Y404 is a 1,200.000 Kc (1.2 MHz) crystal for my R-391. I measured the output of the 1st crystal oscillator using a GPS disciplined frequency counter and it is a bit low. Collins part number is 290 0018 00. Thank you in advance. Mack W4AX -- 73, Mack W4AX https://www.qrz.com/db/W4AX