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Labgear Tri-Boom Mast Digital Aerial (or similar)



 
 
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  #31  
Old September 28th 18, 08:25 AM posted to uk.tech.digital-tv
charles[_2_]
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Posts: 783
Default Labgear Tri-Boom Mast Digital Aerial (or similar)

In article ,
Jeff Layman wrote:
On 28/09/18 04:21, Bill Wright wrote:
On 27/09/2018 23:40, Woody wrote:
On Thu 27/09/2018 22:32, tony sayer wrote:
https://cpc.farnell.com/antiference/...og-periodic-f-
conn/dp/AP01931

I'm sorry to have to disagree in part Tony but there are two things in
the CPC advert that rancour. It says 'highly directional' which we know
a LP isn't (per BW's contribution earlier)


Logs have a reputation for being highly directional because the
front-to-back and front-to-side ratios are very high. However the main
front lobe is actually very wide, so the aerial offers little protection
against interference coming from a quite a few degrees either side of
the tx direction.

The reputation for good directivity comes largely from the analogue
days, because it's unusual for a reflected signal (the cause of
ghosting) to come from the front quadrant. (It can happen though,
especially in cities with high rise flat-sided buildings. It was for
instance a major problem at a lot of the sites I worked at in central
London.)

The wide forward lobe shouldn't put anyone off using a log periodic. To
generalise wildly, transmission stations are often on high ground, which
means that co-channel interference from further away in the same
direction is unlikely to make the trip over the hill.

If the directivity of a log periodic isn't enough it helps a lot to
mount two side by side and combine the outputs.

and in this country what is
the point of any aerial that can only be mounted horizontally in its
basic format?


It's odd that you have to pay extra for a VP clamp. Most logs are
designed so they can be installed both ways. I can only think someone
was unaware the the UK uses VP!


What main transmitters other than Rowridge use HP? I could look it up
but it's quicker to use this newsgroup!


They don't. However some 1500 relays do. And Rowridge is mainly HP.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle
  #32  
Old September 28th 18, 08:26 AM posted to uk.tech.digital-tv
Roderick Stewart[_3_]
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Posts: 2,371
Default Labgear Tri-Boom Mast Digital Aerial (or similar)

On Thu, 27 Sep 2018 23:40:32 +0100, Woody
wrote:

On Thu 27/09/2018 22:32, tony sayer wrote:
https://cpc.farnell.com/antiference/...og-periodic-f-
conn/dp/AP01931


I'm sorry to have to disagree in part Tony but there are two things in
the CPC advert that rancour. It says 'highly directional' which we know
a LP isn't (per BW's contribution earlier) and in this country what is
the point of any aerial that can only be mounted horizontally in its
basic format?

Normally CPC are pretty good at what they sell but I think they've
slipped up with this one!


If it does the job, it does the job, and he says that it does, so I
guess it does. Most TV coverage will be from main stations, which I
understand are all horizontally polarised, so that will be the most
frequent requirement. It makes sense not to include an accessory with
every aerial that only a few purchasers will need.

For what it's worth, I bought a LP aerial long ago when I lived in a
top floor London flat. I had it ceiling mounted in a bay window and
could swivel it through quite a wide angle, while watching the
picture, so a good opportunity to examine the directional properties.
The window faced away from CP so the best reception was from
Hannington, although it was further away. There was a very small range
of angles with perfect reception, and lots of ghosties outside this,
so it did appear to be very directional, just as the textbook (or
perhaps it was a Wireless World article) said.

Rod.

---
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  #33  
Old September 28th 18, 09:01 AM posted to uk.tech.digital-tv
Jeff Layman[_2_]
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Posts: 797
Default Labgear Tri-Boom Mast Digital Aerial (or similar)

On 28/09/18 08:25, charles wrote:
In article ,
Jeff Layman wrote:
On 28/09/18 04:21, Bill Wright wrote:
On 27/09/2018 23:40, Woody wrote:
On Thu 27/09/2018 22:32, tony sayer wrote:
https://cpc.farnell.com/antiference/...og-periodic-f-
conn/dp/AP01931

I'm sorry to have to disagree in part Tony but there are two things in
the CPC advert that rancour. It says 'highly directional' which we know
a LP isn't (per BW's contribution earlier)

Logs have a reputation for being highly directional because the
front-to-back and front-to-side ratios are very high. However the main
front lobe is actually very wide, so the aerial offers little protection
against interference coming from a quite a few degrees either side of
the tx direction.

The reputation for good directivity comes largely from the analogue
days, because it's unusual for a reflected signal (the cause of
ghosting) to come from the front quadrant. (It can happen though,
especially in cities with high rise flat-sided buildings. It was for
instance a major problem at a lot of the sites I worked at in central
London.)

The wide forward lobe shouldn't put anyone off using a log periodic. To
generalise wildly, transmission stations are often on high ground, which
means that co-channel interference from further away in the same
direction is unlikely to make the trip over the hill.

If the directivity of a log periodic isn't enough it helps a lot to
mount two side by side and combine the outputs.

and in this country what is
the point of any aerial that can only be mounted horizontally in its
basic format?

It's odd that you have to pay extra for a VP clamp. Most logs are
designed so they can be installed both ways. I can only think someone
was unaware the the UK uses VP!


What main transmitters other than Rowridge use HP? I could look it up
but it's quicker to use this newsgroup!


They don't. However some 1500 relays do. And Rowridge is mainly HP.


I have always used HP, as with VP Com7/8 aren't transmitted. But they
disappeared on my HP group A yagi with the frequency changes a few
months ago, which is why I am looking at a new log periodic (mainly for
BBC4 HD).

--

Jeff
  #34  
Old September 28th 18, 01:56 PM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 2,952
Default Labgear Tri-Boom Mast Digital Aerial (or similar)

On 28/09/2018 08:25, charles wrote:

What main transmitters other than Rowridge use HP?


You mean VP

I could look it up
but it's quicker to use this newsgroup!


They don't. However some 1500 relays do. And Rowridge is mainly HP.


Bill
  #35  
Old September 28th 18, 07:58 PM posted to uk.tech.digital-tv
Andrew[_6_]
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Posts: 229
Default Labgear Tri-Boom Mast Digital Aerial (or similar)

On 28/09/2018 13:56, Bill Wright wrote:
On 28/09/2018 08:25, charles wrote:

What main transmitters other than Rowridge use HP?


You mean VP

I could look it up
but it's quicker to use this newsgroup!


They don't. However some 1500 relays do.* And Rowridge is mainly HP.


Bill


Glad you posted that, I was getting confused.

I thought that Rowridge also used VP because the sea can have an
influence on the HP signal under some freak weather conditions ?.
  #37  
Old September 28th 18, 09:11 PM posted to uk.tech.digital-tv
Jeff Layman[_2_]
external usenet poster
 
Posts: 797
Default Labgear Tri-Boom Mast Digital Aerial (or similar)

On 28/09/18 19:58, Andrew wrote:
On 28/09/2018 13:56, Bill Wright wrote:
On 28/09/2018 08:25, charles wrote:

What main transmitters other than Rowridge use HP?


You mean VP

I could look it up
but it's quicker to use this newsgroup!

They don't. However some 1500 relays do.* And Rowridge is mainly HP.


Bill


Glad you posted that, I was getting confused.

I thought that Rowridge also used VP because the sea can have an
influence on the HP signal under some freak weather conditions ?.


It's because of possible interference from French transmitters. Much
more information at http://www.aerialsandtv.com/rowridgetx.html

--

Jeff
  #38  
Old September 29th 18, 03:17 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 2,952
Default Labgear Tri-Boom Mast Digital Aerial (or similar)

On 28/09/2018 19:58, Andrew wrote:

Glad you posted that, I was getting confused.

I thought that Rowridge also used VP because the sea can have an
influence on the HP signal under some freak weather conditions ?.


It's because there's some Froggie HP stations on the same channels. The
idea is to protect against interference. But who's going to put up a VP
aerial when two muxes are HP only?

Bill
  #39  
Old September 29th 18, 03:17 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
external usenet poster
 
Posts: 2,952
Default Labgear Tri-Boom Mast Digital Aerial (or similar)

On 28/09/2018 19:59, Andrew wrote:

B & Q aerials are ****e.

Bill


Are they more ****e than Labgear though ?


It's a different type of ****e.

Bill
 




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