Freeview signal problem

At present I have a group A 15-element aerial (Crystal Palace) and a group
C-D 18-element aerial (Midhurst) connected via a passive combiner to a 26 dB
labgear masthead amp. The output of that feeds about 10 metres of coax
(unknown quality, but about 2 years old) connected to a passive triple
splitter in the loft. That feeds 3 separate rooms by at least 10 meters of
unknown quality coax (which is about 20 - 25 years old) to each room.

The CP analogue signal is OK; the Midhurst signal is a bit weak on Ch4.

Freeview on Midhurst is average to poor on most muxes; Mux D is particularly
bad as it has half the power of the others. In general it is OK from CP,
except when reception conditions are affected by the weather. Only in
exceptionally poor conditions does my Hummy have problems with one or two
muxes. An old Panasonic TUCT20 and a Sagem IDT 602 have problems when
reception is anything other than good, and can't pick up Midhurst at all.

I suppose the best way to improve the signal would be to rewire with CT100
coax, but that would be awkward for the in-cavity cable to a couple of the
rooms. As an alternative, I guess I could replace the aerials with something
giving better gain. Both of these will involve some work, and I am still
left with the passive triple splitter.

The easist thing to do first would appear to be replacement of the passive
triplexer with a 4-way distribution amplifier (eg AMD04 -
http://www.phase1electronics.co.uk/a...ier-225-p.asp),
which could also power the masthead amp.

Comments? Criticisms? Am I likely to overload the analogue reception?
What about Freeview when switchover occurs, and the CP and Midhurst signals
are boosted?

TIA

--
Jeff
(cut "thetape" to reply)

"Jeff Layman" wrote in message
news
At present I have a group A 15-element aerial (Crystal Palace) and a group
C-D 18-element aerial (Midhurst) connected via a passive combiner

Dipexer, splitter?

to a 26 dB labgear masthead amp. The output of that feeds about 10 metres
of coax (unknown quality, but about 2 years old) connected to a passive
triple splitter in the loft. That feeds 3 separate rooms by at least 10
meters of unknown quality coax (which is about 20 - 25 years old) to each
room.

The CP analogue signal is OK; the Midhurst signal is a bit weak on Ch4.

Freeview on Midhurst is average to poor on most muxes; Mux D is
particularly bad as it has half the power of the others. In general it is
OK from CP, except when reception conditions are affected by the weather.
Only in exceptionally poor conditions does my Hummy have problems with one
or two muxes. An old Panasonic TUCT20 and a Sagem IDT 602 have problems
when reception is anything other than good, and can't pick up Midhurst at
all.

I suppose the best way to improve the signal would be to rewire with CT100
coax, but that would be awkward for the in-cavity cable to a couple of the
rooms. As an alternative, I guess I could replace the aerials with
something giving better gain.
These aren't alternatives.

Check the quality direct from each aerial. Yes, take a good receiver into
the loft. If it's OK then leave the aerials alone.

If you are combining with a splitter the loss is significant. Combine with a
diplexer if possible.

If you are amplifying the signals by 26dB the cables quality thereafter will
make little difference (unless it's damaged/wet/like string of course.

Both of these will involve some work, and I am still left with the passive
triple splitter.

The easist thing to do first would appear to be replacement of the passive
triplexer with a 4-way distribution amplifier (eg AMD04 -
http://www.phase1electronics.co.uk/a...ier-225-p.asp),
which could also power the masthead amp.

Quite likely the amp would be overloaded with a 26dB masthead in front of
it.

The problem I have here is that to give you any sensible advice I would need
to check all the signals from the aerials with an analyser, and check the
cable losses, etc. Without doing that I'm really just guessing.

Bill

Jeff Layman wrote:

Comments? Criticisms? Am I likely to overload the analogue reception?
What about Freeview when switchover occurs, and the CP and Midhurst signals
are boosted?

Midhurst's DTT muxes are lower power than optimum, and worse still have large
nulls in certain directions. Those nulls also differ from mux to mux.

Any solution you adopt now, will almost certainly need to be re adjusted and
set up once DSO happens (Mid 2012 for your area).

If I were you I'd concentrate on receiving Crystal Palace DTT. Do you really
need the few regional variations Midhurst offer, and if so why not just suffer
them on analogue ? It might even be more cost effective to buy an old Sky box
and dish on ebay, and use that for BBC South and ITV Meridian ?

--
Mark
Please replace invalid and invalid with gmx and net to reply.

Bill Wright wrote:
"Jeff Layman" wrote in message
news
At present I have a group A 15-element aerial (Crystal Palace) and a
group C-D 18-element aerial (Midhurst) connected via a passive
combiner

Dipexer, splitter?

No idea, but I would guess it would have been the cheapest to match the
yagis! I can't get out there to check the mast for a couple of days. All I
can remember is that it appears to be a (red?) plastic box about 7.5 x 7.5 x
2.5 cm. I didn't even look at it when I replaced the labgear a couple of
years ago (minute split in cover allowing water in).


to a 26 dB labgear masthead amp. The output of that feeds about 10
metres of coax (unknown quality, but about 2 years old) connected to
a passive triple splitter in the loft. That feeds 3 separate rooms
by at least 10 meters of unknown quality coax (which is about 20 -
25 years old) to each room.

The CP analogue signal is OK; the Midhurst signal is a bit weak on
Ch4.
As an alternative, I guess I could replace the
aerials with something giving better gain.
These aren't alternatives.

True, but I was using the term to suggest anything which might increase the
signal to the freeview box.

Check the quality direct from each aerial. Yes, take a good receiver
into the loft. If it's OK then leave the aerials alone.

I may not be understanding this correctly, but I can't check the quality
direct from each aerial, as the masthead diplexer/splitter and labgear
amplifier are in the way. I could disconnect the loft triplexer from the
amplifier output, which would eliminate the triplexer and cavity downleads
as a possible cause of signal loss. I would have to take up the amplifier
power supply and one of the freeview boxes as well as the receiver, but that
could be done.

If you are combining with a splitter the loss is significant. Combine
with a diplexer if possible.

There seems to be a bit of confusion out there. I guess I could use
something like this:
http://www.falconsat.co.uk/global-di...xer-p-927.html
or this:
http://www.falconsat.co.uk/triax-tmc...cb7c82ac2f3df4
But this is also said to be a diplexer - but seems to be a splitter:
http://www.falconsat.co.uk/sac-outdo...cb7c82ac2f3df4
Any recommendations? I assume that even though I don't have satellite, any
satellite diplexer would be fine for UHF use.


If you are amplifying the signals by 26dB the cables quality
thereafter will make little difference (unless it's damaged/wet/like
string of course.
Both of these will involve some work, and I am still left with the
passive triple splitter.

The easist thing to do first would appear to be replacement of the
passive triplexer with a 4-way distribution amplifier (eg AMD04 -
http://www.phase1electronics.co.uk/a...ier-225-p.asp),
which could also power the masthead amp.

Quite likely the amp would be overloaded with a 26dB masthead in
front of it.

Hmmm. Would one with variable gain be less likely to be overloaded?


The problem I have here is that to give you any sensible advice I
would need to check all the signals from the aerials with an
analyser, and check the cable losses, etc. Without doing that I'm
really just guessing.

I know, but thanks for the suggestions.

--
Jeff
(cut "thetape" to reply)

Mark Carver wrote:

Any solution you adopt now, will almost certainly need to be re
adjusted and set up once DSO happens (Mid 2012 for your area).

That's why I asked the question. Still, if it was just a matter of putting
in some attenuation to get decent reception in rather than fiddling with the
aerial/amp/downleads, that would suit me.


If I were you I'd concentrate on receiving Crystal Palace DTT. Do you
really need the few regional variations Midhurst offer, and if so why
not just suffer them on analogue ?

We watch the local Meridian news here, rather than London. I am hoping that
we will still be able to receive it after DSO.

It might even be more cost
effective to buy an old Sky box and dish on ebay, and use that for
BBC South and ITV Meridian ?

Unfortunately there are some rather tall trees more-or-less in a south to
east direction...

--
Jeff
(cut "thetape" to reply)

On Sun, 13 Jan 2008 17:21:33 -0000, "Jeff Layman"
wrote:

Mark Carver wrote:

Any solution you adopt now, will almost certainly need to be re
adjusted and set up once DSO happens (Mid 2012 for your area).

That's why I asked the question. Still, if it was just a matter of putting
in some attenuation to get decent reception in rather than fiddling with the
aerial/amp/downleads, that would suit me.


If I were you I'd concentrate on receiving Crystal Palace DTT. Do you
really need the few regional variations Midhurst offer, and if so why
not just suffer them on analogue ?

We watch the local Meridian news here, rather than London. I am hoping that
we will still be able to receive it after DSO.

It might even be more cost
effective to buy an old Sky box and dish on ebay, and use that for
BBC South and ITV Meridian ?

Unfortunately there are some rather tall trees more-or-less in a south to
east direction...

Try disconnecting the passive splitter and connect the coax to just
one telly. If that improves things, replace the splitter with an amp.

Marky P.

Jeff Layman wrote:
Mark Carver wrote:

Any solution you adopt now, will almost certainly need to be re
adjusted and set up once DSO happens (Mid 2012 for your area).

That's why I asked the question. Still, if it was just a matter of putting
in some attenuation to get decent reception in rather than fiddling with the
aerial/amp/downleads, that would suit me.

Yes, no aerial alignment would be required. If you put all the combiners and
and amps in the loft, then re-adjustment can be done in 'comfort'.

If I were you I'd concentrate on receiving Crystal Palace DTT. Do you
really need the few regional variations Midhurst offer, and if so why
not just suffer them on analogue ?

We watch the local Meridian news here, rather than London. I am hoping that
we will still be able to receive it after DSO.

Well, reading some of the ideas on Ofcom's website, one option is for ITV to
drop regional programming after DSO.

Bear in mind that Mux C from Midhurst is co-channel with ITV analogue from
Heathfield (Ch 64), and Mux D Midhurst is co-channel with ITV analogue from
Reigate and Brighton (Ch 60). If you are anywhere near the A23 corridor, those
will be major factors in not being able to receive Mux C and D Midhurst.

--
Mark
Please replace invalid and invalid with gmx and net to reply.

"Jeff Layman" wrote in message
...
Dipexer, splitter?

No idea, but I would guess it would have been the cheapest to match the
yagis! I can't get out there to check the mast for a couple of days. All
I can remember is that it appears to be a (red?) plastic box about 7.5 x
7.5 x 2.5 cm.
It's an old non-screened Fringe item then. Could be anything in there,
including the three coaxes twisted together.


I may not be understanding this correctly, but I can't check the quality
direct from each aerial, as the masthead diplexer/splitter and labgear
amplifier are in the way.
I thought you meant that everything was in the loft. Anyway, aerial repairs
where one of the ground rules states 'You can't go on the roof' is a bit
difficult.


There seems to be a bit of confusion out there.
There's no confusion here. . .


I guess I could use
something like this:
http://www.falconsat.co.uk/global-di...xer-p-927.html
or this:
http://www.falconsat.co.uk/triax-tmc...cb7c82ac2f3df4
But this is also said to be a diplexer - but seems to be a splitter:
http://www.falconsat.co.uk/sac-outdo...cb7c82ac2f3df4
Any recommendations? I assume that even though I don't have satellite, any
satellite diplexer would be fine for UHF use.
No, you need a UHF to UHF diplexer. Mark will come along and figure out
which one you need. Chances are it will be 21-39 and 42-68, or similar.

Quite likely the amp would be overloaded with a 26dB masthead in
front of it.

Hmmm. Would one with variable gain be less likely to be overloaded?
Yes but the more you amplifiy the worse the noise. You should always use
just enough amplification. Amps with built-in attenuators (variables) are
sub-optimal*, usually.

*I put '****e', then decided to be more dispassionate.

Bill