#254676 - 19/04/2005 15:03
DAB unit
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Pooh-Bah
Registered: 13/04/2001
Posts: 1742
Loc: The land of the pale blue peop...
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So whats the opinions on this wee unit. revo seriously considering one to compliment the empeg.
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P.Allison fixer of big engines
Mk2+Mk2a signed by God / Hacked by the Lord
Aberdeen Scotland
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#254677 - 19/04/2005 19:17
Re: DAB unit
[Re: thinfourth2]
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carpal tunnel
Registered: 17/01/2002
Posts: 3995
Loc: Manchester UK
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Expensive, limited performance in marginal areas, messy install, other than that, I'm sure it's fine.
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Andy M
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#254678 - 20/04/2005 04:19
Re: DAB unit
[Re: andym]
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pooh-bah
Registered: 16/04/2002
Posts: 2011
Loc: Yorkshire UK
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I looked at it, but £200 for a compromise solution seems over the top. DAB home units are at the £50-60 mark, car HU's are only hovering just above the £200 mark and now that the major brands have latched on to DAB, prices are bound to fall.
I just had a closer look, you can get a DAB HU for £150, which includes FM/AM//MP3.
Home and portable adaptors are £50 each: But you can get a standalone Matsui home adaptor for £60 (It works well, I have one) and you can get a personal portable for £80 (Double the battery life and much less cumbersome).
So I would think that these people will need to drop prices to stay in the game, and they may well not have the margins.
Edited by boxer (20/04/2005 04:40)
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#254679 - 20/04/2005 06:15
Re: DAB unit
[Re: boxer]
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Pooh-Bah
Registered: 13/04/2001
Posts: 1742
Loc: The land of the pale blue peop...
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Problem is that i have a pretty good MP3 head unit that won't be coming out and i can't be assed with installing a second head unit.
This might not be the cheapest solution but i'v never been in the school of thought that cheaper is better.
So just wondering if anyone has used one.
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P.Allison fixer of big engines
Mk2+Mk2a signed by God / Hacked by the Lord
Aberdeen Scotland
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#254680 - 20/04/2005 06:26
Re: DAB unit
[Re: thinfourth2]
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pooh-bah
Registered: 16/04/2002
Posts: 2011
Loc: Yorkshire UK
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From memory, Andy was looking at adapting one of the Curry's/Dixons
Matsui units for the car, I can't find the thread, so don't know whether he succeeded.
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#254681 - 20/04/2005 07:03
Re: DAB unit
[Re: boxer]
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carpal tunnel
Registered: 10/06/1999
Posts: 5914
Loc: Wivenhoe, Essex, UK
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I haven't had much time to play with it yet. I did go for one quick drive and found that reception wasn't good.
I need to find out whether I can replace the "damp piece" of string aerial with something more substantial.
The thread in question is this one http://empegbbs.com/ubbthreads/showflat.php?Cat=0&Board=offtopic&Number=242500
Edited by andy (20/04/2005 07:07)
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#254682 - 20/04/2005 10:04
Re: DAB unit
[Re: andy]
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pooh-bah
Registered: 16/04/2002
Posts: 2011
Loc: Yorkshire UK
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Quote:
"damp piece" of string aerial
That is the major downside, it pulls in less stations than the wavefinder (Which I've now sold anyway), and is highly susceptible to people walking past, I've put it near the ceiling on a long line lead to get over the problem, for some reason, extending the aerial wire makes reception worse.
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#254683 - 20/04/2005 14:22
Re: DAB unit
[Re: boxer]
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carpal tunnel
Registered: 10/06/1999
Posts: 5914
Loc: Wivenhoe, Essex, UK
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I took it for another test drive today. When it works, it works well, when it doesn't it sucks.
I drove from Reigate to Hook (30 miles or so) and it only managed to lock onto the BBC national MUX for about 5% of the time.
So I need to look at improving the aerial to see if that helps. You say it got worse when you extended it ?
I was looking at either extending it, or fitting a proper DAB aerial.
I know nothing much about aerials. The aerial is just a single wire, I'm guessing that a proper DAB aerial has two connections, antenna and ground ??? If so I guess I have to find somewhere to connect the ground to ???
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#254684 - 20/04/2005 17:06
Re: DAB unit
[Re: boxer]
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carpal tunnel
Registered: 17/01/2002
Posts: 3995
Loc: Manchester UK
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Quote:
I've put it near the ceiling on a long line lead to get over the problem, for some reason, extending the aerial wire makes reception worse.
Code:
Half wave aerial length (in feet):
468
---------
wavelength (mhz)
Quarter wave aerial length (in feet):
236
---------
wavelength (mhz)
See, I did learn something at uni!
Basically there for a given frequency there is an optimum length of aerial. This length can be reduced but only by certain divisors like 1/2 or 1/4. I would imagine the damp string is probably about 80cms long if it's a half-wavelength or possibly 40cms at quarter-wavelength.
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Andy M
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#254685 - 20/04/2005 19:10
Re: DAB unit
[Re: andym]
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pooh-bah
Registered: 16/04/2002
Posts: 2011
Loc: Yorkshire UK
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And indeed, I vaguely remember that from my Royal Signals training, but when you threw your aerial in to a tree, you were just glad it didn't come back and clonk you on the head, 1/2 wave and 1/4 wave didn't occur to you.
And I bet none of you lot know the correct knotting procedure for joining a field telephone cable!
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#254686 - 21/04/2005 05:07
Re: DAB unit
[Re: andym]
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carpal tunnel
Registered: 10/06/1999
Posts: 5914
Loc: Wivenhoe, Essex, UK
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According to this page: http://www.crompton.com/wa3dsp/hamradio/antcalc.htmlthe half wavelength length is 63 centimeters Are you saying that there is nothing to be gained in increasing the length of the damp peice of string beyond this ? Assuming that extending the aerial is a non-starter then I guess a proper in-car DAB antenna is the solution. There are various different types available, here are two that don't require you to drill a whole in the car body: http://www.caraudiodirect.co.uk/product_info.php?products_id=3688http://www.caraudiodirect.co.uk/product_info.php?products_id=3687They all share one thing, a length of coax that needs to be connected somewhere. I know one side of the coax goes to where the damp peice of string is wired, but where would I wire the earth to ? Do I need to find some where in the tuner to wire it, or eath it to the car body ? Is this likely to work, or am I going to be foiled by impedance matching issues (a quick flash back to an antenna lecture during my failed EEE degree).
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#254688 - 21/04/2005 14:03
Re: DAB unit
[Re: mtempsch]
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pooh-bah
Registered: 16/04/2002
Posts: 2011
Loc: Yorkshire UK
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Ah, the Swedish Army had probably moved from SW to FM by the time that they let you loose! I bet you didn't have a 120v and a 1.5 HT & LT batteries to lug about.
When I was crossing fields with a back breaking roll of cable bending me double, a crimping tool would have been a luxury: We had a pair of pliers and a roll of insulating tape!
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#254689 - 21/04/2005 15:25
Re: DAB unit
[Re: boxer]
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pooh-bah
Registered: 02/06/2000
Posts: 1996
Loc: Gothenburg, Sweden
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#254690 - 21/04/2005 16:16
Re: DAB unit
[Re: andy]
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carpal tunnel
Registered: 17/01/2002
Posts: 3995
Loc: Manchester UK
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Quote:
According to this page:
http://www.crompton.com/wa3dsp/hamradio/antcalc.html
the half wavelength length is 63 centimeters
Depending upon which end of the frequency range you look at. I used the same page to check my calculations.
Quote:
Are you saying that there is nothing to be gained in increasing the length of the damp peice of string beyond this ?
Basically, yes. Extending the string wouldn't improve things. Might be worth investigating a different aerial though. I'd imagine earthing the ground of the aerial to the ground of the dab module would suffice. Suppose you need to investigate the impedance values of your module and aerial.
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Cheers,
Andy M
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#254691 - 21/04/2005 18:25
Re: DAB unit
[Re: andym]
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pooh-bah
Registered: 16/04/2002
Posts: 2011
Loc: Yorkshire UK
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Quote:
Suppose you need to investigate the impedance values of your module and aerial
Sad though you well know me to be, I am a member of the Caravan club and, each month, the magazine passes briefly through my house and, I'm absolutely sure that somewhere it had an article on how to connect a home music centre (FM not DAB) to a car radio aerial, making exactly that point: The impedances didn't match, for the life of me I can't remember whether you need a resistor or capacitor or martian to correct this problem.
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#254692 - 21/04/2005 18:42
Re: DAB unit
[Re: andym]
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pooh-bah
Registered: 16/04/2002
Posts: 2011
Loc: Yorkshire UK
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here's that boy, ready to do a bit of splicing now! Sorry the spats and highly polished boots are missing!
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#254693 - 21/04/2005 18:55
Re: DAB unit
[Re: boxer]
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carpal tunnel
Registered: 17/01/2002
Posts: 3995
Loc: Manchester UK
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Is that really you? It's hard to tell at that size.
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Cheers,
Andy M
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#254694 - 21/04/2005 19:03
Re: DAB unit
[Re: boxer]
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carpal tunnel
Registered: 17/01/2002
Posts: 3995
Loc: Manchester UK
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Isn't it a resistor? It's supposed to match the impedance of the radio I think.
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Cheers,
Andy M
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#254695 - 21/04/2005 19:08
Re: DAB unit
[Re: andym]
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pooh-bah
Registered: 16/04/2002
Posts: 2011
Loc: Yorkshire UK
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Quote:
Is that really you? It's hard to tell at that size.
Yep, why do you think I kept it that small!!!!
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Politics and Ideology: Not my bag
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#254696 - 21/04/2005 19:58
Re: DAB unit
[Re: andym]
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carpal tunnel
Registered: 10/06/1999
Posts: 5914
Loc: Wivenhoe, Essex, UK
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Quote:
Suppose you need to investigate the impedance values of your module and aerial.
The DAB car aerials seem to typically be 75 ohms impedance. How would I go about measuring the impedance of the aerial on the tuner ?
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#254697 - 22/04/2005 08:11
Re: DAB unit
[Re: andy]
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carpal tunnel
Registered: 17/01/2002
Posts: 3995
Loc: Manchester UK
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I would imagine it would be something you'd need to try and look up on the module.
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Cheers,
Andy M
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#254698 - 05/09/2006 10:34
Re: DAB unit
[Re: thinfourth2]
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enthusiast
Registered: 07/01/2002
Posts: 274
Loc: Stockport, UK
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Well, I took the plunge and bought a revo off ebay recently. After installing, DAB reception was poor/non existent. Upgrading the aerial had little effect, eventually I sent the unit back to revo for repair. They were great, and repaired the unit FOC (even though it was an ebay purchase). The unit now works perfectly, and I would highly recommend. Its a good work-around for the broken FM seek feature in 2.0 final also 
Edited by jarob10 (05/09/2006 10:35)
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