Similarly, if the Band Switch setting is in the Default mode, then the display will show:
Not In User Mode
If the Band Switch setting is in the Locked mode, then the display will show:
User Mem Locked!
A successful storage operation will display the message:
Saved to: nnn
where
nnn
will be replaced by a band from 160 – 10.
In this manner it is possible for the user to preset favourite frequencies for each amateur band,
and to retrieve them on demand. By selecting the Locked mode, these frequencies can be
protected.
System Calibration & Setup
It is assumed that the initial adjustments and settings have been made.
To enter the System Calibration & Setup menu, turn the transceiver off, and then press and
hold the power button until the message:
JUMA-TRX2 v1.07m
Service Mode
is displayed. To cycle through the various setting screens, briefly press the DISPLAY button.
Set Reference Oscillator Frequency
Default: 180000000Hz
The DDS is fed with the output of the precision crystal oscillator, and in the current models is
a packaged component with an output frequency of nominally 30MHz. The worst-case
tolerance for this oscillator is ±100ppm, which translates to a possible error of ±3kHz at
30MHz, and since this oscillator’s frequency is internally multiplied by 6 in the DDS chip,
this can be as high as ±18kHz at 180MHz.
To correct this, the reference frequency can be set to the frequency resulting from a x6
multiplication of the crystal oscillator’s actual output frequency.
In order to determine the necessary calibration factor, an accurate frequency counter is
essential. If you have access to a counter which has an accuracy of better than at least ±1ppm,
then measure the output frequency of the oscillator using the 10 second timebase, making at
least 10 measurements. Average the results to 2 decimal places and multiply by 6. Round this
figure to 1Hz, and this is the frequency to which the reference oscillator should be adjusted.
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