How to improve this aerial? Replace or move higher?

Recently our TV reception has detriorated markedly, we live near
Woodbridge and get our signals from Sudbury so we're getting on for
"fringe area". The Woodbridge relays don't do anything for us. Until
recently reception was pretty good most of the time with the very
occasional drop out and sometimes a 'bad day' with odd atmospheric
conditions.

I can't see anything obvious that has changed (like failed connectors)
so I suspect that we may be being affected by particularly lush growth
at the tops of some trees which are probably somewhat on our path
towards Sudbury.

Analogue reception has become pretty ropey too as well so I think it's
aerial (or downlead) rather than anytthing else.

So - what to do? The current aerial is a cheap "high gain" one, here
are a couple of pictures ot it:-

http://www.isbd.net/images/DSCF0812.JPG
http://www.isbd.net/images/DSCF0813.JPG

(Sorry they're so dark, it was a very dull day, still gives an idea of
what's there)

It's difficult to make the aerial a *lot* higher where it is but there
is actually another roof where I have *much* better access and could
mount it higher, the only disadvantage there is that it's relatively
remote from the TVs (on a separate building).

So would I be better off with a better aerial or would it be better to
move it to a better location? Can one get wireless connections for a
TV aerial?

If a better aerial seems a good idea what would be recommended? I
think we genuinely do need "wide band" for the Sudbury transmitter.

(In the longer term the trees may be coming down but that's months
ahead and I want to improve things before then, even if it is the trees)


--
Chris Green

wrote in message
...
Recently our TV reception has detriorated markedly, we live near
Woodbridge and get our signals from Sudbury so we're getting on for
"fringe area". The Woodbridge relays don't do anything for us. Until
recently reception was pretty good most of the time with the very
occasional drop out and sometimes a 'bad day' with odd atmospheric
conditions.

I can't see anything obvious that has changed (like failed connectors)
so I suspect that we may be being affected by particularly lush growth
at the tops of some trees which are probably somewhat on our path
towards Sudbury.

Analogue reception has become pretty ropey too as well so I think it's
aerial (or downlead) rather than anytthing else.

So - what to do? The current aerial is a cheap "high gain" one, here
are a couple of pictures ot it:-

http://www.isbd.net/images/DSCF0812.JPG
http://www.isbd.net/images/DSCF0813.JPG

(Sorry they're so dark, it was a very dull day, still gives an idea of
what's there)

It's difficult to make the aerial a *lot* higher where it is but there
is actually another roof where I have *much* better access and could
mount it higher, the only disadvantage there is that it's relatively
remote from the TVs (on a separate building).

So would I be better off with a better aerial or would it be better to
move it to a better location? Can one get wireless connections for a
TV aerial?

If a better aerial seems a good idea what would be recommended? I
think we genuinely do need "wide band" for the Sudbury transmitter.

(In the longer term the trees may be coming down but that's months
ahead and I want to improve things before then, even if it is the trees)



Why has the aerial been bolted on upside down?.. you may just as well have
clamped the boom directly to the mast.

--
Chris Green

Ivan wrote:
wrote in message
...
So - what to do? The current aerial is a cheap "high gain" one, here
are a couple of pictures ot it:-

http://www.isbd.net/images/DSCF0812.JPG
http://www.isbd.net/images/DSCF0813.JPG

[snip]

Why has the aerial been bolted on upside down?.. you may just as well have
clamped the boom directly to the mast.

I have no idea, maybe there was nothing telling which way was "the
right way up". It's not going to have a significant effect on the
performance anyway is it? (Except the loss of a few inches of height)

--
Chris Green

wrote in message
...
Recently our TV reception has detriorated markedly, we live near
Woodbridge and get our signals from Sudbury so we're getting on for
"fringe area". The Woodbridge relays don't do anything for us. Until
recently reception was pretty good most of the time with the very
occasional drop out and sometimes a 'bad day' with odd atmospheric
conditions.

I can't see anything obvious that has changed (like failed connectors)
so I suspect that we may be being affected by particularly lush growth
at the tops of some trees which are probably somewhat on our path
towards Sudbury.

Analogue reception has become pretty ropey too as well so I think it's
aerial (or downlead) rather than anytthing else.

So - what to do? The current aerial is a cheap "high gain" one, here
are a couple of pictures ot it:-

http://www.isbd.net/images/DSCF0812.JPG
http://www.isbd.net/images/DSCF0813.JPG

(Sorry they're so dark, it was a very dull day, still gives an idea of
what's there)

It's difficult to make the aerial a *lot* higher where it is but there
is actually another roof where I have *much* better access and could
mount it higher, the only disadvantage there is that it's relatively
remote from the TVs (on a separate building).

So would I be better off with a better aerial or would it be better to
move it to a better location? Can one get wireless connections for a
TV aerial?

If a better aerial seems a good idea what would be recommended? I
think we genuinely do need "wide band" for the Sudbury transmitter.

(In the longer term the trees may be coming down but that's months
ahead and I want to improve things before then, even if it is the trees)


Firstly mount it with the cradle the right way up and without the mast
running through the elements - like the centre cradle mounted aerial here
http://www.wrightsaerials.tv/aerialp...odern/021.html.

The current method will cause signal attenuation.

Replace the cable with copper on copper double screened co-ax (CT100, PF100
etc) keeping any joints to a minimum and using only F connector joints if
possible.

Consider adding a screened masthead amplifier.

Consider replacing the aerial with a better quality one. For Sudbury a
quality group E should be better than wideband, sadly they appear to be thin
on the ground these days. Someone may be able to suggest one. Blake are
showing an SR18E on their website
http://www.blake-uk.com/page/aerial_benchmark/Aerial_SR

I live just down the road at Felixstowe and have the same problem. Of
course, we are officially outside the Freeview coverage area.

I fitted a DAT75, much to the derision of all the old hands here, but when I
challenged them to find me a wideband aerial (necessary for Sudbury, as you
say) with a better front-to-back ratio they all went quiet. Including the
always helpful Bill.

The reason for the highest possible front/back ratio is that our reception
is comprehensively buggered by picking up stuff from the continent on the
back of the aerial. In "nice" weather like this the problem is usually much
worse (I don't know much about propagation, but someone here will explain
it).

The DAT75 is big and ugly, but so far is the only aerial to provide Freeview
reception with any kind of reliability where I live. Even so, in high
pressure atmospheric conditions I lose Virgin 1, followed by the ITV
channels. The signal strength remains the same, but the "quality" reading
falls right away, confirming that the incoming signal from Sudbury is
probably being corrupted by "noise" off the back of the aerial. So far the
rest of the channels have held out perfectly.

To be perfectly honest, I would be sorely tempted to give it up and go for
Freesat. The big problem right now is the lack of any decent Freesat PVRs,
but in a year's time they should be pretty well sorted. Freeview should
leap into life in our area in 2011, but that's too long to wait, isn't it?

One of Bill's colleagues has done some interesting tests on a number of
aerials and has found one which comprehensively outperforms the DAT75 in
terms of forward gain, at least. What the front to back ratio is like I
don't know, but it might be worth a look.

Bill, could you remind us of that website? (Sorry, I've lost it again).

Thanks,

SteveT

On Wed, 23 Jul 2008 17:24:21 +0100, "Ivan"
wrote:


wrote in message
. ..
Recently our TV reception has detriorated markedly, we live near
Woodbridge and get our signals from Sudbury so we're getting on for
"fringe area". The Woodbridge relays don't do anything for us. Until
recently reception was pretty good most of the time with the very
occasional drop out and sometimes a 'bad day' with odd atmospheric
conditions.

I can't see anything obvious that has changed (like failed connectors)
so I suspect that we may be being affected by particularly lush growth
at the tops of some trees which are probably somewhat on our path
towards Sudbury.

Analogue reception has become pretty ropey too as well so I think it's
aerial (or downlead) rather than anytthing else.

So - what to do? The current aerial is a cheap "high gain" one, here
are a couple of pictures ot it:-

http://www.isbd.net/images/DSCF0812.JPG
http://www.isbd.net/images/DSCF0813.JPG

(Sorry they're so dark, it was a very dull day, still gives an idea of
what's there)

It's difficult to make the aerial a *lot* higher where it is but there
is actually another roof where I have *much* better access and could
mount it higher, the only disadvantage there is that it's relatively
remote from the TVs (on a separate building).

So would I be better off with a better aerial or would it be better to
move it to a better location? Can one get wireless connections for a
TV aerial?

If a better aerial seems a good idea what would be recommended? I
think we genuinely do need "wide band" for the Sudbury transmitter.

(In the longer term the trees may be coming down but that's months
ahead and I want to improve things before then, even if it is the trees)



Why has the aerial been bolted on upside down?.. you may just as well have
clamped the boom directly to the mast.

--
Chris Green

Maybe it's worked loose and fell that way? Anyway, I'd say that's
your problem. Get the aerial mounted so the mast doesn't cut through
the elements & you'll be fine.

Marky P.

In an earlier contribution to this discussion,
wrote:

Ivan wrote:
wrote in message
...
So - what to do? The current aerial is a cheap "high gain" one,
here are a couple of pictures ot it:-

http://www.isbd.net/images/DSCF0812.JPG
http://www.isbd.net/images/DSCF0813.JPG

[snip]

Why has the aerial been bolted on upside down?.. you may just as
well have clamped the boom directly to the mast.

I have no idea, maybe there was nothing telling which way was "the
right way up". It's not going to have a significant effect on the
performance anyway is it? (Except the loss of a few inches of height)


It will have *some* but - more importantly - the junction box will be more
likely to become full of water, which is what might have happened.
--
Cheers,
Roger
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Doctor D wrote:

Firstly mount it with the cradle the right way up and without the mast
running through the elements - like the centre cradle mounted aerial here
http://www.wrightsaerials.tv/aerialp...odern/021.html.

Ah, thank you, a picture is worth a thousand words (in this case anyway).


The current method will cause signal attenuation.

Replace the cable with copper on copper double screened co-ax (CT100, PF100
etc) keeping any joints to a minimum and using only F connector joints if
possible.

It already has good cable.


Consider adding a screened masthead amplifier.

There's an amplifier pretty close to it, it's probably only two or
three metres from the aerial.


Consider replacing the aerial with a better quality one. For Sudbury a
quality group E should be better than wideband, sadly they appear to be thin
on the ground these days. Someone may be able to suggest one. Blake are
showing an SR18E on their website
http://www.blake-uk.com/page/aerial_benchmark/Aerial_SR

Thanks, that's the other sort of advice I was after. You're right,
group E is better than wideband (I took a look at the Wolfbane site
after my original post).

--
Chris Green

"Steve Thackery" wrote in message
...
I fitted a DAT75, much to the derision of all the old hands here, but when
I challenged them to find me a wideband aerial (necessary for Sudbury, as
you say) with a better front-to-back ratio they all went quiet. Including
the always helpful Bill.
I think pretty well any of the very large high gain wideband aerials will
have similar f/b ratios to the DAT75, and some of these will also have the
advantage that they remain intact for many years. The only major performance
difference between any of the 'good' makes of comparable aerial is how much
they fiddle the figures that they give out. There's a natural performance
limit to yagis, and the 'good' aerials are all nudging it. If one make is a
bit better in one respect, it will be a bit worse in another.

One of Bill's colleagues has done some interesting tests on a number of
aerials and has found one which comprehensively outperforms the DAT75 in
terms of forward gain, at least. What the front to back ratio is like I
don't know, but it might be worth a look.

Bill, could you remind us of that website? (Sorry, I've lost it again).

Google for ATV Sheffield.

Bill

wrote in message
...
Recently our TV reception has detriorated markedly, we live near
Woodbridge and get our signals from Sudbury so we're getting on for
"fringe area". The Woodbridge relays don't do anything for us. Until
recently reception was pretty good most of the time with the very
occasional drop out and sometimes a 'bad day' with odd atmospheric
conditions.

I can't see anything obvious that has changed (like failed connectors)
so I suspect that we may be being affected by particularly lush growth
at the tops of some trees which are probably somewhat on our path
towards Sudbury.

Analogue reception has become pretty ropey too as well so I think it's
aerial (or downlead) rather than anytthing else.

So - what to do? The current aerial is a cheap "high gain" one, here
are a couple of pictures ot it:-

http://www.isbd.net/images/DSCF0812.JPG
http://www.isbd.net/images/DSCF0813.JPG

Leaving aside the obvious deficiencies of the aerial the important thing --
the biggest factor by far -- when tree screening is the problem, is the
position of the aerial. You need to sweep the the area, trying every
possible aerial location carefully. One metre can make a massive difference.
On innumerable occasions (OK I lie, it's actually 1,345,602 occasions) I
have done this and then simply moved the same aerial to a new location. The
difference between one location and another with only a few feet between
them can easily be 15dB. Generally the best spot for one channel will be the
best for all of them.

See my ancient piece on this subject:
http://www.wrightsaerials.tv/resourc...-reception.pdf
It creaks like the trees it talks about, but it's still basically valid.

Bill