Ropey Radio Reception?

Ah - Radio Luxembury and Radio Caroline - that brings back memories and dates me at the same time.

As a young student in 1964 I and a few friends lived in rented a semi-basement flat in Plymouth, I had a good old valve radio, but Luxemburg was hard to pull in, very faint.

Then I realised that the phone line that had been put in when the previous married tennants were 'expecting' and needed a phone for the babys arrival was still in place, the handset had gone but the line was in place.

Eureka! Aerial lead from radio was promptly connected to the phone line and now I had a really effective radio aerial of how ever long it was! Didn't look - didn't dare, anyway at that age, who cared!

Luxemburg now pulled in loud and clear, in fact I could trun the volume up to full because of distortion the signal was now so strong. Ripper!

Chris

Edited By ChrisH on 08/05/2021 16:55:47

Radio Luxembourg of blessed memory - 1933 - 1992, when the company was dissolved.

' ' ' '

I suppose I could try that DAB radio again, having been deterred by instructions suggesting a needless complexity akin to the spectrum-analysers I used at work.... in fact I think they were easier to use provided you knew what you were using it for.

I have just paused to look more closely at the wireless in the kitchen. It has a telescopic aerial and no socket for a further aerial.

It was on Radio Three and loud and clear. I tuned to Radio Four: ditto. Not brilliant audio quality I don't expect anyway; but ample radio signal. This was so with the aerial erect or closed and folded down to its clips, on both stations. All that happened in the closed state was my shielding the signal to some extent.

The weather? Thick overcast.

Unfortunately very few FM radios are fitted with a proper aerial socket and the built in whip aerials are woefully inadequate. For best operation a whip aerial should be 1/4 wave, that is about 75 cm, long. The other problem is that in a house the signal will come from multiple paths each with a slightly different delay and interfere with each other. For compact reliable reception a WiFi receiver of some sort is much more reliable and easy to set up.

Russell

A proper plug and socket isn't strictly needed to connect an external antenna. Just wrap a few inches of the coax centre conductor around the base of the telescopic aerial. RF best practice isn't essential - with luck the bodge only has to improve a marginal signal due to the radio being inside the house.

Of course, for best FM reception, go the whole hog. That means putting an antenna high up outside, at least 2 wavelengths away from any nearby structure, maybe a beam aimed carefully at the transmitter, with a pre-amplifier, and connected to a better FM receiver with a proper antenna socket. ega's leaflet covers the ground rather well, and goes so far as to suggest rotating the beam. This contrasts sharply with buying a cheap FM portable and hoping it will work inside a house. Do it properly and the antenna might well cost more than the radio. Much depends on location relative to the transmitter: these don't put down a uniform signal in neat circles. This map shows Mendip's patchy service area. Good signal up several Welsh valleys, and South Dartmoor, but no good for Yeovil, Bristol and Bath, all shielded by high ground.

It's not really possible to tell how strong an FM radio signal is just by listening to it. Radios are fitted with Automatic Gain Control that works hard to maintain the same output whatever the input level. Radios are designed to fool the ear - don't trust it!

AGC fails causing distorted audio when the input is too strong or too weak. Too weak also causes drop outs, where noise intrudes - usually distant weak stations and/or hash. Nigel's symptoms match FM radios demodulating marginally weak signals. I have the same problem: my portable radios work OK in some rooms and are hopeless in others. They all work perfectly in the garden!

Houses are dreadful for radio reception. First the signal arrives mis-phased due to bouncing or diffracting off all the other buildings, hills, trees, lakes, or whatever at ground level between the house and the transmitter. Inside the house it gets worse. Apart from loads of domestic electrical noise, the incoming signal bounces off internal walls, water pipes, electric wiring, metal window-frames, girders, aluminium curtain rails, people, and pretty much anything else bigger than an FM 1/4 wave. What the telescopic aerial gets is a mish-mash depending on a multitude of variables, any of which can alter path lengths causing signal strength to rise and fall mysteriously. Weather can effect FM but it's associated with Sporadic E and Ducting, both relatively unusual. One explanation is folliage. In winter it dies back, which could strengthen subtractive paths; in summer, the subtractive part is weakened.

Russell and I have both suggested the multiple path problem: we're not making it up! The answer is a good antenna. At roof height most things that change path length by bouncing are below the antenna, as is most electric noise.

In communications radio the antenna is the most important part of the system. A high-performance receiver and powerful transmitter connected to a town-centre indoor antenna are easily outperformed by modest equipment connected to an efficient outdoor aerial high up in a good location well clear of obstacles and electrical noise. Most radio amateurs are constrained by their antennas - gardens not big enough, and cluttered take-off due to close neighbours, some of whom run unfiltered VFDs!  Off with their heads!

Dave

Edited By SillyOldDuffer on 10/05/2021 11:09:07

Thank you for all this information!

The reception's pretty good today...