SPI Communication Failure
I tested your setup with my Mega, and it worked OK after a couple of changes. 


You should really set SS high first, before even making it an output. That way the pull-up is activated, and then the moment you make it output it stays high, rather than going to low, then back to high, which looks to the target like a SS pulse.
You don't need to do pinMode() calls on the other SPI pins.
Call SPI.begin() last - after setting SS high.




void setup(){

  Serial.begin(9600);
  SPI.setBitOrder(MSBFIRST);
  SPI.setDataMode(SPI_MODE1);

/// -----CHANGES--------
  digitalWrite(SLAVESELECT_1,HIGH); //disable device
  pinMode(SLAVESELECT_1,OUTPUT);
/// -------------

  SPI.begin();

  digitalWrite(SLAVESELECT_1,LOW); //Enable device
  SPI.transfer(0x0E);  //Send  Fstart Write Enable to Control Reg 
  SPI.transfer(0x13);
  digitalWrite(SLAVESELECT_1,HIGH);

  digitalWrite(SLAVESELECT_1,LOW);
  SPI.transfer(0xC7);  //Send Frequency to Fstart one byte at a time
  SPI.transfer(0x4C);
  digitalWrite(SLAVESELECT_1,HIGH);

  ...




As you can see from the logic analyzer, the output is OK:



The numbers look right too:



Time [s], Analyzer Name, Decoded Protocol Result
-0.000001752000000,SPI,MOSI: 0x0E;  MISO: 0x00
0.000001248000000,SPI,MOSI: 0x13;  MISO: 0x00
0.000014496000000,SPI,MOSI: 0xC7;  MISO: 0x00
0.000017496000000,SPI,MOSI: 0x4C;  MISO: 0x00
0.000030744000000,SPI,MOSI: 0xD0;  MISO: 0x00
0.000033744000000,SPI,MOSI: 0x93;  MISO: 0x00
0.000046992000000,SPI,MOSI: 0x06;  MISO: 0x00
0.000049992000000,SPI,MOSI: 0x13;  MISO: 0x00
0.000063240000000,SPI,MOSI: 0x20;  MISO: 0x00
0.000066240000000,SPI,MOSI: 0x00;  MISO: 0x00
0.000079488000000,SPI,MOSI: 0x30;  MISO: 0x00
0.000082486000000,SPI,MOSI: 0x00;  MISO: 0x00
0.000095736000000,SPI,MOSI: 0x10;  MISO: 0x00
0.000098734000000,SPI,MOSI: 0x02;  MISO: 0x00
0.000111984000000,SPI,MOSI: 0x40;  MISO: 0x00
0.000114982000000,SPI,MOSI: 0xEB;  MISO: 0x00
0.000128232000000,SPI,MOSI: 0x80;  MISO: 0x00
0.000131230000000,SPI,MOSI: 0x0A;  MISO: 0x00


Try the changes to the code, and see what happens.