Hello Nuts, I've been trying to get the analog EFC to work on the FE-5650A (a very close cousin of the FE-5680A). On these oscillators it is normally on pin-8 of the DB-9 (Option 12 and 30). As one of the serial lines is on this pin, I traced the jumper that is placed for the EFC option(s). However, changing the voltage on the pin does not seem to move the frequency (or at least not very much if it does). Anybody know the nominal EFC sensitivity of the 5680?
On tracing things further, I have found that this input goes into the (4 channel) A/D associated with the microproccesor. Changing the voltage gives a value in message 5A that also changes a corresponding amount. The EFC bytes are bytes 5 & 6 of the 5A message, first byte is low second byte is high. Appears to be 12-bit value (0FFF max). The question is - how do you enable the EFC? Maybe it is a bit that has to be set in one of the other messages. (But then how does the uP communicate the EFC value to the physics package?) It (more likely) may be that I have not found the true C-field control circuitry yet and the A/D is just a monitor. I recall someone implementing C-field control on a FE-5680A with the pot disabled, but cannot find it now. If someone can point me to that post I sure would appreciate it. Thanks in advance. Regards, Skip Withrow _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
