Hi All There was a special run of 10MHz OCXO variants of the kit, at some point a couple of years ago. 100 were produced without Si5351A; and instead of the 27MHz crystal they had 10MHz, and 150pF cap

#synth #ocxo #si5351a

well, that explains what I have in two ocxo kits that I purchased in July 2018. they both have these extra parts. the search here quickly supplied the answer! Thanks, Hans, for all that you do. 73, Ge

#synth #ocxo #si5351a

I just finished a second OCXO kit and I freaked out when I found several leftover 151 caps (.15pf). When I looked at the parts list it didn't include these caps so they will go in my parts bin. Also t

#synth #ocxo #si5351a

Hi Alan, Did you ever figure out what the decode sensitivity to errors in the tone offset frequency is? I'm trying to scheme an inexpensive transmitter for WSPR on the 70 cm and maybe even the 33 cm b

#synth

Hi all... The Si5351a datasheet says its reference frequency has to be 25 or 27 MHz. Others here have commented on using 26 and 10 MHz. What are the disadvantages of using other frequencies, other tha

#synth

I've given the board a close review and there's not much I can tell with the board out of circuit. My oscilloscope (Tek T922) does show high frequency signal on the crystal pins so I'll assume it's os

#u3s #synth

In the ProgRoc the synthesizer is supplied 3.3vdc from the internal regulator as well as the 5vdc pull ups. So whether the synthesizer module has it's own 5vdc regulator is of no concern. In the vfo s

#synth

Hans, This is a very low-priority request, but it came to mind recently as I was playing with different TCXOs for the Si5351A Synthesizer Board. What is the possibility - on you next run of boards - o

#progrock #synth

Order of operation is important here, at least if you are using integer math. Try this: P2 = (128 * b) - ((c * 128 * b) / c ) I am ignoring "floor" because that comes for free with integer division. N

#si5351a #synth #programming

Some aspects of SiLabs AN619 appnote bother me regarding transforming "a+b/c" into P1, P2, P3 integer register values. As Hans has done, I'm calculating P1, P2, P3 for a fractional-divider on the PLL

#si5351a #synth #programming

This certainly is a curious equation. Neglecting the floor operator the answer is always zero. Perhaps this is a source of confusion. c or P3 is an integer. You need to pick a number. You shouldn't us

#si5351a #synth #programming

That should have been P2 = (128 * b) - (c * ((128 * b) / c) ) -- mathematically it's the same, but I guess when truncation occurs makes a difference

#si5351a #synth #programming

Certainly SiLabs intended this, which results in an unsigned integer whose range lies between 0-127, hence their floor(128 * b/c) I wonder if you might help the compiler speed up the following calcula

#si5351a #synth #programming

Yes, exactly, and this is why we try to avoid floating point in speed-critical applications when using processors without FPUs.

#si5351a #synth #programming

I’ve been watching this discussion and I have to ask — is anybody watching the hierarchy of mathematical operations? This includes SiLabs. Unless otherwise defined by parentheses, multiplication and d

#si5351a #synth #programming

Yes, single-precision floats are dangerous, especially when calculating that nasty P2 that's giving me grief. recall that P2 requires multiplying "b" by 128, then subtracting (c * floor (128* b/c)). T

#si5351a #synth #programming

Glen, Aren’t you missing something? B and C are normally cast to floats before calculating B/C. Since B is less than or equal C, the ratio is less than or equal to 1. This is then multiplied by 128, r

#si5351a #synth #programming

There is no need to cast these as floats. (128 x b) / c, using all integers and integer math gives you identical results. Yes, you can use floats if you like, and then, assuming enough floating-point

#si5351a #synth #programming

I've not seen the MDAS precedence problem in the SiLabs specs. I will sometimes over-parenthesize my own equations to avoid integer overflow or to use truncation as required, or just to group things t

#si5351a #synth #programming

I keep mentioning Bresenham dividers. Here's a simple pseudocode example: Ratio = b / c counter = 0 loop forever { if (counter < 0) counter = counter + b else counter = counter + (c-b) } And that's it

#si5351a #synth #programming