Hi

I'm planning on installing an FM aerial and using it to "feed" some sockets
around the house. I don't have TV so it will be FM only.

I've already worked out which aerial is suitable. It's a small Ron Smith
aerial and a fair amount of the planning is done. I do however have some
questions which some here might be interested in answering.

(a) Can you recommmend a source of low loss coax cable? Ron Smith
(Luton, Beds) sells it and that is the most likely source on this
occasion, but I don't think Ron Smith will be selling it for very
long as he is selling off the last of his stock as the Ron Smith
business is shut down unfortunately I am going to get all I
need for the first part of my coax installation but there'll be
more in the future for more sockets and so it would be good to
know of a different source. For all I know the stuff in the big
DIY stores is very low loss of course but no doubt someone here
can inform me.

(b) In the past I've always just put the coaxial plugs on the end of
the cable without solder but soldering is recommended in what I've
read so far for good stable connections. I can easily work out how
to solder the inner of the coax, but do people solder the outer
(shielding) and if so what to? Are there plugs better suited to
soldering?

(c) My next question is about burying the cables in walls. Do people
normally just chisel a trough in the wall, put the cable in it,
and then fill it, effectively sealing the cable in, or do people
use a conduit of some sort?

(d) I've looked at some amplifiers at the Maplin web-site. Although
the signal strength is good in my area I might be splitting the
signal up quite a lot as my house gets more populated with radios.
It looks like the mast head amplifiers are only for UHF, judging
by what's available at Maplins, is that the case that mast head
amps are for TV only? Does anyone have any experience of
amplifiers suitable for FM? Is there a source for them other than
Maplins on the net?

(e) Years ago someone told me that even if a radio doesn't have an
aerial socket an external aerial can be used by simply using a
crocodile clip to attach the cable inner to the aerial of the
radio. Is this true? It seems to make sense to me actually.

(f) One of the radios I will be supplying with this small network is
the new Tivoli Clock Radio. Lovely it is too! I notice that with
the American instructions there is a paragraph on the subject of
grounding an external aerial this is to provide protection some
protection against voltage surges and built-up static charges.
They even have quite an elaborate diagram including things like an
"antenna discharge unit" and a "power service grounding electrode
system". Is this grounding of the aerial something to be concerned
about?

You might be amused to know that included in the instructions for the Tivoli
Clock Radio is this bit of advice:

"Do not place this product on an unstable cart, stand, tripod, bracket or
table. The product may fall, causing serious damage to a child or adult, and
serious damage to the product."


--
Patrick

But you can also source some good radio on the Freeserve system where
the audio quality is better than the DAB crap that's around. Satellite
will give you even more choice even the much despised Sky digibox is
good for some tens of radio channels!.

Although I would not disagree with a word of your good technical advice I
must take issue on your description of DAB as crap! I have had digital
radio for three years, in London we have 50 stations to choose from and I
would not go back to listening on FM. My advice would be to buy a DAB
receiver put up a good Band III aerial and enjoy real quality sound.

Robin

On Wed, 17 Sep 2003 22:47:18 +0100, "Robin Prater"
wrote:

Although I would not disagree with a word of your good technical advice I
must take issue on your description of DAB as crap! I have had digital
radio for three years, in London we have 50 stations to choose from and I
would not go back to listening on FM. My advice would be to buy a DAB
receiver put up a good Band III aerial and enjoy real quality sound.

Well ok, but I'm not far from Luton, where the supplier mentioned by
the OP is, and to be honest, we're NEVER going to have 50 stations on
DAB around here, and I'd be surprised if we could even get DAB at all
inside the next 10 years. The rationing of resources has never worked
that way before, and I'd be glad to be wrong if I am, but experience
suggests that's how it will be.

The BBC has announced no certain plans for local radio after the big
switch off, and I am pretty sure that's because they don't have any.
I'd be really glad to be wrong about that too. Not holding my breath
about it though.

I'd like to go get DAB tomorrow, but I can't see any point, they have
yet to make AM or FM work "well" here yet. I understand DAB is
technically more demanding still. Having it happen sounds pretty
unlikely then, given track records to date! I think I better go and
re-research all this as it looks like something you could not make
up, but had all the same! ;O)

Take Care,
Gnube
{too thick for linux}

In article , Robin Prater
writes


But you can also source some good radio on the Freeserve system where
the audio quality is better than the DAB crap that's around. Satellite
will give you even more choice even the much despised Sky digibox is
good for some tens of radio channels!.

Although I would not disagree with a word of your good technical advice I
must take issue on your description of DAB as crap! I have had digital
radio for three years, in London we have 50 stations to choose from and I
would not go back to listening on FM. My advice would be to buy a DAB
receiver put up a good Band III aerial and enjoy real quality sound.

Robin



Don't see it that way. DAB has been seriously degraded by the BBC and
commercial stations because they have lowered the bitrates. This has had
an adverse effect on the overall sound quality which has now gone from
what could have been excellent, to what can now only be described as
mediocre. The only DAB station that can hold its own is radio 3 which is
at 192 K/bits most of the others are at 128 K/bits or even less
sometimes, radio 4 is even in Mono at times!.

In fact the whole systems badly flawed as the encoder in use, MP2, has
now been superseded by better ones so the tech is already 10 years out
of date. But if it suits you then that's fine but the sound of
Terrestrial DAB annoys me intensely. FM isn't perfect either but is far
more natural than what DAB is but a lot of the time FM is adjudged as
poor, and this is only due to insufficient aerial signals.

I would only regard DAB as fit for portable use and for in car, as a
serious medium for home delivery its poor, Satellite is a much better
option or if you only want the local and main BBC channels then FM still
manages to outshine them provided its fed with a clean signal...
--
Tony Sayer

In article , Owain
writes
"Robin Prater" wrote
| But you can also source some good radio on the Freeserve system where
| the audio quality is better than the DAB crap that's around.
| Although I would not disagree with a word of your good technical advice I
| must take issue on your description of DAB as crap! I have had digital
| radio for three years, in London we have 50 stations to choose from and I
| would not go back to listening on FM. My advice would be to buy a DAB
| receiver put up a good Band III aerial and enjoy real quality sound.

DAB is lower bitrates than Freeview and even the BBC has admitted that DAB
is no longer a high fidelity medium in an email that has been circulated on
the 'net.

Good FM analogue, when it happens, is probably the best broadcast sound, but
it still does not compare with good vinyl.

Beg to differ:-)))....

Must admit that I quite like having the option of World Service, Asian
Network or Magic though.


I think that the future of home reception is via satellite delivery.
What's needed now are better satellite receivers..

--
Tony Sayer

In article ,
Owain wrote:
DAB is lower bitrates than Freeview and even the BBC has admitted that
DAB is no longer a high fidelity medium in an email that has been
circulated on the 'net.

Yes. Although R3 and 4 are still ok on DAB IMHO.

Good FM analogue, when it happens, is probably the best broadcast sound,
but it still does not compare with good vinyl.

I'd say the finest broadcast sound quality readily available to all is
probably NICAM on TV. Good FM reception can be much more difficult to
achieve - and costly.

You were ahead up until now. ;-)

Vinyl has inherent distortions that cannot be overcome. And that's before
the physical wear and damage problems. It also requires great compromises
as to what can and can't be cut satisfactorily which invariably means
altering the master recording to suit. CD, for example, doesn't.

Must admit that I quite like having the option of World Service, Asian
Network or Magic though.

I'd say that many who aren't committed Hi-Fi types would be satisfied by
DAB - it suffers from non of the reception problems that plague both FM
and AM. Can have some of its own, though.

I'd say the reason they have reduced the audio quality to cram in more
choice is that it hasn't exactly been a success, numbers wise. But at
least the option is there to later restore bitrates to where most would
find acceptable.

--
*Can vegetarians eat animal crackers?

Dave Plowman London SW 12
RIP Acorn

In article ,
PJ wrote:
Does anyone have any experience of amplifiers suitable for FM?

As a general comment, DAs for FM use are rarely satisfactory.

--
*Sometimes I wake up grumpy; Other times I let him sleep.

Dave Plowman London SW 12
RIP Acorn

In article , Dave Plowman
writes
In article ,
PJ wrote:
Does anyone have any experience of amplifiers suitable for FM?

As a general comment, DAs for FM use are rarely satisfactory.


Have you any reasoning for that assertion Dave?..
--
Tony Sayer

Owain wrote:

"Robin Prater" wrote
| But you can also source some good radio on the Freeserve system where
| the audio quality is better than the DAB crap that's around.
| Although I would not disagree with a word of your good technical advice I
| must take issue on your description of DAB as crap! I have had digital
| radio for three years, in London we have 50 stations to choose from and I
| would not go back to listening on FM. My advice would be to buy a DAB
| receiver put up a good Band III aerial and enjoy real quality sound.

DAB is lower bitrates than Freeview and even the BBC has admitted that DAB
is no longer a high fidelity medium in an email that has been circulated on
the 'net.

Good FM analogue, when it happens, is probably the best broadcast sound, but
it still does not compare with good vinyl.


Yes. 60db S/N ratio at best on FM, up to 75 on vinyl, and better than 80
on CD and no scratches..:-)



Must admit that I quite like having the option of World Service, Asian
Network or Magic though.

Owain

In article ,
tony sayer wrote:
As a general comment, DAs for FM use are rarely satisfactory.


Have you any reasoning for that assertion Dave?..

Most good receivers approach the maximum theoretical sensitivity, so
adding untuned gain before them will do no good. Passive splitting works
just as well. You might get a VHF distribution system to work tolerably
well for clock radios on local reception, but that's about all.

Of course I could be wrong, but I've yet to actually witness for myself
one that does work as well as without.

--
*Few women admit their age; fewer men act it.

Dave Plowman London SW 12
RIP Acorn

In article , The Natural Philosopher
writes
Owain wrote:

"Robin Prater" wrote
| But you can also source some good radio on the Freeserve system where
| the audio quality is better than the DAB crap that's around.
| Although I would not disagree with a word of your good technical advice I
| must take issue on your description of DAB as crap! I have had digital
| radio for three years, in London we have 50 stations to choose from and I
| would not go back to listening on FM. My advice would be to buy a DAB
| receiver put up a good Band III aerial and enjoy real quality sound.

DAB is lower bitrates than Freeview and even the BBC has admitted that DAB
is no longer a high fidelity medium in an email that has been circulated on
the 'net.

Good FM analogue, when it happens, is probably the best broadcast sound, but
it still does not compare with good vinyl.


Yes. 60db S/N ratio at best on FM, up to 75 on vinyl, and better than 80
on CD and no scratches..:-)

You can up that to about 70 odd these days with the right modulator and
tuner. Bit academic all the same..

--
Tony Sayer

On Thu, 18 Sep 2003 19:04:17 +0100, Dave Plowman
wrote:

In article ,
tony sayer wrote:
As a general comment, DAs for FM use are rarely satisfactory.


Have you any reasoning for that assertion Dave?..

Most good receivers approach the maximum theoretical sensitivity, so
adding untuned gain before them will do no good. Passive splitting works
just as well. You might get a VHF distribution system to work tolerably
well for clock radios on local reception, but that's about all.

Of course I could be wrong, but I've yet to actually witness for myself
one that does work as well as without.


Hmm. I don't seem to have any problems in that area.

I have a combined UHF and VHF distribution system as follows:

Feeds from two Televes wideband UHF antennas via Spaun front end
amplifiers each followed by channelising filters. There is another
feed from a set of IKUSI modulators followed by a channelised filter
to incorporate VCR, DVD, satellite and other feeds into the system.
These are combined via a splitter and then the signal from a 4-element
Triax for Band-II is brought in via a diplexer.

The combined signals then fed to an IKUSI CBS901 launch amplifier

http://www.teldis.com/CP-IKUSICBS.htm

This feeds a distribution system of multiple splitters with outlets
going to diplexer sockets - in some cases several per room.

The channelised filters are set to equalise the off-air TV signals as
well as the locally modulated ones. There is then a single gain
control on the launch amplifier to provide the correct UHF level at
the room outputs.

It works out from the design that there should be no uplift for the
Band-II signals - in fact IIRC there's a few dB.

At any rate, I have a variety of tuners of different quality levels
fed from the system. I've checked them on the distribution system as
well as directly from the antenna and there does not seem to be any
noticable difference. A couple of French transmitters come in a bit
better through the distribution system, although were pretty weak
signals beforehand.

Everything's cabled in proper CT100 and care taken with connectors
etc.


..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Thu, 18 Sep 2003 19:04:17 +0100, Dave Plowman
wrote:

In article ,
tony sayer wrote:
As a general comment, DAs for FM use are rarely satisfactory.


Have you any reasoning for that assertion Dave?..

Most good receivers approach the maximum theoretical sensitivity, so
adding untuned gain before them will do no good. Passive splitting works
just as well. You might get a VHF distribution system to work tolerably
well for clock radios on local reception, but that's about all.

Of course I could be wrong, but I've yet to actually witness for myself
one that does work as well as without.


Hmm. I don't seem to have any problems in that area.

I have a combined UHF and VHF distribution system as follows:

Feeds from two Televes wideband UHF antennas via Spaun front end
amplifiers each followed by channelising filters. There is another
feed from a set of IKUSI modulators followed by a channelised filter
to incorporate VCR, DVD, satellite and other feeds into the system.
These are combined via a splitter and then the signal from a 4-element
Triax for Band-II is brought in via a diplexer.

The combined signals then fed to an IKUSI CBS901 launch amplifier

http://www.teldis.com/CP-IKUSICBS.htm

This feeds a distribution system of multiple splitters with outlets
going to diplexer sockets - in some cases several per room.

The channelised filters are set to equalise the off-air TV signals as
well as the locally modulated ones. There is then a single gain
control on the launch amplifier to provide the correct UHF level at
the room outputs.

It works out from the design that there should be no uplift for the
Band-II signals - in fact IIRC there's a few dB.

At any rate, I have a variety of tuners of different quality levels
fed from the system. I've checked them on the distribution system as
well as directly from the antenna and there does not seem to be any
noticable difference. A couple of French transmitters come in a bit
better through the distribution system, although were pretty weak
signals beforehand.

Everything's cabled in proper CT100 and care taken with connectors
etc.


.andy

To email, substitute .nospam with .gl


Are you a sad bu**er or what?

On Thu, 18 Sep 2003 21:50:12 +0100, "harrogate"
wrote:




Are you a sad bu**er or what?



Very happy, thanks for asking..


..andy

To email, substitute .nospam with .gl

In article , Dave Plowman
writes
In article ,
tony sayer wrote:
As a general comment, DAs for FM use are rarely satisfactory.


Have you any reasoning for that assertion Dave?..

Most good receivers approach the maximum theoretical sensitivity, so
adding untuned gain before them will do no good. Passive splitting works
just as well. You might get a VHF distribution system to work tolerably
well for clock radios on local reception, but that's about all.

Of course I could be wrong, but I've yet to actually witness for myself
one that does work as well as without.


Well I can tell you that they do, and they do it very well provided that
they aren't overloaded. I have a Labgear unit that has the FM input
supplied with a 5 element Triax aerial that is aimed midway between the
local TX at Madingley and Peterbourgh and its fine.

The main purpose of the amplifier section is to overcome the splitter or
divider losses. In fact its performance is very good indeed and this is
not too far removed from the performance of the amplifier systems we use
in the "day job", VHF comms radio, which have up to 16 outputs and cost
about 700 quid!....
--
Tony Sayer

On the general theme of aerial installations is there a reasonable way
to wire in several aerial points off one aerial without a distribution
amplifier, ie just using a splitter or splitters. Say I want four
sockets, should I split near the aerial or run a single co-ax as far as
possible before splitting? There would only ever be one socket in use at
once but I can appreciate that long 'stubs' may cause various problems
on the line as a whole.

Colin

Dave Plowman wrote:

In article ,
tony sayer wrote:

As a general comment, DAs for FM use are rarely satisfactory.



Have you any reasoning for that assertion Dave?..


Most good receivers approach the maximum theoretical sensitivity, so
adding untuned gain before them will do no good. Passive splitting works
just as well. You might get a VHF distribution system to work tolerably
well for clock radios on local reception, but that's about all.



Thats true if the front end receiver noise figure is no better than the
boosters which is likley on a decent tuner.. However it is good for crap
radios - as you point out - and does no harm and may overcome
interference pickup in the cable if the local signals are weak.

I tried with and without a 10db booster - no audible difference ona good
tuner - but the 10 db booster does at least feed the 10 coaxial
cables...whereas a passive splittter to do that would have introduced
significant losses.


Of course I could be wrong, but I've yet to actually witness for myself
one that does work as well as without.


I thimk you meant as well with, as without..

I';d say the labgear amp I am using is pretty neutral. Doesn't make it
better, doesn;t make it worse. Its there to buffer and distribute not to
amplify tho.

Andy Hall wrote:

On Thu, 18 Sep 2003 19:04:17 +0100, Dave Plowman
wrote:


In article ,
tony sayer wrote:

As a general comment, DAs for FM use are rarely satisfactory.


Have you any reasoning for that assertion Dave?..

Most good receivers approach the maximum theoretical sensitivity, so
adding untuned gain before them will do no good. Passive splitting works
just as well. You might get a VHF distribution system to work tolerably
well for clock radios on local reception, but that's about all.

Of course I could be wrong, but I've yet to actually witness for myself
one that does work as well as without.



Hmm. I don't seem to have any problems in that area.

I have a combined UHF and VHF distribution system as follows:

Feeds from two Televes wideband UHF antennas via Spaun front end
amplifiers each followed by channelising filters. There is another
feed from a set of IKUSI modulators followed by a channelised filter
to incorporate VCR, DVD, satellite and other feeds into the system.
These are combined via a splitter and then the signal from a 4-element
Triax for Band-II is brought in via a diplexer.

The combined signals then fed to an IKUSI CBS901 launch amplifier

http://www.teldis.com/CP-IKUSICBS.htm

This feeds a distribution system of multiple splitters with outlets
going to diplexer sockets - in some cases several per room.

The channelised filters are set to equalise the off-air TV signals as
well as the locally modulated ones. There is then a single gain
control on the launch amplifier to provide the correct UHF level at
the room outputs.

It works out from the design that there should be no uplift for the
Band-II signals - in fact IIRC there's a few dB.

At any rate, I have a variety of tuners of different quality levels
fed from the system. I've checked them on the distribution system as
well as directly from the antenna and there does not seem to be any
noticable difference. A couple of French transmitters come in a bit
better through the distribution system, although were pretty weak
signals beforehand.

Everything's cabled in proper CT100 and care taken with connectors
etc.



That is consistent with my experience also.

The one exception being truly naff 'alarm clock' radios,

which are SO bad that a bit of a boost improves them :-()




.andy

To email, substitute .nospam with .gl

In article MPG.19d4cdcd7efc61b9989c90@localhost, Colin Blackburn
writes
On the general theme of aerial installations is there a reasonable way
to wire in several aerial points off one aerial without a distribution
amplifier, ie just using a splitter or splitters. Say I want four
sockets, should I split near the aerial or run a single co-ax as far as
possible before splitting? There would only ever be one socket in use at
once but I can appreciate that long 'stubs' may cause various problems
on the line as a whole.

Colin

Yes what you state with long stubs will be problematical. Use a
distribution amp a good one can be had for about 20 quid and then look
forward to many years of use with good clean signals. A splitter will
work but it divides the available signal....
--
Tony Sayer

In article , says...

Yes what you state with long stubs will be problematical. Use a
distribution amp a good one can be had for about 20 quid and then look
forward to many years of use with good clean signals. A splitter will
work but it divides the available signal....

As I live off the grid I was checking the possibility of solutions not
requiring power. Not specifically because of the power but more the
convenience of not having, say, to turn on a DA in one room to watch the
TV in another---my assumption is that for most people the DA is hidden
away and permanently on, not something I can have easily.

I guess at the same time I wire in the aerial cables I could wire in a
switch in each room with an aerial point so that the DA can be turned on
from anywhere---this could get complicated!

Colin

In article ,
tony sayer wrote:
Of course I could be wrong, but I've yet to actually witness for myself
one that does work as well as without.


Well I can tell you that they do, and they do it very well provided that
they aren't overloaded. I have a Labgear unit that has the FM input
supplied with a 5 element Triax aerial that is aimed midway between the
local TX at Madingley and Peterbourgh and its fine.

The main purpose of the amplifier section is to overcome the splitter or
divider losses. In fact its performance is very good indeed and this is
not too far removed from the performance of the amplifier systems we use
in the "day job", VHF comms radio, which have up to 16 outputs and cost
about 700 quid!....

I'll bow to those with superior knowledge, but still maintain that the
average installation using commonly available bits just doesn't work
properly - at least in the way an average UHF TV one does.

--
*Geeks shall inherit the earth *

Dave Plowman London SW 12
RIP Acorn

On Fri, 19 Sep 2003 10:44:23 +0100, Colin Blackburn
wrote:

In article , says...

Yes what you state with long stubs will be problematical. Use a
distribution amp a good one can be had for about 20 quid and then look
forward to many years of use with good clean signals. A splitter will
work but it divides the available signal....

As I live off the grid I was checking the possibility of solutions not
requiring power. Not specifically because of the power but more the
convenience of not having, say, to turn on a DA in one room to watch the
TV in another---my assumption is that for most people the DA is hidden
away and permanently on, not something I can have easily.

I guess at the same time I wire in the aerial cables I could wire in a
switch in each room with an aerial point so that the DA can be turned on
from anywhere---this could get complicated!

Colin

Another option could be a mast head type of amplifier, but not fitted
at the mast head, then followed by a splitter. These can be powered
with 12v and at a few tens of milliamps. Would that be more suitable
than a mains type of device?


..andy

To email, substitute .nospam with .gl

On Fri, 19 Sep 2003 10:47:11 +0100, Dave Plowman
wrote:

In article ,
tony sayer wrote:
Of course I could be wrong, but I've yet to actually witness for myself
one that does work as well as without.


Well I can tell you that they do, and they do it very well provided that
they aren't overloaded. I have a Labgear unit that has the FM input
supplied with a 5 element Triax aerial that is aimed midway between the
local TX at Madingley and Peterbourgh and its fine.

The main purpose of the amplifier section is to overcome the splitter or
divider losses. In fact its performance is very good indeed and this is
not too far removed from the performance of the amplifier systems we use
in the "day job", VHF comms radio, which have up to 16 outputs and cost
about 700 quid!....

I'll bow to those with superior knowledge, but still maintain that the
average installation using commonly available bits just doesn't work
properly - at least in the way an average UHF TV one does.

Could that be because you are in a high signal area, though Dave?
Admittedly Wrotham is a bit further away than Crystal Palace and
Beulah Hill, but is a high power site....

I wonder whether the wideband noise starts to have more of an impact
under high signal conditions.....








..andy

To email, substitute .nospam with .gl

In article ,
am says...

Another option could be a mast head type of amplifier, but not fitted
at the mast head, then followed by a splitter. These can be powered
with 12v and at a few tens of milliamps. Would that be more suitable
than a mains type of device?

It's a possibility. There is a 12V DC supply to the house which I could
utilise. Any particular name or brand I should look for?

Colin

In article MPG.19d4e53e7c239d2b989c97@localhost,
Colin Blackburn wrote:
Another option could be a mast head type of amplifier, but not fitted
at the mast head, then followed by a splitter. These can be powered
with 12v and at a few tens of milliamps. Would that be more suitable
than a mains type of device?

It's a possibility. There is a 12V DC supply to the house which I could
utilise. Any particular name or brand I should look for?

I think many normal DAs also work from a 12 volt DC supply. You'd need to
take the cover off, though. ;-)

--
*Why isn't there a special name for the back of your knee?

Dave Plowman London SW 12
RIP Acorn

In article ,
Andy Hall wrote:
I'll bow to those with superior knowledge, but still maintain that the
average installation using commonly available bits just doesn't work
properly - at least in the way an average UHF TV one does.

Could that be because you are in a high signal area, though Dave?
Admittedly Wrotham is a bit further away than Crystal Palace and
Beulah Hill, but is a high power site....

I wonder whether the wideband noise starts to have more of an impact
under high signal conditions.....

Yes - it could also be intermoduation problems from the large amount of RF
in this part of sauf lunnon.

But a much more clever than me engineer pal in Harrow had simlair
findings. But some time ago - I'd guess things have moved on since then.

--
*Prepositions are not words to end sentences with *

Dave Plowman London SW 12
RIP Acorn

In article , Dave Plowman
writes
In article ,
tony sayer wrote:
Of course I could be wrong, but I've yet to actually witness for myself
one that does work as well as without.


Well I can tell you that they do, and they do it very well provided that
they aren't overloaded. I have a Labgear unit that has the FM input
supplied with a 5 element Triax aerial that is aimed midway between the
local TX at Madingley and Peterbourgh and its fine.

The main purpose of the amplifier section is to overcome the splitter or
divider losses. In fact its performance is very good indeed and this is
not too far removed from the performance of the amplifier systems we use
in the "day job", VHF comms radio, which have up to 16 outputs and cost
about 700 quid!....

I'll bow to those with superior knowledge, but still maintain that the
average installation using commonly available bits just doesn't work
properly - at least in the way an average UHF TV one does.


Its far from Rocket science Dave. However I have heard that due to your
location you do have problems with FM but not everyone is so
afflicted!..
--
Tony Sayer

In article MPG.19d4e052a4d7bd5989c95@localhost, Colin Blackburn
writes
In article , says...

Yes what you state with long stubs will be problematical. Use a
distribution amp a good one can be had for about 20 quid and then look
forward to many years of use with good clean signals. A splitter will
work but it divides the available signal....

As I live off the grid I was checking the possibility of solutions not
requiring power. Not specifically because of the power but more the
convenience of not having, say, to turn on a DA in one room to watch the
TV in another---my assumption is that for most people the DA is hidden
away and permanently on, not something I can have easily.

I guess at the same time I wire in the aerial cables I could wire in a
switch in each room with an aerial point so that the DA can be turned on
from anywhere---this could get complicated!

Colin

Well if you have strong signals then perhaps you can getaway with just
passive splitting. Only real answer is to try it and see.
--
Tony Sayer

On Fri, 19 Sep 2003 11:05:27 +0100, Colin Blackburn
wrote:

In article ,
says...

Another option could be a mast head type of amplifier, but not fitted
at the mast head, then followed by a splitter. These can be powered
with 12v and at a few tens of milliamps. Would that be more suitable
than a mains type of device?

It's a possibility. There is a 12V DC supply to the house which I could
utilise. Any particular name or brand I should look for?

Colin

I was thinking that you could use something like a Labgear CM7274 or
an Antiference UX4. These are masthead amplifiers with 4 outputs
which can go directly to your sockets and can be powered over the
co-ax with 12v DC. Normally they are powered from a distribution
amplifier run from the mains or a separate 12v power supply like the
Labgear PSM112 - these need 3W from the mains.

If you were going to run from a battery, you need a passive device
that sits in one of the co-ax cables and allows you to inject 12v DC -
basically the same as one of the power supply units but without the
mains, rectification, smoothing and regulating pieces. I would
suggest calling Labgear and Antiference and asking if they make
anything like that. Another useful place is Teldis, who distribute
all kinds of TV, satellite and FM distribution equipment. I found
them to be pretty knowledgable on what is on the market..





..andy

To email, substitute .nospam with .gl

In article ,
am says...

I was thinking that you could use something like a Labgear CM7274 or
an Antiference UX4. These are masthead amplifiers with 4 outputs
which can go directly to your sockets and can be powered over the
co-ax with 12v DC. Normally they are powered from a distribution
amplifier run from the mains or a separate 12v power supply like the
Labgear PSM112 - these need 3W from the mains.

If you were going to run from a battery, you need a passive device
that sits in one of the co-ax cables and allows you to inject 12v DC -
basically the same as one of the power supply units but without the
mains, rectification, smoothing and regulating pieces. I would
suggest calling Labgear and Antiference and asking if they make
anything like that. Another useful place is Teldis, who distribute
all kinds of TV, satellite and FM distribution equipment. I found
them to be pretty knowledgable on what is on the market..

Thanks for the names and ideas (everyone else too.) I think I will
initially wire in a splitter---I get a strong signal, hell I can see
Pontock Pike from the bedroom window with a pair of binoculars---then
look at masthead amplifiers and possibly DAs with fancy wiring!

Cheers,

Colin

Colin Blackburn wrote:

On the general theme of aerial installations is there a reasonable way
to wire in several aerial points off one aerial without a distribution
amplifier, ie just using a splitter or splitters. Say I want four
sockets, should I split near the aerial or run a single co-ax as far as
possible before splitting? There would only ever be one socket in use at
once but I can appreciate that long 'stubs' may cause various problems
on the line as a whole.

Colin


Makes no difference.

The problem is to achieve reflectionless splitting. In real terms this
can only be done with matched resistive pads on each end of every
cable,. This is totally impractical - who is goindg to put 75ohm
terminators in every socket in the hose that is not in use? AND that
results in losses, degrading the signal anyway.

Distrubution amplifiers isolate each cable from all the others, That's
what they are there for. Use them.

In article MPG.19d50d857f2bba12989c9d@localhost, Colin Blackburn
writes
In article ,
says...

I was thinking that you could use something like a Labgear CM7274 or
an Antiference UX4. These are masthead amplifiers with 4 outputs
which can go directly to your sockets and can be powered over the
co-ax with 12v DC. Normally they are powered from a distribution
amplifier run from the mains or a separate 12v power supply like the
Labgear PSM112 - these need 3W from the mains.

If you were going to run from a battery, you need a passive device
that sits in one of the co-ax cables and allows you to inject 12v DC -
basically the same as one of the power supply units but without the
mains, rectification, smoothing and regulating pieces. I would
suggest calling Labgear and Antiference and asking if they make
anything like that. Another useful place is Teldis, who distribute
all kinds of TV, satellite and FM distribution equipment. I found
them to be pretty knowledgable on what is on the market..

Thanks for the names and ideas (everyone else too.) I think I will
initially wire in a splitter---I get a strong signal, hell I can see
Pontock Pike from the bedroom window with a pair of binoculars---then
look at masthead amplifiers and possibly DAs with fancy wiring!

Cheers,

Colin

If you can see the Pike from your window then don't bother with an amp a
splitter will do with those sort of levels around. Don't bother with a
masthead type amp as it will overload and cause more grief than what its
worth!..
--
Tony Sayer

In article , says...

The problem is to achieve reflectionless splitting. In real terms this
can only be done with matched resistive pads on each end of every
cable,. This is totally impractical - who is goindg to put 75ohm
terminators in every socket in the hose that is not in use?

Er, that bit is easy. I only use one socket at a time and all the
sockets are accessible. All I need to do is terminate every socket and
then switch the cable to the TV for the terminator for the room I am
using.

AND that
results in losses, degrading the signal anyway.

Distrubution amplifiers isolate each cable from all the others, That's
what they are there for. Use them.

I have said elsewhere why I am not minded to use this route if at all
possible. It is more impracticable for me than having a terminator in
the unused sockets.

Colin

"Colin Blackburn" wrote
| On the general theme of aerial installations is there a reasonable
| way to wire in several aerial points off one aerial without a
| distribution amplifier, ie just using a splitter or splitters.
| Say I want four sockets, should I split near the aerial or run
| a single co-ax as far as possible before splitting? There would
| only ever be one socket in use at once but I can appreciate that
| long 'stubs' may cause various problems on the line as a whole.

You could just wire your aerial to one central point with a socket, have the
cables to the room sockets terminating there on plugs, and plug in whichever
room is required. If you have a strong signal and use good quality
connectors there should be negligible effect on the signal. If,
subsequently, you want to try passive splitters or a distr. amp., the
cabling is already in place.

Owain

On Fri, 19 Sep 2003 9:43:48 +0100, The Natural Philosopher wrote
(in message ):

That is consistent with my experience also.

The one exception being truly naff 'alarm clock' radios,

which are SO bad that a bit of a boost improves them :-()

My clock radio is surprisingly good actually

If you go he

http://www.tivoliaudio.com/locales/gb/

and then click on the "Model 3" button on the left.

I've had it for a couple of days now and I'm becoming rather evangelical
about it

I think it suits classical much better than rock/pop, but I listen to Radio 3
all the time so it suits me fine. There are still some classical shows on
Radio 3.

Having really rather good sound quality at night is lovely. It can interfere
with sex life however...

--
Patrick

On Thu, 18 Sep 2003 21:50:12 +0100, harrogate wrote
(in message ):

Are you a sad bu**er or what?

You'd like my clock radio

--
Patrick

In uk.d-i-y, PJ wrote:

At my local Maplins they have Satellite TV Cable FT100 in 100m roll at 24.99
pounds sterling. Is this the same as CT100?

Probably a cheaper near-equivalent, but maybe the honest stuff. It sells
at 25-30 quid the 100yd reel at not-taking-the-Micheal-on-price places.

Also, they have Satellite Cable FT125 in 100m roll at 59.99 pounds sterling.
Any idea what that is?

CT125 is the next size up from CT100 - slightly bigger outer diameter,
slightly lower attenuation losses over distance, more often used for
distribution feeds in bigger installations (e.g. for piping sat TV signals
or cable-TV feeds round a block of flats); there's CT167 and CT233 sizes
which continue the trend upwards in diameter and lower losses. All of these
more exotic sizes share the same design impedance as CT100 - 75 ohm; but
because they're sold in much lower quantity than CT100, you pay a b-i-g
price hike for them over the CT100 (a bit like the hike in 4mmsq mains
cable compared to 2.5mmsq!). For a domestic installation with "normal"
lengths of cabling, you don't need anything beyond CT100, and it gets
harder - indeed impossible! - to get coax plugs and sockets to mount
neatly to the larger sizes.

HTH, Stefek

On Fri, 19 Sep 2003 23:50:19 +0100, PJ wrote:

On Wed, 17 Sep 2003 21:48:58 +0100, tony sayer wrote
(in message ):

Cable very simple, CT100 the satellite stuff excellent and far better
than the usual low loss string as sold in the sheds use this for
anything..

Thank you for your informative reply. I'm sure I'll have more questions but
for now just this.

At my local Maplins they have Satellite TV Cable FT100 in 100m roll at 24.99
pounds sterling. Is this the same as CT100?

It might or might not be. CT100 has a defined construction and RF
specification. Various other cables purport to be the same and may
or may not be. Some of the cheap ones sold as satellite cable may
have inferior screening or mechanical construction or may have worse
than spec. losses at high frequencies.

Whether this particular cable is OK is hard to know. To be able to
tell that,you would need to know the losses at various frequencies and
compare them to the real thing and Maplin don't seem to publish that
data. As a comparison, RS have a Raydex CT100 for £44 for 100m and
CPC have one for £19.60 for 50m - i.e. almost twice the Maplin price.
Both of these appear to follow the official specs.



Also, they have Satellite Cable FT125 in 100m roll at 59.99 pounds sterling.
Any idea what that is?

This sounds like a copy of CT125, basically a lower loss cable. Again
you would pay just under twice Maplin prices for the official stuff.
The cable diameter is about 8mm rather than 6mm.


..andy

To email, substitute .nospam with .gl

On Fri, 19 Sep 2003 23:42:22 +0100, PJ wrote:



My clock radio is surprisingly good actually

If you go he

http://www.tivoliaudio.com/locales/gb/

and then click on the "Model 3" button on the left.

I've had it for a couple of days now and I'm becoming rather evangelical
about it

I think it suits classical much better than rock/pop, but I listen to Radio 3
all the time so it suits me fine. There are still some classical shows on
Radio 3.

Having really rather good sound quality at night is lovely. It can interfere
with sex life however...

Even Ravel's Bolero??


..andy

To email, substitute .nospam with .gl

On Fri, 19 Sep 2003 23:42:22 +0100, PJ wrote:
-()

My clock radio is surprisingly good actually

If you go he

http://www.tivoliaudio.com/locales/gb/

and then click on the "Model 3" button on the left.

I've had it for a couple of days now and I'm becoming rather evangelical
about it

I think it suits classical much better than rock/pop, but I listen to Radio 3
all the time so it suits me fine. There are still some classical shows on
Radio 3.


So do you think this is a fairly good product? I'm looking for a
good quality bedside radio and also really only listen to classical
content.

I am slightly concerned that there are no technical specs given,
although a lot that are published are, admittedly, somewhat
meaningless.


..andy

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