FM-Dab aerial converter

[RJH]

Anybody had any success with one of these? -

'Conversion Cable DAB+ Antenna AM/FM ISO Jack to ISO Male Signal Amplifier Radio Antenna Aerial for Car Radio'

[Brian]

Not directly.

You may need an adaptor plug / lead between it and your radio for the DAB connector- they vary.

I have something similar fitted ( as standard) in our motorhome - I assume it is tucked away either in the roof or behind the dashboard. There is a short, perhaps 12 to 15 inch if that, antenna on the (composite) roof. The reception is good - I nearly always use DAB, fall back to FM if no DAB coverage.

One thing to watch.

I have a Kenwood Stereo. It has the ability to feed power to the antenna via the coax. It does this by default. With amplified antennas (including mine) this causes a conflict. When first powering up / resetting the radio, you need to go into settings and turn off the option to feed power to the antenna. BUT, you can?t access the menu if it detects the conflict, you must disconnect the antenna, make the change, then reconnect it. After that it is fine, provided the backup power to the radio is maintained. I?ve mentioned this to others and it seems Kenwood aren?t unique.

[Dave Plowman (News]

Didn't work here. I bought a car DAB radio ages ago - and the original aerial was a wing mounted telescopic type. Fine on AM and FM. The radio came with a stick on DAB windscreen aerial - which also didn't work well and looked hideous.

Ended up buying and fitting a roof aerial designed for all of them. That does work very well, but cost as much as some head units. It has separate amps and feeders for DAB and FM/AM.

[bert]

In article [e-mail]>, "Dave Plowman (News)" [e-mail]> writes

I had similar arrangement on my Defender. Worked OK, but I did improve the earth connection on the DAB aerial with some stick on copper tape. The aerial barely noticeable on the windscreen.

[williamwright]

It's just an amplifier. Unless your receiver is very insensitive I can't see how it would help. In fact in strong signal areas it's likely to overload the radio's front end.

Bill

[RJH]

Good to know, thanks.

[RJH]

I'd like to think it'd work, but agreed on the look. Could do without that.

Which I'm obviously hoping to avoid.

[RJH]

Is it though? Does any sort of filtering or stuff happen to make it suitable for DAB?

It does seem odd to me that existing FM aerials can't be used, given all of my DAB portables seem to work with either a dangling wire or unextended telescopic aerial.

Mmm, OK noted, thanks.

[williamwright]

Filters can only remove signals, not add them. No, it's a wideband amplifier, nothing more than that. It probably has a worse noise figure than the tuner in your radio.

Anything RF is a playground for every kind of shark and con man. It's been the same since the days of the crystal set. Radio waves are mysterious and invisible, so the successors of the Victorian mediums find them their natural hunting ground.

When I was a child in the 1950s there was a man who used to stand in the marketplace selling miracle TV aerials. They comprised a coax plug with six feet of wire attached. At the end of the wire was a large army surplus electrolytic capacitor. The price was 5/-. "Take it home and try it. If you aren't completely satisfied bring it back next week for a full refund." But he only attended the market occasionally, probably once every couple on months.

Bill

[charles]

There was a similar seller in Shepherds Bush Market in the '60s

[williamwright]

Judging from his infrequent appearances in Donny it might be the same man!

Bill

[Tim Streater]

Suitable in what way?

Wrong frequency band, I would have said. An FM aerial (on a rooftop at least) is tuned to pick up from 88-105MHz or so, DAB seems to be 170-240MHz or so. A bit of wire is not, of course, tuned vey well.

[charles]

my elderly Band II aerial feeds my DAB tuner with no problems

[Andrew]

Could the (vertical) elderly coax be receiving more signal the ?horizontal dipole though ?

[RJH]

In a way that makes the FM aerial suitable for DAB.

If so, why can't there be some manner of thing that enables that, rather than have to install a completely new assembly? Or maybe the DAB radio unit 'calls' for the required frequency?

(I accept that obviously there can't or there wouldn't be a need for the DAB aerial. Just curious)

[Dave Plowman (News]

The passive convertor I bought to parallel the FM and DAB inputs to the original telescopic aerial did work. Just not well enough.

[Dave Plowman (News]

Car radios tend to have separate inputs for DAB and FM aerials.

[Tim Streater]

You could remove the FM aerial from your roof and rebuild it by hand, I suppose.

What does this mean?

I expect tunable aerials exist but they would require motors etc to move the bits around. I imagine that what they do on radio telescopes.

[The Natural Philosopher]

88-108.lots of stuff on 105,106,107 MHz...

At that frequency a quarter wave is under a foot long

[charles]

so does my hifi unit.