Cable length

"Roy Cook" wrote in message
...

A friend on mine has asked me to try and install a sky dish in his house
which has a large number of tall trees to the south. A Sky installer said
that it was not possible to get reception and walked away. However, a
search has found a spot where we might be able to 'see' the satellite.
This location is about 30 metres from the receiver. Has anybody got an
opinion as to if this length of cable is workable and what would be the
best type to use?
Regards
Roy Cook

Use a bigger dish (90cm), good LNB and CT125 cable obtained from say
Maplin's. Get the right F-connectors for the thicker cable and NO joins.

On Mar 14, 8:00*pm, "R. Mark Clayton"
wrote:
"Roy Cook" wrote in message

...



A friend on mine has asked me to try and install a sky dish in his house
which has a large number of tall trees to the south. A Sky installer said
that it was not possible to get reception and walked away. However, a
search has found a spot where we might be able to 'see' the satellite.
This location is about 30 metres from the receiver. Has anybody got an
opinion as to if this length of cable is workable and what would be the
best type to use?
Regards
Roy Cook

Use a bigger dish (90cm), good LNB and CT125 cable obtained from say
Maplin's. *Get the right F-connectors for the thicker cable and NO joins.

Dish size affects signal to noise ratio, but it has negligible effect
on signal levels per se, so it is of little help in countering the
losses in cable. In fact the use of a 90cm dish instead of a 45cm one
probably equates, in signal level terms, to about 7m of cable.
Admittedly, if the signal levels were so low at the receiver that
receiver noise became a serious factor then the s/n improvement
obtained by the use of a larger dish would definitely help, but that
situation should never occur (if it did the installation is
funamentally flawed). Long before then line amplifiers should be
used.

The difference at 2050MHz over a 30m run between CT100 and CT125 is
1.4dB. Again, it is negligible.

Maplins sell a 125-type cable at £1.79 per metre or £91 per 100m. The
cable does not have a copper sheath. Any aerial or satellite shop will
sell you 100m of proper CT125 for about £50. 30m of Maplins' 125-type
cable would cost £53.70. Maplins is a bad idea.

Don't worry about joints. Two 'f' conns and a barrel has negligible
loss and mismatch. In any case, if CT125 is used (the sensible reason
being that direct burial CT100 is not all that strong, physically) it
will be neccessary to fit a short tail of CT100 at the outlet plate.

Sorry to contradict you Mark.

Bill

"Graham" wrote in message
...
"Roy Cook" wrote in message
...
snip
Remember the Paternoster lift at HO?
http://en.wikipedia.org/wiki/Paternoster


I remember the one at GEC Borehamwood, i think it was
shown in one of the episodes of The Prisoner

Steve Terry
--
Get a free Three 3pay Sim with £2 bonus after £10 top up
http://freeagent.three.co.uk/stand/view/id/5276

"Graham" wrote in message
...


"Roy Cook" wrote in message
...
Hi Graham
I was at GTVR Bradford from '71. I left in '82 to start my own business
which lasted for about 8 years. After that I joined the Civil Service and
went work as a Radio +TV instructor at our local Skill Centre. That
lasted until 1995 when I was made redundant (Thanks Maggie). Upon
re-joining the real world I was surprised to find that wages had gone
down and I was out of touch with the new stuff so I went to work for a
former GTVR colleague as a pawn broker. I have fond memories of my time
at Granada. I'm of the opinion that the 70's and 80's were a 'golden' age
for us TV Tech's. The TV's weren't too complicated (apart from the
Philips sets) and you knew that when you took the back off a set - even
a Finlandia - you were in with a good chance of getting it working. I've
just bought a 37" all singing and dancing LCD TV and I can guarantee that
if it should develop a fault after the warranty runs out it will be
straight in the bin!!
When I handed my notice in I was given a Termination interview and I
remember telling the regional manager that if the company didn't get its
collective finger out all that would be left of GTVR would be a plaque on
the wall at Bedford HO. Now that the company that we knew no longer
exists I bet there isn't even a mucky envelope nailed to the gate post to
mark it's passing.
I retired just before my 60th birthday and haven't regretted it at all.
I'd stopped doing any form of electronic servicing a few years before
when I discovered that it wasn't fun anymore. Occasionally I get asked
for help and advice by friends and this is why I'm going to attempt to
get satellite reception through a 10'x10' gap between two trees. I don't
mind doing this sort of thing now and again, it's a bit different and
helps to keep the grey matter active.

Cheers for now
Roy

Remember the Paternoster lift at HO?
http://en.wikipedia.org/wiki/Paternoster
And the Thorn 2000 in the training room wired to the trainer's lectern?
--
Graham. Tech IVe

%Profound_observation%

Oh yes I'd forgotten about that. A few people tried going over the top and
were told of by the training staff. The Thorn 2000 was a master piece, a
flick of a switch by the Instructor and we could see all manner of weird and
wonderful decoder problems. I thought that the training department did a
reasonable job in the early days. Cut backs later on clipped their wings but
they seemed to do the job by getting us trained up to service colour sets
and VCR's. By the time the Tech IVe came along I'd left the company but a
friend of mine who did the course said he found it difficult working at home
and getting help from the training staff was not always easy.
Regarding Philips, I always thought that they over complicated the systems.
The G8 decoder took a bit of getting used to while the frame scanning
section could be a nightmare to service. If I recall the output transistors
were biased fully on and the driver was used to turn them off during scan.
Any problem with either the oscillator or the driver and the output stage
was history very quickly. Remember the Philips K9 with the parallel line
output transistors? A great idea we were told. If one packs in the other
will run quite happily by itself. The only problem of course was that most
transistors ( BU208A ? ) tended to go collector-emitter short which rendered
that idea pretty much useless. But, as I said before, in general they were
good and interesting times.

Cheers for now
Roy. Tech IV

rnc at blueyonder dot co dot uk