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MMDS - Missing Frequencies / Downconverter Position
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razor99
Newbie
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23. January 2009 @ 16:20 |
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Checked out my receiver box with a friend, he's receiving channels on frequencies 234, 250, 266, 282, 298, 314, 322, 330, 346, 362 and 378
I installed mesh type aerial and downconverter but am only receiving something on frequencies 282, 298, 314, 322, 330. At best the signal quality was 52% on one or two of these frequencies. Managed to watch a little but signal quality is too low.
Any ideas what could be wrong here? would this be a symptom of a misaligned antenna? I've spent forever adjusting it but with no success.
In particular I have a question about connecting the downconverter to the antenna. The antenna has a flat metal section with mounting holes and the downconverter has three sets of holes. The downconverter is Transystem OF of 218-400 I think. It looks like http://www.satandcable.co.uk/s/product_info.php?products_id=81
I used the set nearest the end i.e. the ones furthest from the tip. Are these the correct holes to use? I'm guessing this is important for the focal point and could explain why I'm not getting anything on the lower or higher frequencies ?
I don't know if its relevant but it's vertical polarisation where I am so I unscrewed and rotated the tip accordingly - would the holes to use depend on the polarisation of he signal?
Or do I simply have a poor signal ?
would appreciate any help or suggestions
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Member
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23. January 2009 @ 17:46 |
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This definitely sounds like a signal problem.There are 2 types of downconverters that chorus use but seeing as you are getting a signal on some frequencies it seems you have the right one.I didn't hear you mention a metal plate which is used on the front of the downconverter which is used for drawing in the signal.Have you done a manual scan on the frequencies that you are missing.When you are aligning your aerial you dont have too much leverage,about an inch each way.Check if there are obstructions in your line of sight to the transmitter,trees,buildings and see if you can work around that by going higher or by erecting the aerial where you can avoid them.
This message has been edited since posting. Last time this message was edited on 23. January 2009 @ 17:47
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razor99
Newbie
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23. January 2009 @ 19:06 |
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phil43,
thanks for the reply.
there is no metal plate on front of downconverter, I think I know what you are referring to though. some of the downconverters I have seen have a metal plate that is either vertical or horizontal depending on the signal polarisation. The one I have is as you see at http://www.satandcable.co.uk/s/product_info.php?products_id=81
As regards obstructions, I think I should be okay. I did however try raising it up but that didn't seem to make any difference. Doing manual scan didn't make any difference either.
Am curious as to why I'm missing the lower and higher frequencies that is why I'm wondering about the focal point for the signal and hence whether the holes I'm using to mount the downconverter to the antenna make a difference or not.
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Member
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24. January 2009 @ 08:04 |
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Just out of curiosity can you do a scan at 662.000 and another 1
at 670.000.Try 698.000 as well.Enable network scan in menu when doing these scans and let me know how you got on.
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Fano
Member
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25. January 2009 @ 15:57 |
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Originally posted by razor99:
I used the set nearest the end i.e. the ones furthest from the tip. Are these the correct holes to use? I'm guessing this is important for the focal point and could explain why I'm not getting anything on the lower or higher frequencies ?
Put the screw through the middle set of holes .
Your focal point is wrong as you rightly deduced.
That will improve the signal dramatically.
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razor99
Newbie
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26. January 2009 @ 04:57 |
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Fano, - sounds good, will give it a shot and let you know how I get on. do you know if it matters what holes are used if the signal has vertical or horizontal polarisation?
phil - thanks also for your reply but I don\\\'t understand how I could possibly get anything in the 662 -698 mhz range if my downconverter has an IF of 214-400 ?
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razor99
Newbie
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26. January 2009 @ 05:23 |
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Fano, - sounds good, will give it a shot and let you know how I get on. do you know if it matters what holes are used if the signal has vertical or horizontal polarisation?
phil - thanks also for your reply but I don\\\'t understand how I could possibly get anything in the 662 -698 mhz range if my downconverter has an IF of 214-400 ?
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razor99
Newbie
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26. January 2009 @ 05:40 |
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Fano, - sounds good, will give it a shot and let you know how I get on. do you know if it matters what holes are used if the signal has vertical or horizontal polarisation?
phil - thanks also for your reply but I don\\\'t understand how I could possibly get anything in the 662 -698 mhz range if my downconverter has an IF of 214-400 ?
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razor99
Newbie
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26. January 2009 @ 06:06 |
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Fano, - sounds good, will give it a shot and let you know how I get on. do you know if it matters what holes are used if the signal has vertical or horizontal polarisation?
phil - thanks also for your reply but I don\\\'t understand how I could possibly get anything in the 662 -698 mhz range if my downconverter has an IF of 214-400 ?
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Fano
Member
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26. January 2009 @ 09:52 |
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Originally posted by razor99:
Fano, - sounds good, will give it a shot and let you know how I get on. do you know if it matters what holes are used if the signal has vertical or horizontal polarisation?
I don't know if its relevant but it's vertical polarisation where I am so I unscrewed and rotated the tip accordingly - would the holes to use depend on the polarisation of he signal?
If its Vertical polarisation then you do not need to rotate the tip.
It should be left as normal.
The metal plate on the tip of the downconverter should be pointing Vertical not Horizontal.
Slide the downconverter into the faceplate and put the screw through the middle hole .
If you want Horizontal polarity then you have to rotate the tip 90 degrees.
Hope this helps.
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razor99
Newbie
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29. January 2009 @ 04:28 |
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fano,
tried this out but no success. refixed downconverter using middle holes but not a sniff of a signal. put it back to where it was and got a small bit of a signal again. almost out of ideas now unless I'm unfortunate enough to have a faulty downconverter? As far as I'm concerned I should have adequate line of sight and I think the transmitter is quite close.
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