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uk.tech.digital-tv (Digital TV - General) (uk.tech.digital-tv) Discussion of all matters technical in origin related to the reception of digital television transmissions, be they via satellite, terrestrial or cable. Advertising is forbidden, with no exceptions.

Aerial input.



 
 
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  #11  
Old December 29th 13, 10:22 AM posted to uk.tech.digital-tv
Dave Plowman (News)
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Posts: 5,342
Default Aerial input.

In article ,
Bill Wright wrote:
Dave Plowman (News) wrote:


I've got loads of signal so I suppose I could just add a small cap
inline to remove the DC path. And extinguish that fault LED.


No reason why an isolating cap would reduce the signal significantly.
CPC sell little 'f' type DC isolators. Or you could simply fit an
isolating wallplate.


The wall plate is a custom made one. The obvious way is to insert the
'isolator' in the connection between DA and wall plate, where it won't
show.

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Dave Plowman London SW
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  #12  
Old December 29th 13, 10:39 AM posted to uk.tech.digital-tv
Brian Gaff
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Default Aerial input.

Some do some don't according to my buzzer. I don't see that this has any
bearing on anything at all though, as presumably the ones that are a short
or low resistance simply have a transformer across it or maybe a resistor to
discharge static. If any powered gear is used, it really should be ahead of
the socket whether it be box or tv, as these only send voltage upstream, not
back the other way, the resistance of the input would be of no consequence
surely?
Of course if you were using a resistive splitter and powering the
equipment form only one of the split inputs and the device was ahead of
both, it will short it out, but presumably one does not do it this way!

Brian

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From the Sofa of Brian Gaff Reply address is active
"Dave Plowman (News)" wrote in message
...
What would you expect to measure across the UHF aerial input on a modern
TV, resistance wise? It is working ok - but making the short circuit light
come on on the aerial DA. It does indeed read short circuit. The Topfield
PVR reads approx 175 ohms, and having that before the TV seems to work
fine. But I'm wanting to move things around so this won't be possible.

--
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Dave Plowman London SW
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  #13  
Old December 30th 13, 07:29 AM posted to uk.tech.digital-tv
alan
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Posts: 173
Default Aerial input.

On 28/12/2013 14:33, Dave Plowman (News) wrote:
What would you expect to measure across the UHF aerial input on a modern
TV, resistance wise? It is working ok - but making the short circuit light
come on on the aerial DA. It does indeed read short circuit. The Topfield
PVR reads approx 175 ohms, and having that before the TV seems to work
fine. But I'm wanting to move things around so this won't be possible.


Have you got one of your boxes feeding an (unnecessary) voltage up the
aerial cable to supply an non-existent amplifier? For instance the
Topfield can supply 5V on its aerial input socket. It can be turned
on/off from the menu.

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  #14  
Old December 30th 13, 10:34 AM posted to uk.tech.digital-tv
R. Mark Clayton
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Posts: 1,331
Default Aerial input.


"Dave Plowman (News)" wrote in message
...
What would you expect to measure across the UHF aerial input on a modern
TV, resistance wise? It is working ok - but making the short circuit light
come on on the aerial DA. It does indeed read short circuit. The Topfield
PVR reads approx 175 ohms, and having that before the TV seems to work
fine. But I'm wanting to move things around so this won't be possible.

Even tellies fifty years ago had a few pF in series on the input, so unless
the TV has suffered ESD this is a fault (if it has then it is damage).


  #15  
Old December 30th 13, 11:53 AM posted to uk.tech.digital-tv
Dave Plowman (News)
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Posts: 5,342
Default Aerial input.

In article ,
alan wrote:
On 28/12/2013 14:33, Dave Plowman (News) wrote:
What would you expect to measure across the UHF aerial input on a
modern TV, resistance wise? It is working ok - but making the short
circuit light come on on the aerial DA. It does indeed read short
circuit. The Topfield PVR reads approx 175 ohms, and having that
before the TV seems to work fine. But I'm wanting to move things
around so this won't be possible.


Have you got one of your boxes feeding an (unnecessary) voltage up the
aerial cable to supply an non-existent amplifier? For instance the
Topfield can supply 5V on its aerial input socket. It can be turned
on/off from the menu.


No - and it's switched off on the TV too. With nothing else but the TV
plugged into the DA, the warning light comes on. Not surprising if the DA
is looking for a cable short - as that's what the TV input presents to DC.

--
*Too many clicks spoil the browse *

Dave Plowman London SW
To e-mail, change noise into sound.
 




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