Freesat Transponder 41

ei9go

Have a strange problem with a Bush Freesat HD box.

Losing signal on four channels only.

Channel4 Film4 Film4+1 & More Four+1.

The only thing these channels appear to have in common is that they are all on transponder 41.

No problem with any other channel.

Sam Radford

And all on the same frequency as your DECT telephone?
Try unplugging it/move the base station to another room.

ei9go

Don't have a DECT phone.

If you watch the signal , it fluctuates wildly and stops completely losing lock.

I am wondering if it's the lnb and I will swap the lnb tomorrow and rule that one out.

watty

That transponder is 964MHz. It would be about 25MHz wide, so 951 to 977 approx needs to be clean.

DECT is 1880 MHz–1900 MHz

However ...

GSM is 880.0–915.0 (handset TX) 925.0–960.0 (Base TX)
O2 Has I think 911..915 & 956..960

* Have you decent double screened proper satellite coax?
* Is there a Mobile phone mast within 400m? (base, not handset is potential interference)

Check for any cable damage or loose connectors.

I'm 800m approx from mast and the GSM signals on my discone are massive. Dwarfs the woodcock DAB, DTT, FM radio and analogue TV on the Spectrum analyser.

The USA equivalent to our 433 / 446/ 864 licence free is 902–928 MHz. So even illegally imported USA cordless phone or other 915MHz ISM band gadget (maybe what Sam is thinking of) is just outside the Transponder.
http://en.wikipedia.org/wiki/ISM_band

ei9go

I have swopped boxes--same problem
Swopped the feed on the octo lnb-same problem

Only the cable left.

snaps

no, have you swapped the lnb completely? just changing the feed will still be using the same LNB. I would doubt its cable related otherwise other channels would be affected as well.

ei9go

Have four other boxes running fine from this lnb. I am going to run a cable in the window of the room from the dish just to prove that it is the cable. (if it ever stops raining)

watty

OK, cable kink or damage at some suitable fraction or multiple of (31 x 0.7)cm (wavelength of 964MHz x velocity factor) from either end.

creates a notch filter.