I've just bought a replacement radio alarm clock with DAB radio. The radio will pick up an adequate signal in one location but not where it needs to be.
Is there anything I can do to improve matters? The aerial is a thin wire permanently fixed into the back of the unit.
Yes, get an FM radio or an internet radio! :-)
Oh one of those eh, common in things with Bush fidelity and goodmans names on.
How long is the wire? Obviously not a lot you can do if you don't want to open up the unit. Brian
Can you guarantee perfect reception on FM with a bit of wire for an aerial? No? Not much point in that comment, then.
And can you guarantee perfect internet too all the time?
i-player etc is generally pretty good here. But not all the time.
It may work but the fact that its got just a bit of wire means its meant for strong signal areas and one would hope it has the sensitivity to work. However if you are getting boiling mud noises than either your signal is rubbish or the set is.
If you could open it up and ge inside you might be able to attach a bit of coax to the airial input and the earth to a local earth inside. Then you could terminate it in a socket and use an outside dab aerial. However this might... 1. be making the warrenty invalid or allowing an inadaquately insulated bit of metal to be touched outside the box or Just be impossible to do as the aeriel input is not meant for a real aerial. Incidentally if you attach a cloths peg to the wire and stretch it up as it would be if it was a telescopic one does it then work? If so then there is the answer. Brian
Cut the wire aerial short. Connect the coaxial inner of the cable from an outdoor aerial to it. Leave the coaxial screen unconnected. It will transfer enough signal to work, despite the inefficiency.
Bill
Often wondered if there was a good way to connect an outside aerial to these 'bit of wire' ones.
No, but there's a much better chance than with DAB in my experience. ... and I did put a :-)
I've never had any issues with my internet radios, even when we had fairly slow (2 to 4Mb/s) ADSL.
You can try moving the wire around. We had a similar issue initially and found just a small change made a big difference- as did closing the wardrobe doors (which are mirrored). I assume they upgraded the transmitter as it seems far less sensitive to the position of the wire now.
If you are in a poor signal area, then you may need an external antenna- which (ideally) means a proper connector on the radio. Those on DAB radios tend to be F type- as used on satellite boxes. However, you MAY get away with just linking the inner of the coax to the existing wire. I theory it is 'bad news' but you'd be surprised what rules can be 'bent' when it comes to such things- remember the fashion for coat hangers as car aerials ;-)
Thanks. Tried that, and the wardrobe doors are closed. As you say, the slightest move...
Would a tuned length like these below make much difference bearing in mind the wire would not be kept straight?
------ DAB (170 - 240 MHz)
Bottom of Band 3:
1 Wavelength = 3*10^8 / 175*10^6 = 1.71 meters. 1/4 wave = 43cm and 1/2 wave = 86cmTop of Band 3:
1 Wavelength = 3*10^8 / 240*10^6 = 1.25 meters. 1/4 wave = 31.3cm and 1/2 wave = 62.6cm--------
Schoolboy error. What about velocity factor? How do we know this quarter wave will be connected to something that matches its theoretical 50ohm impedance? Anyway, even a perfectly resonant and matched length of wire will only collect signal that exists, and it will not produce a better signal to local noise ratio than a random length.
Bill
It's worth experimenting by connecting the screen to anything you can find to connect it to.
Bill
Hmm, I've never had much luck with this approach. You almost need the reverse of the long wire balun, though I guess it should be called an unbalun. grin.
Brian
My 25-yo Roberts clock radio alarm is fine on FM with the bit of wire, about 3 feet long, dangling down to the floor and I live at least 50 miles from Rowbridge.
Memories of rabbit ears and TV sets.
So those naughty boys are Pure are misleading us.
A bit more Googling shows that DAB Digital Radio magazine once suggested 31.5 cm which doesn't match the 53 to 86cm suggested by Pure.
"the perfect length for a DAB digital radio aerial is 31.5 cm (based on the frequency used to broadcast the national commercial digital radio stations)"
Now I am extra confused.
By the way, wouldn't a resonant aerial produce a greater signal for the same level of background noise and therefore improve the S/N?
Well in principal yes. The DAB band is now quite wide frequencies from
174 to 239 odd as per;are getting used, so for a simple plain old vertical whip mounted on a ground plane thats say from 300/174 divide 4 x.9 velocity factor say 387 mm to 281 mm.
Not a very wide band device so cut to resonance is a good idea. However a folded dipole much better, in fact we have a now unused dipole that used to carry network rails band 3 service on 206 MHz it's now carrying a 163 MHz channel with no reflected power!.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.