开云体育

P.S. Rafael,?

the laboratory measurement of the BFO is a little more complex operation, you consider that CLK2 is fixed to receive the USB, so it must be 1.5 KHz lower than the center frequency of the quartz filter, considering again that it is impossible obtain perfect filters using a Ladder Filter with quartzes that have the same frequency and fixed capacitors, for the reason that the quartzes are slightly different from each to other and the capacitors have a factory tolerance, so the quartz filters will be different for each ?BITX sold,

A laboratory measurement method is to firsth obtain the attenuation curve of the filter using a network analyzer (using the two connectors for the additional CW filter) and find the two attenuation frequencies at -3dB; calculate the bandwidth and find the frequenzy of center of your filter; turn on the ?BITX and measure the CLK2 with a good frequency meter, calibrate the BFO frequency by fixing it as exactly as possible at a frequency equal to -1.5KHz with respect to the central frequency of the filter.

This should be the measurement method theoretically, but I have not used it, so I cannot guarantee the final effect of the sound in the loudspeaker, when you listen to a signal on the antenna.

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