User Manual

WiNRADiO G3XX VHF/UHF Receiver

Appendix H – Frequency Calibration

The G3XX 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.

The receiver calibration is accomplished by inserting a reference frequency

parameter in the wrG3XX.ini file which resides in the Windows 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 G3XX 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 wrG3XX.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 wrG3XX.ini file with this value, then start the G3XX 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).