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Is there an atmospheric lift on as at 20.18 hrs 15th August 2018??



 
 
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  #11  
Old January 2nd 19, 10:42 AM posted to uk.tech.digital-tv
charles[_2_]
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Default Is there an atmospheric lift on as at 20.18 hrs 15th August 2018??

In article , NY
wrote:
"Brian Gaff" wrote in message
...
Hmm, well it might actually be why some videos tended to create
interference but that was more likely to be cross mod in the amp inside.

I don't think an oscillating amp would be stable enough to be used as a
transmitter! I did use a signal generator as a tv transmitter once
when I was young and foolish and everything was on VHF.


I did that with my signal generator on AM many years ago: I set it to 198
kHz and fed in audio from a tape to the AM input and was able to pick up
that audio on a radio, drowning out R2 (as it was in those days on that
frequency)


no it was 200kHz 'in those days'

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle
  #12  
Old January 3rd 19, 11:43 AM posted to uk.tech.digital-tv
Paul Ratcliffe
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Default Is there an atmospheric lift on as at 20.18 hrs 15th August2018??

On Wed, 2 Jan 2019 10:19:34 -0000, NY wrote:

I did that with my signal generator on AM many years ago: I set it to 198
kHz and fed in audio from a tape to the AM input and was able to pick up
that audio on a radio, drowning out R2 (as it was in those days on that
frequency). It was done as part of a test - once I proved that it worked, I
stopped in case the neighbours complained that someone had hijacked Jimmy
Young :-)


R2 was on 200kHz/1500m until 23 Nov. 1978.
R4 was on 200kHz/1500m from 23 Nov. 1978 until 31 Jan. 1988.
R4 was/is on 198kHz from 1 Feb. 1988.
  #13  
Old January 3rd 19, 01:03 PM posted to uk.tech.digital-tv
NY
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Posts: 1,684
Default Is there an atmospheric lift on as at 20.18 hrs 15th August 2018??

"Paul Ratcliffe" wrote in message
...
On Wed, 2 Jan 2019 10:19:34 -0000, NY wrote:

I did that with my signal generator on AM many years ago: I set it to 198
kHz and fed in audio from a tape to the AM input and was able to pick up
that audio on a radio, drowning out R2 (as it was in those days on that
frequency). It was done as part of a test - once I proved that it worked,
I
stopped in case the neighbours complained that someone had hijacked Jimmy
Young :-)


R2 was on 200kHz/1500m until 23 Nov. 1978.
R4 was on 200kHz/1500m from 23 Nov. 1978 until 31 Jan. 1988.
R4 was/is on 198kHz from 1 Feb. 1988.


Ah, my mistake. I thought the change from 200 to 198 kHz happened in the
final days of R2's usage rather than the first decade of R4's usage of it.

  #14  
Old January 4th 19, 05:32 PM posted to uk.tech.digital-tv
[email protected]
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Posts: 95
Default Is there an atmospheric lift on as at 20.18 hrs 15th August 2018??

The 4 TV aerials are all log periodics mounted on the same mast.

All of them have 4g filter which are then followed by masthead amps before being fed into 2 Televes Avant 5s. The output of the 2 Televes Avant 5s are then combined and then fed through another 4g filter. The reason for this will become clear.

A third Avant 5 is used to process the outputs of 10 CCTV UHF modulators some of which use ch’s 60, 62, 64, 66 and 68.

The output of the 3rd Avant5 is combined with the output of the 4g filter immediately after the combined 1st and 2nd Avant 5 units.

So even if one of the masthead amps was oscillating, I can see that it could emit from the SC aerial.

Some thoughts come to mind, the other 3 aerials are pointing in different directions so I am curious as to how they could pick up emissions from the SC aerial?

If this really did happen, then I can understand that the two Avant 5’s would be trying to modulate the gain of the channel filters to keep the output at 111dBuV but you would think the channel filtering would have helped against unwanted spurious signals getting in?

And given that ther was some substantial 4g filtering, the UHF channels 62, 64 and 66 were troubled. 64 was by far the worst on the CCTV channels

Simply swapping out the SC masthead amp has led to an improvement in the reception of all free view channels and the 800 MHz portion of the CCTV channels......
  #15  
Old January 6th 19, 04:15 PM posted to uk.tech.digital-tv
Mark Carver
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Default Is there an atmospheric lift on as at 20.18 hrs 15th August2018??

On 03/01/2019 13:03, NY wrote:

R2 was on 200kHz/1500m until 23 Nov. 1978.
R4 was on 200kHz/1500m from 23 Nov. 1978 until 31 Jan. 1988.
R4 was/is on 198kHz from 1 Feb. 1988.


Ah, my mistake. I thought the change from 200 to 198 kHz happened in the
final days of R2's usage rather than the first decade of R4's usage of it.


The '9 kHz' scheme for the LW band came a decade after the MW band. And
even then was in two events, the lower half Feb 1 1988, the upper half
late 1989. The Irish 'Atlantic 252' station actually launched
on 254 kHz before moving a month or to later to 252 kHz (It launched
with the '252' branding).


--
Mark
Please replace invalid and invalid with gmx and net to reply.
 




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