Low signal on one q lnb port - stumped

Channel Hopper

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I think this is the Horizontal output (furthest from the feed/ marked on the pull down sleeve).

On a standard 950-2150 analyser the output is approximately 8dB down from the other polarity, I've peaked for skew and changed the LNB over as a last resort, no difference.

No obstructions outside and the dish looks straight and true (it has been running three HD boxes previously with no problem and signals on the OSDs showed 90/90)

So, is one polarity significantly lower on the Astra2 today or is it a quirk of these LNBs, or the switching protocol in the Q system ?
 
rolfw

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Never really compared them, apart from making sure both cables have a signal. If the box works I wouldn't be too concerned, think they like 65db as a safe minimum and an MER of better than 11db, although they'll run perfectly at considerably lower.
 
Channel Hopper

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I tried the same LNB on another dish this afternoon and it is exactly the same so it's not local to the area.

Then I put another Q LNB on the earlier dish and, no change.


Pictures of the analyser readings once the phone has charged up
 
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And before upgrading the dish to Q.

20200110_094056.jpg
 
rolfw

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Could simply be a bad batch of LNBs I guess, or perhaps the PSU is failing on the Satlook and it's more noticeable on the lower voltage? If I get a chance later I'll try a wideband on the Ranger and see if there's any difference between the two outputs.

Edit: Sorry, it's the Horizontals which are weaker, forget some of that comment, have you still got your big meter to check that it isn't to do with the Satlook? :)
 
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Terryl

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It could just be the horizontal polarization, if the satellite is at a low enough elevation (I think Astra 2 is around 27 to 30 degrees elevation) the signals could be bouncing and your getting a small phase cancellation on the H polarity's, if as you said it didn't change on another dish and a second LNB did the same, then it may be the problem.

You have less of a problem with ground bounce on a V transponder then an H.
 
rolfw

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Surely it would have been the same on the Universal Quad if that were the case Terry?
 
Terryl

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I tried the same LNB on another dish this afternoon and it is exactly the same so it's not local to the area.

Then I put another Q LNB on the earlier dish and, no change.


Pictures of the analyser readings once the phone has charged up
I thought he tried a second LNB on the same dish??? Two LNB's with the same problem is a big percentage, is the Q LNB he is talking about the same type as the first?
 
Channel Hopper

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It doesn't help that Sky cancelled their visit yesterday after I completed the changeover, I'm going back to revert the dish th HD again and reconnect the old recievers since the client has been give a month's delay.
 
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Reading this thread


Im now wondering if the second output is possibly an input for the SkyQ boxes (or matrix switching devices) to enable variation of the LNB output band.

Surely not.....
 
Channel Hopper

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Could simply be a bad batch of LNBs I guess, or perhaps the PSU is failing on the Satlook and it's more noticeable on the lower voltage? If I get a chance later I'll try a wideband on the Ranger and see if there's any difference between the two outputs.

Edit: Sorry, it's the Horizontals which are weaker, forget some of that comment, have you still got your big meter to check that it isn't to do with the Satlook? :)
The only other meter I have running is the Horizon USB, which AFAIK has no software to work with SkyQ outside stuff. The Unaohm 741 is awaiting a psi board.

I tried the Satlook on both battery and with mains supply, I very much doubt it is behind the spectrum issues, moreso since the 13/18/22kHz protocol is not required to change the Q LNB output.
 
Channel Hopper

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Reading this thread


Im now wondering if the second output is possibly an input for the SkyQ boxes (or matrix switching devices) to enable variation of the LNB output band.

Surely not.....
Scrap that, the moulding on the LNB confirms one is horizontal and one is vertical.
 
Channel Hopper

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Issue resolved (there wasn't one)

The Horizon USB does have an option for SkyQ installations, so having upgraded (and replaced the batteries, new larger ones are slung underneath), the SkyQ LNBs appear to be fine, as is the dish alignment.

I'm really not sure why there is such a low signal displayed on the Emitor, on one polarity, with the 10.41GHz L.O the screen is showing all signals from around 11GHz upwards, and both ports should be showing

20200117_132038.jpg20200117_132043.jpg20200117_132352.jpg20200117_132357.jpg20200117_133145.jpg
 
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