[Repeater-Builder] Maxar 80 lowband transmit crystal frequency calculation needed

[KP3FT]

Hi all,
I'm buying a Maxar 80 low-band radio, 42-50 Mhz split, D51TSA2300AK,
but I need to figure out what frequency to get the new crsytal cut
for. I am wanting the radio to transmit on 50.063 mhz.  The recieve
crystal is not necessary since it will be used as a 6-meter beacon
transmitter only.  What is the formula for calculating the frequency?
 Thanks!
Jeff KP3FT