1 Hz setting?

[w5sxd]

Perhaps my XG3 is defective.

When running from the PC control program, I need to enter about a 10 Hz change before the output frequency changes.  Is this normal or am I doing something wrong?  The device is adverstised to have 1 Hz steps.

The calibration factor also needs to be changed by more the 1 step to get the frequency to change.  

Also, the levels seem to be accurate at 160m but start to fall off in accuracy as I go up to the higher bands.  Are they supposed to be into a 50 Ohm load?  Are they the level for the fundamental or total power output?

Thanks,

Richard W5SXD

[Paul Saffren N6HZ]

Hi Richard,

What frequency are you generating where you notice this?

The XG3 has 1 Hz resolution over it's fundamental range of 1.5 to 200 MHz.    The calibration should be done at 10 MHz as this is the frequency of the internal crystal.  The values entered for the calibration values do not necessarily produce a linear increase or decrease to the output frequency.  This is due to how the calibration factor is used in the computatation of the output frequency.  You can however get pretty close and then fine tune as needed.

The attenuator stages within the XG3 will have some inherent roll-off at higher frequencies.   The levels are calibrated into a 50 ohm load.  Within the 1.5 - 200 MHz range, the levels should be +/- 1 db (not including 0 dBm which is rated at +/- 3 db).

73,

Paul

[Bill W4ZV]

Paul Saffren N6HZ wrote

The XG3 has 1 Hz resolution over it's fundamental range of 1.5 to 200 MHz.    The calibration should be done at 10 MHz as this is the frequency of the internal crystal.  The values entered for the calibration values do not necessarily produce a linear increase or decrease to the output frequency.  This is due to how the calibration factor is used in the computatation of the output frequency.  You can however get pretty close and then fine tune as needed.

I believe we're confusing the XG3's resolution (1 Hz) with calibration settability (a few Hz at 10 MHz).  The XG3 indeed has 1 Hz resolution but mine is not settable to 1 Hz.  Using WWV at 10 MHz, my factory supplied cal constant is -529.  With that constant my XG3 is only off by 1-2 Hz but I cannot get it any closer.  There's no change in the XG3 from about -534 to -524 cal settings, but then it jumps to about 4-5 Hz off.  

This isn't a big deal to me but you might want to add some explanation to the manual.  I don't expect a product in this class to rival an HP 8640!  :-)

73,  Bill