WiNRADiO G313 Series Frequency Calibration

 
The G313 receiver series features an excellent frequency accuracy and stability for a receiver of its class. It is however possible to improve this accuracy yet further, by individual calibration. This procedure is recommended for experienced users only.

The receiver calibration is accomplished by inserting a reference frequency parameter in the wrg313.ini file which resides in the MyDocuments\WINRADIO\G313 directory. The reference frequency parameter consists of two lines of the following format:

[ClockCalibration]

receiver_serial_number=reference_frequency

The receiver serial number can be obtained for example from the About box in the G313 application. The reference frequency is the actual frequency of the internal reference oscillator in Hz. This is normally 16.384 MHz, i.e. 16384000 Hz.

Each receiver is factory calibrated, so a fundamental correction to the nominal 16.384 MHz reference frequency already exists and is stored in the receiver's internal memory. This correction can be overridden by the new parameter in the wrg313.ini file. To determine the true offset from a perfect tuning, firstly use 16384000 (i.e. the nominal reference frequency in Hz) as the reference_frequency parameter. Say your receiver serial number is 02L27011:

[ClockCalibration]

02L27011=16384000

Save the wrg313.ini file with this value, then start the G313 application. The frequency error will be now much worse because the new parameter overrides the original factory calibration. Then tune the receiver to a known frequency standard. A high-accuracy signal generator can be used, or one of the WWV Time and Frequency Standard stations. Observe the peak with the spectrum scope and listen to the beat frequency in the CW mode with a minimum IF bandwidth. Then note down the frequency difference. (For example, -152 Hz at 10 MHz).

Then scale the frequency difference to 16.384 MHz. For example, if the frequency difference is -152 Hz at 10 MHz, it will be -249 Hz at the 16.384 MHz reference frequency.

To arrive at the corrected reference frequency, subtract the frequency difference from 16384000. In our example, 16384000-(-249)=16384249. The entire reference frequency parameter in the wrg313.ini file will be then as follows:

[ClockCalibration]

02L27011=16384249

Save the wrg313.ini file, then restart the G313 application and observe the difference.

To return to the original factory frequency calibration, simply delete the inserted two lines in the wrg313.ini file. You can also delete the entire file (which will however result in losing all current receiver settings and return to factory defaults for all of them).