Presumably the 4 satellites you can see are in a gently sloping curved tilted line going down to the right. The highest elevation satellite will be the one on the left, towards due south. The lowest satellite will be to the right, towards the south east. The slope of the curved line, in the vicinity of your wanted satellite, will be approx 21 deg. If you aimed due south, you would be looking at the top of the arc and line would be horizontal. Here you can swing the dish sideways and see several satellites, without changing the elevation at all!
Polarisation: The input waveguide to the LNB is rectangular. If the broad faces of the rectangle are on either side, like so
then you have true Horizontal polarisation.
This is your polarisation starting position (for Horizontal name polarisation). Then apply the +21 deg clockwise adjustment, while facing forwards towards the satellite in the sky.
LNB and the meter
The NJR2837 LNB has a 10 GHz local oscillator and is intended for receiving satellite signals in the range 10.95 - 11.7 GHz. These signals appear in the coax cable in the range 950 - 1700 MHz and it is this range that both your meter and the modem need to be tuned to. Your iDirect options file specifies the wanted receive carrier frequency into the modem. Your meter may be tuned to the same signal or, more likely, to a convenient large and powerful DVB-S TV carrier, which must be on the same satellite beam, same polarisation and in the same frequency band range ( 10.95 - 11.7 GHz > 950 - 1700 MHz).
The name "HEX file" is normally associated with the Horizon Meter
, not the iDirect modem. Horizon supply HEX files which pre-program the meter to a DVB-S TV carrier in the range 950-1700 MHz and symbol rate. These HEX files assume some type of LNB, some polarisation, some satellite and beam, some receive location and some carrier freq/symbol rate. All these must match up if the meter is to say "AM22 satellite found". Otherwise the meter is just a simple noise power meter, showing the noise power level from each and every satellite as you go past them.
This goes to the iDirect Modem to set up its receive carrier tuning etc.
Best regards, Eric.