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the combining of TV signals in the early days



 
 
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  #11  
Old April 10th 19, 10:17 PM posted to uk.tech.digital-tv
tony sayer
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Posts: 4,104
Default the combining of TV signals in the early days

In article , Bill Wright
scribeth thus
When ITV started in the mid 50s it was on frequencies around 200Mc/s.
BBC TV was on 50-60Mc/s. (Please don't nit-pick these figures)
Different scenarios emerged for the combining or not combining of the
signals.|

No need to combine:
1. ITV set top boxes had separate aerial sockets so two downleads were
needed and no combiner.
2. A few TV sets had separate aerial sockets labelled BI and BIII.
3. Later on, aerials were made that sent both sets of signals down the
same coax.


A need to combine:
The idea was to use a diplexer. Since these were an indoor unit this
necessitated a second downlead. The diplexers were expensive and so was
the coax at 4d a yard, so the first thing to do was simply tape the two
aerial feeds together on the roof. The pictures would then be
scrutinised for ghosting. If there wasn't any then that was that. If
there was, it was pointed out to the customer, who had to make the
decision whether it was worth the extra cost to have a second downlead
and a diplexer.

Later:
When Anglia started from Belmont on ch7 we used to use a switch on the
windowsill to change from the normal aerial to the ch7 one.

Bill



Remember that lot SAC who made diplexers and the like there still around
as;

http://www.sacelectronics.co.uk/

https://cpc.farnell.com/sac/a1050/spitter-2-way-dc-
pass/dp/AP02304?MER=sy-me-pd-mi-alte&st=SAC


--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.


  #12  
Old April 11th 19, 01:22 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 3,382
Default the combining of TV signals in the early days

On 10/04/2019 22:17, tony sayer wrote:

Remember that lot SAC who made diplexers and the like there still around


Sam Collard. The early UHF/UHF diplexers, well, less said soonest mended.

Bill
  #13  
Old April 11th 19, 12:51 PM posted to uk.tech.digital-tv
tony sayer
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Posts: 4,104
Default the combining of TV signals in the early days

In article , Bill Wright
scribeth thus
On 10/04/2019 22:17, tony sayer wrote:

Remember that lot SAC who made diplexers and the like there still around


Sam Collard. The early UHF/UHF diplexers, well, less said soonest mended.

Bill


Weren't they up to much then?..

--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.


  #14  
Old April 11th 19, 02:01 PM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 3,382
Default the combining of TV signals in the early days

On 11/04/2019 12:51, tony sayer wrote:
In article , Bill Wright
scribeth thus
On 10/04/2019 22:17, tony sayer wrote:

Remember that lot SAC who made diplexers and the like there still around


Sam Collard. The early UHF/UHF diplexers, well, less said soonest mended.

Bill


Weren't they up to much then?..

I used some because at the time we had a good market diplexing Bilsdale
and Emley, and the results were poor. I graphed a few to find out why
and the response of each was unimpressive. I believe things improved
later but by then I'd started using Polytron ones.

Bill
  #15  
Old April 12th 19, 06:05 PM posted to uk.tech.digital-tv
tony sayer
external usenet poster
 
Posts: 4,104
Default the combining of TV signals in the early days

In article , Bill Wright
scribeth thus
On 11/04/2019 12:51, tony sayer wrote:
In article , Bill Wright
scribeth thus
On 10/04/2019 22:17, tony sayer wrote:

Remember that lot SAC who made diplexers and the like there still around

Sam Collard. The early UHF/UHF diplexers, well, less said soonest mended.

Bill


Weren't they up to much then?..

I used some because at the time we had a good market diplexing Bilsdale
and Emley, and the results were poor. I graphed a few to find out why
and the response of each was unimpressive. I believe things improved
later but by then I'd started using Polytron ones.

Bill


Ah! Right, around our way we never combined UHF feeds as such the only
exception was some people managed to get the much thought of, well in
those days, ITV London on CH-23 course that was right next to Sandy
Heath on CH-24 so separate feeder and switches.

Used them sometimes for VHF B1 & B3 and UHF seemed ok ..

As well as just B1 and B3 VHF Way back now..
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.


  #16  
Old April 14th 19, 07:32 AM posted to uk.tech.digital-tv
Chris Holmes
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Posts: 73
Default the combining of TV signals in the early days

Brian (Hi Brian) touched on making aerials Blue Peter Style (some ally strips and a pair of Val’s old knickers, etc)


How would this be done? I can see fixing elements and a reflector to a beam, but where would you connect the core & shield of the coax? (Assuming you didn’t use sticky backed plastic & rubber solution glue).

Cheers

Chris
  #17  
Old April 14th 19, 07:38 AM posted to uk.tech.digital-tv
Chris Holmes
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Posts: 73
Default the combining of TV signals in the early days


On 29/03/2019 09:42, Brian Gaff wrote:
A bit later on some aerials had both build on the same boom and only one
downlead. My guess was that a diplexer was inside the aerial,


“No, most dual band aerials simply used the BI dipole as the active
element for the BIII parasitics. The Antiference X14, X15, and X17
arrays had a length of twin feeder to take the BI signal to the junction
box, which was on the BIII dipole.”

I read that as “On the Bill dipole”!!

BTW, you have mail Bill, I sent you an aerial photo (two aerial photo in fact) the other day.
  #18  
Old April 14th 19, 07:14 PM posted to uk.tech.digital-tv
Bill Wright[_3_]
external usenet poster
 
Posts: 3,382
Default the combining of TV signals in the early days

On 14/04/2019 07:38, Chris Holmes wrote:

On 29/03/2019 09:42, Brian Gaff wrote:
A bit later on some aerials had both build on the same boom and only one
downlead. My guess was that a diplexer was inside the aerial,


“No, most dual band aerials simply used the BI dipole as the active
element for the BIII parasitics. The Antiference X14, X15, and X17
arrays had a length of twin feeder to take the BI signal to the junction
box, which was on the BIII dipole.”

I read that as “On the Bill dipole”!!

BTW, you have mail Bill, I sent you an aerial photo (two aerial photo in fact) the other day.


No signs of that mail Chris. Please resend to but
with 'aerial' spelt correctly.
I do have a succession of Linked in mails from you in the spam.
Apologies, but I haven't done Linked in for many a long year now.

Bill
  #19  
Old April 15th 19, 07:39 PM posted to uk.tech.digital-tv
Terry Casey[_2_]
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Posts: 928
Default the combining of TV signals in the early days

In article 6dd50521-21ed-41a8-b901-e9fb31a22011
@googlegroups.com, says...

Brian (Hi Brian) touched on making aerials Blue Peter Style (some ally strips and a pair of Val?s old knickers, etc)


How would this be done? I can see fixing elements and a reflector to a beam, but where would you connect the core & shield of the coax? (Assuming you didn?t use sticky backed plastic & rubber solution glue).


I did this once as I wasn't having much success with a halo
type indoor aerial in a bedroom without an aerial feed.

I've no idea where the idea came from!

I think the original used two large sheets of copper laminate.

It was built on a sheet of cardboard basically folded into a
vee but with a sort of blunt end to the vee to keep the two
sides slightly apart.

It was a log periodic and the elements and boom were drawn out
on a template which was used to cut two sheets of thick
aluminium foil with a craft knife.

The element/boom sets were then carefully glued to the two
wings with the blunt vee at the front.

Cable fixing was by solder tags fastened to the ends of the
booms by 6BA bolts and washers and the cable secured to the
card so that it exited at the rear in the right place.

It worked slightly better than the other aerial but I
eventually had to bite the bullet and split the existing
aerial feed.

--

Terry

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