log Periodic Aerials

At present I have a yagi-type aerial (contract, I believe) mounted on a one
metre pole fastened to the bargeboards on a gable end of my bungalow. It is
a relatively short aerial with eight directors and a bit of pressed tin for
a reflector and is about 20 years old. It receives transmissions from
Heathfield which can be seen on the southern skyline about 10 km away. I
have no means of measuring the field strength but my Sony CRT IDTV receives
a perfectly adequate signal from all 4 analogue and all the 6 muxes which
are transmitted to the north.
This week we are having the bargeboards and soffits replaced with uPVC and
the aerial will have to come down. I suspect it might prove to be corroded,
if so I will have a new aerial put up - this time fixed to the brick wall.
My question is simply what type should I go for? Presently Heathfield
appears to be wide band but post 2012 it seems it will be group B. Clearly I
would like to be future-proof if possible.
I have been looking on the web for aerials and considered the log periodic
type and, surprisingly, there seems to be a variation in design and sizes.
Some have integral amplifiers, others not. Some have 18 or 26 elements,
others 40. I would have thought that the requirement to cover the band from
channel 21 to 68 with a flat frequency response could be met by a single
unique design. Is there any noticeable difference in performance between
these designs?
I would be grateful for any observations, thanks.

Kenneth

"Kenneth" wrote in message
...
At present I have a yagi-type aerial (contract, I believe) mounted on a
one metre pole fastened to the bargeboards on a gable end of my bungalow.
It is a relatively short aerial with eight directors and a bit of pressed
tin for a reflector and is about 20 years old. It receives transmissions
from Heathfield which can be seen on the southern skyline about 10 km
away. I have no means of measuring the field strength but my Sony CRT IDTV
receives a perfectly adequate signal from all 4 analogue and all the 6
muxes which are transmitted to the north.
This week we are having the bargeboards and soffits replaced with uPVC and
the aerial will have to come down. I suspect it might prove to be
corroded, if so I will have a new aerial put up - this time fixed to the
brick wall. My question is simply what type should I go for? Presently
Heathfield appears to be wide band but post 2012 it seems it will be group
B. Clearly I would like to be future-proof if possible.
I have been looking on the web for aerials and considered the log periodic
type and, surprisingly, there seems to be a variation in design and sizes.
Some have integral amplifiers, others not. Some have 18 or 26 elements,
others 40. I would have thought that the requirement to cover the band
from channel 21 to 68 with a flat frequency response could be met by a
single unique design. Is there any noticeable difference in performance
between these designs?
I would be grateful for any observations, thanks.

I've never found big differences between the gain of different logs. I don't
like the ones with a bit of coax attached because I've found these cables
and connectors to be lossy. The Blake 26 element is very well made and works
as well as any. I'd be surprised if you need an amp, but in any case don't
use an integral one. Fix one at the bottom of the mast where you can reach
it. Very low gain is the most you'll need.

Bill

On 9 Nov., 18:41, "Kenneth" wrote:
At present I have a yagi-type aerial (contract, I believe) mounted on a one
metre pole fastened to the bargeboards on a gable end of my bungalow. It is
a relatively short aerial with eight directors I would be grateful for any observations, thanks.

Kenneth

If you need a new aerial (and only if) and when
Heathfield which can be seen on the southern skyline about 10 km away

http://www.aerialsandtv.com/atvschoi...l#LogPeriodics
or
http://www.vision-products.co.uk/pdf...0(V10-040).pdf

would be a very good choice.

If you have only the one Sony IDTV the aerial a new
quality coax cable is all that you will need - I think.

post-DSO the power of the transmitter will be 20kW
where it is now 1 or 1.6 kW.

Lars

http://www.wolfbane.com/cgi-bin/tvd....L&HT=10&OS=TN6

I've never found big differences between the gain of different logs.
I don't like the ones with a bit of coax attached because I've found
these cables and connectors to be lossy. The Blake 26 element is very
well made and works as well as any. I'd be surprised if you need an
amp, but in any case don't use an integral one. Fix one at the bottom
of the mast where you can reach it. Very low gain is the most you'll
need.


I am planning to fit a new aerial in the next few months and was
naturally hoping to follow the oracle's advice.

But he is a little too Dephic for me this time:

o I had had in mind the Blake DML; but
o Blake's site suggests it comes with cable pre-fitted (eg
http://www.blake-uk.com/page/aerial_dml) so me now fears being struck
down by Zeus's lightning-bolts (or suffering a slow death by
pixellation).

Can a priestess please interpret for me?

--
Robin

"neverwas" wrote in message
om...
But he is a little too Dephic for me this time:

o I had had in mind the Blake DML; but
o Blake's site suggests it comes with cable pre-fitted (eg
http://www.blake-uk.com/page/aerial_dml) so me now fears being struck down
by Zeus's lightning-bolts (or suffering a slow death by pixellation).

Oh yes, sorry. The Blake on has a very short tail of coax and it doesn't
seem to do any harm. I forgot about that. The problems I've had with other
makes seem to be because they use 'f' rt angle connectors which are lossy
(strange but true) and often the connection at the front is very clumsily
made.

Sorry for confusing you.

Bill

In message , Bill Wright
wrote

"neverwas" wrote in message
. com...
But he is a little too Dephic for me this time:

o I had had in mind the Blake DML; but
o Blake's site suggests it comes with cable pre-fitted (eg
http://www.blake-uk.com/page/aerial_dml) so me now fears being struck down
by Zeus's lightning-bolts (or suffering a slow death by pixellation).

Oh yes, sorry. The Blake on has a very short tail of coax and it doesn't
seem to do any harm. I forgot about that. The problems I've had with other
makes seem to be because they use 'f' rt angle connectors which are lossy
(strange but true) and often the connection at the front is very clumsily
made.


Doesn't the aerial in question have the coax pre-installed and
terminated in an F plug physically fitted to the end of the boom rather
than a short tail of coax? An arrangement similar to that shown in the
last pictures on
http://www.satcure.com/tech/logperiodic.htm

Vision now have a different connection method where the coax connection
is made to a f connector fitted to a Printed Circuit Board (PCB) The
special f connector, and a similar blank connector on the PCB, push into
the ends of the two booms with a tight interference fit making the
electrical connections. Shown on the above page or at
http://www.satcure.com/tech/logp_ins.htm

--
Alan

news2006 {at} amac {dot} f2s {dot} com

Alan wrote:

Doesn't the aerial in question have the coax pre-installed and
terminated in an F plug physically fitted to the end of the boom rather
than a short tail of coax? An arrangement similar to that shown in the
last pictures on
http://www.satcure.com/tech/logperiodic.htm

No, the blake has a few inches of coax "dangling" with a rubber boot to
cover the connection.

Thank you Bill (and others) for clarifying that.
--
Robin

"Alan" wrote in message
...
In message , Bill Wright
wrote
http://www.satcure.com/tech/logp_ins.htm

That's a big improvement. I stopped using the Vision ones because of the
crap connections. Might try them again, although the other problem was that
the elements could work loose.

Bill

Isn't the extra cable part of the matching system for the aerial? I think
the old design Antiference was very good even though it had a bit of thin
coax for this purpose.


I hate amplifiers, they tend to be wide open and any nearby pager or other
nasty pmr or data transmitter screws them up big time!

Brian

--
Brian Gaff -
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"Bill Wright" wrote in message
...

"neverwas" wrote in message
om...
But he is a little too Dephic for me this time:

o I had had in mind the Blake DML; but
o Blake's site suggests it comes with cable pre-fitted (eg
http://www.blake-uk.com/page/aerial_dml) so me now fears being struck
down by Zeus's lightning-bolts (or suffering a slow death by
pixellation).

Oh yes, sorry. The Blake on has a very short tail of coax and it doesn't
seem to do any harm. I forgot about that. The problems I've had with other
makes seem to be because they use 'f' rt angle connectors which are lossy
(strange but true) and often the connection at the front is very clumsily
made.

Sorry for confusing you.

Bill