I think I need channel filters

Finally got round to starting to sort out the aerial and distribution
system in our new place. To recap: there were two aerials - one high
gain group A on crystal palace, and a contract group B on sudbury. These
were combined (goruped combiner it turns out) onto a single downlead and
fed into a labgear 6 way amp / splitter thence sockets around the house.

I decided to abandon the CP aerial altogether (since the digital muxes
were almost down in the noise) and concentrate on Sudbury. Looking at
the post switchover allocations suggested a group E aerial. However not
being able to find a decent one of those, I took Bill Wright's advice
and modified a group B to extend the top end.

Anyway that is now fitted and working nicely (took the opportunity to
replace the mortar flaunching on the chimney pots at the same time as
these were wobbling!).

I fitted a variable gain masthead amp:

http://cpc.farnell.com/jsp/level5/mo...cpc/461209.xml

Looking at the feed to the distribution amp (with the gain on the
masthead set to minimum) we now get:

Channel Signal Mux
(dBuV)
39 52 D4
48 51 D3
49 52 D1
50 50 D6
54 48 D5
56 48 D2

Which seems like a reasonable starting point, with the Terry meter
reporting a "pass" for signal to noise on all the muxes. A problem
however is the in band the analogue signals:

44 73 BBC2
51 74 BBC1
(similar level for the others)

Which are at least 20 dB stronger than the digital muxes. (if you ramp
up the gain on the masthead I can push these to over 99 dBuV - which is
where my meter gives up!)

Trying this through the existing splitter amp still did not give
adequate performance. I have come to the conclusion that the labgear is
crap anyway (poor noise etc) and the house co-ax wiring leaves much to
be desired. Tweaking the gain up on the masthead did not really help
much either since I expect it was overloading the input on the splitter
amp with the high analogue signals.

Ditching the current splitter amp altogether, and running the masthead
on full gain, into a passive splitter got reasonable performance on one
socket but marginal on others. Adding a lowish gain setback amp before
the passive splitter got good performance on at least two sockets and
reasonable on others.

So to get robust and reliable digital on all sockets I could do with a
little more headroom coming out of the splitter.

Rewiring the house with decent CT100 will happen at some time - but not
in a hurry (the loss one some runs is quite startling - not helped by
the previous installer deciding to daisy chain two sockets on some of
the runs).


Questions
=========

So should I:

Go with a better distribution amp with moderate gain on each output? If
so any recommendations for one that is not going to be upset by the
disparity in input levels?

Or

Try to level (or for that mater just notch filter) the analogue signals?
(I don't care if we lose all analogue reception)

If the latter, what would be an appropriate device, and when can I order
one from?

How easy are these to setup?

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Questions
=========

So should I:

Go with a better distribution amp with moderate gain on each output? If
so any recommendations for one that is not going to be upset by the
disparity in input levels?

Or

Try to level (or for that mater just notch filter) the analogue signals?
(I don't care if we lose all analogue reception)

If the latter, what would be an appropriate device, and when can I order
one from?

How easy are these to setup?



Go Freesat;?.....
--
Tony Sayer

tony sayer wrote:

Go Freesat;?.....

There's no need to use language like that. He's only asking for advice.

"tony sayer" wrote in message
news
Questions
=========

So should I:

Go with a better distribution amp with moderate gain on each output? If
so any recommendations for one that is not going to be upset by the
disparity in input levels?

Or

Try to level (or for that mater just notch filter) the analogue signals?
(I don't care if we lose all analogue reception)

If the latter, what would be an appropriate device, and when can I order
one from?

How easy are these to setup?



Go Freesat;?.....
--
Tony Sayer

For this many outlets?
It's a good answer for some applications, but where you wish to watch and
record different programmes at multiple outlets it's far from ideal.

I run 6 TV's and at 3 of these we also record. That would require 9 Freesat
boxes, and mean I couldn't easily distribute FM and DAB to each outlet. I
also distribute the output of the Sky box and the DVD/VCR meaning we can
watch Sky pay channels and in-house channels anywhere too.

In article , Silk
scribeth thus
tony sayer wrote:

Go Freesat;?.....

There's no need to use language like that. He's only asking for advice.

Its very good advice..

Why go to all that complication where theres a perfickly simple
alternative available?..
--
Tony Sayer

In article , Doctor D
scribeth thus

"tony sayer" wrote in message
news
Questions
=========

So should I:

Go with a better distribution amp with moderate gain on each output? If
so any recommendations for one that is not going to be upset by the
disparity in input levels?

Or

Try to level (or for that mater just notch filter) the analogue signals?
(I don't care if we lose all analogue reception)

If the latter, what would be an appropriate device, and when can I order
one from?

How easy are these to setup?



Go Freesat;?.....
--
Tony Sayer

For this many outlets?
It's a good answer for some applications, but where you wish to watch and
record different programmes at multiple outlets it's far from ideal.

I run 6 TV's and at 3 of these we also record.

Blimey! your addicted to the telly?..

I should see someone about that!..

U need therapy M8..


--
Tony Sayer

John Rumm wrote:

Finally got round to starting to sort out the aerial and distribution
system in our new place. To recap: there were two aerials - one high
gain group A on crystal palace, and a contract group B on sudbury. These
were combined (goruped combiner it turns out) onto a single downlead and
fed into a labgear 6 way amp / splitter thence sockets around the house.

I decided to abandon the CP aerial altogether (since the digital muxes
were almost down in the noise) and concentrate on Sudbury. Looking at
the post switchover allocations suggested a group E aerial. However not
being able to find a decent one of those, I took Bill Wright's advice
and modified a group B to extend the top end.

Anyway that is now fitted and working nicely (took the opportunity to
replace the mortar flaunching on the chimney pots at the same time as
these were wobbling!).

I fitted a variable gain masthead amp:

http://cpc.farnell.com/jsp/level5/mo...cpc/461209.xml

Looking at the feed to the distribution amp (with the gain on the
masthead set to minimum) we now get:

Channel Signal Mux
(dBuV)
39 52 D4
48 51 D3
49 52 D1
50 50 D6
54 48 D5
56 48 D2

Which seems like a reasonable starting point, with the Terry meter
reporting a "pass" for signal to noise on all the muxes. A problem
however is the in band the analogue signals:

44 73 BBC2
51 74 BBC1
(similar level for the others)

Which are at least 20 dB stronger than the digital muxes. (if you ramp
up the gain on the masthead I can push these to over 99 dBuV - which is
where my meter gives up!)

Trying this through the existing splitter amp still did not give
adequate performance. I have come to the conclusion that the labgear is
crap anyway (poor noise etc) and the house co-ax wiring leaves much to
be desired. Tweaking the gain up on the masthead did not really help
much either since I expect it was overloading the input on the splitter
amp with the high analogue signals.

Ditching the current splitter amp altogether, and running the masthead
on full gain, into a passive splitter got reasonable performance on one
socket but marginal on others. Adding a lowish gain setback amp before
the passive splitter got good performance on at least two sockets and
reasonable on others.

So to get robust and reliable digital on all sockets I could do with a
little more headroom coming out of the splitter.

Rewiring the house with decent CT100 will happen at some time - but not
in a hurry (the loss one some runs is quite startling - not helped by
the previous installer deciding to daisy chain two sockets on some of
the runs).


Questions
=========

So should I:

Go with a better distribution amp with moderate gain on each output? If
so any recommendations for one that is not going to be upset by the
disparity in input levels?

Or

Try to level (or for that mater just notch filter) the analogue signals?
(I don't care if we lose all analogue reception)

If the latter, what would be an appropriate device, and when can I order
one from?

How easy are these to setup?

Running a variable gain amplifier at lowest gain will only increase the
noise level. A fixed low gain amplifier would be better suited. Having
the actual input levels to the masthead amplifier from the aerial would
make it easier to advise you.

Glenn...

tony sayer wrote:
In article , Silk
scribeth thus
tony sayer wrote:

Go Freesat;?.....
There's no need to use language like that. He's only asking for advice.

Its very good advice..

Why go to all that complication where theres a perfickly simple
alternative available?..

Two answers to that:

one, I already have it - using an old cast off sky box and the disk the
previous occupants left behind,

and two

I have a significant investment in freeview kit, including a topfield
PVR and network connection for it.

What I don't have is a bunch of sat boxes, a multiswitch, a quad output
LNB or any of the wiring infrastructure to make freesat a cost effective
multiroom setup.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Glenn Millar wrote:

Running a variable gain amplifier at lowest gain will only increase the
noise level. A fixed low gain amplifier would be better suited. Having

The spec on that amp show a max noise of 2.6dB and a minimum gain of
supposedly 7dB, so that ought to have had some positive benefit. However
the min gain setting was really used just to overcome the initial
download loss and see if the dist amp could do its stuff from there.

the actual input levels to the masthead amplifier from the aerial would
make it easier to advise you.

Just as well I have not taken the ladders down yet (although you just
incurred the wrath of SWMBO for interrupting the tennis!)

Channel @Aerial +mast amp +mast amp
min gain max gain
39 53 56 73
48 53 57 72
49 54 59 74
50 53 56 71
54 51 55 68
56 51 55 68

Analogue bbc1 & 2 :

44 72 77 94
51 75 82 =99

(I note the gain is a bit lower than spec at both ends - but that could
be down to the fact I was powering the amp from my test meter and the
batteries were getting low)



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:
Glenn Millar wrote:

Running a variable gain amplifier at lowest gain will only increase
the noise level. A fixed low gain amplifier would be better suited.
Having

The spec on that amp show a max noise of 2.6dB and a minimum gain of
supposedly 7dB, so that ought to have had some positive benefit. However
the min gain setting was really used just to overcome the initial
download loss and see if the dist amp could do its stuff from there.

the actual input levels to the masthead amplifier from the aerial
would make it easier to advise you.

Just as well I have not taken the ladders down yet (although you just
incurred the wrath of SWMBO for interrupting the tennis!)

Channel @Aerial +mast amp +mast amp
min gain max gain
39 53 56 73
48 53 57 72
49 54 59 74
50 53 56 71
54 51 55 68
56 51 55 68

Analogue bbc1 & 2 :

44 72 77 94
51 75 82 =99

(I note the gain is a bit lower than spec at both ends - but that could
be down to the fact I was powering the amp from my test meter and the
batteries were getting low)



I personally wouldn't be fitting a masthead amplifier. A good quality
distribution amplifier with moderate gain at most, Proception 8way 5dB
gain for example. You don't want signals on analogue at the TV to be
higher than 80 or digital above 60.

Your problem seems to be too much signal instead of too little.