Re: [time-nuts] Things to look for when buying a few FE-5680A's?
Hi If you *need* to lock one of the new FE-5680's 10 or 20 Hz high, you probably can adjust the cap on the VCXO center it's range up there. I doubt it will reliably adjust out to 300 Hz though. For that parts changes or board surgery probably are required. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of John Beale Sent: Thursday, January 26, 2012 1:29 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Things to look for when buying a few FE-5680A's? On 1/22/2012 12:49 PM, Chris Albertson wrote: The current batch of (about) $40 units are different from what was available a year ago. These new ones require 5V DC input in addition to 15V and can only be programmed via RS232 a few Hz away from 10MHz. So they are only good for use as a 10MHz reference Option 2 in the book refers to a different type FE5380 that can be programed over a very wide range of several MHz. I think these are still being sold on eBay but not for $40. They seem to be over $100. In the manual I have (see below) Option 2 is in fact what I got for about $40. This is RS-232 control with very fine resolution, but limited range (10 MHz with a span of +/- 383 Hz according to the manual, although one I tested won't actually stay locked much above 1% of that span). The very wide range version is a different option, perhaps Option 08 (Customer specified frequency, 1 Hz - 20 MHz). --- RUBIDIUM FREQUENCY STANDARD MODEL FE-5680A SERIES OPTION 2 http://www.wa6vhs.com/Test%20equipment/FREQUENCY%20STANDARDS/FE-5680A/5680%2 0TECH%20MANUAL.pdf Table 1: Option Summary [...] Option 02 Remote Digital Control - RS-232; Resolution: 1.8 x 10-7Hz Frequency Adjustment Section 2-3 The FE-5680A output frequency can be adjusted digitally over the RS-232 interface (pins 8 and 9). This feature is available as option 2, and is not available on units purchased without this option. The frequency can be adjusted with a resolution of 1.7854E-7 Hz. For an FE-5680A device with an output frequency of 10 MHz, this corresponds to a relative frequency setting resolution of 1.7854E-14. ___ 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] Things to look for when buying a few FE-5680A's?
At 01:21 AM 1/26/2012, Rex wrote: physical differences (like an sma output). Also, FEI has not been responsive, to my knowledge, to any questions from us surplus consumers/hackers. I wonder if they'd be responsive to a 'group-buy' of documentation or answers? Maybe it comes down to whether it's a hassle to spend time dealing with us, or if releasing info would break agreements with their customers. -- newell N5TNL ___ 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] Things to look for when buying a few FE-5680A's?
On Thu, Jan 26, 2012 at 9:13 AM, Bob Camp li...@rtty.us wrote: Hi If you *need* to lock one of the new FE-5680's 10 or 20 Hz high, you probably can adjust the cap on the VCXO center it's range up there. The frequency division is done by digital logic inside a CPLD and you'd need to re-program the firmware. I think people have found that these new FE5680s don't lock if you move far from 10MHz and you can't get more than a few hundred Hz from 10Mhz by analog adjustment. The option 2 that is in the book is different from the fine scale adjustment the current $40 can do. the true option two units can be programmed over a range of many MHz by sending RS232 commands but the current units can only by programmed over rs232 withina very narrow range about like you'd find on a typical OCXO. I think if you want a wide range oscillator you are best using a DDS chip whos clock is locked to the FE5680 or a Thunderbolt. The FE5680's advantage over a t-bolt is portability. 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.
Re: [time-nuts] Things to look for when buying a few FE-5680A's?
Hi The PPS would indeed be off if you move the 10 MHz (no matter how you do it). The range of the output relative to the 380 Hz digital tune range is restricted by the pull range of the VCXO. There have been plots posted showing the pull range, and it's (lack of) centering. No need to re-shoot any firmware. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Thursday, January 26, 2012 12:36 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Things to look for when buying a few FE-5680A's? On Thu, Jan 26, 2012 at 9:13 AM, Bob Camp li...@rtty.us wrote: Hi If you *need* to lock one of the new FE-5680's 10 or 20 Hz high, you probably can adjust the cap on the VCXO center it's range up there. The frequency division is done by digital logic inside a CPLD and you'd need to re-program the firmware. I think people have found that these new FE5680s don't lock if you move far from 10MHz and you can't get more than a few hundred Hz from 10Mhz by analog adjustment. The option 2 that is in the book is different from the fine scale adjustment the current $40 can do. the true option two units can be programmed over a range of many MHz by sending RS232 commands but the current units can only by programmed over rs232 withina very narrow range about like you'd find on a typical OCXO. I think if you want a wide range oscillator you are best using a DDS chip whos clock is locked to the FE5680 or a Thunderbolt. The FE5680's advantage over a t-bolt is portability. 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.
Re: [time-nuts] Things to look for when buying a few FE-5680A's?
At 11:36 AM 1/26/2012, Chris Albertson wrote: The option 2 that is in the book is different from the fine scale adjustment the current $40 can do. the true option two units can be programmed over a range of many MHz by sending RS232 commands but the current units can only by programmed over rs232 withina very narrow range about like you'd find on a typical OCXO. I don't think this is accurate--the FEI tech manual for option 2 claims tuning resolution of 1.8e-7 Hz, so 32 bits of that is about 770 Hz of tuning range. *Maybe* option 8 (customer specified frequency 1 Hz to 20 MHz) is the wide range RS-232 tuned variant? -- newell N5TNL ___ 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] Things to look for when buying a few FE-5680A's?
Chris, Thank you for the input on the subject. I'll keep my eyes open for the two different kinds. In all honesty, I probably don't need to alter the frequency... I just like the ability to interrogate the unit for other values such as reading the ADC's and health status bits. I've seen other threads about undocumented commands and values, and that sort of stuff kind of intrigues me. Do you know of any other reference manuals for these units? I found one PDF that seems to cover the operation and use of the modules pretty well. I was curious if there were any other docs out there. I know that there's an FAQ site for the units, and I've been reading over that site. Good info. I'll keep my eyes open for the two different kinds. Thank you, Brad Stockdale On 1/22/2012 12:49 PM, Chris Albertson wrote: The current batch of (about) $40 units are different from what was available a year ago. These new ones require 5V DC input in addition to 15V and can only be programmed via RS232 a few Hz away from 10MHz. So they are only good for use as a 10MHz reference Option 2 in the book refers to a different type FE5380 that can be programed over a very wide range of several MHz. I think these are still being sold on eBay but not for $40. They seem to be over $100. Which is which and how to tell? Just look at the price. On Sat, Jan 21, 2012 at 9:59 PM, Brad Stockdaleb...@shinji.net wrote: All, I've been on the sidelines of being a time nut for a while now and I'm working on getting back into things. Before I drifted away from my hobbies, I remember the FE-5680's being around, but I didn't know much about them and was more interested in GPSDO's. I think I'd like to help kickstart my interest in the area again by picking up a few FE-5680A's from eBay. So, I was wondering if there's any certain things I should look for when buying some... It looks like there's a pretty consistent supply right now on eBay... Are there certain sellers that people would recommend? I noticed that Option 2 is the RS-232C stuff. Do most on eBay have this option? Anything in particular I should watch out for? Thanks, Brad ___ 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] Things to look for when buying a few FE-5680A's?
On 1/22/2012 9:49 AM, Chris Albertson wrote: The current batch of (about) $40 units are different from what was available a year ago. These new ones require 5V DC input in addition to 15V and can only be programmed via RS232 a few Hz away from 10MHz. So they are only good for use as a 10MHz reference For historical accuracy, in Jan 2005, I bought an FE-5680A which didn't work with just a 15 V supply. After some hacking, I think I was the first (at least on this list) to figure out that it also needed 5V on one of the pins to operate. I was not able to program that one. Though reminded by these many recent emails, I haven't yet pulled it out of my stash to see if I missed something when I tried to communicate on RS-232 back then. So the *new* ones are not that new, but they are newer than the ones, more commonly known before 2005, that worked on only 15 V and could be programmed over a wide frequency output range. Over the years, one thing is quite obvious -- Frequency Electronics Inc. (FEI) made many similar but different versions of the FE-5680A. There seems to be no definitive way to distinguish versions that have no external physical differences (like an sma output). Also, FEI has not been responsive, to my knowledge, to any questions from us surplus consumers/hackers. It is fortunate that this latest round of FE-5680A's seem to be consistent in characteristics and many clever people have derived a lot of details about their internals and programmatic interface. It is great that the current available surplus product seems consistent, but be aware that there were many indistinguishable iterations of the 5680A on the surplus market over the last decade or so. ___ 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] Things to look for when buying a few FE-5680A's?
The current batch of (about) $40 units are different from what was available a year ago. These new ones require 5V DC input in addition to 15V and can only be programmed via RS232 a few Hz away from 10MHz. So they are only good for use as a 10MHz reference Option 2 in the book refers to a different type FE5380 that can be programed over a very wide range of several MHz. I think these are still being sold on eBay but not for $40. They seem to be over $100. Which is which and how to tell? Just look at the price. On Sat, Jan 21, 2012 at 9:59 PM, Brad Stockdale b...@shinji.net wrote: All, I've been on the sidelines of being a time nut for a while now and I'm working on getting back into things. Before I drifted away from my hobbies, I remember the FE-5680's being around, but I didn't know much about them and was more interested in GPSDO's. I think I'd like to help kickstart my interest in the area again by picking up a few FE-5680A's from eBay. So, I was wondering if there's any certain things I should look for when buying some... It looks like there's a pretty consistent supply right now on eBay... Are there certain sellers that people would recommend? I noticed that Option 2 is the RS-232C stuff. Do most on eBay have this option? Anything in particular I should watch out for? Thanks, Brad ___ 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. -- 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.
Re: [time-nuts] Things to look for when buying a few FE-5680A's?
All, I've been on the sidelines of being a time nut for a while now and I'm working on getting back into things. Before I drifted away from my hobbies, I remember the FE-5680's being around, but I didn't know much about them and was more interested in GPSDO's. I think I'd like to help kickstart my interest in the area again by picking up a few FE-5680A's from eBay. So, I was wondering if there's any certain things I should look for when buying some... It looks like there's a pretty consistent supply right now on eBay... Are there certain sellers that people would recommend? I noticed that Option 2 is the RS-232C stuff. Do most on eBay have this option? Anything in particular I should watch out for? Thanks, Brad ___ 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.
