I have a Cambridge azur 650T tuner. I have a single coaxial cable that at
present feeds from a loft aerial (external is not possible) into the FM
input via a coax connector. The DAB has an F type connector. I would like to
be able to use both FM and DAB from the single cable.

1. If it is possible, what would be the most effective way of setting this
up?
2. Is there an aerial that would support both FM and DAB? (I live in
Wareham, Dorset - BH20 5BB)

Thanks,

Gordon

In article , Gordon MacPherson gordon.macph
scribeth thus
I have a Cambridge azur 650T tuner. I have a single coaxial cable that at
present feeds from a loft aerial (external is not possible) into the FM
input via a coax connector. The DAB has an F type connector. I would like to
be able to use both FM and DAB from the single cable.

1. If it is possible, what would be the most effective way of setting this
up?
2. Is there an aerial that would support both FM and DAB? (I live in
Wareham, Dorset - BH20 5BB)

Thanks,

Gordon


Generally an FM vertical dipole, not that abortion known as a halo,
works quite well on DAB in a lot of areas. You should get a very good
signal from the Rowridge TX on the Isle of Wight. I believe that BBC DAB
is from there and the commercial from Chillerton down in the same
isle!..

Even if you used a 3 element Yagi I suspect there'd still be sufficient
DAB signal as well as enhancing the FM ones..

I think that there are FM/DAB Splitters around, never used one as this
is a DAB free zone!, do not use just a simple splitter as this will
halve the available signal on each band...

--
Tony Sayer

On 30/07/2013 12:17, tony sayer wrote:
In article , Gordon MacPherson gordon.macph
scribeth thus
I have a Cambridge azur 650T tuner. I have a single coaxial cable that at
present feeds from a loft aerial (external is not possible) into the FM
input via a coax connector. The DAB has an F type connector. I would like to
be able to use both FM and DAB from the single cable.

1. If it is possible, what would be the most effective way of setting this
up?
2. Is there an aerial that would support both FM and DAB? (I live in
Wareham, Dorset - BH20 5BB)

Thanks,

Gordon


Generally an FM vertical dipole, not that abortion known as a halo,
works quite well on DAB in a lot of areas. You should get a very good
signal from the Rowridge TX on the Isle of Wight. I believe that BBC DAB
is from there and the commercial from Chillerton down in the same
isle!..

Even if you used a 3 element Yagi I suspect there'd still be sufficient
DAB signal as well as enhancing the FM ones..

I think that there are FM/DAB Splitters around, never used one as this
is a DAB free zone!, do not use just a simple splitter as this will
halve the available signal on each band...


I was looking into this, and:

http://www.aerialsandtv.com/fmanddab...fFM&DABAerials

looks useful.

--
Cheers, Rob

In message , tony sayer
writes
In article , Gordon MacPherson gordon.macph
scribeth thus
I have a Cambridge azur 650T tuner. I have a single coaxial cable that at
present feeds from a loft aerial (external is not possible) into the FM
input via a coax connector. The DAB has an F type connector. I would like to
be able to use both FM and DAB from the single cable.

1. If it is possible, what would be the most effective way of setting this
up?
2. Is there an aerial that would support both FM and DAB? (I live in
Wareham, Dorset - BH20 5BB)

Thanks,

Gordon


Generally an FM vertical dipole, not that abortion known as a halo,
works quite well on DAB in a lot of areas. You should get a very good
signal from the Rowridge TX on the Isle of Wight. I believe that BBC DAB
is from there and the commercial from Chillerton down in the same
isle!..

Even if you used a 3 element Yagi I suspect there'd still be sufficient
DAB signal as well as enhancing the FM ones..

I think that there are FM/DAB Splitters around, never used one as this
is a DAB free zone!, do not use just a simple splitter as this will
halve the available signal on each band...

I think that the first questions a
1. What is the existing loft aerial (vertical, horizontal, dipole,
groundplane, random piece of dangling wire etc)?
2. Have you tried connecting the existing FM feed (which presumably has
a traditional Belling Lee connector) to the DAB F input (using an
adapter)?

If you already get good FM, and the DAB also seems good, then you may
get away with a simple 2-way splitter (preferably a 'proper' 3.5dB
splitter, and not a cheaper 6dB resistive job). If not, an even
more-proper low-loss filtered splitter/diplexer would be better.
[However, if you really do need a filtered job, signal levels must be
rather marginal.]

If you don't get good DAB using the existing FM, aerial, then you'll
have to think about improving things - but only cross that bridge when
you come to it.
--
Ian

In message , RJH
writes
On 30/07/2013 12:17, tony sayer wrote:
In article , Gordon MacPherson gordon.macph
scribeth thus
I have a Cambridge azur 650T tuner. I have a single coaxial cable that at
present feeds from a loft aerial (external is not possible) into the FM
input via a coax connector. The DAB has an F type connector. I would like to
be able to use both FM and DAB from the single cable.

1. If it is possible, what would be the most effective way of setting this
up?
2. Is there an aerial that would support both FM and DAB? (I live in
Wareham, Dorset - BH20 5BB)

Thanks,

Gordon


Generally an FM vertical dipole, not that abortion known as a halo,
works quite well on DAB in a lot of areas. You should get a very good
signal from the Rowridge TX on the Isle of Wight. I believe that BBC DAB
is from there and the commercial from Chillerton down in the same
isle!..

Even if you used a 3 element Yagi I suspect there'd still be sufficient
DAB signal as well as enhancing the FM ones..

I think that there are FM/DAB Splitters around, never used one as this
is a DAB free zone!, do not use just a simple splitter as this will
halve the available signal on each band...


I was looking into this, and:

http://www.aerialsandtv.com/fmanddab...fFM&DABAerials

looks useful.

Useful maybe, but I always worry a little when I see comments like this:
"The round FM “Omni� type antennas do not perform as well as the
half wave dipole and this reflects their design, which gives a
theoretical minus 3 dBd gain figure. That's why we think they're crap
and we don't stock them."

There's nothing wrong with these omnidirectional 'halo' aerials provided
the user knows what the performance is, and knows that he can tolerate
the 3dB of signal loss compared with a straight halfwave dipole. But
being horizontally polarised, they are probably pretty useless when it
comes to the 'accidental' reception of vertically polarised DAB signals.
--
Ian

One thing that everyone has missed is that DAB is vertically
polarised. Thankfully all FM transmissions in the UK are now of
mixed polarisation (i.e. they have both horizontal and vertical
components) so turning your FM aerial vertical (if necessary)
will not be a problem (electronically - might be physically!)

As others have said a simple single half-wave vertical VHF dipole
is the best as (a) it is just about a full wave at DAB
frequencies so will work albeit with a mismatch and (b) it is
near enough omni-directional so will not limit you to your source
Tx station.



--
Woody

harrogate three at ntlworld dot com

In article , Woody
wrote:
One thing that everyone has missed is that DAB is vertically polarised.
Thankfully all FM transmissions in the UK are now of mixed polarisation
(i.e. they have both horizontal and vertical components) so turning
your FM aerial vertical (if necessary) will not be a problem
(electronically - might be physically!)

You beat me to commenting on the polarisations. I suspect that having a VHF
antenna 'work' for DAB may simply be using its coax as the DAB antenna
because the actual antenna is a hopeless match at DAB frequencies. :-)

That said, I just made a DAB antenna using two bits of wire taped to
a wooden stick. (Flower support from the garden center.) 8-]

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Gordon MacPherson wrote...

The DAB has an F type connector. I would like to
be able to use both FM and DAB from the single cable.

1. If it is possible, what would be the most effective way of setting this
up?

It depends on your existing signal level, if it is good then you could
use a simple passive splitter but you may need to use a signal booster
to compensate for the loss incurred in the splitter.

I'm in a similar situation, in that our communal aerial system provides
a single combined (very good) FM/DAB feed.
I tried various ways of getting this to to my FM & DAB tuners
including a couple of passive splitters and they were fine for DAB but
degraded the FM signal too much compared to a direct connection.

In the end I got one of these 1 in 2 out amplifiers
http://www.philex.com/catalogue/prod...d=116&cat=1069
which works well for both DAB and FM. It has a variable gain control
which allows you to fine tune things.

Here are the results of using that on the end of a much derided FM
halo.
http://goo.gl/maps/sF9Yh

--
UnsteadyKen

In message , Woody
writes
One thing that everyone has missed is that DAB is vertically
polarised.

No we haven't. That's why I asked what the existing FM aerial was (but
you've snipped it all).

Thankfully all FM transmissions in the UK are now of
mixed polarisation (i.e. they have both horizontal and vertical
components) so turning your FM aerial vertical (if necessary)
will not be a problem (electronically - might be physically!)

As others have said a simple single half-wave vertical VHF dipole
is the best as (a) it is just about a full wave at DAB
frequencies so will work albeit with a mismatch and (b) it is
near enough omni-directional so will not limit you to your source
Tx station.

If the existing FM aerial is horizontal, to get DAB it would be better
if it could be turned vertical. It should still work well for FM. As you
say, its length will be a complete impedance mismatch for DAB, but it
might work well enough. If not, that's the time that the OP needs to
think about doing things a bit 'more properly'.
--
Ian

In message , Jim Lesurf
writes
In article , Woody
wrote:
One thing that everyone has missed is that DAB is vertically polarised.
Thankfully all FM transmissions in the UK are now of mixed polarisation
(i.e. they have both horizontal and vertical components) so turning
your FM aerial vertical (if necessary) will not be a problem
(electronically - might be physically!)

You beat me to commenting on the polarisations. I suspect that having a VHF
antenna 'work' for DAB may simply be using its coax as the DAB antenna
because the actual antenna is a hopeless match at DAB frequencies. :-)

Aerial impedance mismatch doesn't cause pickup on the coax. However, if
the receiver is getting a reasonable signal, it's possible that a lot of
it isn't coming from the aerial, but is being picked up on the coax.

That said, I just made a DAB antenna using two bits of wire taped to
a wooden stick. (Flower support from the garden center.) 8-]

Indeed, most true enthusiasts will have done something similar. Bamboo
canes also play an important part in such experimentation. Wire
coathangers (straightened, of course, and cut to size!) can also be used
as aerial elements.

Unfortunately, the OP hasn't come back yet to say what his present FM
aerial consists of.
--
Ian