4.4 Configuration
The configuration screen allows entry of various QDX configuration parameters. The default
values are suitable for the vast majority of operating use. The following paragraphs describe each
configuration setting in turn. Use the up/down arrows to select the item you wish to edit. The
cursor is positioned at the last character of the value. Numeric values have a defined field length.
You can press the backspace key to delete the current entry in whole or in part, and type in the
new value. For non-numeric configuration parameters, you can use the left and right arrow keys to
choose between the available values.
TCXO Frequency
Default is 25000000 (25 MHz). This is the oscillation frequency of the QDX TCXO (Temperature
Controlled Crystal Oscillator) and is used for calculating Si5351A parameters for setting the
desired QDX operating frequency.
The supplied TCXO is a high precision component and will normally be found to be within (a one
standard deviation error of) +/- 5 Hz of the specified 25 MHz value. It is not normally particularly
necessary from an operating perspective, to have a more precise operating frequency than this.
Remember that the error is also scaled to the operating frequency. So a 5 Hz error at 25 MHz will
translate to a 2.8 Hz error at 14 MHz.
However the perfectionists among you may wish to calibrate your operating frequency precisely –
and this menu entry is for you!
To configure the correct TCXO reference frequency, you will need to measure your operating
frequency, deduce the error amount, and apply a correction to the TCXO frequency configuration
parameter.
QDX operating manual; firmware 1_04
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