On Sun, 22 Sep 2013 01:25:28 GMT, Windmill wrote:

Can you turn off the LNB power on the receiver to separate the
potential of it being an LNB lockup rather than a steering issue?

That's an excellent idea. It can be done just by using the remote.

Worth a try but there ain't much to "lock up" in an LNB, not unless
they are using a sledge hammer to crack a nut.

I don't even know what's in an LNB. There must be something like a
tuned cavity and a gallium arsenide transistor or IC to generate the
local oscillator frequency (the specs usually seem to talk about a
stability of +/- 2 MHz, which I suppose isn't much as a percentage of
10 GHz).

Yep LO of some sort.

And there's some sort of polarisation switch, apparently selectable by
changing the DC supply voltage from the receiver down below,

Yep, magnetic some how in the feed horn/wave guide.

and some sort of 22KHz modulated tone, also from the receiver, though
I've forgotten what that does in an LNB (frequency selection?

Think it's justa 22 kHz tone on or off. Selects which block of
frequencies to send down as the IF signal. Lo-Band or Hi-Band.

LNB selection when there are multiple LNBs ?).

Got me there, I've always assumed that LNB switching was done
manually or possibly part of the DiscEq protocol.

--
Cheers
Dave.