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PLJ-8LED Frequency Counter User Operating Manual 10

FAQ

1. Will the frequency counter generate any interference when installed in a transceiver?

Zero interference is impossible because the microcontroller, crystal and LED driver all produce some

radiated RF noise, but the level is quite low. Some measures have been taken in the design of the

module to keep certain components away from the transceiver. If interference is encountered, try

changing the position of the module or install a shield.

2. What is the reason for frequency display instability?

First, make sure the quality (strength, stability, etc.) of the input signal meets the minimum

requirements of the module (see Technical Data section). The input cable connecting to the signal

should use shielded wire, and the power supply should also be suitable. Check it has no noise or

ripple.

3. Why is the display showing values when there is no input signal?

Check if the ripple on the power supply being used with the module is too large, then check whether

if something near the module is generating a strong signal. The module can reject invalid signals by

using signal filtering. On the low range (CH L), filtering removes invalid signals below 50kHz, and

below 20MHz on the high range (CH H). This will then result in the normal display showing zero with

no input signal.

4. Since the display is limited to eight digits, how can it display the “hundreds of megahertz” and

gigahertz digits with 0.1s and 1s gate times?

By reducing the gate time or using the LSD function, it is possible to obtain a suitable frequency

display.

For example, when measuring 450.000 000 MHz signal:

When the LSD is OFF (See Menu setup section above)

 1S gate display: 50.000.000

 0.1S gate display: 450.000.00

When the LSD is ON

 1S gate display: 450.000.00

 0.1S gate display: 450.000.0

When measuring a 2400.000 000 MHz signal:

When the LSD is OFF

 1S gate display: 00.000.000

 0.1S gate display: 400.000.00

When the LSD is ON

 1S gate display: 400.000.00

 0.1S gate display: 2400.000.0

Sanjian Studio PLJ-8LED-C User Manual

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