On 2017-01-02 01:31, wb6bnq wrote: Hello Bill
Thanks for your response and the pdf manual. There's lots of good information in there. You are certainly right in that there's a few things that I have not understood. Unfortunately this has not changed after having read your response:
That "R" number is actually the Rb frequency divided by 136 plus the upward fine tuning of the C-field pot. See PDF page 16 & 17 of the attached PDF operational manual for the FEI-5650.
In the comprehensive post[*] that I quote in my original request, Mark states that "THE R= REFERENCE FREQUENCY IS NOT THE FREQUENCY THAT THE PHYSICS PACKAGE IS SHIPPED TUNED TO!!! It is the frequency produced by the physics package at the minimum setting of the C-field potentiometer." This seems to be contradictory to what you wrote. Either the R value is determined at the C-field pot minimum frequency position as Mark stated, in which case it does not contain the upward C-field tweaking. Or it is determined after the final tweaking as you say. Either way I don't understand how to incorporate the R reference frequency into my calculations, which is what Mark seems to be suggesting.
The "F" number is truly a 32 bit number, not just the first 8 digits but all 16 of them.
The F number has 16 hex digits. Since each of those digits represents a nibble (i.e. half a byte, 4 bits), I end up with 16*4 = 64 bits. Not just 32. The first 8 digits of the F number however represent a 32 bit number, which is also the size of the the phase accumulator in the AD9830 which makes sense in my opinion. I think I absolutely failed to grasp what you're trying to tell me here :-( Re-reading the paragraph in [*] that starts with "You can set the divisor" did clear up something for me though -- looks like there's nothing weird with the F-number stored in my unit; the last byte is indeed 0x00. I still don't quite understand why this parameter is potentially stored at a higher precision than what the DDS can deliver.
It would probably have been better to purchase one of the Rb's that already output 10 MHz instead of hacking the option 58. BUT that is just my opinion.
You are probably right on that, yet getting any of those surplus standards off of ebay seems to be a bit of a hit-or-miss thing anyway. At least I get the learning experience, that's gotta count for something :-). Thanks again for your response and best regards Matt _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
