is Jammer effects on KU-band  

If the system has been working normally then:
Poor LNB connection.
Antenna mispointed due to wind, vandalism etc.
Water in the feed.
Interference from new carrier on same or opposite polarisation.

If this is a new system which has not yet worked:
Not yet pointed at the correct satellite (you have peaked up on the wrong one).
Wrong polarisation.
Wrong options file.

Best regards, Eric.

Not yet pointed at the correct satellite: You will be able to peak up on any and all satellites but the modem won't lock, give higher voltage and go green till you have the correct satellite and correct polarisation.

Large error in polarisation angle will give the same effect as wrong satellite.

Slightly misadjusted polarisation angle will give signal lock but marginal low quality due to interference from the other polarisation.

I've just thought of another possibility, associated with new equipments.  You may have the wrong LNB.  Ku band LNBs come with a variety of local oscillator frequencies e.g. 9.75 GHz, 10 GHz, 10.6 GHz, 11.3 GHz etc.  You need the correct LNB so that the L band frequency into the modem (as in options file) + the LNB LO freq = the actual satellite downlink frequency.

Regarding possible local inteference, C band tends to be affected by WIMAX services that operate on lower inband or nearby frequencies.  Ku band is not affected by WIMAX.  Ku band may be affected by radio relay links or nearby radar systems.  For a new service I would not expect local interference/jamming to be a problem unless the local environment was obviously full of radio transmitting devices.

If you have some good reason to suspect a local jammer/interferer, then put a 3 dB splitter in the LNB cable and connect a spectrum analyser via the DC block side connector. Hold the feed horn and LNB in your hands and point it around in all directions to identify the source.

Best regards, Eric

Unless the receive LED on the modem goes green the hub will not be able to control the modem and carry out any tests.  If the hub turns the main outlink carrier off then the 6 volts will drop if you are pointed at the right satellite - but they won't want to do this if there are 50 other sites in use.

Low volts is most likely due wrong satellite or polarisation.  If the elevation angle on the bracket reads correct on the scale, what volages do they see when they try pointing at the next two satellites along the orbit each way. They may alternatively be on completely the wrong satellite, a long long way away, due to some misunderstanding.  Are they looking in a plausible azimuth direction?.

Is there any chance that the the feed position is wrong, dish upside down, wrong holes in feed support arm etc.  Trees/wall/roof blocking the beam ?

Does the 5 - 6 volts appear to be associated with a satellite, or is the figure of 6 volts unchanging wherever the antenna is pointed.  Does the figure drop right down if the antenna is pointed away from any satellite ?

If the voltage is fixed and unchanging then test the LNB.  The LNB on its own might show a very low voltage if pointed up at the sky and slighly higher voltage if pointed at warm hand or the ground. If you point the LNB at a local interference source the volts should go up. Then re-attach the LNB to its filter arm.

Best regards, Eric

If you are located in the outer contours of the coverage beam and the voltage is too low for the modem to lock up then you need a larger dish.  1.4 times the diameter will give 3 dB improvement in dish gain.

Have you tried pointing at several other satellites along the orbit each way ? It is quite likely you are on the wrong satellite. Elevation scale may be in error by a few deg (due to clamp tightness, pole not exactly vertical and dish sag) and azimuth may be in error by several deg also due to approximations and local magnetic anomaly.

If the polarisation is wrong or not adjusted accurately, correct this.  Set the receive polarisation to the named, nominal, polarisation initially.  Then turn the feed by the calculated adjustment angle.  Positive adjustment is clockwise, as viewed with you standing behind the dish and facing forwards towards the satellite in the sky. If you use this dish pointing calculator (Iraq) it shows you a picture of what your polarisation should look like (approx). Drag the map from Iraq to any country in the world. Set polarisation to +/- 1 deg accuracy if possible and be prepared to make a few deg adjustment under verbal instruction from the hub.

The remote modem must not transmit until the modem RX has gone green and the hub can successfully send commands to it.

Height above sea level makes negligible difference to pointing angles. Ignore this.  Mountains blocking the view to the satellite do matter of course.

Best regards, Eric.

Get the hub to issue you with an options file with much wider acquisition range.  This is particularly applicable if you are using cheap, unstable, DRO type LNB.  PLL type LNB is recommended for low bit rate outlinks (e.g 2 Mbit/s with DVB-S2).

Best regards, Eric.