Re: [time-nuts] FE-5680A decoded - another piece of the puzzle
I did the mod and getting to pin 5 was tough. However Doug mentioned that there is another point to the left of the chip thats easier to get to. Don't recall the point. But if the lead ever comes off of 5 I can assure you I will find it. :-) My unit zeroed about at about 2 V. So I am using a 10 T 10 K bourns pot with 1000 counter. Then a 3.3V reg directly attached with bypass caps driven by 8 V from the regulated supply in the RB. Very clean, 3 leads into the RB. Using shielded cable through the pot hole that actually does nothing. Regards Paul. On Tue, Jan 31, 2012 at 2:19 AM, John Beale be...@bealecorner.com wrote: On 1/29/2012 8:22 PM, Skip Withrow wrote: 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. I added that post to the FE-5680A FAQ, and added my own photo also to help locate the part. Note, I have not actually tried this modification myself. http://www.ko4bb.com/dokuwiki/**doku.php?id=precision_timing:** fe5680a_faq#adding_an_analog_**adjustment_pothttp://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:fe5680a_faq#adding_an_analog_adjustment_pot Original post was by Bill Riches, Thu, 22 Dec 2011 14:01:18 -0800 __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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.
[time-nuts] FE-5680A decoded - another piece of the puzzle
Tue Jan 31 14:15:57 UTC 2012 I did the mod and getting to pin 5 was tough. However Doug mentioned that there is another point to the left of the chip thats easier to get to. Don't recall the point. But if the lead ever comes off of 5 I can assure you I will find it. :-) My unit zeroed about at about 2 V. So I am using a 10 T 10 K bourns pot with 1000 counter. Then a 3.3V reg directly attached with bypass caps driven by 8 V from the regulated supply in the RB. Very clean, 3 leads into the RB. Using shielded cable through the pot hole that actually does nothing. Regards Paul. +++ In case you missed it I had posted the information and a photo of the spot to more easily solder the 100K resistor to give you EFC. I'd go with Bill Riches' suggestion to have the 100K in series with the EFC line. I connected the lead from the 100K to a pin on the DB-9 connector that was freed up when I put the 5V regulator inside so I could run off a single supply. Here's what I did. +++ Sun Jan 15 18:31:39 UTC 2012 I didn't solder the resistor directly to pin 5 of the IC. I found that pin 5 was connected to a nearby SMD capacitor that was a little easier to solder to. Attached is a photo of the correct location if you want to try bringing the EFC out for analog control. http://farm8.staticflickr.com/7170/6702435071_f684967719_b.jpg Mon Jan 16 04:16:53 UTC 2012 I'm not sure what HEX number was loaded into my 5680A but the frequency was just slightly off from 10Mhz. Pin 5 on my 27M4BI quad opamp 'floats at 2.599V and to get 10Mhz out it needs to be at 2.445V. I guess I could correct the frequency digitally so it is at 10Mhz with pin 5 floating but I don't feel it is necessary. The output frequency I measured with zero volts on pin 5 (through the 100K resistor) was 10,000,000.028Hz and with 5V it was pretty close to 9,999,999.969Hz or .031Hz low so it's close to centered. I tried using a 2K 10-turn pot with about 10K on each side to restrict the tuning range further and give me finer control. After the 5680A had been on for a while I tried setting the frequency as close to 10Mhz as I could and watch the drift on my scope using the 10Mhz Rb from my Datum 9390 GPS receiver as the reference. The 5680A seemed to stay within 5ns for 45 minutes so the resolution on the pot is quite good and the 5680A seems quite stable. The pin 5 IC connection is the non-inverting input to the opamp and I'm not sure if connecting the 100K resistor to the inverting input, pin 6, would give you a positive change in frequency for a positive change in voltage or not. If you're using a pot for adjustment or if the controller can be programmed to change the polarity, it doesn't really make any difference and pin 5 works just great. I'm glad Bill Riches found this input and posted the information. -Arthur ___ 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.
Re: [time-nuts] FE-5680A decoded - another piece of the puzzle
Thanks Arthur. Thats the thread I was referring to. On Tue, Jan 31, 2012 at 10:25 AM, Arthur Dent golgarfrinc...@yahoo.comwrote: Tue Jan 31 14:15:57 UTC 2012 I did the mod and getting to pin 5 was tough. However Doug mentioned that there is another point to the left of the chip thats easier to get to. Don't recall the point. But if the lead ever comes off of 5 I can assure you I will find it. :-) My unit zeroed about at about 2 V. So I am using a 10 T 10 K bourns pot with 1000 counter. Then a 3.3V reg directly attached with bypass caps driven by 8 V from the regulated supply in the RB. Very clean, 3 leads into the RB. Using shielded cable through the pot hole that actually does nothing. Regards Paul. +++ In case you missed it I had posted the information and a photo of the spot to more easily solder the 100K resistor to give you EFC. I'd go with Bill Riches' suggestion to have the 100K in series with the EFC line. I connected the lead from the 100K to a pin on the DB-9 connector that was freed up when I put the 5V regulator inside so I could run off a single supply. Here's what I did. +++ Sun Jan 15 18:31:39 UTC 2012 I didn't solder the resistor directly to pin 5 of the IC. I found that pin 5 was connected to a nearby SMD capacitor that was a little easier to solder to. Attached is a photo of the correct location if you want to try bringing the EFC out for analog control. http://farm8.staticflickr.com/7170/6702435071_f684967719_b.jpg Mon Jan 16 04:16:53 UTC 2012 I'm not sure what HEX number was loaded into my 5680A but the frequency was just slightly off from 10Mhz. Pin 5 on my 27M4BI quad opamp 'floats at 2.599V and to get 10Mhz out it needs to be at 2.445V. I guess I could correct the frequency digitally so it is at 10Mhz with pin 5 floating but I don't feel it is necessary. The output frequency I measured with zero volts on pin 5 (through the 100K resistor) was 10,000,000.028Hz and with 5V it was pretty close to 9,999,999.969Hz or .031Hz low so it's close to centered. I tried using a 2K 10-turn pot with about 10K on each side to restrict the tuning range further and give me finer control. After the 5680A had been on for a while I tried setting the frequency as close to 10Mhz as I could and watch the drift on my scope using the 10Mhz Rb from my Datum 9390 GPS receiver as the reference. The 5680A seemed to stay within 5ns for 45 minutes so the resolution on the pot is quite good and the 5680A seems quite stable. The pin 5 IC connection is the non-inverting input to the opamp and I'm not sure if connecting the 100K resistor to the inverting input, pin 6, would give you a positive change in frequency for a positive change in voltage or not. If you're using a pot for adjustment or if the controller can be programmed to change the polarity, it doesn't really make any difference and pin 5 works just great. I'm glad Bill Riches found this input and posted the information. -Arthur ___ 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. ___ 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.
Re: [time-nuts] FE-5680A decoded - another piece of the puzzle
Skip previously in these threads there was a direct real analog control that was discovered. I have used it and it works well. The thread describes how to get to it. Regards Paul On Sun, Jan 29, 2012 at 11:22 PM, Skip Withrow skip.with...@gmail.comwrote: 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 -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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.
Re: [time-nuts] FE-5680A decoded - another piece of the puzzle
On 1/29/2012 8:22 PM, Skip Withrow wrote: 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. I added that post to the FE-5680A FAQ, and added my own photo also to help locate the part. Note, I have not actually tried this modification myself. http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:fe5680a_faq#adding_an_analog_adjustment_pot Original post was by Bill Riches, Thu, 22 Dec 2011 14:01:18 -0800 ___ 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.
[time-nuts] FE-5680A decoded - another piece of the puzzle
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 -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
