LW/MW/SW local noise sources

[turretslug]

It seems that, strange as it may seem, there is a mechanism by which filament lamps can produce Barkhausen-Kurz oscillations. So even the simplest and most innocuous-seeming devices can cause problems.

[ms660]

One day most properties will have a DC feed....maybe.

Lawrence.

[Restoration73]

Prior to Ofcom, RA, and DTI, interference problems were dealt with by BT/BPO/GPO.
My first broadband router was called a BT Home Hub, without question one of the
most disgusting RF devices ever made polluting the entire spectrum - I was delighted
when one day it went up in smoke!

[mister valve]

Noise generated on 'long, medium & short wave bands by modern equipment is really getting totally out of hand. Virtually all digital, PSU switching & Fluorescent lighting equipment generate it. I mentioned this to a BBC Engineer some years ago, and his answer was "Get your self a D.A.B. Radio then you won't pick up this noise". This, of course, was of no help to me, as a vintage wireless collector - (though the answer was fairly predictable)! I have found that the only way to almost eliminate the air-born interference on L.M. & S. is to make a fairly long wire loop aerial with one end connected to the 'Aerial Socket', & the other end to the 'Earth Socket'. Making the loop as wide as possible & in the vertical plane. This does detune the aerial tank circuit some what, so the sensitivity is slightly reduced, but in reality, the AVC will compensate for this, & with (almost) all that noise removed, it does make AM radio usable again. Even 'RTE Radio 1' & 'Droitwich Radio 4' come through loud and clear on Long wave (here in Blackpool) - both were obliterated by noise on an open ended traditional Aerial . As for Mains born 'mush', it is possible to get mains filters which should prevent most of the noise from reaching the set.

[julie_m]

It's around this point that someone usually mentions a deliberate plot to allow analogue radio to go to rack and ruin in order to force people onto DAB and sell off "our" airwaves to the highest bidder, and the moderators apply the padlock. Just saying .....

[mister valve]

I forgot to mention that a Ferrite Rod or a directional Frame Aerial when properly peaked to the frequency you are listening to and rotated correctly will also largely ignore the air born digital 'mush' provided you keep the Aerial well away from a known noise source. Perhaps the 'governing powers' don't think there are still people out there who use non resonant long wire Aerials for their A.M. 'Wireless sets' Maybe they think of us as "Barmy Eccentrics" stuck in the past.... I know I am

[Keith]

Originally Posted by mister valve

"Get your self a D.A.B. Radio then you won't pick up this noise".

Some of these "interference generators" have been known to prevent DAB radios from receiving any usable signal at all. Reception then will be totally noise free - i.e. silent!

Originally Posted by mister valve

I have found that the only way to almost eliminate the air-born interference on L.M. & S. is to make a fairly long wire loop aerial with one end connected to the 'Aerial Socket', & the other end to the 'Earth Socket'.

Pretty much any balanced aerial (loop, doublet, dipole etc) has more chance of rejecting local noise. This can be further enhanced by the use of an aerial tuning/matching unit.

[Brian R Pateman]

Originally Posted by ajs_derby

It's around this point that someone usually mentions a deliberate plot to allow analogue radio to go to rack and ruin in order to force people onto DAB and sell off "our" airwaves to the highest bidder, and the moderators apply the padlock. Just saying .....

Dead right there AJS!

There are other forums for this sort of discussion. It invariable ends in tears on here.

On the bright side... My LW/MW/SW aerial is a loop at the end of the garden as far away from other houses as possible. I get a very clean signal, OK it's a bit of a faff (only once) but no more than putting up a 100' aerial as was done in the past.

Nothings free (apart from the universe which popped out of nowhere), getting a good signal takes a bit of work, worth it for our old sets. And they deserve a good one to let their performance show.

[Radio Wrangler]

Blackpool?

I understand that most of the illuminations have moved over onto LED light sources, and that probably means lots of switch-mode current regulators.

What happens to the noise floor across LF-HF when the big switch-on happens?

It ought to be a well-defined moment, making comparison easy (and also at the daily on/off times). It's a very large-scale experiment already being done for us, and there are lots of long above-ground wires as radiating elements.

Just wondering... It would be interesting for a group across the country to monitor such a synchronised mass turnon/off.

David

[jsbhavsar]

How about shielding the radio in the household?
Somewhere on this forum I saw the Philips BX998X radio with two ferrite rod aerial assembly kept in the mesh. The mesh acts as a shield. Shield against? I assume it shields the ferrite rod assembly from internal or external interference, but I maybe wrong here.

Can the valve radio sets of the 1950s and 1960s be modified in the 21st century by adding extra circuits to shield the 'external interference' entering the RF / AF amplifier so that we?