Re: [time-nuts] Adding adjustment pot to 5680
Arthur, Nice pixs well lit with good detail. If only I had spent some time digging around that would have been much easier to solder to. May change it the next time I am in the unit. I do agree that the reg was running pretty hard but you attached it to at least a 115 degree heat sink. (At least in open air with real attached heat sinks) I am unsure as to what I will do. Clearly I have the 7805 on an external heatsink. Nice and cool. I ran the wires through the pot hole to a cheap bournes 10K 10 turn pot. Since my plan is not for portable operation but a rack mounted device I will use a very stable external regulator and at 3.3 or 5 V then a very good 10 turn .1% linear 10K with numeric readout counter. Flea market special. Sort of scratch my head. I like the larger external heatsinks I was using and the fact that they kept that center rail at 115 degrees should extend the life of the electronics even though the RB ref tube is the real life limit. I think the only comment I have read is that someone added a heatsink for thermal mass stability. Lots of pondering on my part. Last check Ref at 8.26 E-12. I am noticing 500 ps semi regular phase jumps. Fact is it could be my other even older lucent RB. Time to get serious with the HP 5065 and the z3801. Who is fibbing to me?? Regards Paul On Sun, Jan 15, 2012 at 1:31 PM, Arthur Dent golgarfrinc...@yahoo.comwrote: paul swed: Hardest part is attaching the 100K resistor to the ic. Boy thats small. 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 Where others had commented that the internal 7805 I added was running without a heatsink and would be close to max ratings, I started to worry and decided to mounted it on the heatsink that runs down the middle of the 5680A using an existing mounting hole that is used to mount a TO-220 device on the other side. The screw used to mount that device is too long so I replaced that screw with one that doesn't go quite 1/2 way through the heatsink and used an identical screw to mount the 7805 on the connector side of the heat sink. I had to elongate the mounting hole in the 7805 so it Wouldn’t interfere with the cover or the dimple in the cover where the screw that holds the cover on screws into the heatsink. The photo linked below shows the better way to mount the 7805 so you can use a single 15V supply for the 5680A. http://farm8.staticflickr.com/7157/6702428471_5a7b96068d_b.jpg -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] Adding adjustment pot to 5680
I have read about the EFC mod for the 5680A by Bill Riches and adapted for external by Arthur Dent. Nice work. Maybe I missed a detail in all the recent messages -- Question: Has anyone measured or calculated the tuning sensitivity of the pin-5 EFC voltage? (Hz/V number) ___ 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] Adding adjustment pot to 5680
I have not but it is sensitive and suspect I actually may have the answer in my notes. I was pretty much attempting to range it in to match my operating RB and it did that quite well. But as I say I suspect I could back out the sensitivity, maybe. Regards Paul On Sun, Jan 15, 2012 at 8:58 PM, Rex r...@sonic.net wrote: I have read about the EFC mod for the 5680A by Bill Riches and adapted for external by Arthur Dent. Nice work. Maybe I missed a detail in all the recent messages -- Question: Has anyone measured or calculated the tuning sensitivity of the pin-5 EFC voltage? (Hz/V number) __**_ 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.
Re: [time-nuts] Adding adjustment pot to 5680
Just did the pot addition to my FE5086 and it works very well The systems still warming up and its actually apart with external heat sinks for cooling so I can get to places. Hitting 8.6 ^ -12 after first eyeball adjustment on the scope drifting 5 ns in 9:36 minutes. Time to flip from scope mode to 5371 counter ns drift timing so I don't have to stick around. Hardest part is attaching the 100K resistor to the ic. Boy thats small. I plan to bring the leads out through the fake pot hole to a nice 10 turn pot for control. I also have counters for the pots. I also do not have the 1 pps out. Not that it matters to me actually. I did probe around looking just for the heck of it and no luck. Further updates Created a excel drift calculator for use with readouts from 5371 counter. Final setting so far 4.76E-12. Clearly on my unit the pot I am using could be better and I need to adjust the range for about 0-3vdc. Had been using the 8 V regulated supply. Thanks David and Arthur for the thread and mod. Regards Paul WB8TSL On Thu, Jan 12, 2012 at 7:05 AM, Arthur Dent golgarfrinc...@yahoo.comwrote: Look forward doing other tests like voltage sensitivity and bringing out the C field for external adjustment. EWKehren at aol.com ++ But how do you adjust the RgO output frequency? That's why I asked if A DDS would be used. Nevermind. I just found it. The RgO cell can be frequency adjusted magnetically. David + I decribed the very simple way I added an external EFC feature to my 5680A unit using a pin in the DB-9 connector that was freed-up after I installed an internal +5V regulator inside the 5680A so I only needed a single +15V supply to power the 5680A. Check my post of Mon Jan 9 21:06:12 UTC 2012 to see what I did using Bill Riches information where he described connected an internal pot. The new EFC pin 'floats' at 2.5V and 0-5V works fine to adjust the frequency slightly. -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] Adding adjustment pot to 5680
Arthur, 800mW will give you a 52C rise in junction temperature over ambient when not mounted to anything. The 5680s get pretty hot, probably 50C internally (has anyone measured it?). That will put you at 102C. Make sure the flavor of 7805 you selected is rated for that (most are rated for 125C). Not all are, and not all have thermal shutdown. As for reliability, without any derating, this won't give you much margin. Don't forget the cap on the output. Bob - Original Message - From: Arthur Dent golgarfrinc...@yahoo.com To: time-nuts@febo.com Sent: Tuesday, January 10, 2012 10:50 PM Subject: [time-nuts] Adding adjustment pot to 5680 You are driving the 7805 near its limit. As a rule of thumb, a TO-220 case can disipate about 1W of power, if it's free-standing. You have max 100mA with a voltage difference of 10V, resulting in 1W max. Ie the 7805 will be running at a considerable high temperature. As you have there a good heat sink already (the case), i'd mount the 7805 against the case and use wires to connect it. Attila Kinali ++ I had considered mounting the 7805 on the vertical heatsink you see to the left of the 7805 in my photo, using a short screws in either side of the the tapped hole that is already there and use leads to connect the 7805 to the connector pins, but felt it wasn't necessary. Directly connecting the regulator to the DB-9 pins was much simpler. FYI, the load is not 100Ma as you assumed, that is the max rating of the 78L05 that I didn't use. The actual load the 7805 sees in the 5680A is about 80Ma so even at the higher temperatures inside the case I don't see a problem. You are correct that it might be a better practice to mount the regulator on the heat sink, especially if this were a production item, but in this case I felt it was overkill. http://farm8.staticflickr.com/7013/6668466093_90782cf7e9_b.jpg -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] Adding adjustment pot to 5680
Just one data point: Last night, I taped a thermocouple to the top case of a unit and read 50C. Joe Gray W5JG On Wed, Jan 11, 2012 at 7:12 AM, Robert Benward rbenw...@verizon.net wrote: Arthur, 800mW will give you a 52C rise in junction temperature over ambient when not mounted to anything. The 5680s get pretty hot, probably 50C internally (has anyone measured it?). That will put you at 102C. Make sure the flavor of 7805 you selected is rated for that (most are rated for 125C). Not all are, and not all have thermal shutdown. As for reliability, without any derating, this won't give you much margin. Don't forget the cap on the output. Bob - Original Message - From: Arthur Dent golgarfrinc...@yahoo.com To: time-nuts@febo.com Sent: Tuesday, January 10, 2012 10:50 PM Subject: [time-nuts] Adding adjustment pot to 5680 You are driving the 7805 near its limit. As a rule of thumb, a TO-220 case can disipate about 1W of power, if it's free-standing. You have max 100mA with a voltage difference of 10V, resulting in 1W max. Ie the 7805 will be running at a considerable high temperature. As you have there a good heat sink already (the case), i'd mount the 7805 against the case and use wires to connect it. Attila Kinali ++ I had considered mounting the 7805 on the vertical heatsink you see to the left of the 7805 in my photo, using a short screws in either side of the the tapped hole that is already there and use leads to connect the 7805 to the connector pins, but felt it wasn't necessary. Directly connecting the regulator to the DB-9 pins was much simpler. FYI, the load is not 100Ma as you assumed, that is the max rating of the 78L05 that I didn't use. The actual load the 7805 sees in the 5680A is about 80Ma so even at the higher temperatures inside the case I don't see a problem. You are correct that it might be a better practice to mount the regulator on the heat sink, especially if this were a production item, but in this case I felt it was overkill. http://farm8.staticflickr.com/7013/6668466093_90782cf7e9_b.jpg -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] Adding adjustment pot to 5680
On Mon, 9 Jan 2012 13:06:12 -0800 (PST) Arthur Dent golgarfrinc...@yahoo.com wrote: On the inside of the case where the DB-9 pins go through the circuit board, I mounted a 7805 fixed regulator. I cut a piece out of pin 4 and connected the output of the 7805 to the board side of the pin with a tantalum cap for bypass. I decided not to use a 78L05 because at the elevated temperature I felt it would be cutting it too close to the 100MA current limit. [...] http://farm8.staticflickr.com/7013/6668466093_90782cf7e9_b.jpg You are driving the 7805 near its limit. As a rule of thumb, a TO-220 case can disipate about 1W of power, if it's free-standing. You have max 100mA with a voltage difference of 10V, resulting in 1W max. Ie the 7805 will be running at a considerable high temperature. As you have there a good heat sink already (the case), i'd mount the 7805 against the case and use wires to connect it. Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ 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] Adding adjustment pot to 5680
As has been mentioned by Pete and others the majority of the inexpensive 5680 units can only be adjusted for frequency by inputting rs232 info. I am experimenting with a simple mod to add a fx adjust pot to my unit. I removed the unconnected dummy pot and glued a miniature 100 k pot upside down in the area where the original pot was. Its connections are on the top of the pot. Cold side of pot went to ground, hot side of pot went to output of 8 volt regulator through 1 k resistor. Wiper goes through a 100k resistor to pin 5 of the chip next to the ribbon connector. (To find pin 5 have unit positioned with db9 connector at upper left, ic area will be in lower right. Pins 1 through 7 are between the chip and the ribbon connector - pin 1 is at the extreme right next to the marking on the chip - count left to pin 5! I got my 8 volts from the 8 volt regulator that is the first xsistor of the two that are mounted on the vertical heatsink. The third pin is 8 volts output. Pins are counting down from db 9 connector area. Three hours after doing this mod my unit is about 5x10-12 high. The voltage on pin 5 is 3.52 volts. I have my thunderbolt 10 mhz output triggering my 465, the 10mhz from 5680 going to vertical input, time base set to .1 usec and the x10 mult on giving me .01 usec per div. With a stopwatch I time the time it takes for the trace to move one division. I divide the seconds measured and divide that into 1 to the minus 8th and get the offset. in this case 1 to the minus 8th divided by 195 seconds gives me about 5 parts in 10 to the 11th. The trace is moving to the left which means the osc is high. I would appreciate any of the 5680 gurus to go over my math and what I have done and let me know if I am all wet!! Thanks to all of the threads on this unit that have been on this list. 73, Bill Riches, Wa2dvu Cape May, NJ -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of saidj...@aol.com Sent: Thursday, December 22, 2011 1:39 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Using Thunderbolt to Discipline FE 5680A? Hi there, maybe this has already been discussed here.. There is a small hole on the side of the unit with a small trim-pot visible through the hole. Does anyone know if this is an analog frequency adjustment? If it is, maybe that trimpot connection can be used as disciplining input.. Thanks, Said In a message dated 12/22/2011 09:20:57 Pacific Standard Time, albertson.ch...@gmail.com writes: I think the FE-5680A has to course of adjustment to be used in the fast control loop inside the t-bolt Chris Albertson Redondo Beach, California ___ 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.
