Problem with 10714 mux on 28E

I find it amazing that considering the huge spectrum available items of
equipment still manage to pick frequencies that cause interference.

Brian

--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email:
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"Bill" wrote in message
...
In message , Bill Wright
writes
This is the Channel Four mux. Anyone come across a terrestrial
interference problem affecting only this mux? We have one and can't seem
to find out the source of the interference.

Bill
Pedestrian crossing light motion sensor? That happened in Milton Keynes a
while back.

Or a very self inflicted one in my house a microwave/PIR sensor on the
alarm system. Thinking about it, that one was knocking out the Ch4 mux
too.

A quick look with the spectrum anyliser showed up a massive carrier that
went when the alarm was switched off, and the back up battery removed. the
cure was to retune it a fraction with a bit of anti static foam
strategically placed on the oscillator.

Best of luck.

--
Bill
( A different one )

On 23/12/2012 09:50, Bill Wright wrote:
This is the Channel Four mux. Anyone come across a terrestrial
interference problem affecting only this mux? We have one and can't seem
to find out the source of the interference.

Bill


I have had this as well in the past.

Its basically computers near to the run of the co-ax cable or dish or LNB.

Its often made worse with the lid/case missing off the computer or if
you've recently upgraded a component such as a graphics adapter.

Moving the PC away is the only thing that has worked for me.

Also have you bought a new set top box recently? These are really cut
down computers....


Stephen.

On 23/12/2012 17:05, Bill wrote:
In message , Bill Wright
writes
This is the Channel Four mux. Anyone come across a terrestrial
interference problem affecting only this mux? We have one and can't
seem to find out the source of the interference.

Bill
Pedestrian crossing light motion sensor? That happened in Milton Keynes
a while back.

Or a very self inflicted one in my house a microwave/PIR sensor on the
alarm system. Thinking about it, that one was knocking out the Ch4 mux
too.

A quick look with the spectrum anyliser showed up a massive carrier that
went when the alarm was switched off, and the back up battery removed.
the cure was to retune it a fraction with a bit of anti static foam
strategically placed on the oscillator.

Best of luck.


Yes thats a good one..

wireless alarm systems
RF thermostats
DECT cordless phones
or even a change of mobile phone network and/or phone. ...

In message , Stephen H
writes

Bill
Pedestrian crossing light motion sensor? That happened in Milton Keynes
a while back.

Or a very self inflicted one in my house a microwave/PIR sensor on the
alarm system. Thinking about it, that one was knocking out the Ch4 mux
too.

Yes thats a good one..

wireless alarm systems
RF thermostats
DECT cordless phones
or even a change of mobile phone network and/or phone. ...


The microwave alarm sensors transmit on 10GHz which is also where the
muxes are, which doesn't help, they are received directly by the LNB,
some of the others may appear on the IF and get picked up by the sat' RX
if they are strong enough to get into the coax.

--
Bill
( A different one )

In message , Bill
writes
In message , Stephen H
writes

Bill
Pedestrian crossing light motion sensor? That happened in Milton Keynes
a while back.

Or a very self inflicted one in my house a microwave/PIR sensor on the
alarm system. Thinking about it, that one was knocking out the Ch4 mux
too.

Yes thats a good one..

wireless alarm systems
RF thermostats
DECT cordless phones
or even a change of mobile phone network and/or phone. ...


The microwave alarm sensors transmit on 10GHz which is also where the
muxes are, which doesn't help, they are received directly by the LNB,
some of the others may appear on the IF and get picked up by the sat'
RX if they are strong enough to get into the coax.





http://www.hkvstar.com/technology-ne...y-in-alarm-mot
ion-detection.html

10.687 GHz UK EN 300 440

Not very far away from 10.714 allowing for aging and drift of what is a
cheap mass produced device.


Yes, I'm bored, plenty of time at Christmas for Googling.
--
Bill
( A different one )

In article , Peter Duncanson
scribeth thus
On Sun, 23 Dec 2012 11:24:31 +0000, Andy Burns
wrote:

Bill Wright wrote:

Andy Burns wrote:

Both 964 MHz and 114MHz seem to fall into bands used by navaids ...

Sorry Andy, what?

It ought to be *me* asking *you* about LNB IFs, so I'll assume you know
why those frequencies ...

Navigational aids used by aircraft, transmitters not necessarily near an
airport, they look like small flying saucers on google maps, e.g.
http://goo.gl/maps/xLvHd

DME transmits in 962 to 1213 MHz range
http://en.wikipedia.org/wiki/Distanc...ring_Equipment

VOR transmits in 108 to 118 MHz range
http://en.wikipedia.org/wiki/VHF_omnidirectional_range

In fact the requirements on VHF Band 2 broadcast transmitters are quite
severe in order to not interfere with those. Especially transmitters
operating near the band edge and there are stringent restrictions on
direct "upward" radiation for the same reason!.....

--
Tony Sayer

On 23/12/2012 09:50, Bill Wright wrote:
This is the Channel Four mux. Anyone come across a terrestrial
interference problem affecting only this mux? We have one and can't seem
to find out the source of the interference.

Bill


DECT phone base station?

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