High Gain Aerials?
Fludge
I'm in a strong signal area but have a crappy little aerial in the loft and
so am getting nothing on the freeview. I'm willing to invest in a high gain
aerial, but it's going to have to go in the loft too since I'm renting and
am not allowed to drill or fix anything to the outside of the house. I know
that having it in the loft is a disadvantage, but I reckon if I get a good
enough aerial it'll help a little. What kind are the best to go for? I
thought about looking in Maplin since I know they have quite an extensive
range. Any advice?
Doctor D.
"Fludge" <wi...@freeuk.com> wrote in message
news:BBzbb.8744$vX3.1...@wards.force9.net...
1. High gain aerials are big, ensure you have enough space in the loft. Be
prepared to fiddle with locations to avoid interference.
2. Buy the correct group aerial for your local analogue and digital
transmissions or a wideband if required. I've used the Triax Unix 52 range
with good results. You may not need a high gain aerial merely a quality 18
element aerial such as the Antiference TC18 of the correct group. If you
don't know which group you need, ask here naming your transmitter.
3. Use CT100 or similar double screened co-ax (See
http://www.screwfix.com/app/sfd/cat/pro.jsp?id=10633&ts=40617) in a single
length from aerial to Freeview box if possible.
4. I would avoid buying an aerial from Maplin or similar. I've used both
http://www.jwhardy.co.uk/pages/pl_ant_ter.html who didn't charge post and
packing, and http://www.scantec.org.uk/www/Cats.asp?mc_id=2 who add postage
(and VAT sometimes.) Both delivered on time and with no fuss.
Basil
>
Without being facetious, I'd strongly recommend using a competent aerial
contractor. There are a lot of cowboy installers out there, but asking
around should yield a recommendation. A decent local contractor should know
a lot about the nuances and peculiarities of the area; a little knowledge
can be priceless.
I had a good local installer pop a new wideband on a stack on the roof and
replace the old-coax in the house; I had similar decent co-ax installed as
Doctor D. recommends on a multidrop system. I now have a couple of Nokia
9850s (yep, I know) on the ends and get a rock solid picture in all
weathers. Good cable, good quality amps if needed plus a good installer -
you may need all three.
- basil
Bill
freely to find the optimum position. Another thing, the elements of the aerial
tend to be detuned by the proximity of metal or even masonry, and then there's
capture area, well you don't want to hear about that but it means that the
aerial needs space all around it to work properly. The upshot of all this is
that generally the results of putting a big aerial in the loft are
disappointing. I would never use anything bigger in a loft than a good quality
18 element such as the Antiference TC18.
How long is the cable? Maybe a masthead amp would help.
Bill
--
History teaches us that men and nations behave wisely once they have exhausted
all other alternatives.
Abba Eban, The Times, 1970.
BillR
> "Fludge" <wi...@freeuk.com> wrote in message
> news:BBzbb.8744$vX3.1...@wards.force9.net...
> Any advice?
>>
>
> Without being facetious, I'd strongly recommend using a competent
> aerial contractor. There are a lot of cowboy installers out there,
> but asking around should yield a recommendation. A decent local
> contractor should know a lot about the nuances and peculiarities of
> the area; a little knowledge can be priceless.
>
> I had a good local installer pop a new wideband on a stack on the
> roof and replace the old-coax in the house;
Got local aerial experts in and they fitted high gain aerial with CT100
cable.
Even showed me the various signals on their spectrum analyser.
Cost £150 but is worth as FW is now rock solid
Dave Walker
Do mastheads wear out or maybe have they improved in recent years?
I live in a freeview no go area, but having installed a hi gain wideband
antenna, new coax I am getting all channels virtually solid, but the
occasional breakup and audio squeaks drive my better half to near violence.
Today I bought a setpal receiver, supposed to work better in low signals,
but in fact its worse than the Goodmans gdb2 it replaces.
However it does tell me a few things, that my signal strength is 90%, but my
signal quality is only about 25%, digital quality about 80%. Signal/noise
is low on all muxes, sometimes dipping below 15dB.
The only thing (?) I haven't tried is changing the masthead amp, I used the
existing 8-10 year old item, it looked tidy, was dry, no corrosion etc.
Any ideas what the setpal figures are telling me - would a new high gain
(23db maxview from RS, just £15) make things better or worse in anyones
opinion?
NB I did try without the amp in circuit to make sure one was needed - no
digital reception at all.
Dave
Dave Walker
Dave Walker
R. Mark Clayton
"Dave Walker" <pinbal...@btinternet.com> wrote in message
news:bknph6$3veb4$1...@ID-75957.news.uni-berlin.de...
> Hi,
> Do mastheads wear out or maybe have they improved in recent years?
Mastheads do get hammered pretty badly. Wind, rain snow, nearby lightening,
sun. All this temperature cycling reduces the life expectancy of the
components. If any water gets in, then it will probably be a goner. Same
applies to LNB's.
OTOH there are normally few high reliability components inside, so ten years
is a reasonable expectation.
John Rumm
> The only thing (?) I haven't tried is changing the masthead amp, I used the
> existing 8-10 year old item, it looked tidy, was dry, no corrosion etc.
> Any ideas what the setpal figures are telling me - would a new high gain
> (23db maxview from RS, just ?15) make things better or worse in anyones
> opinion?
The main improvement you will probably be able to get by changing the
amp it to get a fully screened one. Many of the older designs were not
that well screened which is more of an issue with DTT. I recently
replaced a old unscreened mast head amp with a Triax fully screened one
and it has resulted in far less "glitching" on DTT (made a noticable
improvement to analogue as well).
--
Cheers,
John.
/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/
Dave Walker
> amp it to get a fully screened one. Many of the older designs were not
> that well screened which is more of an issue with DTT. I recently
> replaced a old unscreened mast head amp with a Triax fully screened one
> and it has resulted in far less "glitching" on DTT (made a noticable
> improvement to analogue as well).
>
I tried wrapping the whole thing in tin foil and earthing that to braid !
It may be imagination, but I reckon gliching calmed down a bit after that.
Have you a link for triax stuff? I usually get my stuff from RS, but they
only have maxview.
How about if I screen it myself internally, or are we talking about
something better than sticky tin foil on the inside!
Dave
Bill
>digital reception at all.
It's working then. A different one won't be any better.
Bill
Doctor D.
Research Communications GaAsFET masthead amplifiers with very low noise.
Don't know anything about them, but what he says appears to make sense! Have
a look and see what you think.
John Rumm
> I tried wrapping the whole thing in tin foil and earthing that to braid !
> It may be imagination, but I reckon gliching calmed down a bit after that.
Well that ought to help....
> Have you a link for triax stuff? I usually get my stuff from RS, but they
> only have maxview.
I got my one from CPC. But checking the catalogue it looks like they now
have a different range..... having said that these:-
http://custom1.farnell.com/cpc/product.asp?catalog%5Fname=cpc+catalogue&category%5Fname=&product%5Fid=253384
or if that URL is too long try:
http://tinyurl.com/oeht
look rather similar.
> How about if I screen it myself internally, or are we talking about
> something better than sticky tin foil on the inside!
A tad upmarket from that ;-) It was a tin plated steel box with soldered
/ folded edges etc. All the connectors were F-Type as well. I opted for
a single input single output amp with a gain of 22dB and a noise figure
of <2dB. I then used a good quality labgear inductive splitter on the
output.
Dave Walker
Thanks John,
in fact the spec (and part number) is identical to the RS offering, 439
4539 , which is a few pounds more, but with cpc`s delivery and hassle factor
it pretty much evens out!
Jonathan Buzzard
wrights...@aol.com.co (Bill) writes:
> The problem with big aerials in the loft is that you can't move them around
> freely to find the optimum position. Another thing, the elements of the aerial
> tend to be detuned by the proximity of metal or even masonry, and then there's
> capture area, well you don't want to hear about that but it means that the
> aerial needs space all around it to work properly. The upshot of all this is
> that generally the results of putting a big aerial in the loft are
> disappointing. I would never use anything bigger in a loft than a good quality
> 18 element such as the Antiference TC18.
> How long is the cable? Maybe a masthead amp would help.
That all depends on your loft now. Take my sisters loft you could easily
enough room to swing a Televis DAT75, have it pointing in *any* direction
you care and one metre clear all around it. My Grandmother used to
live in a bungalow that was much the same.
Personally I use a DAT75 with a margin rasing/masthead amplifier thingy
in the loft to get Freeview from what is not my main transmitter. It works
just fine for Freeview and all but Channel 4 and five in analogue.
JAB.
--
Jonathan A. Buzzard Email: jonathan (at) buzzard.me.uk
Northumberland, United Kingdom. Tel: +44 1661-832195
John Rumm
To be honest I have never had any problem with CPC with either delivery
or returns, but I did receive a letter from them once, appologising for
the poor delivery performance - so I suppose there must be someone out
there getting grief!
Andy Dee
The higher the gain, the more susceptable they are to surrounding
objects...
The type that has four dipoles stacked vertically in front of a grid
reflector works the best in a loft.
A
Bill
>or returns, but I did receive a letter from them once, appologising for
>the poor delivery performance - so I suppose there must be someone out
>there getting grief!
Same here. I bet internal politics was the cause of that letter. Rubbing
someone's nose in it.
Machiavellian Bill.
--
Bill
>reflector works the best in a loft.
An interesting observation. Could you elucidate?
Curious Bill
Jonathan Buzzard
Andy Dee <andy...@snotmail.con> writes:
> Fludge wrote:
>> Hi.
>> I'm in a strong signal area but have a crappy little aerial in the loft and
>> so am getting nothing on the freeview. I'm willing to invest in a high gain
>> aerial, but it's going to have to go in the loft too since I'm renting and
>> am not allowed to drill or fix anything to the outside of the house. I know
>> that having it in the loft is a disadvantage, but I reckon if I get a good
>> enough aerial it'll help a little. What kind are the best to go for? I
>> thought about looking in Maplin since I know they have quite an extensive
>> range. Any advice?
>>
>>
> High gain aerials dont work in the loft.
Funny mine does...
> The higher the gain, the more susceptable they are to surrounding
> objects...
Then shift them out the way.
> The type that has four dipoles stacked vertically in front of a grid
> reflector works the best in a loft.
Er, that type of aerial is specificily for reducing ghosting. If
you have a large metal water tank behind the aerial then yes it
will be good. However in general it is distinctly not the best type
of aerial for loft usage.
Andy Dee
to back ratio and is not affected too much by being in the loft, wet
tiles and all.
If you have ever looked at how badly a high gain yagi is affected when
it is basically indoors, you would see my point.
This is not only an opinion, it is personal experience which I offer in
good faith.
Certainly a high gain aerial will *work* in the loft, but you have
wasted your money, its performance will be badly degraded.
A
Jonathan Buzzard
Andy Dee <andy...@snotmail.con> writes:
>
> Er, as you put it. That type of aerial has 12dB gain, a very good front
> to back ratio and is not affected too much by being in the loft, wet
> tiles and all.
> If you have ever looked at how badly a high gain yagi is affected when
> it is basically indoors, you would see my point.
That depends, as I have pointed out many lofts have more than
enough room to put a high gain yagi in. When I am boarding out
my sisters loft later this year I will take my DAT75 and take
some photographs to prove the point if you want.
> This is not only an opinion, it is personal experience which I offer in
> good faith.
> Certainly a high gain aerial will *work* in the loft, but you have
> wasted your money, its performance will be badly degraded.
Well all I can say is that it does better than any other aerial I
have tried in the loft and gets me Freeview which none of the
others did. Now you can tell me I have wasted my money, and that
it won't work till your blue in the face but I am now getting
a signal that previously I was not.
original yido
"Jonathan Buzzard" <jona...@buzzard.org.uk> wrote in message
news:u3lvkb...@192.168.42.254...
you are not in a strong signal area.i'm in a strong signal area I receive
all freeview channels with a 50p bootsale aerial on top of my tv.
Jonathan Buzzard
"original yido" <origin...@btinternet.com> writes:
>
> "Jonathan Buzzard" <jona...@buzzard.org.uk> wrote in message
> news:u3lvkb...@192.168.42.254...
>> In article <bkvd08$eb7$1$8302...@news.demon.co.uk>,
>> Andy Dee <andy...@snotmail.con> writes:
>> >
>> > Er, as you put it. That type of aerial has 12dB gain, a very good front
>> > to back ratio and is not affected too much by being in the loft, wet
>> > tiles and all.
>> > If you have ever looked at how badly a high gain yagi is affected when
>> > it is basically indoors, you would see my point.
>>
>> That depends, as I have pointed out many lofts have more than
>> enough room to put a high gain yagi in. When I am boarding out
>> my sisters loft later this year I will take my DAT75 and take
>> some photographs to prove the point if you want.
>>
>> > This is not only an opinion, it is personal experience which I offer in
>> > good faith.
>> > Certainly a high gain aerial will *work* in the loft, but you have
>> > wasted your money, its performance will be badly degraded.
>>
>> Well all I can say is that it does better than any other aerial I
>> have tried in the loft and gets me Freeview which none of the
>> others did. Now you can tell me I have wasted my money, and that
>> it won't work till your blue in the face but I am now getting
>> a signal that previously I was not.
>>
>>
>
> all freeview channels with a 50p bootsale aerial on top of my tv.
>
What's that go to do with the price of bread?
The claim was high gain aerials don't work in a loft, I was pointing
out that they do, I have a functioning one that works. The fact that
you can get all the freeview channels with a settop aerial is irrelevant
to the topic at hand.
JAB.
--
Jonathan A. Buzzard Email: jonathan (at) buzzard.me.uk
Northumberland, United Kingdom. Tel: +44 1661-832195
Bill
>out that they do, I have a functioning one that works.
The claim (waddya mean 'claim'?) was that the performance of high gain aerials
is seriously compromised by the proximity of masonry, wiring, plumbing, etc,
and that since large high gain aerials are more difficult to position in
cramped surroundings, their use in lofts is unlikely to be worthwhile.
Bill
Jonathan Buzzard
The claim was not that it was "unlikely to work" but "don't work".
I find this sort of emphatic claim annoying because (a) they
do work, and (b) many lofts have more than enough room to house
a large aerial without problems and any degredation to their
performance due to procimity of stuff.
Bill
When you use a lot of aerials and you try a high gain one and it is no better
than a much smaller cheaper one you say it 'doesn't work'. That doesn't mean
you don't get any reception, it is aerialriggerspeak meaning that the thing
isn't cost effective.
Bill
Jonathan Buzzard
Perhaps, but the misses the point. The aerial in question has been
swapped several times over a number of years each time putting a
larger aerial in and each time getting better results.
The basics is that my normal reception comes from the Newton relay
in the Tyne valley. I have an unobstructed see the transmitter from
the front rooms of the house, and it is just 6300m away. However this
does not carry five and no Freeview. For this I need to point an
aerial at the Fenham transmitter, which is about 12400m away in the
opposite direction and which requires from this location to
be about 2m above the ridge to have a clear view of the transmitter.
Now about seven years ago I decided to see if I could add in an
aerial to the system to receive Channel 5 from the Fenham transmitter.
Tried a little 10 element job which was not very good. I tried adding
a masthead amplifier which imporved things but not enough, I then
tried an Antiference Xtra gain job which produced a watchable picture
but still a bit grainy.
Earlier this year I got a DEC-2000t box to record stuff from BBC7.
It just about worked, though some of the multiplexs didn't work,
noticably the ones carrying ITV1/Channel4. Also the signal strenght
was so marginal you where getting occasional dropouts.
So I decided to upgrade the aerial again. I selected a Televis DAT75
with their margin rasing device and ditched the masthead amplifier.
I now get all the Freeview channels, with only very occasional dropouts,
and it is actually good enough for all but Channel 4 of the analogue
channels.
Now you can tell me it won't work, you can tell me it is not cost
effective till you are blue in the face. However the reality is
that it does work. As it is the only way of getting Freeview
in this house short of sticking a great big ugly 2 metre high
pole on the roof that would be unlikely to survive the first
winter gale round here, and not meet the local planning regulations
anyway you claim it is not cost effective till you are blue in the
face as well.
Granted it was not exactly cheap, but it works, and for something
to be more cost effective it would have to work at a lower price.
There is nothing more silly than someone claiming something won't
work or is not cost effective when there is a working example that
proves things to the contary.
Bill
>work or is not cost effective when there is a working example that
>proves things to the contary.
>
There is nothing more silly than generalising from one experience, when others
have had thousands of similar experiences. Yesterday I was at a house where
reception was very much better in the loft than on the roof. If that had been
the only experience I had, any general conclusion I might draw from it would be
very misleading.
It may well be that none of the negative factors associated with high gain
aerial in lofts apply in your case. That's unusual but perfectly possible. It
wouldn't be a good basis for general advice, however, such as is handed out in
this newsgroup.
Your conclusions might also be invalid for other reasons. It is impossible for
a big aerial to occupy exactly the same point in space as a small one, because
it's bigger, so you cannot by definition be comparing like with like. This is
one of the big problems when aerials are tested. A partial solution comes from
the fact that the aerials under test are installed in free space, or as close
as we can get. This means they are a very long way from anything else. Fixings
and cables present an obvious problem. It is really difficult to draw
meaningful comparisions between aerials, even under ideal scientific
conditions. If a new type of aerial came out I wouldn't dream of drawing any
conclusions about it whatsoever having used it once.
Bill
Jonathan Buzzard
wrights...@aol.com.co (Bill) writes:
>>There is nothing more silly than someone claiming something won't
>>work or is not cost effective when there is a working example that
>>proves things to the contary.
>>
>
> There is nothing more silly than generalising from one experience, when others
> have had thousands of similar experiences. Yesterday I was at a house where
> reception was very much better in the loft than on the roof. If that had been
> the only experience I had, any general conclusion I might draw from it would be
> very misleading.
I was not generalising. I was pointing out that the claim that high
gain aerials do not work in lofts was patently false. I only *ever*
need one counter example to prove this statement wrong.
Further more just because I have cited one particular example does not
mean that I don't know of other examples where high gain aerials work
in lofts.
You at times seem determined to maintain that this is really the case,
or that it is rare for them to work. I on the other hand have only
known them not to work on one occasion. Then again on that occasion
they don't work out on the roof either, and I would be impressed
indeed if you could get a decent analogue reception at this particular
address with any combination of aerials.
Sure I don't have the depth of experience you have, but I have never
known them to not work when aerials outside also work.
The point is that if someone asks about a high gain aerial in a loft
they are likely to have reasons for wanting the aerial in a loft (could
be planning regulations in a conservation area for all you know),
and have already tried all the other options.
Therefore if people are going to say something about high gain aerials
in lofts, they should say something that is accurate, not something that
is inaccurate, false and wrong. It might be that it will work for
them and the gamble in the expense is worth it.
I make no appologies for pointing out incorrect statements of fact; ever.