Randy wrote:
if one is distributing 10 Mhz, does it really matter what the circuit does at 300 and 900 Mhz??
That depends on what it is feeding and what noise and other signals are getting to the DA input. Some synthesized 10 MHz sources produce energy well above 10 MHz.
I consider nonmonotonic behavior to be a design flaw in general (except where it is specifically desired or you are up against the bleeding edge of technology and it can't be avoided), so I eliminate it at every opportunity as long as the fix doesn't cause worse problems. In this case, the nonmonotonicity is cured by replacing an 8¢ transistor with a 16¢ transistor, and some other small benefits are realized at the same time, so I say it's 8¢ well spent. Nearly a whole dollar extra for a 12-output DA. The noise bump is cured by restricting the 3 dB bandwidth to ~80 MHz, which does not affect the 10 MHz but may help the receiving instrument if it is sensitive to VHF noise (although the magnitude of the bump is not large).
I consider these good prophylactic design measures. Practicing them keeps you out of trouble that you might not even know was threatening, whether or not it makes a practical difference WRT a particular design.
Best regards, Charles _______________________________________________ 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.
