Re: si5351 crosstalk #radiuno

Glenn
 

This is a fairly old thread but I recently did some testing on my own version Si5351 board with buffer chips on each output, which maybe of interest.   I only tested 2 outputs, 0 and 2, for cross-talk as I had a VFO/BFO Raduino style board set-up to test. Frequencies of ~10.7MHz and 17.8MHz so can only comment on this setup. There maybe differences at other frequencies etc.

My Si5351 PCB is based on the Adafruit style and Sch with same pin-out, and the comparison was between the Adafruit and my buffered version. The buffered outputs were fed thru a 47R resistor and 100nF cap to the SA in the buffered board.  And only via a 100nF cap in the Adafruit version. ie Raduino style. Each of the 74LVC1G04GW buffer chips was supplied with Vcc via it's own ferrite bead and 100nF cap to ground, filter. (not visible, as on bottom of the PCB)

Typical cross-talk of the Adafruit board was around -50dB from output 0 to 2 or output 2 to 0. Output levels into the SA at fundamental, approx. +4dBm.

My buffered version was better by around 8-10dB for cross-talk and output at fundamental increased to approx. +8-9dBm.

Glenn vk3pe




On Sat, Sep 22, 2018 at 07:43 PM, <lynatmts@...> wrote:
Hey Glenn, So what were the results of adding the buffer stages? 
Thanks

Lyn
--
"You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat."

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