GPSDO

Hi Neil, I haven't used the internal GPSDO, but I do have the Leo Bodnar unit connected to my 6400. It works great, but you have to be careful how you power it. I originally powered it from a wall-wart switching power supply which introduced an enormous amount of noise into the receiver. I now power it from the main station supply, an Astrom RS-70M, and there is no discernable noise.

The Leo Bodnar unit works very well, but I don't know how much better the Flex internal unit disciplines the oscillator or if you get other advantages from the Flex GPSDO.

The 6000 rigs can be put right on frequency with the calibration routine, but with the GPSDO, occasional frequency calibrations become unnecessary.

I should note that I originally got the Leo Bodnar GPSDO for my Rigol spectrum analyzer. Since it is now part of my shack, I use it with my 6400. I probably would not have bought it just to calibrate the 6400, as the Flex cal routine works so well. It doesn't hurt that I am only 50 miles from WWV in Ft. Collins...