Re: [time-nuts] Symmetricom TimeSource 2700
I don't know how (or if) they deal with the distance from the cell. The accuracy of the PPS signal from CDMA time receivers is usually specified as no better than 10 microseconds or so, so they may just assume the cell tower is close enough not to make it worse than 10 microseconds. I'm pretty sure at least some systems have something much better than that. The FCC requires some sort of pretty good location reporting for 911. I think the requirement is something like better than 100 yards more than 95% of the time. The cell phone companies can do it any way they want. GPS is one choice. Another is triangulation from cell towers. 100 meters is 300 ns which is a lot less than 10 microseconds. -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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] SDR GPS
On 24/11/11 12:19, Poul-Henning Kamp wrote: Has any of you played with this: http://www.sparkfun.com/products/8238 I have. I managed to log data, write code to use FFT correlation search and then lock-up to a good strong bird and decode the sub-code. One has to look in a few books to get it but it's fun. Much harder to real-time decode, but I didn't spend quality time on achieving an efficient digital RF section. The dataformat is inefficient with only 2 out of 8 bits used, so one might consider stuffing the bits, but it would be a trivial fix. Cheers, Magnus There is also a limitation in the orginal module limiting continous data collection to 30(?) seconds. You need to remove a timer in the (USB) microcontroller on the device and recompile. This was no problem with open source tools. -- Björn ___ 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] troubleshooting a FE-5680A (got two; only one works)
Just yesterday I received two FE-5680A units from China. One of them works and one doesn't achieve lock. Both are labelled with FEI P/N 217400-30352-1. Here's a photo of the one that works, the other looks just the same but different serial number. https://picasaweb.google.com/109928236040342205185/FE5680A#5680473663653140162 FE-5680A Rb #1: At startup, RF out (pin 7) ramps from 9.999828 to 10.66 MHz for a few minutes, then locks at 10.00 MHz and pin 3 drops low. The RF signal is about 2 Vpp. Power draw at startup about 25 W, dropping to 10 W. FE-5680A Rb #2: RF out scans from 9.999799 to 9.94 MHz repeatedly, and does not achieve lock. Pin 3 remains high. The RF signal is about 1 Vpp (half the level of the working unit). Power draw similar to unit #1. Any suggestions for what might be done to prod the 2nd unit towards working? I see some things which might be trimmer caps on the board, and what might be a round heating element(?) soldered to a crystal can in this photo: https://picasaweb.google.com/lh/photo/0WRM10pGG0Kd89Ji80yoa9MTjNZETYmyPJy0liipFm0?feat=directlink thanks for any advice! John Beale N8JUF ___ 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] z3801a, z3805a, z3815a, z3816a, thunderbolt and thunderbolt
Hey Thanks for the reply, I have 2 uses for the GPSDO, ref clock for NTP server or 10mhz ref clocks for the labs. If I find one is not suitable for one task, I can try it on another. I have built a few GPSDO and regularly change oscillators, so I have a good idea about the circuitry and performance. Having said that it gets very hard to approach a professionally designed unit. Actually, I am toying with the idea of 3 separate Thunderbolts connected to NTPD using thunderbolt drivers. Each of the Trimble's will use a separate antenna (3 active antenna cost less than a splitter, go figure) But I am beginning to ask myself why?! Isn't it good enough already? mark Date: Tue, 29 Nov 2011 12:20:45 +0100 From: Azelio Boriani azelio.bori...@screen.it To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] z3801a, z3805a, z3815a, z3816a, thunderbolt and thunderbolt II Message-ID: cal8xpmnzspuxnim-hbmzgp5-sfqadxroq19_yznkqgojmc3...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 A long-time data collection? I can test an HP58503A (I think it is the Z3801A), I have the Z3815A and the TBolt. Of course I need time to test... On Tue, Nov 29, 2011 at 10:37 AM, Hal Murray hmur...@megapathdsl.netwrote: ma...@non-stop.com.au said: Hi All, Risking opening a potential can of worms, has anyone have a specs roundup of GPSDO? Ideally, Maximums of Phase noise, Jitter, accuracy... One of the variables is the quality of the antenna, both position and loss in the cable. -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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] troubleshooting a FE-5680A (got two; only one works)
John, Instead of trying to fix it you should fault the unit back to seller and get a refund or have him send another unit. I would also attempt to get them to pay for the return shipping as well. After all it is their fault they sent a bad one when all of them are claiming that they are working correctly. As for troubleshooting, that is way easier said then done. These newer series of FE-5680's are much more digital in nature then the older design, which makes it much harder. The company that makes them is not and will not give out information. BillWB6BNQ John Beale wrote: Just yesterday I received two FE-5680A units from China. One of them works and one doesn't achieve lock. Both are labelled with FEI P/N 217400-30352-1. Here's a photo of the one that works, the other looks just the same but different serial number. https://picasaweb.google.com/109928236040342205185/FE5680A#5680473663653140162 FE-5680A Rb #1: At startup, RF out (pin 7) ramps from 9.999828 to 10.66 MHz for a few minutes, then locks at 10.00 MHz and pin 3 drops low. The RF signal is about 2 Vpp. Power draw at startup about 25 W, dropping to 10 W. FE-5680A Rb #2: RF out scans from 9.999799 to 9.94 MHz repeatedly, and does not achieve lock. Pin 3 remains high. The RF signal is about 1 Vpp (half the level of the working unit). Power draw similar to unit #1. Any suggestions for what might be done to prod the 2nd unit towards working? I see some things which might be trimmer caps on the board, and what might be a round heating element(?) soldered to a crystal can in this photo: https://picasaweb.google.com/lh/photo/0WRM10pGG0Kd89Ji80yoa9MTjNZETYmyPJy0liipFm0?feat=directlink thanks for any advice! John Beale N8JUF ___ 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] troubleshooting a FE-5680A (got two; only one works)
Try to re-initialize it. I think that it is possible to reset the unit. My LPFRS, for example, has two commands (F00, C00) to reset the fine and coarse tuning to the factory default. I have to read the FE5680A datasheet to confirm but generally digital units have factory defaults, resets, presets and so on. On Wed, Nov 30, 2011 at 10:26 AM, WB6BNQ wb6...@cox.net wrote: John, Instead of trying to fix it you should fault the unit back to seller and get a refund or have him send another unit. I would also attempt to get them to pay for the return shipping as well. After all it is their fault they sent a bad one when all of them are claiming that they are working correctly. As for troubleshooting, that is way easier said then done. These newer series of FE-5680's are much more digital in nature then the older design, which makes it much harder. The company that makes them is not and will not give out information. BillWB6BNQ John Beale wrote: Just yesterday I received two FE-5680A units from China. One of them works and one doesn't achieve lock. Both are labelled with FEI P/N 217400-30352-1. Here's a photo of the one that works, the other looks just the same but different serial number. https://picasaweb.google.com/109928236040342205185/FE5680A#5680473663653140162 FE-5680A Rb #1: At startup, RF out (pin 7) ramps from 9.999828 to 10.66 MHz for a few minutes, then locks at 10.00 MHz and pin 3 drops low. The RF signal is about 2 Vpp. Power draw at startup about 25 W, dropping to 10 W. FE-5680A Rb #2: RF out scans from 9.999799 to 9.94 MHz repeatedly, and does not achieve lock. Pin 3 remains high. The RF signal is about 1 Vpp (half the level of the working unit). Power draw similar to unit #1. Any suggestions for what might be done to prod the 2nd unit towards working? I see some things which might be trimmer caps on the board, and what might be a round heating element(?) soldered to a crystal can in this photo: https://picasaweb.google.com/lh/photo/0WRM10pGG0Kd89Ji80yoa9MTjNZETYmyPJy0liipFm0?feat=directlink thanks for any advice! John Beale N8JUF ___ 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. ___ 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] Symmetricom TimeSource 2700
It's been a while, but from what I remember the sync channel message does indeed include the system time (which is the same as GPS time with a UTC offset) and also the PN code offset that this cell is using. This leaves the only remaining unknown as the path delay to the cell and the possible error in the local clock on the BTS. The other possible source of error is that if one of the sites loses GPS lock, it will flywheel - this will generate a yellow alarm, but this is not communicated over the air interface - I suspect that the largest component of that stated 10uS maximum timing error is based on worse-case accumulated phase error. I also suspect this is why that Symmetricom box is tracking multiple pilots, so it can isolate and discard any that appear to be significantly out. Regards, Pete On Wed, Nov 30, 2011 at 1:37 PM, Dennis Ferguson dennis.c.fergu...@gmail.com wrote: I think they track both the CDMA pilot and sync channels. The latter channel sends a message which tells the phone about the cell, and gives gives the phone enough information to figure out the time of day. I'm pretty sure CDMA phones have to know what time it is before they register with the cell. To receive the paging channel and negotiate a registration the phone has to receive and send the long code chip sequence, which I think is 2^40 bits long and takes more than a month to repeat. The phone has to know what time it is before it has any hope of tracking that. I don't know how (or if) they deal with the distance from the cell. The accuracy of the PPS signal from CDMA time receivers is usually specified as no better than 10 microseconds or so, so they may just assume the cell tower is close enough not to make it worse than 10 microseconds. Dennis Ferguson On 29 Nov, 2011, at 18:54 , Peter Bell wrote: Assuming it's just tracking the CDMA pilots, the 1PPS output is likely not aligned with UTC. The problem is that the pilot channel is just a PN sequence with no modulating data - so when you lock to it you can know that your local clock is 19200Hz * 64 chips/bit (1.228MHz) - but that's all you know. Even the code phase doesn't tell you anything, since there are two unknowns - the first is the distance to the cell and the second is the code phase offset on this specific pilot (each BTS has it's modulating sequence offset by an integer multiple of 64 chips to reduce mutual interference) - the second piece of information you can obtain by reading one of the overhead channels, but the first is basically not available just using a receiver (your phone can do it, since it can ask transmit back to the BTS and measure the round trip timing offset). ___ 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] troubleshooting a FE-5680A (got two; only one works)
I tend to agree with this - but it looks like it's already been opened, which could cause problems. Some things you can quickly check are that the lamp housing and the Rb cell shielding are getting hot (use a thermometer, not your fingers!) and that the lamp is lit by checking for a purple glow at the back of the lamp housing. I suspect these are all OK, though, since the current consumption is about the same as the other one. One of my dead units had a bad 3.3V regulator (MAX882, on the back of the board - input is 5B on pin 5, output is 3.3V on pin 4) - since that 3,3V line runs the Xilinx PLD that divides down the clock and you have a low output signal, it sounds possible... If your supplies are good, try scoping the photocell testpoint - it's the one above and slightly to the right of the FPC going to the Rb cell assembly in your photo 4 of 8 - it should show a signal when the oscillator frequency sweeps through the Rb resonance frequency - if you can't see anything at all, then check to make sure that the VXCO is actually sweeping through 10MHz - if not, you can try adjusting C217 to centralise the sweep range. If if is going through 10MHz and there is no signal, check the drive to the snap diode on that little RF connector - you should see a 60MHz signal mixed with about 4.3MHz - if that looks good, and the there is still no signal at the photocell, suspect the physics package. Regards, Pete On Wed, Nov 30, 2011 at 5:26 PM, WB6BNQ wb6...@cox.net wrote: John, Instead of trying to fix it you should fault the unit back to seller and get a refund or have him send another unit. I would also attempt to get them to pay for the return shipping as well. After all it is their fault they sent a bad one when all of them are claiming that they are working correctly. As for troubleshooting, that is way easier said then done. These newer series of FE-5680's are much more digital in nature then the older design, which makes it much harder. The company that makes them is not and will not give out information. BillWB6BNQ John Beale wrote: Just yesterday I received two FE-5680A units from China. One of them works and one doesn't achieve lock. Both are labelled with FEI P/N 217400-30352-1. Here's a photo of the one that works, the other looks just the same but different serial number. https://picasaweb.google.com/109928236040342205185/FE5680A#5680473663653140162 FE-5680A Rb #1: At startup, RF out (pin 7) ramps from 9.999828 to 10.66 MHz for a few minutes, then locks at 10.00 MHz and pin 3 drops low. The RF signal is about 2 Vpp. Power draw at startup about 25 W, dropping to 10 W. FE-5680A Rb #2: RF out scans from 9.999799 to 9.94 MHz repeatedly, and does not achieve lock. Pin 3 remains high. The RF signal is about 1 Vpp (half the level of the working unit). Power draw similar to unit #1. Any suggestions for what might be done to prod the 2nd unit towards working? I see some things which might be trimmer caps on the board, and what might be a round heating element(?) soldered to a crystal can in this photo: https://picasaweb.google.com/lh/photo/0WRM10pGG0Kd89Ji80yoa9MTjNZETYmyPJy0liipFm0?feat=directlink thanks for any advice! John Beale N8JUF ___ 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. ___ 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] HP 5071A Cs beam standard on eBay
You guy have probably found it already, but for the people who didn't, it's here: http://www.ebay.com/itm/280778451033 I don't see them showing up on eBay too often. And prices were a bit higher last time I saw them, even though I saw a couple going really cheap on dovebid too. The older 5061 shows up frequently, but often in an untested condition (== defective). Can anybody tell what a reasonable price for a 5071 is and what the potential risks are of buying a used one (besides a worn out tube (or being scammed))? ___ 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] Determining Time-Nut infection severity.
Since we dont have WWVB here in Australia, and since I have an oregon weather station that wants WWVB to timesync to, I am also building a small WWVB emulator, to make it work correctly. Or you can get your WWVB generator on eBay: http://www.ebay.com/itm/120714765000 For the price it'd be include PSK. But while you're at it, hook it up to your redesigned 5062C and do your neighborhood a favor ;-) ___ 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] Determining Time-Nut infection severity.
A spare Linux machine with a 192 KHz sound card could generate the signal directly, then use a modified audio amp to boost the signal. You could write the software to emulate a choice of stations. On 11/30/2011 06:19 AM, Robert Deliën wrote: Since we dont have WWVB here in Australia, and since I have an oregon weather station that wants WWVB to timesync to, I am also building a small WWVB emulator, to make it work correctly. Or you can get your WWVB generator on eBay: http://www.ebay.com/itm/120714765000 For the price it'd be include PSK. But while you're at it, hook it up to your redesigned 5062C and do your neighborhood a favor ;-) ___ 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. -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ 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] Bluetooth for Tbolt
Just because a device has Bluetooth does not mean that all profiles are supported. The serial port emulation has its own profile, and the computer you want to use has to support that profile in order to be able to send and receive data serially via Bluetooth. I have been messing with Bluetooth for a while and it has been very frustrating. I have several Blueetooth adapters for my laptops, and they all support different sets of profiles, even though most support the most common profiles like mouse and headset. For instance, there are several different, incompatible profiles for audio via Bluetooth. I would be surprised (pleasantly) if the iPaq supported the serial profile. My Dell Axim for instance does not. It does support a Bluetooth headset of the type you use with a cell phone but it does not support the Stereo Audio profile for the GE 99004 stereo receiver I have. My Blackberry on the other hand supports both. Didier Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: Robert Atkinson robert8...@yahoo.co.uk Sender: time-nuts-boun...@febo.com Date: Tue, 29 Nov 2011 12:29:11 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Robert Atkinson robert8...@yahoo.co.uk, Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Bluetooth for Tbolt Hi Bert, About a year ago I bought a packaged RS-232 to Bluetooth adaptor on ebay (about 1/20 the cost of an apparently identical device from a professional solution provider). Looks just a 9 way D plug and shell with an antenna were the cable normally goes. Plugged it into the front of my T-Bolt and my laptop's exsiting Bluetooth found it as a serial port and it worked fine. Robert G8RPI. P.S Most iPaq's have Bluetooth, anyone up for an enhancement to Thunderhead to get it to network? From: ewkeh...@aol.com ewkeh...@aol.com To: time-nuts@febo.com Sent: Tuesday, 29 November 2011, 9:30 Subject: [time-nuts] Bluetooth for Tbolt Searching on our favorite auction site for a not time or frequency related project I ran across a Bluetooth adapter 190527209620 and 190508188703. After checking with some of you, smarter than me, I am convinced this module will work as a Tbolt interface, eliminating that pesky cable and having to unplug it before powering up the PC. All this for less than $ 8 ! I did buy some of the modules in the hope that some one will rise to the occasion and develop a solution. Bert Kehren ___ 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. ___ 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] troubleshooting a FE-5680A (got two; only one works)
I would just combine these recommendations - see if the local XO can be adjusted to lock. If so, problem solved. If not, then try to return and replace the unit. Ed ___ 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] troubleshooting a FE-5680A (got two; only one works)
Hi At this point I'd contact the seller. You know that the part has a problem and you have done enough checking to be sure it's nothing trivial (like a loose wire). The worst that can happen is he does not reply, the best is that he sends you another part for free. There are a number of possibilities in-between the two. At this point you have a pretty good case. Once you start twiddling this or that, you are not in as good a position. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of John Beale Sent: Wednesday, November 30, 2011 2:18 AM To: time-nuts@febo.com Subject: [time-nuts] troubleshooting a FE-5680A (got two; only one works) Just yesterday I received two FE-5680A units from China. One of them works and one doesn't achieve lock. Both are labelled with FEI P/N 217400-30352-1. Here's a photo of the one that works, the other looks just the same but different serial number. https://picasaweb.google.com/109928236040342205185/FE5680A#56804736636531401 62 FE-5680A Rb #1: At startup, RF out (pin 7) ramps from 9.999828 to 10.66 MHz for a few minutes, then locks at 10.00 MHz and pin 3 drops low. The RF signal is about 2 Vpp. Power draw at startup about 25 W, dropping to 10 W. FE-5680A Rb #2: RF out scans from 9.999799 to 9.94 MHz repeatedly, and does not achieve lock. Pin 3 remains high. The RF signal is about 1 Vpp (half the level of the working unit). Power draw similar to unit #1. Any suggestions for what might be done to prod the 2nd unit towards working? I see some things which might be trimmer caps on the board, and what might be a round heating element(?) soldered to a crystal can in this photo: https://picasaweb.google.com/lh/photo/0WRM10pGG0Kd89Ji80yoa9MTjNZETYmyPJy0li ipFm0?feat=directlink thanks for any advice! John Beale N8JUF ___ 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] Bluetooth for Tbolt
So the question is, does the Ipaq BT implementation support SPP? If so, then this should work. The BT serial interface on the Ipaq will have to be paired to the BT serial device on the Tbolt by whatever process is in the Ipaq. After that, use a terminal program on the Ipaq to connect to the port, and see what data you get. ___ 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] Determining Time-Nut infection severity.
On Wed, Nov 30, 2011 at 7:38 AM, Chuck Forsberg WA7KGX N2469R c...@omen.com wrote: A spare Linux machine with a 192 KHz sound card could generate the signal directly, then use a modified audio amp to boost the signal. You could write the software to emulate a choice of stations. A time code generator is included in the NTP distribution. By default it is not built. I think it is a .C file that likes in a directory called test. This software is designed for testing time code receivers 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] troubleshooting a FE-5680A (got two; only one works)
[Peter Bell] ...check to make sure that the VXCO is actually sweeping through 10MHz - if not, you can try adjusting C217 to centralise the sweep range. Thanks Pete, you are exactly right. As mentioned, the VCXO was sweeping from 9.999799 to 9.94 MHz with no lock. I found that the C217 trimmer was nearly at minimum C already, but a tiny tweak to move it to absolute minimum C shifted up the center frequency 30 Hz, which (just) enabled a lock at 10.00 MHz. Given the pre-existing C217 setting, I wonder if this unit was marginal even from the factory. I don't know what minimum value C217 has, but I could remove C217 completely which might center it more. Or, maybe there is a way to increase the VCO tuning range, no doubt at a cost in phase noise. Asking for a replacement unit is another option, but I'm just too impatient for that, so I'm taking it as an opportunity to learn something. (in fact I did send him a note, but I'm not expecting anything.) Thanks to Pete and the time-nuts list for the solution! -john ___ 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] Bluetooth for Tbolt
If you can get that part working, let me know and I'll give you a way to choose a different COM port in Thunderhead. On Wed, Nov 30, 2011 at 12:10 PM, David VanHorn d.vanh...@elec-solutions.com wrote: So the question is, does the Ipaq BT implementation support SPP? If so, then this should work. The BT serial interface on the Ipaq will have to be paired to the BT serial device on the Tbolt by whatever process is in the Ipaq. After that, use a terminal program on the Ipaq to connect to the port, and see what data you get. ___ 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] z3801a, z3805a, z3815a, z3816a, thunderbolt and thunderbolt
There are some issues using a Thunderbolt with NTP. See http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver29.html (the stuff about event polling). Also, you will need http://www.tapr.org/kits_fatpps.html (or something like it) if you want to use its PPS signal with NTP. On Wed, Nov 30, 2011 at 4:08 AM, Mark C. Stephens ma...@non-stop.com.auwrote: Hey Thanks for the reply, I have 2 uses for the GPSDO, ref clock for NTP server or 10mhz ref clocks for the labs. If I find one is not suitable for one task, I can try it on another. I have built a few GPSDO and regularly change oscillators, so I have a good idea about the circuitry and performance. Having said that it gets very hard to approach a professionally designed unit. Actually, I am toying with the idea of 3 separate Thunderbolts connected to NTPD using thunderbolt drivers. Each of the Trimble's will use a separate antenna (3 active antenna cost less than a splitter, go figure) But I am beginning to ask myself why?! Isn't it good enough already? mark Date: Tue, 29 Nov 2011 12:20:45 +0100 From: Azelio Boriani azelio.bori...@screen.it To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] z3801a, z3805a, z3815a, z3816a, thunderbolt and thunderbolt II Message-ID: cal8xpmnzspuxnim-hbmzgp5-sfqadxroq19_yznkqgojmc3...@mail.gmail.com Content-Type: text/plain; charset=ISO-8859-1 A long-time data collection? I can test an HP58503A (I think it is the Z3801A), I have the Z3815A and the TBolt. Of course I need time to test... On Tue, Nov 29, 2011 at 10:37 AM, Hal Murray hmur...@megapathdsl.net wrote: ma...@non-stop.com.au said: Hi All, Risking opening a potential can of worms, has anyone have a specs roundup of GPSDO? Ideally, Maximums of Phase noise, Jitter, accuracy... One of the variables is the quality of the antenna, both position and loss in the cable. -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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. ___ 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] Determining Time-Nut infection severity.
A time code generator is included in the NTP distribution. By default it is not built. I think it is a .C file that likes in a directory called test. This software is designed for testing time code receivers The one I know about is util/tg2.c From the top of the code: * This program can generate audio signals that simulate the WWV/H * broadcast timecode. Alternatively, it can generate the IRIG-B * timecode commonly used to synchronize laboratory equipment. It is * intended to test the WWV/H driver (refclock_wwv.c) and the IRIG * driver (refclock_irig.c) in the NTP driver collection. -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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] Unplug T-bolt before booting up...??
Check my wiki, look for Mouse Interference With Serial Port under Precision Timing http://www.ko4bb.com/docuwiki/doku.php Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: Michael Baker mp...@clanbaker.org Sender: time-nuts-boun...@febo.com Date: Tue, 29 Nov 2011 11:15:01 To: time-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: [time-nuts] Unplug T-bolt before booting up...?? Hello, TimeNutters-- I have heard of the problem of needing to unplug a T-bolt before booting up the (Windows) computer but I have never seen that problem myself. I have had a T-bolt running on several different desktops and laptops and never experienced it. I do recall that there was a fix for this problem but have no idea what it is. Mike Baker ___ 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] Line Voltage frequency Interface morphed to batteries
I hooked up a 47k resistor from line to the 50 ohm input of my 5334B and it just worked. That's something I wouldn't do. It's too easy to forget to push the 50 ohm button. I might do it if I had a handy 50 ohm terminator built into a BNC pass through. That would be easy to verify with a quick glance. I am watching the 60 Hz drift all around as I type this (although not all that far, seems to be holding within 0.01 Hz tonight). I'm surprised you are that close. How long have you been watching? I think 0.1 Hz (low) is where the US power companies have to file paperwork so they try (very) hard to avoid getting that low. Here is what I saw. Each data point is averaging over 10 seconds. http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/60Hz-Jul11-12-freq.png -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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] Determining Time-Nut infection severity.
A spare Linux machine with a 192 KHz sound card could generate the signal directly, then use a modified audio amp to boost the signal. You could write the software to emulate a choice of stations. Chuck, There's software under leapsecond.com/tools that you'll find helpful in this effort (wwvb* tco*). Have a look at: http://www.leapsecond.com/notes/wwvb2.htm I also have a version that uses a standard 44.1 kHz sound card to generate audio at 60kHz/N (for example 6/11 = 5454 Hz) and then plays the sound through headphones next to a WWVB clock. The Nth harmonic of the magnetic coupling between the headphones and the clock does the trick. It works (but I found the high pitched sound obnoxious). /tvb ___ 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] George Daniels, master watchmaker, dies
http://www.economist.com/node/21540211 ___ 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] George Daniels, master watchmaker, dies
I had the pleasure of listening to him talk at a British Horological Institute (BHI) meeting a few years back. A great watchmaker. Rob Kimberley -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Prologix Sent: 30 November 2011 20:56 To: 'Discussion of precise time and frequency measurement' Subject: [time-nuts] George Daniels, master watchmaker, dies http://www.economist.com/node/21540211 ___ 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] Symmetricom TimeSource 2700
Yes, you are correct. 10 microseconds comes directly from the CDMA spec, it is the amount of time the reference at a base station is allowed to drift when it is in holdover before it is out of spec and needs to be removed from service. I still don't know what they do about path delay since (as you point out) I believe this can be measured only after a handset has registered with the tower, and the timing receivers never register. And the path delay can be quite large if you live far enough away from civilization. When I take my Verizon phone to Toronto it often registers with a Verizon tower which must be at least 20 miles away (i.e. the width of the lake). If that was the distance to the only tower the timing receiver had to listen to that would be more than 100 microseconds of delay, and I don't see how it could correct that. Dennis Ferguson On 30 Nov, 2011, at 02:42 , Peter Bell wrote: It's been a while, but from what I remember the sync channel message does indeed include the system time (which is the same as GPS time with a UTC offset) and also the PN code offset that this cell is using. This leaves the only remaining unknown as the path delay to the cell and the possible error in the local clock on the BTS. The other possible source of error is that if one of the sites loses GPS lock, it will flywheel - this will generate a yellow alarm, but this is not communicated over the air interface - I suspect that the largest component of that stated 10uS maximum timing error is based on worse-case accumulated phase error. I also suspect this is why that Symmetricom box is tracking multiple pilots, so it can isolate and discard any that appear to be significantly out. Regards, Pete On Wed, Nov 30, 2011 at 1:37 PM, Dennis Ferguson dennis.c.fergu...@gmail.com wrote: I think they track both the CDMA pilot and sync channels. The latter channel sends a message which tells the phone about the cell, and gives gives the phone enough information to figure out the time of day. I'm pretty sure CDMA phones have to know what time it is before they register with the cell. To receive the paging channel and negotiate a registration the phone has to receive and send the long code chip sequence, which I think is 2^40 bits long and takes more than a month to repeat. The phone has to know what time it is before it has any hope of tracking that. I don't know how (or if) they deal with the distance from the cell. The accuracy of the PPS signal from CDMA time receivers is usually specified as no better than 10 microseconds or so, so they may just assume the cell tower is close enough not to make it worse than 10 microseconds. Dennis Ferguson On 29 Nov, 2011, at 18:54 , Peter Bell wrote: Assuming it's just tracking the CDMA pilots, the 1PPS output is likely not aligned with UTC. The problem is that the pilot channel is just a PN sequence with no modulating data - so when you lock to it you can know that your local clock is 19200Hz * 64 chips/bit (1.228MHz) - but that's all you know. Even the code phase doesn't tell you anything, since there are two unknowns - the first is the distance to the cell and the second is the code phase offset on this specific pilot (each BTS has it's modulating sequence offset by an integer multiple of 64 chips to reduce mutual interference) - the second piece of information you can obtain by reading one of the overhead channels, but the first is basically not available just using a receiver (your phone can do it, since it can ask transmit back to the BTS and measure the round trip timing offset). ___ 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. ___ 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] z3801a, z3805a, z3815a, z3816a, thunderbolt and thunderbolt
Hi Justin, There are some issues using a Thunderbolt with NTP. See http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver29.html (the stuff about event polling). The Trimble Palisade (aka Acutime, Acutime 2000, Acutime Gold) has a nice feature called Event input. Event input The Acutime Gold accepts an external event input in the shape of an RS-422 pulse. The external event pulse input is supported on Port A (pins 6 and 7). The Acutime Gold transmits a TSIP time packet (0x8F-0B or 0x8F-AD) in response to the event input. The TSIP packet increments the event count field for each event received. The event time stamp is generated within 488 nanoseconds of its arrival at the Acutime Gold interface connector. The prefered mode for the palisade driver is to use this feature. When the driver was adapted for Thunderbolt is was seen as a problem that the Tbolt receiver lacked the Event input. I have not runt a Tbolt with NTP, but it should be very doable with the Palisade driver in the Thunderbolt-mode. Another option could be the Parse-driver http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver8.html running in the Trimble TSIP mode. (mode 10) -- Björn ___ 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] z3801a, z3805a, z3815a, z3816a, thunderbolt and thunderbolt
I've done it before with the Palisade driver in non-polling mode. It works, but you have to rely on the timing of a serial port and apply your best guess for a delay. If he's trying to detect phase differences between multiple thunderbolts, the serial port + OS combination might be too jittery to measure that difference. On the other hand, I suspect using a FatPPS and the ATOM driver would be even less jittery than polling (if it worked), so maybe it's a moot point. On Wed, Nov 30, 2011 at 4:56 PM, b...@lysator.liu.se wrote: Hi Justin, There are some issues using a Thunderbolt with NTP. See http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver29.html (the stuff about event polling). The Trimble Palisade (aka Acutime, Acutime 2000, Acutime Gold) has a nice feature called Event input. Event input The Acutime Gold accepts an external event input in the shape of an RS-422 pulse. The external event pulse input is supported on Port A (pins 6 and 7). The Acutime Gold transmits a TSIP time packet (0x8F-0B or 0x8F-AD) in response to the event input. The TSIP packet increments the event count field for each event received. The event time stamp is generated within 488 nanoseconds of its arrival at the Acutime Gold interface connector. The prefered mode for the palisade driver is to use this feature. When the driver was adapted for Thunderbolt is was seen as a problem that the Tbolt receiver lacked the Event input. I have not runt a Tbolt with NTP, but it should be very doable with the Palisade driver in the Thunderbolt-mode. Another option could be the Parse-driver http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver8.html running in the Trimble TSIP mode. (mode 10) -- Björn ___ 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] z3801a, z3805a, z3815a, z3816a, thunderbolt and thunderbolt
[Context is TBolt using Palisade driver with NTP.] On the other hand, I suspect using a FatPPS and the ATOM driver would be even less jittery than polling (if it worked), so maybe it's a moot point. Works fine for me. I have one box that doesn't need the FatPPS. It might be interesting to track down which chips work with narrow pulses and/or how wide it has to be for a given chip. -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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] Line Voltage frequency Interface morphed to batteries
Hal, I don't know what I'd do if i had reliable power like that. Here at work (the lab) It's normal to see outliers of anything between 58hz and upper 63. As I had commented before, this power distribution in this area is terrible (South Western Pennsylvania) Steve On Wed, Nov 30, 2011 at 3:06 PM, Hal Murray hmur...@megapathdsl.net wrote: I hooked up a 47k resistor from line to the 50 ohm input of my 5334B and it just worked. That's something I wouldn't do. It's too easy to forget to push the 50 ohm button. I might do it if I had a handy 50 ohm terminator built into a BNC pass through. That would be easy to verify with a quick glance. I am watching the 60 Hz drift all around as I type this (although not all that far, seems to be holding within 0.01 Hz tonight). I'm surprised you are that close. How long have you been watching? I think 0.1 Hz (low) is where the US power companies have to file paperwork so they try (very) hard to avoid getting that low. Here is what I saw. Each data point is averaging over 10 seconds. http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/60Hz-Jul11-12-freq.png -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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] troubleshooting a FE-5680A (got two; only one works)
It does seem rather off frequency - the other thing that might be worth checking is to verify that the PTC thermistor soldered to the crystal is getting hot, since failure of that would seem likely to induce frequency errors of about that magnitude. Regards, Pete On Thu, Dec 1, 2011 at 2:01 AM, beale be...@bealecorner.com wrote: [Peter Bell] ...check to make sure that the VXCO is actually sweeping through 10MHz - if not, you can try adjusting C217 to centralise the sweep range. Thanks Pete, you are exactly right. As mentioned, the VCXO was sweeping from 9.999799 to 9.94 MHz with no lock. I found that the C217 trimmer was nearly at minimum C already, but a tiny tweak to move it to absolute minimum C shifted up the center frequency 30 Hz, which (just) enabled a lock at 10.00 MHz. Given the pre-existing C217 setting, I wonder if this unit was marginal even from the factory. I don't know what minimum value C217 has, but I could remove C217 completely which might center it more. Or, maybe there is a way to increase the VCO tuning range, no doubt at a cost in phase noise. Asking for a replacement unit is another option, but I'm just too impatient for that, so I'm taking it as an opportunity to learn something. (in fact I did send him a note, but I'm not expecting anything.) Thanks to Pete and the time-nuts list for the solution! -john ___ 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] Line Voltage frequency Interface morphed to batteries
On 11/30/2011 3:06 PM, Hal Murray wrote: I hooked up a 47k resistor from line to the 50 ohm input of my 5334B and it just worked. That's something I wouldn't do. It's too easy to forget to push the 50 ohm button. I might do it if I had a handy 50 ohm terminator built into a BNC pass through. That would be easy to verify with a quick glance. The unit is specified to be able to handle 200 volts DC + peak AC on the input in high impedance mode either X1 or X10. I just tried it and it has no problem with it. I am watching the 60 Hz drift all around as I type this (although not all that far, seems to be holding within 0.01 Hz tonight). I'm surprised you are that close. How long have you been watching? A couple of hours. I think 0.1 Hz (low) is where the US power companies have to file paperwork so they try (very) hard to avoid getting that low. Here is what I saw. Each data point is averaging over 10 seconds. http://www.megapathdsl.net/~hmurray/time-nuts/60Hz/60Hz-Jul11-12-freq.png ___ 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] Compensating phase differnces in dual frequency GPS receviers?
Hi Attila, [ L1 / L2 timing differences ] How do dual frequency receivers deal with that? I've also been toying with the idea of an inexpensive dual- or tri-band GPS SDR, especially since there are now quite a few satellites emitting L2C, the civil L2 signal. (Though I'd still like to try my hand at the fancy L2 semicodeless schemes.) I think that manufacturers calibrate out the timing differences between channels (as well as group-delay variations within a channel). There must be some remaining error, though, e.g. over temperature, depending on the filter technology. ObTimeNuts: There's an interesting recent thesis on GPS for time and frequency metrology: http://www.ptb.de/cms/fileadmin/internet/fachabteilungen/abteilung_4/4.4_zeit_und_frequenz/pdf/Feldmann_2011_Dissertation.pdf Section 5.1.3 has a few words on exactly this channel-filter-delay issue. The author measures a coefficient of 20 ps per degree for a pair of receivers. Cheers, Peter ___ 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] Compensating phase differnces in dual frequency GPS receviers?
Speaking of GPS's L2C signal, it turns out there's a timing difference between L2C and L2, namely 90 degrees of phase (nominally). Apparently there was some controversy over whether to include this correction in the RINEX files. The RINEX 3.0 document has details. Even with all this complexity, it would be really nice for everyone to have access to ~2 ns time, as a significant upgrade to present-day inexpensive systems giving ~20 ns time using single-frequency pseudorange. Cheers, Peter ___ 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] Heated crystal? Rb tube corrosion (FE-5680A)
I've been paying particular attention to the discussions involving the FE-5680A frequency standards of recent attention. I do not have a FE-5680A yet, but rather I am studying what is shared from the others prior to buying. At the very least I want to know what I'm up against should I get a DOA module. It appears that these units use a heated crystal.(..i sure hope it's heater and not an acoustic resonator). Has anyone performed sub 1degree c drift testing against a known stable source? What are the performance gains by using tighter temperature control? Also It appears that quite a few of these have corroded Rb tube interfaces. My guess is the corrosion is a tale-tale sign of small amounts of rb gas leakage in combination with the raised temperatures of the tube oven? If this is the case I suppose a visual check of the tube interface for corrosion would yield a fair approximation of the tube condition? Lastly, is the Rb tube a quartz tube or is it a metal(silver lined?)canister sealed with polymer tape? Thanks, Steve ___ 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] Heated crystal? Rb tube corrosion (FE-5680A)
HUH ? What, exactly, do you mean by corroded Rb tube interfaces ? bILLwb6bnq Steve . wrote: snip Also It appears that quite a few of these have corroded Rb tube interfaces. Thanks, Steve ___ 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] Heated crystal? Rb tube corrosion (FE-5680A)
Bill, I was starting to think i may have to crack open an instrument to get a picture. But i found a reference online. http://n1.taur.dk/fe5680a-2/IMG_1375.JPG Note the corrosion around the cheaper metal parts (screws, spacers, shell). I can't speak for the FE-5680A, but when i see something like this in the instruments i maintain it's a tale-tale sign gas mitigation. Steve On Thu, Dec 1, 2011 at 12:16 AM, WB6BNQ wb6...@cox.net wrote: HUH ? What, exactly, do you mean by corroded Rb tube interfaces ? bILLwb6bnq Steve . wrote: snip Also It appears that quite a few of these have corroded Rb tube interfaces. Thanks, Steve ___ 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] Line Voltage frequency Interface morphed to batteries
[Context is HP 5334B inputs.] The unit is specified to be able to handle 200 volts DC + peak AC on the input in high impedance mode either X1 or X10. Thanks for the heads up. Somehow, I thought they were much more delicate than that. -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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.
