[time-nuts] HP 53131A Power Off Mod
I had also modified my HP 53132A but kept it extra simple and the modification allows me to use the counter normally.. On my HP 53132A I just mounted a toggle switch in one of the unused holes for the back panel BNC input connectors and wired the switch in series with the power connector. The front panel power/standby switch is unmodified and works as usual and if I want to completely power down I can reach around to the back and turn the added switch to the off position. Much easier than the other modifications I've seen and is easily removable if you want to sell the unit unmodified. -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] Looking for some Frequency Electronics info....
Some time ago bought one on Ebay for under $50 just because it looked interesting. It isn't a prototype but most of the FEI units probably had limited production. It seemed to be more complicated than I expected it to be but if I understood it better it would make more sense. The 10Mhz board is enabled/disabled by the int/external switch. The 10Mhz output and EFC from this oscillator board are connected to the interface board. I believe that these 2 boards and the switch/connector on the back allow you to use the internal 10Mhz oscillator to output 10Mhz and send 10Mhz on (perhaps a connector marked J4) to a comparator board. If I recall this part of the unit should work independant of the other boards. The comparator board is probably a PLL that compares its 10Mhz input with its 100Mhz input and outputs an EFC voltage to the 100Mhz oscillator. the 100MHz oscillator output goes to the amplifier board with two 100Mhz outputs on the back panel. There is also a 100Mhz signal that goes back to the PLL board so the 100Mhz is locked to the 10Mhz oscillator or an external input (if I remember correctly). There are also other wires that control the light and other stuff but I didn't trace them out and my unit seems to work as intended. ___ 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] Looking for a cheap low tempco EFC pot
It may not be the best way but what I do with an LPRO is use a 10-turn pot and set it to the center of its range then adjust the internal pot to give me an output of 10 Mhz. Basically that gives me a voltage divider where the top and bottom resistors have the same TC so the offsets pretty much cancel. I've also found that just using a 10-turn pot just doesn't give me fine enough control so if I need 10K I'll put a 4.5K fixed resistor on either side of a 1K 10-turn pot giving me the resolution I want and the TC of the pot has a much smaller effect. -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] Identify RFTGM-II-XO Part
If I recall there are 2 MMIC chips, the large one you mention (U105) and a smaller black plastic one (U100) to the left of the big one and to the right of the 15 Mhz crystal filter. Just above the chips you will see 2 inductors marked L101 and L102 that supply the d.c. power to the chips. The larger U105 chip on the right feeds its output through the PLP-18-11 low pass filter to the 15 Mhz output connector. If you don’t need 15 Mhz,you may be able to remove U105 rather than try to replace it and connect the output of the oscillator through a capacitor to the input of the LPF and use the 15 Mhz SMA connector as a 10 Mhz sine output. I haven’t tried this but it might work. -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] Absolute phase
I have 2 antennas mounted on opposite ends of a roof and both of them feed commercial GPS DA/splitters and I can have as many as 10 receivers running at one time for testing. I have also used one of the high frequency type F TV passive splitters with one D.C. feed through and added 200-300 ohm resistors from the other outputs to ground. All this has seemed to work just fine but one of the older receivers apparently radiated its L.O. out the antenna coax and would interfere with a couple of other receivers I connected to the same DA. Connecting one 10 Mhz references to the external trigger on my scope and feeding 2 other GPS receivers to the input channels (all from the same antenna DA), I can watch the slow drift at 2 ns/div with respect to the trigger and sometimes one receiver drift one way as the other receiver drifts in the opposite direction and sometimes they drift the same way. The drift is generally less than 2 ns but it is there and I assume it depends on what the internal ‘housekeeping’ of the receiver is doing and what birds they are using. So bottom line, they aren’t ‘locked’ to each other but are generally close. -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] Thunderbolt question
Pin 1= 0v Pin 2= 0v Pin 3= 0.749V Pin 4= 4.892v Pin 5= 0v Pin 6= 3.417v I’d say it would be an MMIC amp similar to this device. It has the same pin-out so it is a possibility. The Amp In my newer version is an 23 db gain device but 8-pin so I Suspect your version may have similar specs. Here is a Datasheet on the MGA-87563 6-pin device. http://www.efo.ru/components/avago/catalog/files/pdf/AV01_0200EN.PDF ___ 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] Thunderbolt question
Actually that isn't my photo I linked to but one I just Googled. That is probably a board revision most people don't have but it was the first one I saw so I used it just to show that the GPS receiver is part of the only circuit board and not another easily replaceable board like in some other units. I just took a couple of photos of the later revision of the board for anyone interested in seeing what might be fried. In the photo of the top of the board the signal comes into a filter then to a 25db amp marked AM50002 by Macom. Above the filter near the input is where the decoupled +5VDC for the antenna is connected. If you are only reading 0.5VDC, if your're lucky it might only be the amp is fried and that could be an easy fix. If the 5VDC is ok with the amp input pin lifted, it might be the only problem. I wouldn't bet on it though. The 4031 I believe is a 1575.42 SAW filter The photo of the bottom of the receiver area shows a Sawtek filter and other parts. At the bottom of the photo is C460, a feedthrough capacitor and that might be where the receiver output is but where my Tbolts are working I don't feel the need to look into whether you could connect the output of a seperate GPS receiver there to make it work. I do have one Tbolt that has no oscillator. I brought the EFC and 10Mhz connections to SMA connectors on the back so I can test other oscillators or GPSDOs that don't have an easy way to monitor of graph the stability of those units and using Lady Heather gives me a good way to compare the graphs to ones I'm used to. You might possibly be able to replace the built-in receiver but it might be easier to buy a working Thunderbolt. http://i906.photobucket.com/albums/ac262/rjb1998/GPS%20top%201_zpslgxunnyw.jpg http://i906.photobucket.com/albums/ac262/rjb1998/GPS%20bottom%201_zpschvruppt.jpg ___ 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] Thunderbolt question
The Thunderbolt is a single board with the GPS receiver in the lower right between the oscillator case and the connectors in the photo in this link. https://www.eevblog.com/forum/testgear/trimble-thunderbolt-gps-disciplined-oscillator/?action=dlattach;attach=102948;image ___ 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] How get FEI-Zyfer 380 GPSDO to talk with computer?
I have sent a copy of FEI-Zyper GPSMonInstallerV1.14 (2007) to jsrobbins at earthlink.net -Arthur Dent ___ 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] A Symmtricom GPSDO Board
I have two similar Symmetricom GPSDO boards but with a slightly different parts layout that were manufactured in about 2012. The OCXO in the first one is 4.1950 Mhz and there is a 10 Mhz VCO next to it. The second one has a Symmetricom SA22-c Rb oscillator. The large blank spot in question is for the version of these that would have the Rubidium oscillator and the copper foil is part of the heat sink for that version. I haven’t checked the output frequency of the SA22-c but it is probably the same as the OCXO version. -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] PRS10 rubidium lamp module failure
..."apparently got hot enough to create a localized thermal runaway in its lead wire." I don't think that explanation is correct. There are no signs of discoloration caused by overheating anywhere else in the photo and yet the lead wire has apparently melted as you say. That would probably require at least a 2000 degree temp which would cause lots of damage. Are there any signs of chemical contamination that could have caused this? Not the same but In older equipment that had leaky Hg batteries I've seen similar damage. -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] GPS Outage..
>kb8tq at n1k.org said: Pretty much all of our surplus gizmos are cell tower surplus (like 99.99%). True - I believe all the Trimble Thunderbolts came from Andrew/Grayson/Geometrix WLS2A-24-G or similar Wireless Location Sensors. I know I removed over 200 T-bolts from these units personally. -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] Einstein Special on PBS
Tom wrote: "I'll make just a one word correction to your summary. The clocks run a bit faster not because of "the spinning earth" but because of "the earth"." You are correct, I misspoke. While that point may have been wrong I did check the elevation of Mount Sunapee and it is indeed at 2726 feet as measured by USGS and others. When I posted before I 'assumed' the researchers were from MIT or one of the Boston area schools (or UNH) and would therefore be at sea level. Rewatching the video they do say that the second clock is at sea level but they don't mention where they are. The drive up to the base of the mountain would probably be 1 to 1.5 hours so the 1st clock didn't go from sea level to 2726 feet instantaneously so during that travel time it was probably at an average of about 500' which is near the average elevation in New Hampshire. If the experiment had been conducted in the Burj Khalifa in Dubai, United Arab Emirates and the elevator could go from sea level to about 2000 feet, which may be the top floor, the experiment might be more exact because you'd eliminate the travel time. -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] Einstein Special on PBS
In the special it looks like they used two HP5071A standards, an SRS620 counter, and a scope. They first made sure the stds were in sync then took one to the building at the top of the ski lift on New Hampshire's Mount Sunapee at 2726' elevation for 4 days where it would be running a little faster because it would be slightly further from the center of the spinning earth. After bringing the 5071A back from the top of the mountain they checked the difference in the start of square waves displayed on the scope and detected the 5071A at altitude was now 20ns ahead of the 5071A kept at sea level, as predicted, if I understood everything correctly. They explained that the clocks in the GPS satellites traveling at a much higher speed had to correct for the speed difference which also verified Einstein's theory. My wife and I were on the top of Mt. Sunapee this summer where we enjoyed the views but didn't run any experiments. ;-) -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] 3GHz prescaler for Pendulum counters
Just a note to say that I bought one of these prescaler boards for my CNT-81. One problem is the way the board mounts in the CNT-81 the "in" connector is toward the back instead of toward the front like some of the other counters and I had to make a longer input cable. Pawel does now know this and maybe a different cable can be included for these counters in case you can't make one. Be sure to check on this so there aren't any surprises. When I put the prescaler board in and connected a signal it didn't divide properly. After getting the service manual and checking the schematic I found the problem was the way the motherboard was set up to detect which prescaler was installed. There are resistors of 10K, 20K, and 40K going from the 3 ID pins (16,14,and 12) to a common 100K to ground. On Pawel's board for the PM6681/ CNT-81 pin 16 is jumpered high to +5 to select the correct divisor ratio with pins 14 and 12 not connected so they should be low. Unfortunately the resistors on the motherboard feed the +5VDC from pin 16 back through the resistors to pins 14 and 12 so all 3 pins are high and this screws up the ratio. If you have the service manual go to the schematic "Logic Circuits, unit 1 sheet 2(6)" and look at grid C 11 to see what I mean. I had to tie pin 14 and pin 12 low to make the prescaler work as it should & it does work great! I hate to think what an OEM board would cost so this is a really good deal and I recommend it. -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] Magellan GPS OEM 10 Channel -- Looking for pinout or any documentation
I have sent an email with an attached copy of a PDF file of a similar Magellan 16-pin OEM 5000 receiver to Mariusz. -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] Trimble Thunderbolt and David Partridge divider boardquestion
>Tom Van Baak tvb at LeapSecond.com >Mon Oct 12 11:31:17 EDT 2015 > >"For those of you who want to follow the link Chris provided >without his personal google search metadata, the correct URL is: > http://www.perdrix.co.uk/FrequencyDivider/Frequency%20Divider%202.pdf I believe that the link above shows photos of the original board from 2008 and the link below goes to photos of the updated 2010 board that I bought that has 4 added 6800 Mf capacitors. Pretty much the same other than that. http://www.perdrix.co.uk/FrequencyDivider/ -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] Lucent RTFG-u DE-9 connectors
The connectors are the same but the mounting posts that are tapped for 4-40 screws that are used on two of the connectors are not used on the other DB type connectors and they use a quick disconnect type of post. The mating connector on the cable end has a piece on each side of the connector shell that has a slotted hole on the side of the slide that faces the RFTG and this piece slides side to side and grabs the head of the post on the RFTG that looks like a small round button and this locks the cable onto the unit. On the few connectors that you would be using I would change those small button head posts for the threaded ones and leave the rest as they are. I saw a lot of these quick locking connector shells on industrial routing equipment in the 1990s and hated them. -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] Rohde & Schwarz GPSDO
I believe that like a lot of the Meinberg receivers that this uses a down converter to give an IF frequency of 35.4 MHz. If you don't have the converter that apparently isn't included with the receiver you have a $300 paperweight. You might want to check with the seller before bidding. -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] Trimble GPSDO board
"Arthur, I did read your posts before I composed my email. You made no mention of getting the RS-232 to work.." Again, reread my specific post of Sat Aug 22 11:19:31 EDT 2015 that describes the RS-232 in detail. The green light is also described in one of my posts -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] Trimble GPSDO board
"Did anyone have any luck in talking to this unit?" Reread my posts that describe what I did. Mine works great. -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] Trimble GPS board
Here is an update on the 57964-60 GPSDO board that I bought. After figuring out what it needed for power (it is definitely 5.6-6.0VDV) and communications as I previously posted, I built it into a nice enclosure and fed the 10 Mhz output into my modified Tbolt so I could get a graph of the output. The graph doesn't show the first 10 minutes after power-up because the 10 Mhz isn't active until the GPS locks. It looks to be a pretty reasonable GPSDO in a small package. The labels on the front and back panels are just in the photoshop pictures shown in the link below and I haven't made the physical labels yet. Note that I did remove the on-board LEDs and reset switch and then mounted replacements on the front panel where they would be useful. I have no idea what equipment these GPSDOs were used in so I have no idea whether there is going to be a lot of them appearing for sale in the future or just a few. I hope that if there are a lot of these available someone with the knowledge can make a Lady Heather type program to see what the thing is doing. Using a terminal emulator program works but is really clunky. http://i906.photobucket.com/albums/ac262/rjb1998/GPSDOx4_zpsu2cugpwg.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] Trimble GPS board
Bob Camp wrote: "There’s also this listing that shows an pair of 9 pins tacked on the same board:" If you look closely that is a daughter board the seller made that is mounted on top of the Trimble board. Some of the listings use the 50-pin ribbon cable connector to connect to some form of interface board they have. I should clear up some previous statements that I made that were inarticulate and lead to some confusion. When I wrote: "The supply voltage required is stated to be 5.6 to 6VDC and this goes to an LT1764A low dropout regulator set to 5VDC out so my 'guess' is that 6VDC should be the minimum supply voltage to make sure the regulator keeps working properly.", I actually meant the supply should be 6VDC-period. You don't have to get into higher math to determine what voltage to use. As to the current the oscillator (or the entire board) draws, at start-up it is 2A as one of the Ebay listings states. As the oven warms up this dropped to about 0.8A on each of the 2 boards I have. The specs for the LT1764A shows the minimum differential agree pretty much with what I had measured. At power-up it was about 0.4VDC and warmed-up it was about 0.2VDC. I measured the dropout voltage to be less than 5.4V warm. Using a common wall-wart fixed regulated power supply of 6VDC is a common sense decision. I would not try using anything higher, even not knowing as Angus (not.again at btinternet.com) pointed out, there are circuits that are powered by the input voltage before it goes through the LT1764A. Quite often you can find an adequate 6VDC power supply at the local Goodwill or at a fleamarket. Anyone buying just the board and trying to find a nice enclosure to build it into might want to check out Ebay item 250597854445 which appears to be a (6" x 4.1" x 2.2") black extruded aluminum case identical in style to what is used in some of the ready made units. Also check Ebay 351340026725 for some 6" MCX to SMA panel mount cables that look like the ones they use with some of the GPSDOs you see on Ebay. Note I have no connection (pun) with these sellers but I have ordered these items to use with the 2 board- only units I bought at $42.90 each (including shipping). I also plan to remove the two 2-color LED from the underside of the pc board and mount 2 others LEDs on the front panel to let me see what the unit is doing. I'll probably move the reset switch as well. Another note is to check the listings carefully because the price seems to change frequently on some of the listings for these Trimble units. After I bought the 2 I wanted the price on that listing jumped to $48 then to $61 and the quantity dropped to zero. Also if you don't want to be cheap like me and go through the hassle of building your own unit from scratch (although it is a learning experience), you can buy the complete package from some sellers for about $150. Finally keep in mind that most of the info in this thread is preliminary and like many have pointed out, may still have errors. We're all trying to make it easier for others but we ain't perfuct! -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] Trimble GPS board
rbenward at verizon.net wrote: "See below, here is a 73090 OCXO (same as on some of those GPSDO boards) powered by +12V." You are incorrect in your assumption that the link you have supplied shows a 73090 OCXO powered by +12VDC. The BOARD is indeed powered by 12VDC (or 15VDC if you read the listing) but if you look at all the photos you will see a 3-terminal regulator on the bottom of the pc board. The Trimble GPSDO I'm supplying 6.3VDC to had a 5 volt regulator that has a measured output of 5.00VDC and the supply pin on the oscillator had that 5.00VDC on it, not the 6.3VDC from my supply. A continuity check shows a direct connection from the regulator's 5 volt output directly to the oscillator's supply pin. Because of the higher current drawn by the 5 volt oven, running the input to the board at 12VDC and wasting all that power as heat would not be wise. 6.3VDC makes me happy and they chose a LDO regulator for a good reason. The one error I did notice is I said the board locked after it found satellites but that is incorrect. It does find satellites quickly but takes about 10 minutes to lock and that is when the 10Mhz output is enabled. I did some of my checking around 1AM and that is not a good time for clear thinking or writing. -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] Trimble GPS board
"Does anyone have any information or experience with this small Trimble GPSDO?" I had previously posted that what I thought these boards were and how they might work and said I was waiting for 2 of these boards that I had ordered to arrive. Yesterday the 2 boards arrived in an Epacket from China. If you order more than one board check them carefully on arrival because the 2 I received were placed back-to-back with no padding in between and a couple of the small SMD components on the back side were partially ripped off the pc board. Fortunately the damage was repairable and both boards are ok. What I found was that there are at least 2 different versions of this GPSDO and although both function the same, the location of some of the parts differ. First, there is the understandable language barrier and if the sellers do have information that could help you get the board up and running, it isn't included in the English listings. Some of the info you can glean from looking at all of the photos of the various units for sale on Ebay is just from arrows on the photos telling where to connect power and get the 10Mhz output. It took me a lot of trial and error plus tracing out some of the runs to get to a point of where the boards were working as intended. The supply voltage required is stated to be 5.6 to 6VDC and this goes to an LT1764A low dropout regulator set to 5VDC out so my 'guess' is that 6VDC should be the minimum supply voltage to make sure the regulator keeps working properly. With the multicontact connector facing you you will see a 5A fuse near the back right edge of the connector. I soldered the '+' supply lead from my power supply (that puts out about 6.3VDC regulated) to the left end of this fuse and the '-' supply lead to the ground plane on the left of the connector. Using too high an input VDC could cause the regulator to dissipate too much heat. When the board is powered up with the antenna and the 10Mhz output connected you will see no 10Mhz output. There are two 2-color LEDs on the board, on top of one version, and on the bottom of the other version. One is the ALARM LED and the other is the ACTIVITY LED. On power-up both light red then go out (if all is well) then the ACT LED stays on solid green for maybe 10 minutes until the GPS receiver starts to track satellites. At this point the ACT LED starts to flash a slow green and the 10Mhz output is turned on. After a few more minutes when the board achieves lock the ACT LED starts flashing green at a higher rate. On the left front corner of the board is the 1 PPS connector. To the right of that connector are 4 unpopulated holes for a connector. I traced those out and found 2 went to a RS-232 chip that appears to be a different type depending on which of the boards you receive. The left hole is ground (RS-232 pin 5 on the computer end), then the next hole is not connected, then RS-232 pin 2, then pin 3 being the hole with the square index pad on the right. Using a terminal emulator program and 57600 8N1N I was able to communicate with the board. Typing '?' will give you a long list of all the commands it will accept. For instance, 'STAT' and 'POSSTAT' are 2 of the commands that will give you info on how the board is working. Typing *IDN? at the UCCM-P > prompt returns 57964-60 for my board and POSSTAT shows up to 12 satellites can be tracked. The date code on my unit is 2009. The board seems to work well but the OCXO runs pretty hot so it probably isn't a double oven. The multicontact connector probably has most of the functions and LED signals available but I couldn't see using it so I'll get whatever signals I want directly off the pc board. -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] Trimble GPS board
"Does anyone have any information or experience with this small Trimble GPSDO?" If you search on Ebay for more of the same GPSDO you will find that there are several sellers offering these units. The units are a Trimble 57963 (x) where x is a revision letter. Some have a different oscillator number and some have a shield over the GPS section but I don't know the differences-yet. I have 2 that should be here soon if all goes well. Read the listings and you will see that they have an RS-232 interface and run on 5.6 to 6VDC if you believe the given info. Some of the sellers are building these into nice boxes and selling them for $150 if you want a ready made unit. Some of the listings have PC screen shots that show some information. Seems to track 12 SVs so these are pretty new. I 'think' the date is 2009 from some chip numbers. -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] yet another GPSDO
I made some progress with the Symmetricom CGBA card I bought on Ebay and mentioned here last Friday. After getting it running and checked out, I took a closer look at the board to see if I could communicate with it. What I found was 3 unused holes on the board marked 'USER' and 2 of those pads had runs going to an MB3232I (MAX232) RS-232 chip. After I tried several things that didn't work I finally got it to respond at 9600 8N1 and typing '?' displayed the list of SCPI commands it accepts. It was made by Samsung in December, 2003 and seems to have an 8-channel receiver. I'll remove the onboard LEDs and mount them on the front panel of the box I'm building it into (I do like flashing LEDs!) and not have any other display on the unit, the PC terminal emulator program should be enough. There is a link below to a photo of 2 of the data screens it displays. I suspect the H/W fails are because it isn't plugged into its intended backplane. -Arthur http://i906.photobucket.com/albums/ac262/rjb1998/CGBA%20screen_zpsbizmqype.jpg ___ 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] yet another GPSDO
I picked up yet another version of a GPSDO on Ebay the other day. I thought that I'd mention this because sometimes when one unit shows up there are a lot more that will be listed for sale later, like with the many Lucent RFTG units that are currently being sold on Ebay. This one is a Symmetricom CGBA with absolutely no info other than the photos in the listing. The board is about 9"x13" and has date codes from 2003. It has a Symmetricom 5Mhz OCXO that feeds a doubler with L/C filtering and a 10Mhz crystal to further filter the 10Mhz and give a nice clean sine wave feeding a 27 ohm termination resistor. Then the signal goes to 3 EL2257 dual gated opamps That seem to make the signal look much worse so there may have been more than one design engineer on this project. ;-) I traced out 2 lines for power, each one goes thru its own fuse to a diode bridge so it doesn't care about polarity. >From the bridge the power goes to several discreet onboard switchers that give +12, +12 OCXO, -12, +5, and +3.3VDC. I found that the minimum voltage to make the board operate was 22-28VDC so I'm running it on 36VDC. The current draw is 0.5A cold to 0.25A with the OXCO warmed up. The GPS is made by Furumo and has what looks like an HP part number 0960-1060(HP31) and has +5VDC for an active antenna on the antenna connector. There are unused pads on the main board for SMA size connectors that are marked 10M, PP2S, 4.096M, 100Hz, 30.72M, 40.96S, and 8K. Not all of these are active and the 3 dual opamps are not 'on' either so some of the pins in the connectors on the back of the assembly may do some controlling of signals or these may be options not implemented on this board. When powered up it goes through a light flashing sequence then the GPS LED goes flashing green when it sees the satellites, then solid green when it locks, and the ACT LED turns from flashing red to flashing green. Using my modified Tbolt to test the unit shows it stays within +/-200PPT for about the first 2 hours then settles down. There is an RJ-45 connector on the front plus there is a 15 pin 'D' connector behind the panel that may have been for some testing purpose because it can't be accessed from the front. At this time I'm just happy to see how well it works and later I'll see if I can communicate with it somehow. -Arthur http://i906.photobucket.com/albums/ac262/rjb1998/CGBA_zpsd4rricto.jpg ___ 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] Leap Second video
Here is a short video of the leap second compared to a regular clock. http://youtu.be/725ECUOXqeY -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] Tuning a Trimble Thunderbolt
wb6bnq wrote: “I am a little confused. In your screen shot the overdetermined clock says you are at precisely 46.00 North by 7.0 East at 547 Meters.” I think I have the answer. I know when I was selling Tbolts I would PhotoShop out every digit after the decimal point so the displayed JPEG wouldn’t show my location. If Lat. was exactly 46.00 then it would show that, not just 46.(blank). ___ 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] Trimble Thunderbolt question, splitting its output.
The telco equipment that all these Tbolts came from had the 10 Mhz output feed 2 different modules using a MicroCircuits ZFSC-2-1-S two-way 0° 50 ohm power splitter. There are some of these splitters for sale on Ebay but almost any other similar unit should work. ___ 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] OXCO insulation
If you check the popular auction site you can find several listing for Aspen Aerogel SPACELOFT Insulation. One listing has a 10"x14"x.2" piece for $7 including shipping and another listing has 481 rolls for $1.8 million, in case you have several ovens you need to re-insulate. ;-) http://www.ebay.com/itm/171328843398? -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] Another use for a Trimble Thunderbolt
>’d say that the plot is telling the truth. It also seems to be giving >you information fast enough that thermal drift and barometric pressure >is not to big an issue. If you had to wait a day or three for the same >data, drift would be a much bigger issue. Yes, when you get to the >“close enough” trace, drift may be an issue. (yes close enough is >indeed close enough …). Keep in mind that I'm talking about using a GPS signal from a Thunderbolt to adjust a common rubidium standard that would be used in a telco or other piece of general test equipment and thermal drift and barometric pressure effects are never an issue for me. >I suspect that if you try the trick with something way far off frequency >(many 10’s of ppm), the GPS may not play nice. At any normal tune range >on an Rb, it should be fine. Actually it does play nice-very nice over any range I'm interested in. Keep in mind that I wanted a simple method that would work with a 10 Mhz frequency standard to give me closer readings than I could get by watching the scope or the counter. I can easily use just the counter to check the frequency of a less than stellar oscillator so what I'm describing would be used with a fairly close 10 Mhz frequency standard and not one that isn't even close. The Pendulum CNT-81 frequency counter I have can display a 10 Mhz error to 5 decimal places in 10 seconds using the math function and an external time base. Anyone who has used a WWVB comparator remembers the plot zipping back to the zero position when the plotted frequency difference would exceed the chart's maximum deflection. The Thunderbolt's display on Lady Heather works exactly the same way. If you look at the plots in the link that follows you will see that the 10 Mhz appears very stable but it is actually set by a synthesizer to be 10,000,000.025000 hz in the upper trace and so to keep it in the vertical center position on the graph I have an oscillator offset of -2500 PPT in Lady Heather. In the lower trace the synthesizer frequency is set to 10,000,000.010 hz and the offset is -1000 PPT to keep the 10 Mhz trace centered. The reference for the synthesizer and the Thunderbolt is the GPS signal from the Tbolt so the same reference is used for everything. http://s906.photobucket.com/user/rjb1998/media/tboltplots_zpsd20a083b.jpg.html -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] Another use for a Trimble Thunderbolt
Those of you who know I had hacked the RFTG-u REF 1 GPS years ago and had one running for 4 years before other time nuts discovered these units probably won't be too surprised that I have tried another hack that may have limited interest but works for me. Having owned a large number of Thunderbolts, I ran across a few that needed repairs of various sorts. One of these had a defective oscillator so I removed the OXCO and brought the EFC and 10Mhz connections out through the side of the case with SMA connectors so I could test various oscillators, as others have done before. Then I got to thinking that if I connected the Thunderbolt up to run and output to Lady Heather but connected a free running oscillator to the 10Mhz input, ignoring the EFC connection, it might work as a comparator to plot the drift of the free running oscillator. I have a few Efratom/Datum Rubidium standards I'm adjusting and I can watch drift on my scope at 5 ns/cm or the 10 Mhz output to the 5th decimal place on my Pendulum CNT-81 counter and try to determine which way it's drifting but that gets old pretty fast. The 10 Mhz output from Lady Heather appears to be an instantaneous reading so that always looks very good but the PPS output appears to be the cumulative signed difference between the GPS and the free running oscillator. The link is to a plot from Lady Heather with just the 10 Mhz and PPS signals on the screen. The EFC is still trying to control the oscillator but seeing it isn't connected the readings could range from a meaningless 0-5 volts and I don't care about the temp plot either. I also know that there are other ways of doing this but the definition of "yankee inginuity' is doing things the hard way. I could also check an RFTG-u REF 1 with the antenna off to see how well it keeps to the correct frequency on holdover. I suspect that like the Z3801 it tries to predict and adjust the output when the GPS signal goes away. Take a look at the plot where I adjust a rubidium standard and see what you think. http://s906.photobucket.com/user/rjb1998/media/TboltRbadjF2_zps3a1a9922.jpg.html -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] Frequency distribution isolation transformers YCL 20F001n arrived
paulswedb at gmail.com "Another Time-nut suggested the use of 10 baseT ethernet transformers for 10 MHz isolation that he pulls from old ethernet boards. The 20F001n. These are available from UTSource on ebay at 90 cents each NOS. Ordered 20. Well I have to say as a BPF or something for 10 Mhz they are lousy.. " Before you pooh-pooh these transformer/filters, try feeding a 10Mhz square wave into a one of these filters and check out the fairly clean sine wave you get out. These are handy cheap units and I have used them in the past as a quick and not so dirty way to clean up a 10Mhz signal. Several companies made these and they are all basically the same unit. http://elcodis.com/parts/900719/FL1012.html#datasheet http://akizukidenshi.com/download/ds/ycl/20F001NG.pdf -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] KS problem
" http://evoria.net/AE6RV/KS/KS.Screen.pnghttp://evoria.net/AE6RV/KS/KS.Status.png " works better as http://evoria.net/AE6RV/KS/KS.Screen.png http://evoria.net/AE6RV/KS/KS.Status.png -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] Nortel Trimble GPSDO
"I did miss it. I just did a search and found this thing discussed back in July." Joe Gray W5JG + Search Sept 2013 and you will find the NTBW50AA discussed as well as a NTPB15AA I modified (w/photo link). -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] Lucent KS-24361 15 Mhz and 10 Mhz
I had Planned to eventually convert the 5 Mhz output I added from J8 on the Lucent RFTG-u REF1 (that I described previously) to 10 Mhz. Since I made that 5Mhz modification 4 years ago I have been using the 5 Mhz sinewave output for some of the equipment I have around the bench that can use it directly plus I have a modified Spectracom 8140 distribution amp that take a 5Mhz input and will output a clean 10Mhz sine wave. The 5-10Mhz doubler circuit described by John Roos seems like a good way to accomplish what I wanted to do. I started looking around for parts I might already have that I could use to construct the circuit and I found a lot of what I needed. Having dismantled about 200 of the wireless locator units that held the Thunderbolts that I sold on Ebay, I had a large pile of the machined R.F. subassemblies left over and they had a large number of MCL (Micro-Circuits) and other really neat R.F. stuff. I found a MCL RMS-2 (5-1000 Mhz) mixer that would work well for the mixer and then found a 10Mhz 2-stage amp with filters on one of the circuit boards that should give me the clean 10Mhz sine wave that I want. I have tried the amp and it seems to work well. When fed with either a sine or a square wave the output is a clean sinewave that can drive 50 ohms. The power required is +/-7VDC at low current and that voltage goes to 2 on-board regulators to provide +/-5VDC that supply the 2 amps. Feeding the +/-15VDC from the REF 1 power supply through two 200 ohm resistors provides the +_7VDC for the amps' on-board regulators. The inductors I need for John Roos's 90 degree phase shifter circuit should be here in a couple of days and then I can permanently mount the amp board right behind the front panel connectors near the middle of the REF 1. On the outside chance that the unit actually needs the 15MHZ signal for some purpose this added board will not affect that signal in any way. At least for me this is a good solution. Here is a link to a photo of 2 different revisions of the board, one with a discrete lowpass filter and one with the MCL SCLF-10.7 package. After stripping off the other stuff I don't need there is plenty of room for the rest of the parts from John Roos's circuit. -Arthur http://i906.photobucket.com/albums/ac262/rjb1998/Amps2_zpsf115c599.jpg ___ 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] Minicircuits specs
Here is a link to a pretty exhaustive list of MCL models that would be handy if you only need published specs. -Arthur http://www.minicircuits.com/MCLStore/ModelSearch?model= ___ 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] lightening protection of a GPSDO system / optical isolated distribution amp
Here is a link to a good 12 page description of grounding practices/requirements. http://www.reeve.com/Documents/Articles%20Papers/AntennaSystemGroundingRequirements_Reeve.pdf ___ 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] Lucent KS-24361 Web Page
"If you refer to the picture of the microprocessor board, you will notice that the locations marked D1, D2 and D3 are populated by zero ohm resistors. That means that the 3 V microcontroller was powered from 5V. I am actually amazed that they worked at all, let alone worked for a while. It is a shame that fluke.l saved on the cost of 3 diodes that way. The 1N4148 is $.02 at Mouser in 25 pieces lots." Didier KO4BB +++ What I did (and I've mentioned this before) is to replace the three zero ohm resistors with one red LED. The forward voltage drop is about 1.7vdc so it makes a pretty nice zener, and you have a power indicator to boot. -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] Yet another GPSDO
You can see a similar product by this seller direct - http://www.cart100.com/seller/bg7tbl/ http://www.cart100.com/Product/38848104218/ Looks like a similar product at almost 3 time the Ebay price. There are more photos at the second link under 'specifications' and you can read MV89A on the Morion oscillator and see some wires patching an error on the bottom of the PC board. Note that the seller also has a frequency doubler at about $10. -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] Yet another GPSDO
I just noticed this on Ebay. The seller has several other related items but the pricing is kind of confusing. No a lot of info. http://www.ebay.com/itm/GPS-DISCPLINED-CLOCK-GPSDO-10M-OUTPUT-SQUARE-WAVE-/111514491254 -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] Z3801 question on EFC at 81000 but stable
"I also seem to recall pix of the Z3801 oscillator and there were not any adjustments. I sure hope I missed something." Thanks Paul WB8TSL + There is an adjustment on the inner 10811 oscillator but it isn't easy to get to. Here is a description. http://www.2917.com/EBAY-images/10811-60165/10811WEB/Inside%20the%20HP%2010811%20Dual%20Oven.htm -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] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812...
Could someone who has both the REF 0 and REF 1 units check to see if the REF 0 unit has U1 missing. U1 is an AD7849 serial input, 14-Bit/16-Bit DAC on my REF 1 units but is missing on an old REF 0 I just dug out of the to-do pile. Someone may have already mentioned this and I missed it. -Arthur http://www.analog.com/en/digital-to-analog-converters/da-converters/ad7849/products/product.html ___ 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] NPR Story I heard this morning
Lester Veenstra lester at veenstras.com Tue Nov 4 16:56:29 EST 2014 wrote: "And you can get a "I climbed Mt. Washington" sticker for your clock." +++ It may be a little OT but I actually worked on the summit for the Mount Washington Weather Observatory for 4 winters as well as climbing the mountain both summer and winter over 70 times and I don't have one of those stickers. :-( -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] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812...
GandalfG8 at aol.com GandalfG8 at aol.com Sun Nov 2 09:08:30 EST 2014 wrote: "Ooh err, whoops, and oh dear !! Arthur, I've only just had a chance to look at your latest photos, and unless I've really got my wires crossed, if you'll pardon the expression:-), your links on J5 are not shown on pins 2, 10, 12, and 15, but on pins 4, 6, 11, and 13." + Darn-I'm glad someone was paying more attention than I was when I wrote that years ago. Apparently when I was documenting what modifications I had made I just picked up a 15 pin D plug shell to get the numbers instead of looking at the obvious numbers on the RFTG socket connector and those connectors being mirror images have the numbers reversed. I was out geocaching yesterday and didn't catch up on the new posts until this morning so I'm a little late in responding. I also checked to see if I had any other scribbles on the changes I made and found this: "If pin 2 is held low the 'ON' LED will flash. A pulse low will turn it on. The RC timer holds pin 2 low to flash for about 6 seconds so you can see it actually happens then pin 2 returns high and the 'ON' LED stays on solid." So apparently some of the parts I added were to just make the light look like they were working correctly (can you spell OCD?) and may not be necessary. As I originally said, this was a hack and I wanted others to duplicate what I had done to see if any of it made sense to them. At least it appears that by adding the circuit I came up with and/or adding jumpers you can get the RFTG-u REF 1 unit to work without the slave unit. I just ordered another RFTG-u REF 1 and will see if I can modify that and get it to output 10Mhz instead of 5Mhz like my original unit. Sorry about the screw up on the numbers. -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] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812...
Keep in mind that I made the modifications to my RFTG-u REF 1 almost 4 years ago and the details of why I did what I did are kind of foggy today. It was a pure hack but I *believe* that the circuitry as well as the jumpers were required, or at least I thought so. The big problem with getting something like this to work is that after spending a lot of time on it I generally go on to the next project and as long as what I did works, I forget about it because it is a one of a kind thing. The photo link below shows the 5Mhz buffer amp I connected to the TP in front of the oscillator that uses a mounting bracket that is secured by the BNC connector that outputs the 5Mhz. The 24V/2A power supply that I mounted on the back connects across the diode on the circuit board as shown. The transistors and other components of the modification that are mounted free form on the back of the J5 connector get the +5VDC from the header directly in back of J5. The wire on the left goes through an existing hole on the circuit board to connect to the fault LED. I was hoping that someone else would duplicate the modification just to reassure me that what I did wasn't black magic. It looks like Nigel is doing just that-thanks. http://i906.photobucket.com/albums/ac262/rjb1998/RFTG-uREF1_zps546e4c82.jpg ___ 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] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812A GPSDO system
Bob Stewart bob at evoria.net “…I have both of my units sitting on the bench. I found that I needed to connect them together to get the REF1 unit to come out of standby….” Bob Camp kb8tq at n1k.org “I suspect that somebody will have to figure out what the 15 pin connector / jumper is doing. On previous RFTG units there was a way to re-wire the crossover interface to fake out the slave detect process. That would let you run a single GPS equipped box and have it behave correctly. Without the fake wires trick none of them played nice without the slave being present….” ++ Reposting what I had posted over a week ago, in case you missed it…. Arthur Dent golgarfrincham at gmail.com Wed Oct 22 13:59:48 EDT 2014 “…Way back on Fri Jun 11 16:48:43 UTC 2010 I posted about using one of these units I had modified but at the time there wasn't a single person who was interested. I have been using the RFTG-u REF1 since then and it is a nice unit. The modifications I added (including a power supply -see photo) allows the lights to cycle through their normal sequence on warm-up and the second unit isn't needed at all….” -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] Lucent KS-24361/Z3812A GPSDO initial setup
I can't remember when I initially powered up my RFTG-u REF 1 how long it took to give me the green light but I *believe* it was a long time, maybe the better part of 24 hours. I think after testing and being fustrated I forgot to turn it off one night and the next day things looked normal. I have since either lost power or unplugged the unit and when powered up it always takes 14 minutes to aquire satellites, go through the start-up secquence, and give me the green light. If I recall when I first tried getting it to work I had a problem with being impatient and not waiting for the unit to complete the survey or whatever it was doing. I didn't have a computer connected so I was kind of flying blind. To answer another question, the RFTG-u REF 1 does supply +5 volts to the antenna connector to power the active antennas. -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] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812...
Anthony Roby aroby at antamy.com wrote: "My curiosity got the better of me so I ordered these earlier this week and received them today. I've powered both up and quickly measured the 10MHz output. I don't yet have a GPS antenna feed that I can connect, so couldn't check that out. And I need to look into why both of the units have the Fault and StdBy lights illuminated. I was surprised how compact they are and they weight next to nothing. And they are very nicely made. I took the tops off both and took some photos (see http://goo.gl/87e8GG), but have not ventured into unscrewing everything to get to the bottom of the boards. From the top, I didn't immediately spot anything extra on the board for the 10MHz out. All the extras appear to be for the GPS, but the underside of the boards may tell a different story." Without an antenna the units will not operate properly and the "ON" light will stay off. Near the front of the oscillator on the edge of the board is a hole marked "J8". This is the 5Mhz sine wave from the oscillator and I fed this through a capacitor to my buffer amp to get 5Mhz out. -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] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812...
Oops, photo link didn't make it in my last post http://i906.photobucket.com/albums/ac262/rjb1998/RFTG-uREF1photo1_zps87c505ca.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] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812...
GandalfG8 at aol.com GandalfG8 at aol.com Wed Oct 22 04:35:40 EDT 2014 "Similarly, with this RFTG-u kit I'd be more inclined to look for ways of routing the native 5MHz from the GPS conditioned Milliren 260 series oscillator to the outside world, and to just treat any other use found for the processed 15MHz as a bonus:-)" ++ This was kind of my thinking on trying to use this Lucent unit as well. Way back on Fri Jun 11 16:48:43 UTC 2010 I posted about using one of these units I had modified but at the time there wasn't a single person who was interested. I have been using the RFTG-u REF1 since then and it is a nice unit. The modifications I added (including a power supply -see photo) allows the lights to cycle through their normal secquence on warm-up and the second unit isn't needed at all. I can't give you any reason why I used the general purpose transistors instead of a single IC quad inverter which might have worked as well or how I stumbled upon why I did what I did back then but it does work. Here's what I posted to Time-Nuts 4 years ago. "Like most Lucent units the RFTG-u REF1 was made to run with another back-up unit for redundancy, needed an interconnect cable, and has no information available. I managed to figure out a way to make it work as a standalone unit and ran the 5Mhz from the OXCO thru a QBits amplifier to give me 5Mhz output instead of the Lucent standard of 15Mhz. I haven't carefully checked it against the other GPSDOs I have running but with the modifications I made to allow it to work solo, it seems to be a pretty good plug-and-play unit." -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] Old 500 kHz oscillator
One of these was my first frequency standard that I used as a marker for checking the calibration of an old Collins TCS-12 receiver I used around 1959. I built a small power supply for the oscillator and used it for a few years until the filament opened and it died. Even way back then I felt that it was worth saving and set it aside to repair later. This past spring I was at the Nearfest ham fleamarket in Deerfield, New Hampshire and found 2 new oscillators on a table. The seller had no idea what they were and at the end of the day I bought the 2 of them for a total of $5, because, like Pete, I just had to have them. I searched around in one of my many junk boxes and found the original dead one I had bought over 50 years ago. (I know most of you won’t find that too strange but my wife thinks my affliction is sad.) The difference between the original and these 2 that I just bought is there was a covered access hole to trim the original but the 2 I just got lack that. Where I had opened the unit up all those years ago I compared the schematic you show to the circuit of my original and they do differ slightly. The cover over the crystal oven says ‘Bulova AB-200 crystal oven’ and there is a thermostat (not shown on your) bypassed by a .01Mfd. The date on the crystal can inside marked ‘VC-1-NL RCA’ is 1/57 so that and my previous experience will help date them. My original only has the 1.5-7pf NPO trimmer and uses a fixed cap across the inductor in the plate circuit. One of these days I’ll power one up and see how I view its accuracy compared to my GPSDO. -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] Cutler NAA on 24.0kHz....
"Not sure whats up with the link when I click it I get the download. Its a 2.5MB file http://www.glkinst.com/test-equipment/manuals/Tracor900A.pdf. " The problem with the above link is the period is included as part of the link when you click on it. It will work without the period. -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] WWVB for Time Nuts
On August 10th Dale J. Robertson wrote: "How does patent infringement litigation get started anyway? I would think that the infringement claim would have to be specific i.e. "you are infringing on our patent number blah, claims blah, blah, blah & blah. not just "you are infringing on our patent. you need to halt production immediately and can't resume until you have properly guessed how you are infringing and stop, or, pay us a crapload of money"." Exactly. Many years ago the multi-national company I worked for had a corporate lawyer visit our plant to discuss patents and related legal matters. One example he used was of another division of our company wanting to enter a market where a competitor had an established commercial product on the market for a couple of years. What they did was go out and buy 2 of the devices and strip them down, copying everything, even down to unused holes in the internal mounting plates. Basically the only difference between the product they released and the competitor's was perhaps the color and the company logo on the front of the unit. Obviously they were sued and after a lawsuit that lasted a couple of years they settled for a large sum of money and had to stop producing the exact copy. During this time the company was able to design their own product that didn't infringe on any patents of the competitor. The lawyer explained that copying this product, which allowed them to establish themselves in the market, and settling the lawsuit, was still far less expensive than waiting and trying to enter the market after the competitor had a long head start and name recognition of the product. Companies have lawyers and bean counters, not just engineers. ;-) -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] Any Isotemp OCXO107-10 Info?
The photo looks like one of the 2 units I have but the info on one if my oscillators says: CTS Knights 970-2074-0 5 Mhz 0410-2540 8947 I'm pretty sure the last numbers are the date code. If more than one company made these units they could have been in some piece of equipment made under military contact where they required a second source and/or spares. -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] Any Isotemp OCXO107-10 Info?
Sounds kind of like this oscillator. I found it to be very low power but it took about a week for it to really settle down and until then I was continually adjusting the EFC. http://i906.photobucket.com/albums/ac262/rjb1998/Oscillator_zps63a30a2f.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] Trimble/Nortel 45000 GPS Locked Reference Oscillatorboard
quartz55 quartz55 at hughes.net Tue Dec 24 10:06:49 EST 2013 "I'd like to see some of your LH traces if you don't mind, especially the osc trace. I don't seem to be able to get my osc trace less than ~400 ppt/div." ++ Here is a 17 hour LH plot of my NTPB15AA 05 which is about the same device, although perhaps a little older. I've found this particular unit very stable. I do have a NTBW50AA which isn't quite as stable but still pretty good. http://i906.photobucket.com/albums/ac262/rjb1998/tbolt12112013_zps21348f7b.gif -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] Crude Survey Technique
Brooke Clarke wrote: "Most low cost hand held and car GPS receivers can only display direction based on changes in position." True, but the Garmin 62s handheld that I use for geocaching and hiking ($200-$400) has a 3-axis, tilt-compensated electronic compass that shows your heading even when you're standing still and holding the unit upright or at an angle. Accuracy is +/-2° except near the poles where it is +/-5° . My Casio watch on the other hand is +/-11°, if you hold it level. -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] powering Trimble Thunderbolt with -5V rather than -12V
Having dismantled a good number of the wireless locator units that these Trimble Thunderbolts were in I can tell you that the DC-DC power supply in these units did not have a -12VDC output but put out -7VDC instead. If I recall the DAC output voltage of almost all the T-bolts I tested was between about +0.1 and +0.8VDC and this has allowed some people to use just a +5 and a +12 supply and not even connect the -12 line or ground it. If the EFC required for the OCXO to output 10Mhz was a negative voltage (which it was for some people), not having a negative supply would cause a problem. I don't recommend not using a - supply but the level of the negative regulated supply doesn't appear to be that critical. -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] TBolt temperature sensor
>Didier Juges shalimr9 at gmail.com >Wed Sep 11 12:24:51 EDT 2013 >"With all that discussion about the old temperature sensor in the TBolt no >longer being available,..." Actually I've bought all mine on Ebay and they are still available from the same seller plus others have some of the old revisions as well. It looks like the seller I used has over 500 units left. These are Rev C2 chips. The 3rd line of characters on the chip end with "C2". The Rev "D" will work as well but do not use the Rev "E" chips because that's where the problem started to appear. Check: http://www.ebay.com/itm/140376728803 Item # 120552309518 appear to be Rev C2 chips as well. -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] New NTBW50AA
>"I would say the temp sensor is working, but still why those jumps?" Ah, that new temp plot looks like the 'normal' staircase steps I was talking about. The previous plot didn't look right with all the little steps in between. As I mentioned before, and Bob mentioned, any problem with the thermometer chip would only affect carryover and that is probably going to be a rare occurence. The T-bolt used a Dallas Semiconductor DS1620 and Dallas made an 'improvement' that caused this problem in the T-bolts. Apparently either the T-bolt firmware couldn't understand the LSD of the temp string or the new revision chip didn't display it and would display the temp steps as several times worse than the older DS1620 chips. The cure for the T-bolts was to replace the DS1620 Rev E chip with an older DS1620 Rev D or Rev C and the plot would look normal. There was never any indication that this caused any problem in operating the T-bolt but replacing the DS1620 chip sure made the plot look better. I replaced all those in the T-bolts I sold because most buyers would freak out if they saw the steps caused by the Rev E chip. The NTPB15AA I have was apparently made in April 2003 and your NTBW50AA was made in November 2004. This problem started showing up in T-bolts made after mid-2004 so I suspect the NTBW50AA has the same problem for the same reason (although the first plot you showed does look flakey as well). If you want to replace the chip it isn't that hard to do and I've bought the DS1620 Rev C chips on Ebay for cheap. -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] New NTBW50AA
>Mark Sims holrum at hotmail.com >Tue Sep 10 09:03:24 EDT 2013 > >Again, THE TEMPERATURE SENSOR IS NOT BROKEN!! The firmware in >some of these units (those from NTPX modules) does NOT read the temperature >sensor in high-res mode. I have sold over 200 T-bolts and had to replace about 30 of their thermometer chips, most because of the revision problem causing the 'stepped' temp plot, but some because of chip failure. If this were the typical low res problem the yellow trace would show the characteristic uniform staircase steps, not the random jumps to some common value that it never exceeds. If you look closely at the plot you'll see many very small changes that are far smaller than any of the steps would be. Also there are major portions of the trace where it is absolutely flat and I doubt that this is really happening. I'll stick with broken but maybe someone else with another NTBW50AA can run LH and show what their graph looks like. -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] New NTBW50AA
I have a slightly earlier version, or a close cousin, of the NTBW50AA that I modified and I've posted photos of it on this list before: http://i906.photobucket.com/albums/ac262/rjb1998/NTPB15AA05.jpg The LH plot from the NTBW50AA by quartz55 doesn't look quite right. Here is a LH plot from my NTPB15AA unit with most of the scale factors set the same as the scale factor in the plot from the NTBW50AA to make it easier to compare. http://i906.photobucket.com/albums/ac262/rjb1998/NTPB15A_zps19b3bd33.jpg If you look at the temp plot from my unit it has small steps and is what I'd expect to see. The plot from the NTBW50AA looks like it has some smaller steps but it looks like it hits a limit at 36.750 and doesn't go beyond that value, which isn't right. It looks like a higher order bit is being turned on and off randomly causing the large apparent jump in temp, which probably isn't really happening because some of the other traces would be affected by any real jump that large. You could just ignore it because it would probably only have an effect during carryover. The NTBW50AA oscillator probably hasn't settled down yet because the DAC voltage is changing a lot more than mine and the 10Mhz doesn't look anywhere near as stable. The design of the 2 units appears nearly identical so I'd expect similar performance. Also the OSC ADEV at 1 tau isn't close to what mine appears to be. That may improve after the unit has been on for a month or so but the temp plot just doesn't look right so the sensor may be bad. -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] Z3801 replacement
To answer the question of whether the Nortel/Trimble units will work with Lady Heather, here is a photo of my modified NTPB15AA with the T-bolt monitor built-in. This version I bought from RDR-electronics works fine. http://i906.photobucket.com/albums/ac262/rjb1998/NTPB15AA05.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] GPS antenna splitter
The amp/splitter I've bought from seller RDR-electronics on Ebay have been Minicircuits ZAPD-3DB-1575-3, 2-way GPS Antenna Splitter N-f. I didn't see any for sale right now but they show up from time to time. See item # 300915251060 to see what they look like. -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] +12 Volts 1A (plus a bit) supply?
>The OCXO in the TBolt has a linear controller. It drops back to about >150 to 250 ma on the +12 line after warmup. It's been at least 40 >years since I saw an on/off oven control in production …. > >Remember that the +12 feeds the oscillator circuit. The more crud on >the 12 volts, the worse the phase noise of the output. A linear >regulator is a good idea. Note that the +12 for the oscillator goes through a 1 ohm resistor to a linear SO-8 8L08A regulator to supply +8 to the oscillator inside the OXCO case. There is also some bypassing. I had posted some photos of the innards some time ago. -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] GPS receivers W/timing outputs greater than 1PP
>But do they have a actual website. I did not find one or a webstore? >How is it you even knew they had the items?? >Thanks >Paul I have bought many items from them and have always been satisfied with the items I've bought and their service. They sell on Ebay and that is where their 'store' is. Try this link: http://stores.ebay.com/RDR-Electronics?_trksid=p2047675.l2563 -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] Thunderbolt GPS "APP" updates?
"The two apparently were manufactured within 3 months of one another." I'd say 9 months. The firmware revision from 2.2 to 3.0 is the 3 months you mentioned and from what I could gather ( which may or may not be correct) mainly changed the algorithm for handling carryover and unless you're without a lock for a long time you'll not notice any real difference. I wouldn't worry about it. -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] 9390 GPS RX
On May 24th Mark C. Stephens asked: "Does the 9390-5588A have the 16.618 Mhz Vectron oscillator externaly located on one of the wire wrap boards?" Well I had to dig it out and open it up to see. Actually I mispoke when I said my 9390 had an FRK, it turned out that was another unit I was thinking of, this 9390 has an FRS-C dated 1994. I have a photo link to the innards of that 9390 and it doesn't appear to have a seperate osc like 2 of my older 9390s. I will say that other than the time display having the 1024 week error that this 9390 works quite well. http://i906.photobucket.com/albums/ac262/rjb1998/9390-5588Ainside_zps306f0a89.jpg?t=1369998545 An older 9390 I have isn't as high as the one you have but has the same height circuit boards mounted at an angle so they would fit into the smaller chassis. That unit has the somewhat standard 16.368Mhz OXCO with cable going to the receiver board. Power supply problems in this 9390 just like yours except this p.s. is a sealed unit. http://i906.photobucket.com/albums/ac262/rjb1998/9390older_zps9f9a7bd7.jpg?t=136195 The oldest unit I have is a much higher unit and has larger circuit boards and lots of interconnecting cables and that one has never worked and maybe some day I'll get a chance to look at it but as a practical matter it probably isn't worth the effort. The link below has a photo of the oldest big 9390 and to the left of it you can see the height of the 9390 with the slanting circuit boards. http://i906.photobucket.com/albums/ac262/rjb1998/9390oldest_zps391f0130.jpg?t=136230 As I said it appears that the 9390 model number covers a wide range of different configurations, styles, and dates and they were almost all one of a kind units. This makes getting a manual for a particular unit difficult. -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] 9390 GPS RX
I have owned a similar 9390-5588A with the FRK Rb inside for a few years now. Although the Rb is quite old, the unit locks in just 3 minutes and finds the GPS time (off by 1024 weeks, 16 sec, UTC) in four minutes and displays an initial PDOP 03. I have reset the time to the correct UTC time but after a short period it always reverts to the original time. If I recall the antenna voltage was +12vdc and I traced the line and reconnected it to +5vdc. The antenna is roof mounted and runs through a Lucent GPS ant amp/5-way splitter. I don't recall which ones it was now but I did have a problem with 2 of these old GPS receivers on the same antenna, apparently reradiating enough of a signal from the LO or whatever so that it knocked the other receiver off line. My version of this vintage 9390 has an added switch on the front to choose where it gets the 1PPS signal to compare and it has both an a.c. and a d.c. supply. From what I have seen almost no 2 of these units were exactly the same so it is hard to find an exact manual and I don't have one at all so it made setting this unit up kind of difficult. The circuit boards directly in front of the FRK use wire-wrap connector so they could customized these units for each end-user. -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] Lady Heather numbers
>Garren Davis garren.davis at qlogic.com >Tue Mar 12 12:55:48 EDT 2013 > >I found the 1 ohm resistor from the 12 volt pin to the heater circuit >popped off its solder pads and was laying between the insulation >and the metal enclosure. ++ You might want to check the 2 photos and the description of the OXCO I posted on Wed Feb 27 14:09:01 EST 2013 to give you a visual of the innards. Photo links are repeated below. -Arthur http://i906.photobucket.com/albums/ac262/rjb1998/OXCOinside1_zps02c43ce6.jpg http://i906.photobucket.com/albums/ac262/rjb1998/OXCOinside2_zps2b758675.jpg ___ 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] nteresting looking crystal on ebay
>That's one of the better ones - clip mounted. Here's a better view of the innards where you can see the wire from the XTAL to the green support soldered at both ends. Below the support the wires are spot welded. http://i906.photobucket.com/albums/ac262/rjb1998/Blileyxtal2_zps9c0dacb1.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] Interesting looking crystal on ebay
>This style of crystal was quite common at one time, and yes, it fits a >valve base but it's for a B7G 7 pin base, not B6G as suggested in the >auction. The XTAL is a Bliley BG6 which has nothing to do with the number of pins. The link below is a photo I just took of a Bliley BG6 series with 2 wire leads. This is a 5000.000KC (Khz came much later) replacement for the GR1113 standard. http://i906.photobucket.com/albums/ac262/rjb1998/Blileyxtal_zps55b52920.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] Nortel EBSCTM-C / NTPB15AB-05
>Has anybody traced out the connections on the DB-37 connector on >the back of this beast yet? I never looked at the 37-pin connector on the back of the unit but back in December, 2012 I did post that I had added a display and an A.C. supply to the one I had and it seems to be working fine. I use LH to control and keep track of how it's doing but as others have mentioned, not all the set-up data you tell it to save gets saved. The link to the photo I'd previously posted is below. -Arthur http://i906.photobucket.com/albums/ac262/rjb1998/NTPB15AA05.jpg ___ 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] Lady Heather numbers
There has been a lot of speculation about the innards of the OXCO in the Thunderbolt so here is what I found inside a dead one that I opened. I didn’t trace the circuit out so most of the description that follows is just from a cursory look and may not be totally correct. Below are links to a couple of photos of the oscillator board. The OXCO in the Thunderbolt (Trimble 37265) is a single oven unit. The circuit board is mounted on the connection pins and has fiberglass mats on top and bottom for thermal isolation. There are two +12VDC input pins, one for the oven and the other for the oscillator power. The +12V pin for the oscillator goes through a 1 ohm resistor to a 8L08A 8V three- terminal linear regulator which powers the oscillator and most of the other electronics. The ‘heater’ that is powered by a separate +12V pin is a 2N4921 transistor mounted on the copper block with the crystal and the thermistor. There is a diode between the input pin and the transistor for reverse polarity protection but not on the oscillator input pin. From reading some of the past post about people connecting the power to the Tbolt incorrectly, this would explain why the heater still works but there is no output. The 1 ohm and/or the 8L08A are destroyed while the heater circuit was protected. Other stuff on the Tbolt board probably gets destroyed as well. The crystal is marked OFCG-P, Div of Oak Ind and this one is marked 86.3C for the temperature. The oven controller is an LM358 dual OP-AMP and there is a 10-turn pot that I believe sets the oven temp. It looks like the 10Mhz output goes through a couple of transistors, a transformer, and some L-C stuff before going to the output pin. There is a SOD-323 device marked VD1 which may be a BB639 varactor for the EFC adjustment. -Arthur http://i906.photobucket.com/albums/ac262/rjb1998/OXCOinside1_zps02c43ce6.jpg http://i906.photobucket.com/albums/ac262/rjb1998/OXCOinside2_zps2b758675.jpg ___ 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] altinex switches
I haven't looked any further but the daughter boards in the unit have 75 ohm resistors which I'm guessing determines the input/output impedance of the unit. If that's the case it should be easy to switch it to 50 ohms although it may not make any real difference. -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] GPStar Plus: Rubidium, anyone?
Despite what has been previously posted I’ve found my 565s to be very good frequency references for my counters and they seem to compare well to the Thunderbolts. I haven’t run any long term checks but comparing Tbolts to 565s on my scope from time to time I’ve never seen any jumps or significant frequency drift (at 5ns/cm). The 565s generally report parts in E-12 to E-14 depending on conditions. In regard to replacing the crystal oscillator with a rubidium, I tried that once using an X72 and wasn’t impressed. It worked o.k. but as you can see from the manual specs below the only gain would be during long periods of signal loss or ‘coasting’. As long as you have a signal the average accuracy will be the same and I feel the OCXO could possibly be a little less noisy and perhaps have better short term stability although I never checked it. -Arthur 565 (High Performance Quartz) Accuracy Error Time Locked1 X 10-12 (1 day average) Coasting. 5 X 10-10/day (Rubidium) Accuracy Error Time Locked1 X 10-12 (1 day average) Coasting. 2 X 10-11 /day ___ 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] altinex switches
I just bought the last one at 11:30PM. -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] Low noise power supplies?
>But the only NiCd I know about are the AA sized ones. I have some of the wet NiCd batteries that are capable of putting out 200A continuously. I'm assuming the internal resistance is pretty low. ;-) 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] MTI 260 Stability Plot
>Has anyone run a stability plot (0-100 or 1000 seconds) on the MTI 260.. There are several sub-models of the 260 in either AT or SC cuts with widely different characteristics. It might help to know which one you have. The ones on the popular auction site may be custom built units. Try checking the info at: http://www.mti-milliren.com/pdfs/260.pdf -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] Serial port / Mouse issue (was mentioned in"Thunderbolt Monitor")
Besides the previous mentioned Time-Nuts reference in this thread to the so-called "psychomouse" problem on November 1, 2010 there was a thread on November 29, 2011 entitled "Unplug T-bolt before booting up...??" that had most of the information covered here. Although this problem has been known for years I still haven't made the change to the laptop I use for testing Thunderbolts and have gotten used to the occasional surprise of watching the mouse cursor dart all over the screen. ;-) -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] Interval Timer Recommendation
>> The manual states that loosing the settings on a 6680 is no big problem , >> but on the 6681 you loose the interpolator calibtation. And it sounds >> like that's not a good thing. >> I didn't know you had to watch out for Battery on a PM6680/81. >> >> CFO - Tnut-Beginner >> Denmark The battery in the 6680 is just a CR2032 with legs so it isn't a big deal to replace it. Attached is a photo showing the 6680 battery in the lower left corner of the photo with the yellow plastic around it for those who would like to see what would be involved in changing it. Both the 6680 and the 6680B counters that I own have batteries that have been in at least 6 years and both batteries still read very good so replacing them isn't something you would have to do often. If you use the math or any of the other functions where you store a series of steps to recall later, the battery backed up memory is quite handy. The 6680 in the attached photo is a little different than most because it has a Datum/Symmetricom X72 rubidium oscillator I installed for the internal time base. -Arthur http://i906.photobucket.com/albums/ac262/rjb1998/6680battery_zpsb93793b7.jpg ___ 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] time-nuts Digest, Vol 101, Issue 152
Bob Camp- "A quartz crystal in insensitive to magnetic field. This being Time Nut's that's not the whole story. Ferrite core inductors can indeed exhibit a bit of static mag field sensitivity. Your OCXO may or may not have some in it." "Precision crystals have clips made from nickel. The posts are likely Kovar. That's been true for a *long* time. Neither one is very magnetic. Both likely are hard enough to be even less magnetic than they might be." +++ I've had a Manson Lab RD-180 running for about 35 years other than short down time to change batteries. I've always kept it oriented in the same direction once I initially adjusted it because I had read that the earth's magnetic field would cause a small frequency shift in the crystal frequency. I took this at gospel and never looked into the subject any further. After seeing this thread (that has now lost it's original title) I did a quick search and found plenty of references including this one that goes into detail about testing that was done to quantify this effect. The section "VI Conclusion" is a good summation. http://www.ieee-uffc.org/frequency_control/teaching/brendel198.html -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] Nortel NTPB15AA (Trimble) GPSDO
I picked up one of the Nortel NTPB15AA (Trimble) GPSDO from the common auction site and decided adding a monitor display to the front panel would be a good idea. The entire unit draws about 300ma at 48vdc at power up and there is room inside the case for a small AC power supply. There is already a switching triple output dc-dc converter so I'm not too worried about added noise, at least for my application. This will make a nice self contained package that I can use to supply 10Mhz to my counters. There is a link below to a photo of the unit with the added monitor to show what it looks like. -Arthur http://i906.photobucket.com/albums/ac262/rjb1998/NTPB15AA05.jpg ___ 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] Thunderbolt oven / non-stable operating temperature
I believe that the high temperature alarm you see is triggered at 50 degrees C. If that is what you're seeing without artificially raising the temperature of the Thunderbolt by insulating it so it can't radiate the heat, what I said about replacing the chip is correct but if it is staying within a few degrees over the course of the day and is in the 40 degree C range without being insulated, the DS1620 thermometer chip is o.k.. -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] Thunderbolt oven / non-stable operating temperature
>I feel like shouldn't need to fuss with ambient conditions this heavily >for an OCXO, and find myself researching construction / design for a DIY >outer-oven to wrap the thunderbolt in. > >Anyone have experience with non-stable temperature on a trimble thunderbolt?" The temperature you see is not from the OCXO but from the thermometer chip near the RS-232 connector. The DS1620 is probably at fault and the rest of the Thunderbolt is operating as it should. I've see a lot of Thunderbolts and the most common failure mode of the non E revision DS1620 thermometer is for them to display -55 degrees C although it could just have erratic output like yours. The erratic temperature that it is reporting could cause the processor to try to compensate for the erratic jumps and cause the Thunderbolt output to be less stable. The DS1620 should be replaced. -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] GPSDO Alternatives
>On Mon, Dec 4, paul swed wrote: >Yes sir $139. But boy I have not seen cheap tbolts in bit. As I recall >$260 these days? > >On Mon, Dec 3, 2012 at 9:12 PM, Bob Camp wrote: > >> Hi >> >> The gotcha is that you go from paying surplus prices to paying new prices. >> New price to new price, they certainly are cheaper. Not so easy to beat a >> $100 TBolt on price (if you can find one). >> >> Bob >> Comments like these make me smile because they're kind of like the ads you used to see for buying $50 jeeps from DOD. Yes, someone at some time in the distant past had probably bought one jeep for $50 but these ads continued for decades like urban legends and a lot of people believed them. As to Tbolt prices, over the past year or so I had sold close to 200 Tbolts on the popular auction site at $170 each so I have a pretty good idea what the market was like during that time. All the Tbolts I had were removed from the original equipment and tested by me so all the units I sold were clean and worked exactly as they were intended to work. If you watched the price of all the Chinese dealers over this same period last year they all went up in unison, first to $189, then to $260 as Paul mentioned above. What you would have noticed if you checked the actual units sold is that they were not selling any at those prices but buyers were getting their Tbolts from me instead. I suspect that all the Chinese dealers are basically store front resellers for some distributor who set the price. As others on this list had commented, the condition of some of the electronic parts from China indicate that these parts like Tbolts and OXCOs were removed at some scrapyard by someone who didn't know or care what they were but was only interested in throughput and the parts were thrown into bins for later distribution and sale. Check the photos of bent and/or rusted OXCOs for listings 170950828042, 170558942064, and 300579197899 to see what I mean. -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] Z3801 Replacement GPS Receiver Card
>>> The GPS receiver in my Z3801 has died and I need to replace it. >> Go to ebay and type "oncore" in the search box. There are MANY available >> starting at just about $20. >Search for "oncore vp" (which is what a z3801a needs), and you won't >find ANY, at any price. On Ebay rdr-electronics has a 6-channel VP for an opening bid of $25 plus shipping. Check Item number 360488854495 that ends in 2 days. Read the listing to see if this is what you need. I've bought many items from this seller and never had any problems. -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] 60 Hz line quirks, anybody recognize this stuff?
> IMO, you have an instrumentation issue. I don't think the power grid can > do anything like that. > > YMMV, > > -John I agree. If this was happening on the grid by the time this blip had traveled down the line to you it would have been so filtered through transformers and other devices and you wouldn't see sharp edges on the waveform but see a slightly rounded distorted waveform, not the sharp transitions you are seeing. If it isn't your test equipment then it is still something local to you like a loose electrical connection in your house momentarily causing your voltage to drop and then it arcs to reconnect the power. If you use an AM radio (not use a radio in the A.M. ;-) ), you could hear this as static or clicks as you observe this waveform on the screen. -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] oscillators
>I don't know that there is any data showing the TBolt adjusting for aging >during holdover. In other words: showing the holdover DAC voltage changing >at a completely constant temperature. > >Bob I haven't seen any data either but here is information from section 5.1.2 of the 2003 Thunderbolt manual: "Kalman filtering is a technique that improves the performance of a GPS disciplined clock when GPS drops out. This state is called holdover. During holdover the clock relies solely on the oscillator. Oscillator performance is subject to two basic effects. First, changes in environmental temperature can cause the oscillator to speed up [or] slow down. Second, the oscillator has a natural tendency to drift over time. This is called aging. Both temperature and aging can be mathematically predicted. However, the characteristics vary from crystal to crystal. The Kalman filtering monitors the unique oscillator performance over time and temperature and records this behavior. Then when the clock goes into holdover this filtering corrects for these effects producing a more accurate clock. The longer a clock has to ’train’ the better the Kalman filtering performance will be. 24 hours is considered the minimum necessary for good performance" -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] newbie question Thunderbolt supply
> >I think I remember comments about it being used by the DAC. Wasn't there >some mention of the TBolt working with a dead -12 supply, but only as long as >the DAC output was above 0. > That was the conclusion. Actually the units these Thunderbolts were removed from used -7VDC instead of -12VDC. Many Thunderbolts will operate with the -12VDC line grounded but it shouldn't be left floating. It wouldn't be a good idea to run the Thunderbolt without some negative voltage on this line and where it's easy to find a triple output supply, why take the chance. The +12VDC is mainly for the oven and internal to the OXCO it goes to a +5VDC linear regulator for the oscillator circuit so the +12VDC isn't as critical as the +5VDC. -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] T-Bolt Temperature
>Hi: >What is the temp chip reading? Is it reading the oven temperature or just >the ambient temperature? >Ron > The DS1620 thermometer chip is in the corner of the pc board next to the RS232 connector and diagonally opposite the OXCO so it reads ambient temperature. -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] Z3815A Internal SMA 10Mhz Output
> >Not "every" GPSDO has a 10MHz OCXO. > That is certainly true although from a time-nuts point of view, 10Mhz is certainly a very nice number. I have linked to a photo of both sides of a Trimble 1.5"x5" GPSDO built about 2008 that has a 1" square Trimble branded OXCO that has a 76.80Mhz as well as a 1PPS output. It requires 3.3VDC for power. http://i906.photobucket.com/albums/ac262/rjb1998/Trimble76_80.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] T-Bolt Temperature
>Do you know the part number of a chip to replace the DS1620? The part number is the same, DS1620. What is important is the revision of the DS1620. When Dallas Semiconductor/Maxim 'improved' the chip and went from REV-D (or D2) to REV-E they made a change in the way the data was sent to the outside world. Lady Heather displays the temperature from REV-E chips in distinct step instead of a smooth curve. I have used REV-C2 chips as replacement and they work just fine. Note the chip revision has little or nothing to do with the Trimble REV letter on the outside of the Thunderbolt case, the latest Thunderbolt revision from 2005 just happens to be a REV-E. -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] T-Bolt Temperature
>I have two Thunderbolts that I'm monitoring with >Lady Heather. The temperature on the older unit >(MFG 2/26/2004) seems to track the >environment. The newer one (MFG 11-24-2004) >shows 44.75 °C and only changes in increments of exactly 1°. All REV-E Thunderbolts with date codes after about mid-2004 used the DS1620 "E" chip and have this problem. Buyers have been told and believe the REV-E units are somehow superior to previous revisions so they will ask a known problem unit. I think they have seen articles on the internet that show really old units with the noisy Piezo OXCO and somehow believe that only the REV-E Thunderbolt has the newer Trimble OXCO, which is not true. After about 2001 all REV-A through E Thunderbolts had the new Trimble OXCO. I doubt you could find any with the older Piezo OXCO now. As far as I know there is only one U.S. seller of Thunderbolts on Ebay that replaces the DS1620 in these affected REV-E units with one that will display correctly with Lady Heather. I've heard several stories from buyers who have bought problem Thunderbolts from resellers, many of whom don't do any real testing to see their units work properly or are stable. Ask questions before you buy. -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] Thunderbolt GPS and frequency divider loading question
>I'd put the distribution amplifier between the TB and the divider > >Dave > The units that these Thunderbolts were removed from solved this problem by feeding the 10Mhz output through a power splitter. One output from the power splitter went to a 2-way distribution amplifier and the other went to what apprears to be a synthesizer module. -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] Morion MV89A pics
>Hi > >I do not believe FE owns Morion. The most certainly own space in the Morion >factory. Last time I was there I saw the space. > >Bob 'Own' may have been too strong a word but FEI is invested in Morion and the FEI site doesn't describe Morion as a wholly-owned subsidiary but one of its "Affiliated Companies". Either way the photo I posted show that the FE-489A has an identical oscillator to to the MV89A, or would you say 'similar'? ;-). -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] Morion MV89A pics
I just got an DOXCO made by Frequency Electronics, Inc., so the first thing I did was remove the screws from the outer cover to open it up and check out the insides. Once I removed the foam so I could see the oven, I had the feeling of deja vu. but I'd never owned one of these units before. I realized that it was exactly the same as the oven inside a Morion MV89A that I've seen on this list and where FEI apparently owns Morion it wasn't too much of a surprise. The OXCO part number is FE-489A which is pretty close to the Morion MV89A part number as well. Attached is a photo of the FE on the left and the photo of the Morion from this list on the right. http://i906.photobucket.com/albums/ac262/rjb1998/FE-489A89A1024.jpg Here is a view of the entire board which has a DB-9 connector to connect to the outside world. In the foreground is the output which converts the 5Mhz output of the oscillator to 15Mhz that goes to the SMA connector. The size of this OXCO is exactly the same as the 5650A rubidium oscillator by FEI. Adjustment may be digital and/or analog. . http://i906.photobucket.com/albums/ac262/rjb1998/FE-489A606-1.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.
