-sight (that's why TV antennas need to be high enough and point towards the transmitter). If your local hill contains a significant amount of iron, then it could be sinking a lot of signal.


 
 Return to top of page · Post #: 12 · Written at 9:35:36 AM on 1 May 2016.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5385

I can get 2CH (Sydney) (519km) sometimes day, but at night it will fade in & out. But as I have said before 2AY Albury (70.86km NE) will start to fade in & out, late afternoon. It is North of Albury also in the shadow of a hill. You can see this by using Google maps.

Distances are from GPS line of sight.


 
 Return to top of page · Post #: 13 · Written at 3:01:28 PM on 1 May 2016.
JamieLee's Gravatar
 Location: Clare, SA
 Member since 27 March 2016
 Member #: 1894
 Postcount: 510

Very interesting, yes my old laptop interferes with the Philips radiogram, but not the others! We don't have an NBN box yet in our area, might have to shield the damn thing when we do get one! I might look into building an AM transmitter, which I could then couple with an FM receiver, or digital TV set top box, to transmit to my radio's in order to listen to Jazz through them... Entertaining the idea!


 
 Return to top of page · Post #: 14 · Written at 3:33:54 PM on 1 May 2016.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6760

I might look into building an AM transmitter

5AU and 5CS live stream on the internet, so you could also put that through a mini transmitter -- as long as it is a noise-free audio feed from your PC.


 
 Return to top of page · Post #: 15 · Written at 4:24:23 PM on 1 May 2016.
Brad's avatar
 Administrator
 Location: Naremburn, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 7389

GTC's idea is the one I think. The AM repeating of the FM signal will rebroadcast the interference.

Watch your download quota though.


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A valve a day keeps the transistor away...

 
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