Amateur Rigger's Diary (very long)

Hi, I'm back from Ilfracombe! Job done and lots to talk about. Blody
miserable weather most of the time, but aerial is up & running with
better than expected results.

Got to Ilfracombe 3.30am Thursday morning. Had to be there for 7am
for Ikea to turn up (anytime between 7am & 6pm they said). ****ing
down with rain all the way down there & most of Thursday, so no
outdoor aerial rigging today, so I sorted out the incredibly badly
wired coax wall sockets.

http://i22.photobucket.com/albums/b3...6devon0001.jpg

All were wired like this & with no real reason. But one thing I must
say I was relieved about, all internal cabling was double screen CT100
equivalent (cable was labelled HYC100 CAI something or other). All
cables went into the loft space and unconnected. Thanfully, they were
all labelled (lounge, kitchen, etc) so that was good. I had a good
look at the local aerials, and excluding the Ilfracombe relay, most
pointed at Wenvoe, with only one in the whole town pointing at Carmel.
Anyway, to test signal strength, I assembled the Televes X43 and put
it in the loft, pointing at Carmel. Connected to just to the front
bedroom coax feed & tuned in the telly. No digital signal & grainy
analogue. Back to the loft to spin it round to Wenvoe, re-tune and
received BBC mux 1 at 40% signal and watchable analogue. Decided that
Wenvoe would be the obvious choice. BTW, Ikea never turned up! They
decided to call it a day at 4pm & buggered off back to Bristol! My
friend wasn't at all happy. But to cut a long story short, managed to
get the delivery re-arranged for Saturday.

Friday morning looked fairly promising. At least it wasn't raining.
Got the ladder up on the roof & I scaled up it to remove the old
aerials. What ~I saw when I was up there wasn't good. The rusty old
bracket & lashing cable were cemented into the chimney! Removal of
that item was impossible. Luckily, the mast broke off in my hands and
was lowered top the ground.

http://i22.photobucket.com/albums/b3...6devon0002.jpg

Here's a shot of the remains of the diplexer.

http://i22.photobucket.com/albums/b3...6devon0011.jpg

I clambered back up onto the roof, straddling the apex (not
comfortable) with a cradle bracket & lashing cable & fixed that up
there. BTW, i'm not that good at heights, & was rather terrified
through out the installation. As I was tightening the lashing, the
heavens opened I was bloody drenched! Down I came & that was that for
the day.

Saturday was the driest day of all, so I managed to complete the job.
X43 attached to the top of the 6' mast, I carried that up onto the
roof very gingerly. Wind was getting up as well & the thing was
swaying around like buggery. Just about managed to get the U-bolts on
to hold it in place (lost one nut, it slipped down the roof, but
luckily missed the guttering & landed in the front garden, where it
was retrieved by my friend and returned to me). I managed to rescue
the old group CD aerial from the old install & stuck it on the new
mast pointing at Ilfracombe. It was only to get the local news so
wasn't important. Then we hit a snag. How do we get the cable into
the loft? Going under a tile wasn't possible, so my friend went into
the loft and found light coming through at the eaves of the dorma. It
wasn't the neatest solution as the cables ran a little way down the
tiles, but it had to do.

http://i22.photobucket.com/albums/b3...6devon0010.jpg

http://i22.photobucket.com/albums/b3...6devon0009.jpg

Now all the outside work was done, I popped up into the loft to wire
it all up. I wasn't sure if connecting both aerials together would be
successful, due to Wenvoe frequencies overlapping Ilfracombe. I just
connected Wenvoe first via a loft mounted amp and tuned in the telly.
Success! Found all muxes (BBC Mux 1 at 100%, and all others at 50%).
Unfortunately, ITV mux A (the one with Five on) had poor quality
rating & was breaking up quite badly, but all others were perfect.
Now, I tried connecting the two aerials together using a splitter.
DTT was fine, but analogue was terrible. I then tried a K/CD diplexer
& to my surprise, worked perfectly. One mux on Ch50 was attenuated
quite a lot, but picture was not affected at all. BTW, I connected
diplexer after the amp, so the Ilfracombe analogue wasn't amplified.
This fed 4 rooms with no loss of quality.

So that's it. All done and dusted and my friend (who owns the house)
is very happy. Just left to show you the neighbour's aerials & a pic
of the Ilfracombe relay. Thanks for listening.

http://i22.photobucket.com/albums/b3...6devon0009.jpg

http://i22.photobucket.com/albums/b3...6devon0017.jpg

Marky P.

"Marky P" wrote in message
...
Hi, I'm back from Ilfracombe! Job done and lots to talk about. Blody
miserable weather most of the time, but aerial is up & running with
better than expected results.

Got to Ilfracombe 3.30am Thursday morning. Had to be there for 7am
for Ikea to turn up (anytime between 7am & 6pm they said). ****ing
down with rain all the way down there & most of Thursday, so no
outdoor aerial rigging today, so I sorted out the incredibly badly
wired coax wall sockets.

http://i22.photobucket.com/albums/b3...6devon0001.jpg


You seem to have left unshielded sockets in place - very bad practice!

I clambered back up onto the roof, straddling the apex (not
comfortable) with a cradle bracket & lashing cable & fixed that up
there. BTW, i'm not that good at heights, & was rather terrified
through out the installation. As I was tightening the lashing, the
heavens opened I was bloody drenched! Down I came & that was that for
the day.

Always use a proper roofing ladder and safety equipment!

One mux on Ch50 was attenuated
quite a lot, but picture was not affected at all.

Wait until it rains and you will be getting a phone call.

On Mon, 26 Feb 2007 22:02:17 -0000, "Si"
wrote:


"Marky P" wrote in message
.. .
Hi, I'm back from Ilfracombe! Job done and lots to talk about. Blody
miserable weather most of the time, but aerial is up & running with
better than expected results.

Got to Ilfracombe 3.30am Thursday morning. Had to be there for 7am
for Ikea to turn up (anytime between 7am & 6pm they said). ****ing
down with rain all the way down there & most of Thursday, so no
outdoor aerial rigging today, so I sorted out the incredibly badly
wired coax wall sockets.

http://i22.photobucket.com/albums/b3...6devon0001.jpg


You seem to have left unshielded sockets in place - very bad practice!

I clambered back up onto the roof, straddling the apex (not
comfortable) with a cradle bracket & lashing cable & fixed that up
there. BTW, i'm not that good at heights, & was rather terrified
through out the installation. As I was tightening the lashing, the
heavens opened I was bloody drenched! Down I came & that was that for
the day.

Always use a proper roofing ladder and safety equipment!

One mux on Ch50 was attenuated
quite a lot, but picture was not affected at all.

Wait until it rains and you will be getting a phone call.

Eh?

Marky P.

water is a good attenuator of UHF, the attenuation due to water increases
with increasing frequency....

increasing rain density provides more attenuation....

its more marked on satellite dishes due to the higher frequencies used.

Stephen



"Marky P" wrote in message
...
On Mon, 26 Feb 2007 22:02:17 -0000, "Si"
wrote:


"Marky P" wrote in message
. ..
Hi, I'm back from Ilfracombe! Job done and lots to talk about. Blody
miserable weather most of the time, but aerial is up & running with
better than expected results.

Got to Ilfracombe 3.30am Thursday morning. Had to be there for 7am
for Ikea to turn up (anytime between 7am & 6pm they said). ****ing
down with rain all the way down there & most of Thursday, so no
outdoor aerial rigging today, so I sorted out the incredibly badly
wired coax wall sockets.

http://i22.photobucket.com/albums/b3...6devon0001.jpg


You seem to have left unshielded sockets in place - very bad practice!

I clambered back up onto the roof, straddling the apex (not
comfortable) with a cradle bracket & lashing cable & fixed that up
there. BTW, i'm not that good at heights, & was rather terrified
through out the installation. As I was tightening the lashing, the
heavens opened I was bloody drenched! Down I came & that was that for
the day.

Always use a proper roofing ladder and safety equipment!

One mux on Ch50 was attenuated
quite a lot, but picture was not affected at all.

Wait until it rains and you will be getting a phone call.

Eh?

Marky P.

"Si" wrote in message
...
You seem to have left unshielded sockets in place - very bad practice!
In practice the screening from the backbox is generally adequate. Various
manufacturers brought out fully screened outlets but they don't seem to have
caught on. They are rarely necessary in my opinion, except in very noisy
environments. Signal levels at the outlet should be sufficient to make noise
received at the outlet unimportant. If not, why not?

Bill

"Mallory" wrote in message
...
water is a good attenuator of UHF

This is news to me.

Bill

"Marky P" wrote in message
...
Hi, I'm back from Ilfracombe! Job done and lots to talk about. Blody
miserable weather most of the time, but aerial is up & running with
better than expected results.

It's a commendable effort, but don't be too smug! You don't actually have
any figures to show how far above threshold the various muxes are. You might
have muxes that seem fine but in fact are only a few dB above going
pearshaped. Let's just hope not. Only time will tell.

Do you know Marky, what you've done there would be my worst nightmare.
Installing without any means of measuring the signal levels, carrier/noise,
and BER I mean. I would feel as if I was driving down the motorway with a
blindfold on. And I would drive away with no idea whether I'd done a good
job or not.

I'm not trying to devalue your achievement here, because you did the
research carefully and you seem to have made a pretty good stab at doing a
decent job. But really, your ignorance is bliss. Yes, it might be fine, for
ever. Or it might not . . .

Bill

On 2007-02-27, Bill Wright wrote:

Installing without any means of measuring the signal levels,
carrier/noise, and BER I mean. I would feel as if I was driving down
the motorway with a blindfold on. And I would drive away with no
idea whether I'd done a good job or not.

Hello Bill, I live in a marginal signal area (North Dorset), and three
of the contractors sent out to fit my aerial installation had no
proper measuring tools, only one had the right meter, I even saw the
block error rates myself. Only that installer got a half-decent
reception, the ones who came after made it worse.

Now I've decided that I'll get around to doing it myself, is there any
way for me to get hold of a decent meter without spending masses of
cash, or any other way of measuring S/N ratio and BER in realtime?
The contractor who had the right gear no longer works for the local TV
company and I can't contact him. Is it common to be able to hire
these things?

--
Blast off and strike the evil Bydo empire!

....snip...

Wait until it rains and you will be getting a phone call.


To be fair, he did mention a little precipitation more than once in his
write up so I suspect it got a little test or two in the wet.

Paul DS.

In article , Ian Rawlings
wrote:


Now I've decided that I'll get around to doing it myself, is there any
way for me to get hold of a decent meter without spending masses of
cash, or any other way of measuring S/N ratio and BER in realtime? The
contractor who had the right gear no longer works for the local TV
company and I can't contact him. Is it common to be able to hire these
things?

I don't know what a good-quality claibrated instrument for the above might
cost. However I can suggest two alternatives which I've used.

1) Buy a few 3dB, 6dB and 12dB pads from someone like Maplin. Then
experiment with these to see if your chosen TV/RX works OK with a fair
amount of attenuation to the signal. If it works OK with well over 12dB of
attenuation then it should be fine in normal use. If only a few dB tends to
upset reception then problems may occur in normal use.

2) Some DTTV boxes give an indication of signal which makes more sense than
the usual 'blobs or bar'. e.g. the Nokia 221T has a display that shows the
signal level in dBm and the BER. These values aren't particularly accurate,
but are useful - particularly in conjunction with (1).

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html