In message on Sun, 10 Apr 2011 15:44:15 +0100
BartC wrote:

"tony sayer" wrote in message
...
In article , BartC scribeth

I never solder those things, and I expect the tiniest amount of
capacitance
will do the job. Actually, I often only have to hold the plug near the RF
socket on a TV, and I start to get a picture, on an analogue set at least.

(In fact, I'm just done a test on a digital TV, disconnecting the RF lead
at
a joint: if the outer screen is in contact, I start to get a picture when
the inner core is 2 or 3 mm away from the centre pin! So the signal can
jump
an air gap of a tenth of an inch, and from one point to another, while an
unsoldered wire will have a 1 or 2cm length in a hollow tube so a greater
capacitive effect)


Sorry but thats not very good practice or science come to that. If in
the RF I work in we had unsoldered joints there would be fires and
smoke;!..

The signal from a TV aerial is at microscopic power levels. And I do tend to
bend the inner core of the coax to make sure it makes contact inside the
hollow pin of the plug.

But if it doesn't, doesn't it just form a tiny capacitor? (And I wouldn't be
surprised if the first thing the signal encountered inside the TV was an
actual 10pf or 100pf series capacitor.)

Well, the reactance of a 100pF capacitor at Ch 21 is 3.4 ohms, dropping to 1.8
ohms at Ch 68, so it wouldn't have a major effect on matching.

But the tiny capacitor inside the plug has a much smaller capacity! One
picofarad, perhaps? Or less?

Which means multiplying the figures above by 100 for 1pF or even 10,000 for
0.1pF. so, 300 ohms to about 3k at Ch. 21. I don't think it is going to match
to 75 ohms any more - do you?
--

Terry

Ian Jackson wrote:
In message ,
Terry Casey writes
In message on Sun, 10 Apr 2011
16:06:39 +
0100
Ian Jackson wrote:

In message , Alan
writes
In message ,
Terry Casey wrote
but,
if your amp uses 'Belling' style connectors (like an ordinary aerial
plug/socket on a TV, find a local shop that sells components - or
to Maplin
- and buy a 75 ohm resistor (the old fashioned kind with wire
connections) and
a plug. (If you can't get a 75 ohm resistor, 82 ohms is acceptable.)

Or fit a F type 75 ohm termination to a F to a Belling Lee converter
http://www.admac.myzen.co.uk/F_coax/
A few quid for the lot from Ebay.

If you're not 'into' electronics, that's by far the easiest way to do
it.

I've been in the electronics industry since the 1960s and, surprisingly,
I've never come across any commercial Belling Lee 75 ohm terminations.

Teleste used IEC (belling) connectors on their CATV kit and I'm sure
they also
provided a 75 ohm termination ...

In contrast, F terminations are everywhere. [I presume that that is
because they are used on professional equipment in the cable TV
industry.] I've always had to make my own B&Ls, or do as suggested
above.

A resistor and Belling plug would be much cheaper though!

I did have a bit 'contact' with the Teleste headend equipment. I
remember the short purpose-made jumpers, but I don't recall finding any
IEC/B&L terminations being used with it. While I'd be surprised if
Teleste didn't supply them (for use where required), I've never seen
them offered in any vendors' catalogues etc (although 'The Natural
Philosopher' has).

Yep. I just checked, and I've got one on a spare port on my dis amp. Its
just a knurled block with a belling lee plug integrated into it - no
makers markings.

this place seems to have em

http://www.jwhardy.co.uk/shop/pages/...onnectors.html

"IEC169-2 CoaxPlug 75 ohm Terminator each" @ 60p a hit.


Which if you are not happy to source resistors and solder, is a good
price, I reckon.

I have to say that that is the ONLY source I found on the web tho, which
supports the proposition that these are rare birds indeed.

In message , The Natural Philosopher
writes
Ian Jackson wrote:
In message ,
Terry Casey writes
In message on Sun, 10 Apr 2011
16:06:39 +
0100
Ian Jackson wrote:

In message , Alan
writes
In message ,
Terry Casey wrote
but,
if your amp uses 'Belling' style connectors (like an ordinary aerial
plug/socket on a TV, find a local shop that sells components - or
Maplin
- and buy a 75 ohm resistor (the old fashioned kind with wire
connections) and
a plug. (If you can't get a 75 ohm resistor, 82 ohms is acceptable.)

Or fit a F type 75 ohm termination to a F to a Belling Lee converter
http://www.admac.myzen.co.uk/F_coax/
A few quid for the lot from Ebay.

If you're not 'into' electronics, that's by far the easiest way to do
it.

I've been in the electronics industry since the 1960s and, surprisingly,
I've never come across any commercial Belling Lee 75 ohm terminations.

Teleste used IEC (belling) connectors on their CATV kit and I'm sure
they also
provided a 75 ohm termination ...

In contrast, F terminations are everywhere. [I presume that that is
because they are used on professional equipment in the cable TV
industry.] I've always had to make my own B&Ls, or do as suggested
above.

A resistor and Belling plug would be much cheaper though!

I did have a bit 'contact' with the Teleste headend equipment. I
remember the short purpose-made jumpers, but I don't recall finding
any IEC/B&L terminations being used with it. While I'd be surprised
if Teleste didn't supply them (for use where required), I've never
seen them offered in any vendors' catalogues etc (although 'The
Natural Philosopher' has).

Yep. I just checked, and I've got one on a spare port on my dis amp.
Its just a knurled block with a belling lee plug integrated into it -
no makers markings.

this place seems to have em

http://www.jwhardy.co.uk/shop/pages/...onnectors.html

"IEC169-2 CoaxPlug 75 ohm Terminator each" @ 60p a hit.


Which if you are not happy to source resistors and solder, is a good
price, I reckon.

I have to say that that is the ONLY source I found on the web tho,
which supports the proposition that these are rare birds indeed.

And, at 60p a go, a bargain!

BTW, I wonder how many people terminate unconnected outputs from
Freeview set-top boxes? With the impending demise of all analogue
transmissions, and a dearth of STBs with RF modulators, there is no
longer any reason to connect the output of an STB RF bypass to the TV
set aerial input. I feel it would be 'nice' to terminate it (using the
'IEC169-2 Coax Plug to Plug Coupler' in the row above the 'IEC169-2
CoaxPlug 75 ohm Terminator'.
--
Ian

In message on Sun, 10 Apr 2011 18:32:29 +0100
The Natural Philosopher wrote:


Yep. I just checked, and I've got one on a spare port on my dis amp. Its
just a knurled block with a belling lee plug integrated into it - no
makers markings.

this place seems to have em

http://www.jwhardy.co.uk/shop/pages/...onnectors.html

"IEC169-2 CoaxPlug 75 ohm Terminator each" @ 60p a hit.


Which if you are not happy to source resistors and solder, is a good
price, I reckon.

I have to say that that is the ONLY source I found on the web tho, which
supports the proposition that these are rare birds indeed.

I don't know what the postage would be for a small order but, at that price for
one-off, especially considering the rarity, that has got to be a bargain!

I can't be bothered to check but I bet Maplin would want more for the plug and
resistor for the DIY approach!

--

Terry

In message , Ian Jackson
wrote

BTW, I wonder how many people terminate unconnected outputs from
Freeview set-top boxes?

I found that I had to terminate the unused outputs from a wall plate
where Satellite, UHF and FM were triplexed into one down cable.
http://www.admac.myzen.co.uk/termination/
Without the 75 ohm terminations on the unused satellite outputs the
frequency response on the UHF was very "peaky" and with the terminations
the response was virtually flat (response taken from the Freeview box
signal strength figures channel 24 to 59).

--
Alan
news2009 {at} admac {dot} myzen {dot} co {dot} uk

In message , John
Rumm writes
On 10/04/2011 11:11, Ian Jackson wrote:
In message , BartC writes
"Bill" wrote in message
...




Another favourite problem is pin of the plug, assuming a Belling Lee
plug
rather than an F. Quite often for speed the installer will not solder
the
coax inner to the pin of the plug, maybe he will have crudely crimped it
with a pair of side cutters, most likely not though. This can lead to
problems years down the line with corrosion isolating the coax inner
from
the pin. Any slight movement could have remade the connection. Although
the pin and inner may not have been making contact there could have been
enough capacitance for a signal to get across, but not strong enough to
give a good picture.

I never solder those things, and I expect the tiniest amount of
capacitance
will do the job. Actually, I often only have to hold the plug near the RF
socket on a TV, and I start to get a picture, on an analogue set at
least.

You're just asking for trouble!

(In fact, I'm just done a test on a digital TV, disconnecting the RF
lead at
a joint: if the outer screen is in contact, I start to get a picture when
the inner core is 2 or 3 mm away from the centre pin! So the signal
can jump
an air gap of a tenth of an inch, and from one point to another, while
an unsoldered wire will have a 1 or 2cm length in a hollow tube so a
greater capacitive effect)

I feel quite sick!

If you can't (or can't be bothered to) solder the coax solid inner
conductor into the pin, instead of 'crimping' it with a pair of side
cutters or pliers, I reckon it's better first to put a slight 'kink' the
inner conductor at about 5mm from the end. The kink should be made
sufficient to make it quite difficult to push the conductor into the
pin. Not only does it give you a reliable, relatively permanent contact,
but it has the additional advantage that the plug can later be removed,
and re-used!

Also you can (with most sockets) leave a little inner poking out the
end of the B&L plug F connector style. So the inner itself will make
contact with the socket.

Indeed. There's more one way of (incorrectly) skinning a cat. But while
'crimping' the pin with a pair of side-cutters or 'kinking' the centre
conductor before insertion are pretty sound methods of achieving a
reliable contact, I really can't approve of this one.

Anyway, now we have three ways of bodging/botching the centre conductor,
perhaps it's time to turn our attention to question of how not to deal
with the braid?
--
Ian

In message on Sun, 10 Apr 2011 20:39:39 +0100
Alan wrote:

In message , Ian Jackson
wrote

BTW, I wonder how many people terminate unconnected outputs from
Freeview set-top boxes?

I found that I had to terminate the unused outputs from a wall plate
where Satellite, UHF and FM were triplexed into one down cable.
http://www.admac.myzen.co.uk/termination/
Without the 75 ohm terminations on the unused satellite outputs the
frequency response on the UHF was very "peaky" and with the terminations
the response was virtually flat (response taken from the Freeview box
signal strength figures channel 24 to 59).

That isn't at all surprising. The triplexer - same thing applies to diplexers
too - consists of tuned circuits. Both frequency and impedance are important
factors in the design of these tuned circuits, so they are designed with both
input and output impedances of 75 ohms. Leaving the output impedance of one of
them at infinity, i.e.: unterminated, will make it perform in an entirely
unpredictable way which can also upset the response of the section which is
actualy in use - as you have both found and proved!

--

Terry

In message on Mon, 11 Apr 2011 08:13:25 +
0100
Ian Jackson wrote:

In message , John
Rumm writes

Also you can (with most sockets) leave a little inner poking out the
end of the B&L plug F connector style. So the inner itself will make
contact with the socket.


Ooh! Nasty!

Indeed. There's more one way of (incorrectly) skinning a cat. But while
'crimping' the pin with a pair of side-cutters or 'kinking' the centre
conductor before insertion are pretty sound methods of achieving a
reliable contact, I really can't approve of this one.


Seconded!

Anyway, now we have three ways of bodging/botching the centre conductor,
perhaps it's time to turn our attention to question of how not to deal
with the braid?

The responses to that could be VERY interesting ...!

I will sit back and wait with interest ...

--

Terry

In article ,
Terry Casey scribeth thus
In message on Sun, 10 Apr 2011 14:37:03 +0100
tony sayer wrote:

In article ,
Terry Casey scribeth thus
In message on Sun, 10 Apr 2011
12:30:10 +0100
MM wrote:

Can one get a terminator from Wilkinson,


Unlikely!

Yeah!, Wilkinson's do couplers...


That is hardly a terminator - and, unless they do the uncommon male-male
coupler, it won't even fit!

What do you suggest he puts on the other end of the coupler, anyway ...?


Loosen up Terry it was only intended as a joke

Don't take it all too seriously... Chill out bro;!....
--
Tony Sayer

In article , BartC scribeth
thus
"tony sayer" wrote in message
...
In article , BartC scribeth

I never solder those things, and I expect the tiniest amount of
capacitance
will do the job. Actually, I often only have to hold the plug near the RF
socket on a TV, and I start to get a picture, on an analogue set at least.

(In fact, I'm just done a test on a digital TV, disconnecting the RF lead
at
a joint: if the outer screen is in contact, I start to get a picture when
the inner core is 2 or 3 mm away from the centre pin! So the signal can
jump
an air gap of a tenth of an inch, and from one point to another, while an
unsoldered wire will have a 1 or 2cm length in a hollow tube so a greater
capacitive effect)


Sorry but thats not very good practice or science come to that. If in
the RF I work in we had unsoldered joints there would be fires and
smoke;!..

The signal from a TV aerial is at microscopic power levels. And I do tend to
bend the inner core of the coax to make sure it makes contact inside the
hollow pin of the plug.

But if it doesn't, doesn't it just form a tiny capacitor? (And I wouldn't be
surprised if the first thing the signal encountered inside the TV was an
actual 10pf or 100pf series capacitor.)


Makes no odds it should be connected properly not half done or bodged.,.

You won't find the likes of Bill Wright doing that..

--
Tony Sayer

In article ,
John Rumm wrote:
On 10/04/2011 11:11, Ian Jackson wrote:

I feel quite sick!

If you can't (or can't be bothered to) solder the coax solid inner
conductor into the pin, instead of 'crimping' it with a pair of side
cutters or pliers, I reckon it's better first to put a slight 'kink'

Also you can (with most sockets) leave a little inner poking out the end
of the B&L plug F connector style. So the inner itself will make contact
with the socket.

I now use a brand (can't remember which offhand but available from a B&Q
near you) which has a grub screw for the inner conductor. Not cheap at
shed prices, but then I only need them once or twice per year and they
do seem neatly made - all metal except for the insulating bush.

Nick
--
Serendipity: http://www.leverton.org/blosxom (last update 29th March 2010)
"The Internet, a sort of ersatz counterfeit of real life"
-- Janet Street-Porter, BBC2, 19th March 1996

On Sun, 10 Apr 2011 13:49:44 +0100, Terry Casey wrote:

A terminator is just a 75 ohm resistor.

But not just any 75 ohm resistor. Many use a spiral track on an
insulating former, nice little inductor... Heaven knows what the
actual impedance will be at UHF frequencies.

--
Cheers
Dave.

In message , Nick Leverton
writes
In article ,
John Rumm wrote:
On 10/04/2011 11:11, Ian Jackson wrote:

I feel quite sick!

If you can't (or can't be bothered to) solder the coax solid inner
conductor into the pin, instead of 'crimping' it with a pair of side
cutters or pliers, I reckon it's better first to put a slight 'kink'

Also you can (with most sockets) leave a little inner poking out the end
of the B&L plug F connector style. So the inner itself will make contact
with the socket.

I now use a brand (can't remember which offhand but available from a B&Q
near you) which has a grub screw for the inner conductor. Not cheap at
shed prices, but then I only need them once or twice per year and they
do seem neatly made - all metal except for the insulating bush.

In nearly types all I've seen where there is a screw, the tiny screw (or
its hole) is easily stripped, or is already stripped before you touch
it. You (well, I) usually end up by having to soldering the inner!
--
Ian

On Sat, 09 Apr 2011 23:36:27 +0100, John Rumm
wrote:

Well it sounds like you have escaped that for the mo, although with the
switch to digital you may not be out of the woods yet ;-)

Right, the new LCD TV has arrived and I've set it up in the kitchen.
Found 77 digital TV channels, 35 Radio, 22 Data/Other (what ever those
are).

**It also found 14 analogue channels**, which astonished me. I had
always assumed a digital TV can only receive digital signals. I've
switched through BBC One, Two, ITV, Channel 4 and Five, no problem.
Five gives the best picture (reception).

Initially, I tried setting up the TV in the living room, the one place
where the picture was grainy on the analogue portable. The LCD TV said
"weak or no signal".

So there's definitely a problem there. To cease with the guess-work I
have measured the actual length of the cable from the amplifier to the
wall plate: 13 metres +/- 20cm

The length to the kitchen wall plate is a lot shorter. I haven't
measured it, but it'll be about 6m

MM

In article , MM
scribeth thus
On Sat, 09 Apr 2011 23:36:27 +0100, John Rumm
wrote:

Well it sounds like you have escaped that for the mo, although with the
switch to digital you may not be out of the woods yet ;-)

Right, the new LCD TV has arrived and I've set it up in the kitchen.
Found 77 digital TV channels, 35 Radio, 22 Data/Other (what ever those
are).

**It also found 14 analogue channels**, which astonished me. I had
always assumed a digital TV can only receive digital signals.

Nope.. Our new Sony receives analogue and digital expect that round
these parts analogue is off the air from the 13th but it still has its
uses for a couple of analogue security cams that are in the distribution
system...


I've
switched through BBC One, Two, ITV, Channel 4 and Five, no problem.
Five gives the best picture (reception).

Initially, I tried setting up the TV in the living room, the one place
where the picture was grainy on the analogue portable. The LCD TV said
"weak or no signal".

So there's definitely a problem there. To cease with the guess-work I
have measured the actual length of the cable from the amplifier to the
wall plate: 13 metres +/- 20cm

The length to the kitchen wall plate is a lot shorter. I haven't
measured it, but it'll be about 6m

MM

--
Tony Sayer

MM wrote:
Snip
Initially, I tried setting up the TV in the living room, the one place
where the picture was grainy on the analogue portable. The LCD TV said
"weak or no signal".

Which proves you have a cable related fault. Or, as an outside chance, a
fault on the distribution amplifier. But you've tried swapping the
connections round at the amplifier end?

So there's definitely a problem there. To cease with the guess-work I
have measured the actual length of the cable from the amplifier to the
wall plate: 13 metres +/- 20cm

The length to the kitchen wall plate is a lot shorter. I haven't
measured it, but it'll be about 6m

Which, with undamaged cable and a decent joint at each end will make sod
all difference. If one had been 50 metres and the other a couple of
metres, maybe you'd see a difference you could show with a meter.

--
Tciao for Now!

John.

On Mon, 11 Apr 2011 19:41:01 +0100, John Williamson
wrote:

MM wrote:
Snip
Initially, I tried setting up the TV in the living room, the one place
where the picture was grainy on the analogue portable. The LCD TV said
"weak or no signal".

Which proves you have a cable related fault. Or, as an outside chance, a
fault on the distribution amplifier. But you've tried swapping the
connections round at the amplifier end?

Yes. No diff.


So there's definitely a problem there. To cease with the guess-work I
have measured the actual length of the cable from the amplifier to the
wall plate: 13 metres +/- 20cm

The length to the kitchen wall plate is a lot shorter. I haven't
measured it, but it'll be about 6m

Which, with undamaged cable and a decent joint at each end will make sod
all difference. If one had been 50 metres and the other a couple of
metres, maybe you'd see a difference you could show with a meter.

You mean, the 13 metre distance should be fine, yes? (I mean, to the
living room wall plate.)

Does it make a difference that there is another unconnected aerial
cable in the same conduit? What they did on constructing the house is
plan for a satellite dish in case the buyer might eventually want one,
so they left a lengthy coil of aerial cable (presumably the CT100 that
has been referred to in this thread) in the corner in the living room.
This is routed up though the same conduit in which the said 13m length
of cable from the loft-mounted amplifier is routed. I just wondered if
there mightn't be some sort of interference between the two cables,
the "loose" unconnected roll and the one connected to the wall plate.

Note that this "spare" roll of cable is taken up into the loft through
the conduit and then there is another generous length of it lying
around for any future satellite dish installer to make use of.

MM

In article , MM
scribeth thus
On Mon, 11 Apr 2011 19:41:01 +0100, John Williamson
wrote:

MM wrote:
Snip
Initially, I tried setting up the TV in the living room, the one place
where the picture was grainy on the analogue portable. The LCD TV said
"weak or no signal".

Which proves you have a cable related fault. Or, as an outside chance, a
fault on the distribution amplifier. But you've tried swapping the
connections round at the amplifier end?

Yes. No diff.


So there's definitely a problem there. To cease with the guess-work I
have measured the actual length of the cable from the amplifier to the
wall plate: 13 metres +/- 20cm

The length to the kitchen wall plate is a lot shorter. I haven't
measured it, but it'll be about 6m

Which, with undamaged cable and a decent joint at each end will make sod
all difference. If one had been 50 metres and the other a couple of
metres, maybe you'd see a difference you could show with a meter.

You mean, the 13 metre distance should be fine, yes? (I mean, to the
living room wall plate.)

Does it make a difference that there is another unconnected aerial
cable in the same conduit?

Umm ... you are on the -right- cable aren't you?..

Has happened...

What they did on constructing the house is
plan for a satellite dish in case the buyer might eventually want one,
so they left a lengthy coil of aerial cable (presumably the CT100 that
has been referred to in this thread) in the corner in the living room.
This is routed up though the same conduit in which the said 13m length
of cable from the loft-mounted amplifier is routed. I just wondered if
there mightn't be some sort of interference between the two cables,
the "loose" unconnected roll and the one connected to the wall plate.

Note that this "spare" roll of cable is taken up into the loft through
the conduit and then there is another generous length of it lying
around for any future satellite dish installer to make use of.

MM

--
Tony Sayer

On Mon, 11 Apr 2011 22:07:28 +0100, tony sayer
wrote:

In article , MM
scribeth thus
On Mon, 11 Apr 2011 19:41:01 +0100, John Williamson
wrote:

MM wrote:
Snip
Initially, I tried setting up the TV in the living room, the one place
where the picture was grainy on the analogue portable. The LCD TV said
"weak or no signal".

Which proves you have a cable related fault. Or, as an outside chance, a
fault on the distribution amplifier. But you've tried swapping the
connections round at the amplifier end?

Yes. No diff.


So there's definitely a problem there. To cease with the guess-work I
have measured the actual length of the cable from the amplifier to the
wall plate: 13 metres +/- 20cm

The length to the kitchen wall plate is a lot shorter. I haven't
measured it, but it'll be about 6m

Which, with undamaged cable and a decent joint at each end will make sod
all difference. If one had been 50 metres and the other a couple of
metres, maybe you'd see a difference you could show with a meter.

You mean, the 13 metre distance should be fine, yes? (I mean, to the
living room wall plate.)

Does it make a difference that there is another unconnected aerial
cable in the same conduit?

Umm ... you are on the -right- cable aren't you?..

The spare roll (for the provison of a satellite dish) is not connected
to anything. Just routed down the same conduit to the living room,
terminating in said spare roll (which one doesn't really notice as
it's tucked behind the TV table).

What I could try is a 15m length of CT100 to which I could fit the
appropriate connectors, one end for the amp in the loft, the other to
the TV (or buy a ready-made cable). Then I could string out the 15m
and see whether the TV complains then of a weak signal.

I'd pull the cables out of the conduit if I could, but they are really
tight in there. Why the bloody hell the builder couldn't have used two
separate conduits, beats me. Would have added minimal cost to the
overall cost of building, and they didn't stint elsewhere. Generally,
the house is a quality build, compared to some other modern, new
houses I've seen. Very small local builder.

MM

On Mon, 11 Apr 2011 22:07:28 +0100, tony sayer wrote:

Does it make a difference that there is another unconnected aerial
cable in the same conduit?

Umm ... you are on the -right- cable aren't you?..

Has happened...

Quite frequently but earlier everything was working well after the
cable in the loft was rerouted but it was then fiddled with again and
is now broke again. I suspect a break/kink in the cable somewhere. As
there is a spare length just switch over to that.

--
Cheers
Dave.

On Mon, 11 Apr 2011 23:51:43 +0100 (BST), "Dave Liquorice"
wrote:

On Mon, 11 Apr 2011 22:07:28 +0100, tony sayer wrote:

Does it make a difference that there is another unconnected aerial
cable in the same conduit?

Umm ... you are on the -right- cable aren't you?..

Has happened...

Quite frequently but earlier everything was working well after the
cable in the loft was rerouted but it was then fiddled with again and
is now broke again. I suspect a break/kink in the cable somewhere. As
there is a spare length just switch over to that.

Ah, well, I suppose I could do that, but it would negate the provision
by the builder for a satellite dish later on. However (thinking
aloud...), why should I bother myself about what the next owner,
whenever that might be, wants or doesn't want. Until your suggestion
above, I had kind of looked at that spare roll of cable as sacrosanct!

MM

In article , MM
writes
On Mon, 11 Apr 2011 23:51:43 +0100 (BST), "Dave Liquorice"
wrote:

On Mon, 11 Apr 2011 22:07:28 +0100, tony sayer wrote:

Does it make a difference that there is another unconnected aerial
cable in the same conduit?

Umm ... you are on the -right- cable aren't you?..

Has happened...

Quite frequently but earlier everything was working well after the
cable in the loft was rerouted but it was then fiddled with again and
is now broke again. I suspect a break/kink in the cable somewhere. As
there is a spare length just switch over to that.

Ah, well, I suppose I could do that, but it would negate the provision
by the builder for a satellite dish later on. However (thinking
aloud...), why should I bother myself about what the next owner,
whenever that might be, wants or doesn't want. Until your suggestion
above, I had kind of looked at that spare roll of cable as sacrosanct!

MM

If installed by the builder then don't get your hopes up that it's
decent stuff.

Strip the sheath on a bit at the end of a spare and/or on the reel and
compare with the pics here to be su

http://www.wrightsaerials.tv/article...-quality.shtml
--
fred
FIVE TV's superbright logo - not the DOG's, it's ********

In article , MM
scribeth thus
On Mon, 11 Apr 2011 22:07:28 +0100, tony sayer
wrote:

In article , MM
scribeth thus
On Mon, 11 Apr 2011 19:41:01 +0100, John Williamson
wrote:

MM wrote:
Snip
Initially, I tried setting up the TV in the living room, the one place
where the picture was grainy on the analogue portable. The LCD TV said
"weak or no signal".

Which proves you have a cable related fault. Or, as an outside chance, a
fault on the distribution amplifier. But you've tried swapping the
connections round at the amplifier end?

Yes. No diff.


So there's definitely a problem there. To cease with the guess-work I
have measured the actual length of the cable from the amplifier to the
wall plate: 13 metres +/- 20cm

The length to the kitchen wall plate is a lot shorter. I haven't
measured it, but it'll be about 6m

Which, with undamaged cable and a decent joint at each end will make sod
all difference. If one had been 50 metres and the other a couple of
metres, maybe you'd see a difference you could show with a meter.

You mean, the 13 metre distance should be fine, yes? (I mean, to the
living room wall plate.)

Does it make a difference that there is another unconnected aerial
cable in the same conduit?

Umm ... you are on the -right- cable aren't you?..

The spare roll (for the provison of a satellite dish) is not connected
to anything. Just routed down the same conduit to the living room,
terminating in said spare roll (which one doesn't really notice as
it's tucked behind the TV table).


Yes but the right cable is connected .. sure of that?..

What I could try is a 15m length of CT100 to which I could fit the
appropriate connectors, one end for the amp in the loft, the other to
the TV (or buy a ready-made cable). Then I could string out the 15m
and see whether the TV complains then of a weak signal.


Yes good idea..

I'd pull the cables out of the conduit if I could, but they are really
tight in there. Why the bloody hell the builder couldn't have used two
separate conduits, beats me. Would have added minimal cost to the
overall cost of building, and they didn't stint elsewhere. Generally,
the house is a quality build, compared to some other modern, new
houses I've seen. Very small local builder.

MM

Quite .. maybe there're crushed can cause all manner of odd problems..
--
Tony Sayer

In message o.uk on Mon, 11
Apr 2011 12:10:59 +0100 (BST)
Dave Liquorice wrote:

On Sun, 10 Apr 2011 13:49:44 +0100, Terry Casey wrote:

A terminator is just a 75 ohm resistor.

But not just any 75 ohm resistor. Many use a spiral track on an
insulating former, nice little inductor... Heaven knows what the
actual impedance will be at UHF frequencies.

Something that it doesn't seem easy to find data on - but there is a graph on
the Vishay data sheet at

http://www.vishay.com/doc?20135

which indicates that reactance versus resistance for a 0.35W 75 ohm carbon film
resistor is virtually unity up to 1GHz!

--

Terry

In message ,
Terry Casey writes
In message o.uk on Mon, 11
Apr 2011 12:10:59 +0100 (BST)
Dave Liquorice wrote:

On Sun, 10 Apr 2011 13:49:44 +0100, Terry Casey wrote:

A terminator is just a 75 ohm resistor.

But not just any 75 ohm resistor. Many use a spiral track on an
insulating former, nice little inductor... Heaven knows what the
actual impedance will be at UHF frequencies.

Something that it doesn't seem easy to find data on - but there is a graph on
the Vishay data sheet at

http://www.vishay.com/doc?20135

Blank screen!

which indicates that reactance versus resistance for a 0.35W 75 ohm
carbon film
resistor is virtually unity up to 1GHz!

Indeed.

While cracked carbon resistors potentially are likely to have the lowest
inductance, they are neither high tolerance no high stability.
Surprisingly, some spiral cut metal film resistors don't seem to have
excessive inductance. That said, I recall an impromptu production-line
change to a certain type of resistor (Electrosil, I believe) causing
serious problems at as low as 200MHz.

I suppose that today's tiddly chip resistors are too small to have much
inductance . Mind you, I'm surprised they are big enough to have any
resistance!

As for making good terminations, even though the resistor has some
inductance, the secret is to space the resistor at the right distance
above a groundplane. This adds capacitance, distributed along the length
of the resistor. In effect, the inductive resistor becomes part of a
transmission line, and a good wideband match can be maintained to the
cut-off frequency.
--
Ian

In message on Tue, 12 Apr 2011 16:40:40 +
0100
Ian Jackson wrote:

In message ,
Terry Casey writes

Something that it doesn't seem easy to find data on - but there is a graph on
the Vishay data sheet at

http://www.vishay.com/doc?20135

Blank screen!


Strange!

I clicked the link in your reply and it instantly downloaded a third copy of
the file!

(The second copy is from where I checked the link in my previous post ...!)

--

Terry

In message ,
Terry Casey writes
In message on Tue, 12 Apr 2011 16:40:40 +
0100
Ian Jackson wrote:

In message ,
Terry Casey writes

Something that it doesn't seem easy to find data on - but there is a
graph on
the Vishay data sheet at

http://www.vishay.com/doc?20135

Blank screen!


Strange!

I clicked the link in your reply and it instantly downloaded a third copy of
the file!

(The second copy is from where I checked the link in my previous post ...!)

It's nearly an hour later, and I've tried it again. Eventually, my
computer decided there was a PDF to download, which I did. [Still got
the blank screen, though!] I see that the Vishay resistors are high
quality carbon film, which explains their good RF characteristics.
--
Ian

On Tue, 12 Apr 2011 10:29:50 +0100, fred wrote:

In article , MM
writes
On Mon, 11 Apr 2011 23:51:43 +0100 (BST), "Dave Liquorice"
wrote:

On Mon, 11 Apr 2011 22:07:28 +0100, tony sayer wrote:

Does it make a difference that there is another unconnected aerial
cable in the same conduit?

Umm ... you are on the -right- cable aren't you?..

Has happened...

Quite frequently but earlier everything was working well after the
cable in the loft was rerouted but it was then fiddled with again and
is now broke again. I suspect a break/kink in the cable somewhere. As
there is a spare length just switch over to that.

Ah, well, I suppose I could do that, but it would negate the provision
by the builder for a satellite dish later on. However (thinking
aloud...), why should I bother myself about what the next owner,
whenever that might be, wants or doesn't want. Until your suggestion
above, I had kind of looked at that spare roll of cable as sacrosanct!

MM

If installed by the builder then don't get your hopes up that it's
decent stuff.

Strip the sheath on a bit at the end of a spare and/or on the reel and
compare with the pics here to be su

http://www.wrightsaerials.tv/article...-quality.shtml

Okay.

I had another brainwave a few minutes ago. Is there a wireless way of
connecting the aerial amplifier to the TV?

MM

John Rumm wrote:
On 13/04/2011 10:17, MM wrote:
On Tue, 12 Apr 2011 10:29:50 +0100, wrote:

In , MM
writes
On Mon, 11 Apr 2011 23:51:43 +0100 (BST), "Dave Liquorice"
wrote:

On Mon, 11 Apr 2011 22:07:28 +0100, tony sayer wrote:

Does it make a difference that there is another unconnected aerial
cable in the same conduit?

Umm ... you are on the -right- cable aren't you?..

Has happened...

Quite frequently but earlier everything was working well after the
cable in the loft was rerouted but it was then fiddled with again and
is now broke again. I suspect a break/kink in the cable somewhere. As
there is a spare length just switch over to that.

Ah, well, I suppose I could do that, but it would negate the provision
by the builder for a satellite dish later on. However (thinking
aloud...), why should I bother myself about what the next owner,
whenever that might be, wants or doesn't want. Until your suggestion
above, I had kind of looked at that spare roll of cable as sacrosanct!

MM

If installed by the builder then don't get your hopes up that it's
decent stuff.

Strip the sheath on a bit at the end of a spare and/or on the reel and
compare with the pics here to be su

http://www.wrightsaerials.tv/article...-quality.shtml

Okay.

I had another brainwave a few minutes ago. Is there a wireless way of
connecting the aerial amplifier to the TV?

Not realistically.

well yes and no.

And realistically, BUT its complex.

You could have a selection of tuner dongles couple to a computer that
would relay live video streams over a wifi link to computers geared to
receive them..

Or to could build your own relay station, and downconvert the TV bands
into lower channel numbers ( to prevent instability) and re-radiate into
your location..


But a bit of cable does seem a lot simpler.

On Wed, 13 Apr 2011 12:52:59 +0100, The Natural Philosopher
wrote:

John Rumm wrote:
On 13/04/2011 10:17, MM wrote:
On Tue, 12 Apr 2011 10:29:50 +0100, wrote:

In , MM
writes
On Mon, 11 Apr 2011 23:51:43 +0100 (BST), "Dave Liquorice"
wrote:

On Mon, 11 Apr 2011 22:07:28 +0100, tony sayer wrote:

Does it make a difference that there is another unconnected aerial
cable in the same conduit?

Umm ... you are on the -right- cable aren't you?..

Has happened...

Quite frequently but earlier everything was working well after the
cable in the loft was rerouted but it was then fiddled with again and
is now broke again. I suspect a break/kink in the cable somewhere. As
there is a spare length just switch over to that.

Ah, well, I suppose I could do that, but it would negate the provision
by the builder for a satellite dish later on. However (thinking
aloud...), why should I bother myself about what the next owner,
whenever that might be, wants or doesn't want. Until your suggestion
above, I had kind of looked at that spare roll of cable as sacrosanct!

MM

If installed by the builder then don't get your hopes up that it's
decent stuff.

Strip the sheath on a bit at the end of a spare and/or on the reel and
compare with the pics here to be su

http://www.wrightsaerials.tv/article...-quality.shtml

Okay.

I had another brainwave a few minutes ago. Is there a wireless way of
connecting the aerial amplifier to the TV?

Not realistically.

well yes and no.

And realistically, BUT its complex.

You could have a selection of tuner dongles couple to a computer that
would relay live video streams over a wifi link to computers geared to
receive them..

Or to could build your own relay station, and downconvert the TV bands
into lower channel numbers ( to prevent instability) and re-radiate into
your location..


But a bit of cable does seem a lot simpler.

I thought there were these gadgets advertised whereby you could watch
a program anywhere in the house?

MM

On Wed, 13 Apr 2011 13:36:32 +0100, John Rumm
wrote:

That's a "video sender". They can transmit a single channel of baseband
video (i.e. 0 - 6MHz, not the 450 - 950MHz of UHF RF from the aerial).
So you could take the AV out from a VCR for example, and send it to a
remote TV using one of these. That is not what you want to do however -
you want the full RF band.

Okay, I'll shut up now!

MM

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember MM saying
something like:

I thought there were these gadgets advertised whereby you could watch
a program anywhere in the house?

Yes, and they're pretty crap most of the time.
I had one, put up with it for a year, but soon got tired of its
idiosyncrasies and replaced it with a run of CT100.

MM wrote:

I thought there were these gadgets advertised whereby you could watch
a program anywhere in the house?

Yes, they transmit *one* program, not *all* programs.

In message , MM
wrote

I thought there were these gadgets advertised whereby you could watch
a program anywhere in the house?

But those signals start out at 1 Volt 6MHz and not 0.00005V at 800MHz
you get from your aerial.

--
Alan
news2009 {at} admac {dot} myzen {dot} co {dot} uk

In message on Wed, 13 Apr 2011 20:01:09 +0100
Alan wrote:

In message , MM
wrote

I thought there were these gadgets advertised whereby you could watch
a program anywhere in the house?

But those signals start out at 1 Volt 6MHz and not 0.00005V at 800MHz
you get from your aerial.

You told us that you've got a spare cable there already.

Why are you so determined not to use it?

And dreaming up all sorts of weird, complex and unworkablem 'solutions' as
excuses for not doing so ...?

--

Terry

In message , MM
wrote

Because the "spare" cable was put there for a purpose! Namely to
facilitate the installation of a satellite dish, should any future
owner want one. Thus, it is not spare cable just lying around like the
builder forgot it when they put their ladders away and went home.
Crikey, I've said this several times already!

These days you would need two cables for a satellite PVR so why not the
use SPARE cable you have already and worry about installing something
else when the need arises.

Are you actually sure that this cable is fully screened and suitable for
satellite and not some general purpose cable of lesser quality? Builders
are not noted their grasp of what is required for various technologies
and will tend to fit what is on sale at the builders merchants.

--
Alan
news2009 {at} admac {dot} myzen {dot} co {dot} uk

On Thu, 14 Apr 2011 17:32:06 +0100, Alan
wrote:

In message , MM
wrote

Because the "spare" cable was put there for a purpose! Namely to
facilitate the installation of a satellite dish, should any future
owner want one. Thus, it is not spare cable just lying around like the
builder forgot it when they put their ladders away and went home.
Crikey, I've said this several times already!

These days you would need two cables for a satellite PVR so why not the
use SPARE cable you have already and worry about installing something
else when the need arises.

Are you actually sure that this cable is fully screened and suitable for
satellite and not some general purpose cable of lesser quality? Builders
are not noted their grasp of what is required for various technologies
and will tend to fit what is on sale at the builders merchants.

I'm only saying what I was told by the builder when he handed over the
property.

MM