VLASYNA and VLASYNB give the VLA F6 synthesizer settings for the A and C IFs VLASYNA and for the B and D IFs VLASYNB. The value will be near 3900 MHz and must be N*50 +- 10.1 MHz. It will be rounded to the nearest MHz for the ``//LO'' card but should be given to full precision here to facilitate frequency calculations. The LO is passed through a filter that has the range 3435 - 4065 MHz. Allowed settings, some of which will not pass through this filter, are:
3310.1, 3339.9, 3360.1, 3389.9, 3410.1, 3439.9, 3460.1, 3489.9, 3510.1, 3539.9, 3560.1, 3589.9, 3610.1, 3639.9, 3660.1, 3689.9, 3710.1, 3739.9, 3760.1, 3789.9, 3810.1, 3839.9, 3860.1, 3889.9, 3910.1, 3939.9, 3960.1, 3989.9, 4010.1, 4039.9, 4060.1
There are actually even more allowed values at the low end, but it is not clear that it is possible to use them.
If the parameter EVLA is set, VLASYNA and VLASYNB must still conform to N*50 +- 10.1 MHz, but there is no limit on the range. The EVLA LO system is entirely different, and the program that converts the VLA style file to an EVLA file will do the necessary conversions. Also when EVLA, the VLAFEAB and VLAFECD parameters are not checked.
SCHED can determine the value of this parameter from the frequency catalog if that file includes an entry that covers the desired VLA setup.
Note that, if any of FLUKEA, FLUKEB, VLAFEAB, VLAFECD, VLASYNA, VLASYNB, VLAIF, FEFILTER, or VLAROT are specified, both LO and FI cards will be made. In such cases, any other parameters allowed to default will be set to the standard value for the specified VLABAND.