[time-nuts] Symmetricom/Datum FTS-1050A Disciplined Frequency Standard (long time constant loops)
Speaking of long time constant analog loops for oscillator disciplining, see the attached PIX of the loop filter module from an FE AN/URQ-23. Also a PIX of the schematic. It is switch selectable for 1 or 100 Second time constants. I is also hermetically sealed to prevent leakage effects as it uses a 2500 MegOhm resistor! The Op Amp used is an AD515K. I've played with it in the loop of an HP5065A. Cheers, Corby___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Regarding HP 5065A upgrade to 10811-oscillators
Hi, The -60109 usually does have the very good short term stability at short Tau but to actually use it you need to go open loop on the 5065A or 5061A/B. In closed loop the instrument actually drives the stability and pretty much any 10811 variant will work. HP knew this and recommended going open loop to test stabilities at the shorter Tau. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] HP 5065A, no 2nd harmonic.
With that offset either the oven set point has changed or there has een a component value shift in the oscillator circuit. The easiest way to test is to stick in another 10811 if available. You could also install one of the original 105 style oscillators if you have one. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Re: HP 5065A, no 2nd harmonic.
Jared, You have to be within .25Hz so yes I'd say that's most likely your problem! Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] HP 5065A, no 2nd harmonic.
Jared, There is a non-hermetic electrolytic cap in the A7 (100uf C3) that if it leaks can "eat" the lead or trace off killing the gain.. Pull the A7 and take a look at that. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Fw: HP 5065A, no 2nd harmonic.
Jared, A few things to try. On the bottom of the chassis Connect a scope to A8 pin 9. You should have a 137Hz (approx) sine wave of around 200mv P-P. If OK on the bottom of the chassis then connect the scope to A7 TP2 AC coupled. In open loop and with the 5Mhz within .1Hz you should see a signal that will vary from fundamental on each side to a 2nd harmonic when exactly on frequency. (between .5 and 6VP-P.) If you see it then switch to operate and see if the control voltage reading will follow if you move the fine Quartz adjust back and forth. If yes then the A7 2nd harmonic channel is most likely bad. If you don't see it then measure the DC voltage at A3 TP2, it should be > 4.5VDC. If not make sure the 5Mhz into A3 is correct (1VRMS). What is the serial number of the mainframe? Good Luck, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Passive Maser teardown
Subject: Passive Maser teardown Just added "update 5" to http://www.leapsecond.com/maser/ It gives details on "digging down" to the cavity of the Maser. Cheers! Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] HP 5061 mini tube retrofit into 5071A part 2!
Hi! Here is part 2 of the notes for installing HP 5061A/B "mini" tubes into the 5071A. Cheers, Corby eepromnotesb.docx Description: MS-Word 2007 document ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Noise floor test of my homemade DMTD
Tobias, To get accurate noise floor at the lower Tau you need to make sure your delay between each channel is set to as close to zero as possible. A variable phase shifter or various lengths of cables/connectors will work. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Primary frequency standard
In reference to: "It would be cool to say one has a "primary standard", So, I think we should be careful with the term, it's get thrown around too lightly." Any of the hobby grade used Cesium standards is actually a Primary frequency standard as it does meet the definition of: A frequency source that meets national standards for accuracy and operates without the need for calibration against an external standard. They ARE able to meet their accuracy specs without calibration against an external standard. The definition does not exclude them. I realize that Metrology usage may be different but the definition makes no judgement as to how performance levels! Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Need wires from scrap HP cesium tubes
Working on a project and need the following. The HP high stability tubes have a pair of violet and violet/white wires exiting the potting that have the nylon push on connections. These were for the degaussing connection. I'm looking for 3 more sets of these wires. I do have a big pile of dead tubes but only managed to find a few of these. Anyone have some dud tubes laying around they could cut them from? I'd pay $5.00 + the shipping for each pair. Thanks for your help! Corby Dawson ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
[time-nuts] Better than average Rb oscillator
Skips data is very nice! But speaking of dropping into the -14ths, the HP 5065A is hard to beat. (Unless you are fortunate enough to have an 8607 option 8 sitting in your lab!) The Yellow trace on the attached comparison plot is my 5065A, it's a really excellent performer and drops into the -14ths between 64 and 100 Seconds. A simply good performer will usually reach that level by 128 to 256 Seconds. This of course if the unit has been aligned and optimized properly. One thing this means is unless you have a good Maser or another good 5065A it's really hard to test the 5065A performance! Cheers, Corby___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Interesting widget for 5MHz standard fans
Walter, The widget is a module from the FTS 4050 series of Cesium standards. I have a couple of these modules. Schematics are in the manuals. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] A SIMPLE TIME INTERVAL COUNTER FOR DMTD WORK + Simple Dual Mixer
For some DMTD stuff on EEVBlogForum: https://www.eevblog.com/forum/metrology/dmtd-board/ https://www.eevblog.com/forum/metrology/dmtd-tutorial/ And lastly, https://www.eevblog.com/forum/metrology/a-simple-time-interval-counter-fo r-dmtd-work/ Many Thanks to Tom Van Baak for his help with this project! Cheers, and Happy New Year! Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Happy 20th Year
Thanks for the work in keeping this valuable resource up and running! Much appreciated. Corby Dawson ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Holiday Hydrogen Glow!
And here is an EFOS2 Maser glow. Happy holidays, and Merry Christmas! Corby___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP5061 Cesium ion pump question
The gettering in the tube is only for capturing any stray Cesium atoms that don't get caught in the main gettering patch. If the gettering fails or gets too loaded up then the Cesium background level will get too high causing poor SN. The ion pump is for any gases. When a tube is off for extended times any gas atoms lingering or leaking slowly into the tube than happen to impinge on either the mass Spectrometer filament or the Cs oven filaments get capture by the filaments. They function as excellent getters! (this even if the ion pump is on) Now this is not by design but results in the filaments being "loaded" with the gas atoms. Then when you turn the tube on the filaments light up and expell a burst of gas. This of coarse causes the ion pump current to rise and trips off the filaments, Once the ion pump removes the burst the cycle repeats until the filaments have expelled the trapped gases. Then the ion pump can handle the load and pump the tube down completely. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP5065a cfield issue
Paul, One other thing to check. Put a DC coupled scope on the C-field pot wiper and rotate the pot back and forth. Make sure there are no jumps or noise. Sometimes the pot gets noisy in a section. Rotating it back and forth across the bad sections will usually clean it up. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP5065a cfield issue
Paul, C-field current is adjustable from 2.5 to 6ma. I use a clip on milliammeter. Also you can kludge in an HP 3325A/B in place of the A1 synthesizer to see if that's the problem. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Early Christmas - DMTD up and running
Skip, Nice! Now you can go down another rabbit hole!!! Nothing fancy is needed for noise floor DMTD tests! Here is a PIX of what I use. - A passive SMA power splitter - a couple short SMA cables - an assortment of sma M to SMA F adaptors (elbows work nice) - A variable phase shifter from an HP 8405A (You can manage without it!) Feed a good oscillator into the passive power splitter. Connect the two outputs to the inputs of the DMTD unit. Observe the count from your counter: -If it's near full scale switch the start and stop cables at the counter and or switch the RF input cables. Once you have a count that is in the low end of the count insert a very short cable or SMA connector into one or the other RF input channel of the dual mixer. Inserting the short delay into one of the channels will cause the count to drop. Continue adding small delays to that channel until the count underflows to the full scale region. Then remove the last delay added. Then make sure all SMA junctions are tight Now go ahead and take data to get your noise floor. Take data for an hour and avoid drafts and movement around the system. Cheers, Corby___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] "When you google word ..."
Also when you google "alien deviation" you get: About 11,800,000 results (0.50 seconds) Cheers! :>) Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Query about insulated coax panel connectors
The 106D DMTD unit was designed by NBS (now NIST), and the BNC connectors I mentioned were also isolated from the chassis. The shield side was bypassed to the chassis ground inside via a 50 Ohm resistor and a .1uf capacitor. I retained those when I converted to isolated SMA. The center pin and shield were then sent via coax to the various points. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Query about insulated coax panel connectors
Hi, My NBS 106D DMTD originally had all BNC connectors but after finding out BNCs are not the best for DMTD units I retrofitted it with insulated SMA connectors. I used nylon washers on both sides. See PIX. Cheers, Corby___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] 5065A Rb Cavity RX - Varactor repair
If the unit fails again just diconnect the 60Mhz output jack from A3 and Ohm from the center pin to shield on the cables connector with a semiconductor setting on the DVM. Try both directions as the diode can be installed either way. If you can "see" the diode that way it is most certainly good. If not the there are 3 SMC connectors in the route inside the cavity end. Check those for tightness. The diode is NOT easily accessible although the whole cell assy screws out easily. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] 5065A Rb Cavity RX - Varactor repair?
Ulf, I have never had a 5065A with a bad or malfunctioning step recovery diode in the physics package. MANY other problems are more likely the cause. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Help getting 53131A to talk over RS232
I have done this before (years ago) but now I can't seem to get a count out over the RS232 port. I scoped pin 2 (pin ground) and can't see any data no matter what I try. I seem to remember a "secret" trick from back then but can't recall it. I'm counting time difference between two 1PPS signals. Please Help!!! Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] BVA 8600 Available for sale: Link to Dropbox photos/ADEV plot.
Jorge, The longer Tau (BLUE) was measured against an excellent HP5065A Rubidium. The shorter Tau (Red) was measured against an excellent FTS 1200 Quartz. Hope that helps. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] FE-5680A Comm question!
Thanks for the inputs! I downloaded RealTerm and I could (eventually) get the unit send a response but could not get it to change frequency. Then I noticed you have to send an XOR checksum byte at the end of that command! Duh. Worked fine then. Anyway I can now program the frequency in an alternate way if the VX4XV program can't be found! (Anyone know a current link to a copy?) It's a little tedious but you should not need to calibrate the unit very often! Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] FE-5680A Comm question!
Hi, I have a few FE-5680A, one version with two labels and another version B with one label. The version B can be talked to with Hyperterminal or Ruby4 and does not work with VK4XV's program. The two label version I can only get to talk with VK4XV's FE-5680Calibrator program. I found info for that version saying you can send Hex to the device directly such as 2D 04 00 29 which should readout the current offset value but I can't seem to make it talk! I tried Hyperterminal and SerialCom but no response. Is there a trick to sending HEX? Since it does talk with the VX4XV's program I know I'm connected OK. I can't find VX4VX's program online for download so need another option. Any help or ideas as how to communicate via Hyperterminal would be VERY appreciated! Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] 5065A A3 (Series 2644A) Schematic
Ulf, Here is the schematic of the late version A3. For some reason when I rotate it won't save rotated so it's upside down! When I get the parts lists and theory/alignment pages scanned I'll send them to you off list. A friend dug up a copy of my Gerber file What I think I might do is get 10 or 20 boards made and then if anyone is interested I'll sell them. That would be more convenient I think? Cheers, Corby A32644Aschematicrot.pdf Description: Adobe PDF document ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Nice FE5680A on ebay!
Hi, I just listed a nice tested FE5680A on eBay http://ebay.us/vkiYWa?cmpnId=5338273189 I have several more in testing that will be listed also. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Dead 5065A - Regarding A3 (Series 2644A)
Ulf, I can scan the 2644A schematic and parts list. It might be a day or so. I also have an ExpressPCB file of a 2644A board I made. I have retrofitted that board into several (8 or so) A3 modules. I'll also add a PIX of a partially populated one. You have the boards made with a 2MM thickness if I remember correctly. You need the frame from the old module as well as taking two of the can transformers and L13 from the old unit. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Dead 5065A - Some comments - Some questions...
Ulf, The A1 modules are most likely OK. They do not need stellar performance for the 5065A to easily beat spec. The A3 modules are another matter! If you are indeed feeding them with 1VRMS and can't get a good output at J8 then something is not right! HP made several versions of the A3, the series 2644A was the last and was completely redesigned. It is much more reliable! I've mentioned this before, the ceramic tuning caps seize up and you MUST break the rotors free before aligning the module! If you don't you will most likely break the rotor connection! If they don't turn with MODERATE pressure they need attention. If the rotor slotted shaft turns but the rotor does not it broken! Replacing them is a pain so again break them free first. Using a stiff plastic shaft lever or push horizontally at two spots 90 degrees apart listening for the rotor to "snap" free. Once you can get the proper A8 RF level the bias pot and matching network needs to be tuned. I usually just put the variable inductor slug 1/8" down from the top of the form and just leave it there. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] FE5680A comparator question
I see by searching around I see that the FE5680A uses a MAX913 comparator to square up the signal. Has anyone drawn out the schematic of how that is implemented? I want to try one for a project but the data sheet does not show examples. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Isolated +20V for lamp supply
Luciano, You should "Ohm out" the lamp connector shield to the chassis with nothing connected to the connector. Depending on how your optical unit is mounted there is a good chance the lamp assy is grounded to the chassis through the threaded stud! Especially so if the optical is the newer unpainted one. If so isolating it as you detailed does not change anything! Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Wanted: Some FE5650 or 5680A (rev B) synthesizer modules
Hi, Thought I'd see if anyone has some "dead" FE 5650A or FE 5680A (the rev B). I'm looking for a few of the synthesizer modules for some experiments. I don't need the rest of the unit. It's the board with the two tiny pushbuttons on it. See PIX. Willing to pay, but not too much! Cheers, Corby (In the USA)___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] "The Penultimate HP5065 A15"
Luciano, I agree entirely! I like the motto "do no harm"! When I try a mod such as replacing the dead op amp on the A9 board. I make before and after tests to make sure no degradation has occurred. Since this means parts in 10 -14th AD at 128 Seconds most don't have the capability. However a lot of Time-nuts can test in mid parts in 10-13th from 1 to 100 Seconds so can at least compare that part of the performance. Mods like HP made to move the bridge rectifier from A15 to the chassis can be made without such testing. That said a replacement A15 card to replace a 'Crispy crittered" or badly damaged one would be welcome. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] "The Penultimate HP5065 A15"
>> C-field polarity switch. An experiment. If nothing else >> I will be able to measure the residual magnetic field. There is no requirement to do any thing other than switch the C-field polarity. No optical stuff needed. The PRS10 switches the C-field polarity at a 5HZ rate to reduce magnetic effects and does not do any optical tricks! Back in Nov 2017 I detailed my A15 mods: Set Zener current to minimum TC (I achieved < 1PPM/C at the +20V output) This involved disconnecting the C-field circuit and replacing it with a dual (in series ) LM299AH and 1PPM resistors. Jumperable settings and a low TC pot for adjustment. I would have liked to use 3 LM299AH to give me 21 Volts but would need to switch the input to the unregulated supply to give enough overhead. The higher the voltage into the C-field string the lower the TC contribution from the C-field coil itself. The posts have the details and schematic. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Double balanced mixer question
Hi, I'm feeding 5.0 MHZ and 5.01MHz into an HP10514A mixer. A buffer and a 12dB attenuator feed each input and a 50 Ohm buffer amp (10Mhz) is on the output. I get a nice sine output but get the 1Hz as amplitude variations. Playing with input levels I can minimize the variations but the best I can get is a 3.2 V P-P with a .4 V P-P amplitude modulation. Are there mixer schemes I can use that will eliminate the amplitude variations? Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP 10811 versions for 5065A
Magnus and Tom, Thanks. I'm not (and don't want to be!) a phase noise nut! However I am an Allan Deviation nut and have documented many 5065A with the 10811 retrofit that drop into the -14ths between 64 and 128 Sec and the best show 4.5X10-14th at 1000 Sec. So I'd say the original circuit does not degrade performance that much! Unfortunately I can't play around with that 7474 stage and see if I can help performance as I not longer have access to an active Maser. :( Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP 10811 versions for 5065A
Magnus, You mentioned: "The produced noise is at least 10 dB worse than you would expect. This impacts long term stability response as I have reported earlier." Can you refer me to the info you posted earlier or elaborate? Thanks, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP 5065A Nifty A9 repair with pinout
Hi all, Attached is a PIX showing the opamp pinout! Cheers, Corby___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] time-nuts Digest, Vol 192, Issue 25
Luciano, Hi I understand your A9 is the older version like the one in my post but with the original opamp module. I tested the 5065A with an unmodified and then one with the LH156H mounted and the 24 Hour phase plots were both clean and the AD were the same. My lab is not climate controlled so it was a good environment to do the test. There would be no advantage to install the LH156H unless the original opamp fails. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] f-multipliers from VHF to 10 GHz
This NLTL is cheaper @ $2436.56! MLPNC-7100S1SMA800 Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Need a couple pages from the HP 5062C manual
Hi, I have a manual but it does only goes up to serial prefix 1836A and therefore does not have the manual changes for the 1844A series. Actually I have one page I photocopied years ago. The top of the page reads: MANUAL CHANGES MODEL 5062C and 5062C OPT. 010 Page 3 It shows steps 10 thru 23 of an alignment procedure. Bottom of the page reads: Figure 1. Troubleshooting Adjustments I need a copy of pages 2 and 4 that have the rest of the steps. Can anyone help? Thanks, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Any spare HP 5065A A3 and HP5062C A10 modules?
Hi, Doing some experiments and need HP 5065A A3 and/or HP5062C A10 modules. They are the 5 to 60 MHz and 5 to 90 MHz multiplier modules. Anyone have some laying around? Cheers, Corby Dawson ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Modern HP5065A adjustment ideas
Poul-Henning, Hi! I never use the XY method in the manual. It's much easier just to use the scope in the normal mode. I don't try to synch the scope, just use the fine horizontal control to give me a few cycles on the trace with it close to stationary (slow roll). The splitting is easy to adjust out. One trick if you run out of range on the phase pot: Insert a 137Hz signal thru a 10Meg resistor (see test cable described in the manual) into A7. Monitor the input pin to the phase detector and manually adjust the signal generator for a peak amplitude. This measures where the A7 bandpass filter is centered. Now adjust the A8 modulation frequency to match the measured frequency. This sometimes makes it much easier to adjust the phase. I very seldom measure the SN since it's met if you have >500mV at A7TP2. Also if you run an AD plot and you meet or exceed specs the SN is OK. I have seen some units with a SN of 6000! Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Crystal filters in test equipment
The hp 00105-6013 and its variants used in the older 105A, 5061A, 5065A, and a couple counters also has a crystal filter (5Mhz). I believe it's the last HP oscillator to do so. If your output amplitude seems low try tweaking the filter adjustment! Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP 106B on Ebay
If whoever bought it needs advice I have repaired a couple of them. It does not have a dewar. Both the units I worked on had low to mid parts in 10 -13th from 1 to 100 Sec. They do take 3 to 4 hours to warm up so don't be impatient. Aging wont slow down for several weeks. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Used HP 5061A cesium tube
Luiz, When shopping for a used tube look for a standard "mini" tube like the one in the ebay listing. https://www.ebay.com/itm/HP-Agilent-5061A-Cesium-Frequency-Standard-w-Opt -01-C13-Good-Working-Unit/233521981160?hash=item365efea6e8:g:HeAAAOSwY2pe Z~fB Don't trust any option 4 high stability tubes to have much life. The "mini" has the black plastic inserts to boost the diameter up to that of the original tube. Also FTS 4050 and 4060 tubes can be installed in the 5061A/B without too much work. Just remember you don't know how much life you will get from a used tube. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Pressure sensitivity of Rb vapor cell standards
Attila, I believe your original question was how to compensate for atmospheric pressure changes on the cell. It is the cell that is affected by pressure NOT the lamp! This post gives some info. https://www.febo.com/pipermail/time-nuts/2016-May/097829.html Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Symmetricom 023-63008-07 5MHz Crystal Oscillators
Bob, I just might play at the mixing to see if it will work! Hmmm, 16 oscillators give a cold current of 12.8 Amps! The direct sellers you find with Google sell them for <$20.00 each. One of them: https://www.teewtfstore.com/index.php?main_page=product_info&products_id= 244548 This seller (can't quite figure out where they are located) Seems to indicate Canadian dollars? If you buy 4 or more at $13.16 CA shipping is free. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] 5065 photo/lamp problem
Magnus, If you apply a +20V supply to the lamp connector you should see 125-150ma unlit and it drops bit when it lights. Also measure from the lamp connector center pin to the outside conductor with an Ohmmeter. You should have around 3.33K. The 1.33K resistor (in series with a 2.0K) is a common problem. it can open up or rise in value. I usually replace this resistor in units I service even if it measures good. I use a 1.3K 2% MOX resistor. Also check the approx. 12 Ohm resistor on the standoffs to see if it opened up. If you pull the lamp assy. you can place a spec-A lead and see the RF. Should be approx 88Mhz. (not critical) Once power is applied the lamp should start (cold) within a minute or so, warm it starts fast. If you place a scope on A7 TP2 and with the lamp assy removed allow some florescent lighting to fall into the interior you should see a large 50 or 60Hz signal from the light falling on the photocell. That is a quick check of the A7! Cheers, Corby Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP 5065A "known unit" update
Hi, They keep coming out of hiding! Currently my list shows 246 total units of which 26 are the latest prefix 2816A units. Anyone that has one that hasn't send me their Serial number please do! Cheers, Corby Dawson ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Need info from a very old HP 5065A manual!!!
Hi, The oldest manual I have for the 5065A is for a prefix 1220A and the oldest change it lists is for the prefix 820 units. Does anyone have an older manual that is for or lists the changes for a prefix 808 unit? Need the info for the front panel adj mag field/loop open/operate switch. All the more recent units don't have the adjust mag field position on the switch! Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Dead 5061B
Jim, The filament is a hot wire ionizer that functions to ionize the atoms in the beam so that the mass spectrometer will be able to steer them to the electron multiplier. It is a thin ribbon and not likely to be reattached once it burns open. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Cold Rubidium over hyped?
The pressure sensitivity for a classic design can easily be eliminated. I'm pretty sure that the old Varian R20 cell was mostly immune. Either using the R20 design or stiffer convex ends in a modern design would work. Also a sealed optical unit has been used to get rid of the pressure problem. Any of these methods would be trivial in a new design. The Rb/glass absorption is mostly in the lamp, when using the proper glasses in the cell and using similar lasers to what the cold standard uses eliminates that. Newer RF architecture would also help, NLDL multiplier, low noise synthesis, etc. My main gripe was that either they were either intentionally reducing the performance of their masers or using a setup that did not do justice to them. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Cold Rubidium over hyped?
Well I have been looking at the data in the https://www.researchgate.net/publication/325499937_A_portable_cold_87_Rb_ atomic_clock_with_frequency_instability_at_one_day_in_the_10-15_range link and find that maybe they are overstating their performance! In the plot of figure 5 my HP 5065A almost perfectly matches the Allan deviation out to 1000 Sec.! (Although mine does have VERY good performance) Also if you look at figure 7 all the Maser data shown seems to be from poorly operating Masers so any judgement of better clock performance versus the Masers is a bit much! The figure 5 data looks much better but still is not beating a good active Maser. The EFOS2 a 1982 vintage Maser as well as the MHM 2010 and several other modern Masers I could find data for show between 2 and 5X10-15th at 1000 Sec. The MHM 2010 specs at 5X10-15th at 100Sec and 2.0X10-15th at 1000Sec All the Masers shown are worse than that spec! Also my old Kvarz passive maser has 2x10-13th at 100 Sec just shy of matching the top two Masers at 100Sec, which I don't believe! Something does not add up in their data! So I'm not really that impressed and would take an Active or Passive Maser anyday. Just wonder if some 5065A can get so impressive that they don't just make a modern large/cool cell classic Rubidium with modern electronics technology! Certainly would be cheaper and more long lived also. Just my thoughts! Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Dead 5061B
Jim, The ion pump supply is fine if the Cs oven reading is OK. A zero reading is fine on the Ion pump current. Yes do check the ionizer filament continuity and if its OK check the voltage across it. Should be around 1 VDC. If all that looks good pull J1 off A7 and feed it into a high impedance voltmeter and redo the low freq. test. If it looks good You might have a bad A7. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Rubidium cell or lamp rejuvenation.
The following references describe the main failure mode of Rubidium lamps which is Rubidium depletion. If the thermal design is correct and the oven and supporting circuitry are working properly any condensed Rubidium will be redistributed (back into the tip-off region) during operation. On the 5065A I have seen two completely dead bulbs that were caused by Rubidium depletion. Dana, as far as why the liquid Rubidium does not appear to be moved by gravity I can only assume that surface tension holds it in place. On the two lamps I have seen with Rubidium on the surface of the bulb the Rubidium definitely melts when using the heat gun. You can see it wiggle if shaken but it will not run down into the tip by gravity. You have to heat the envelope hot enough to vaporize the Rubidium and "chase" it back down into the tip. Also I have operated several 5065A for years with the optical unit sitting vertically on the bench. This position puts the tip-off at the top and did not cause the Rubidium to migrate down into the envelope! I suspect any observed Rubidium on the bulb envelope to be caused by excessive storage temperature or oven problems. The older blue optical units are particularly prone to oven problems. Cheers, Corby https://apps.dtic.mil/dtic/tr/fulltext/u2/a494259.pdf page616 The lamp network presents a range of loads as a function of lamp mode, and the circuit has been characterized under these various conditions to ensure proper operation. Starting may require the exciter to redistribute condensed rubidium inside the lamp by rf induction heating. https://apps.dtic.mil/dtic/tr/fulltext/u2/a150787.pdf page 11 The excess metal charge is constrained by thermal gradients in the tip-off region. The tip-off is formed when the lamp is "pulled" off the vacuum manifold. The lamp envelope is mounted in a metal base with a thermal potting material. The thermal potting material facilitates the transfer of heat from the base, which is the point of temperature control, to the glass envelope. The metal atoms in the vapor are due to the saturated vapor pressure above the metal charge, which is determined by the temperature of the metal, and thus good temperature control is essential for stable lamp operation. http://www.wriley.com/A%20History%20of%20the%20Rubidium%20Frequency%20Sta ndard.pdf page 5 The classic problem with Rb lamps has been life and reliability due to rubidium depletion as the excess Rb diffuses into the glass envelope. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Rubidium cell or lamp rejuvenation. WAS-HP 5065A owners, a question!
JF, Reference your statement: "Sorry, but I don't agree with your first statement about the 5065A : after long use, the rubidium plates on the inner envelope of the lamp (like silver on a mirror) and years after years the Rb light and photo I decreases." After working on the 5065A for over 40 years and across the full range of Serial numbers and ages of instruments (somewhere over 70 units) I have only seen Rubidium plated on the inside of the bulb twice. All the other lamps provided performance that met the HP specifications. The design of the lamp assy causes the tip of the lamp to be cold compared to the bulb causing the majority of the Rubidium to condense into the tip. The two bulbs were in units where the lamp oven winding shorted and "cooked" the lamp Assy. Those two bulbs were recovered using a heat gun. I suppose if the unit was stored for years in a very hot environment the Rubidium could get out of the tip but as long as the lamps starts you can just let it run for a week or so and it will condense back into the tip. If a you have a bulb that exhibits the plating I would recommend that you measure the lamp oven temperature to make sure it is not too hot. Also the two nuts on the lamp assy. rod that protrudes out of the cover should clamp the outer cover firmly between them. The outer cover is a heat sink for the lamp assy. and maintains the Rubidium in the tip. Operating for years without this clamping might cause what you saw. Other units specifically the Efratom FRS were poorly designed and are known for this problem. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Cesium shipping exemption. (was) HP5071A with bad tube.... can I get one used?
Well I can't figure out how to attach the link but if you search for "hp 5071a shipping exemption" in google you will find : "PDF] Shipping Instruction - Cesium & Rubidium ... - Microsemi how to" Click on it and it will open a PDF of the form. You will see that it exempts most requirements, the training mentioned is reading the instructions in the form. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Rubidium cell or lamp rejuvenation. WAS-HP 5065A owners, a question!
There are two separate Rubidium migration problems. The first is Lamp flooding which occurs when too much Rubidium enters the main bulb and plates onto the bulb envelope. (usually after long storage or storage at high temperatures) This mainly in the small telecomm Rubidiums due to design flaws. The 5065A is immune to this problem and I believe the PRS10 is also. The second is cell flooding where too much Rubidium enters the resonance cell and blocks the light. This is mainly a 5065A problem although older Varian V4700 and R20 units also can be effected. The procedure in the manual cools the tip of the stem and collects the Rubidium back where it belongs! This takes about a week and then after reconfiguring the TED back to normal cooling levels another week to stabilize the Rubidium level in the cell. Telecomm units have "starved" cells and don't exhibit this effect. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP 5065A owners, a question!
Hi, How many of you leave your 5065A on all the time? Approximately how many years have you had it running without major maintenance? My current "gold standard" 5065A has been running for over 5 years. Cheers! Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Ancient HP 5065A on ebay
There is an 5065A on Ebay that has the earliest SN I have ever seen. 808-00031 or maybe 00051? Maybe the first one sold? If the lamp oven has not fried it might be a fun project. It has the Patek analog clock. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP OCXO's 10544A and 10811A
Walter, The 10811 uses an SC cut crystal and a more modern oven control circuit. Much better short term stability and warmup than the 10544 it replaced! Cheers, Corby http://www.leapsecond.com/museum/10544/1972-Oct-hp-10544A.pdf http://www.leapsecond.com/museum/10811a/90027-1.pdf ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] It is possible to "recharge" a hydrogen maser?
Luiz, Found some more info on replenishing the Hydrogen in the Kvarz CH1-76 and CH1-75. Anders had the procedure pretty close for a fully charged canister from the vendor. However recharging the original is a bit more challenging! Use care and protective gear from the high and low temperatures involved! Here are added steps somewhat paraphrased: - open up (HFO, mag-shield etc.) enough to have access to the H-canister - open the insulation around the canister and remove it from its oven. - disconnect the canister from the Maser. (Threaded connector) - connect canister to a manifold and vacuum pump and pump it down for 24 hours. - make an oven and heat the canister to 300 Degrees C for another 24 hours while still running the vacuum system - Close off valves to isolate the evacuated canister and remove vacuum pump. - Attach a hydrogen regulator set to 240PSI to the manfold and purge the lines up to the isolating valve. - Open the isolating valve and leave the hydrogen connected to the canister - the canister should get warm as it charges, you can blow cold air on it to help. - Once the cannister no longer heats and has cooled down close off the Hydrogen valve. - Also close the isolation valve to the canister. Now here I'm not sure as I would think there is a step to purge the air from the Maser lines. Not sure how that would be done? - with the canister still connected and the isolation valve closed immerse the canister in liguid Nitrogen until it stops boiling off, then wait 5 more minutes. - now while the canister is still cold remove it from the manifold and reconnect it to the Maser. (Gloves Please) At this point once the canister comes back up to room temperature you would be ready to leak test and reassemble the Maser. I'm actually working with a friend to install a new Hydrogen system into a CH1-76. NO LN2 or 300 Degree temperature involved! The new system will be outside the shield and use a commercial hydride canister. A Solid-H BL-18. Here is the rough outline for it's installation. - open up (HFO, mag-shield etc.) enough to have access to the H-canister - open the insulation around the canister and remove it from its oven. - disconnect the canister from the Maser. (Threaded connector) - mount the new fully charged canister with its attached valves on the bottom right underside of the Maser (charging the new canister is similar to that detailed above) - run the new hydrogen line to where one of the slots in the shield will be. - Screw the Maser hydrogen line onto the new lines fitting. - Attach a vacuum pump to the 1/4" hose barb on the purge valve - Run the pump and open the purge valve. Wait 20 minutes to purge the line. - close the purge valve and remove the vacuum pump - Open the canister valve to allow Hydrogen into the Maser. - leak test the lines and reassemble the Maser. Pictures and more details will be showing up in the EEVBlog Metrology forum. Keep in mind that since you have more room in the CH1-75 you could probably install a small compressed Hydrogen bottle and regulator instead of the Hydride storage outlined! Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Is the lifetime of a Rb standard dependent on operating orientations
Hi, At operating temperature the lamp, filter cell (if used) and the resonance cell only have gaseous Rubidium in them. Only exception is early designs that have a "stem" on the resonance cell that exits the cavity. There is a small amount of liquid Rubidium in the stem and in the 5065A a thermoelectric cooler is used to set the amount of Rubidium that eventually enters the cell. No orientation problems an any Rubidium standards due to "puddling". However if a 5065A is stored for MANY years or stored at an extended period at high temperatures more Rubidium than desired can "flood" the cell. At operating temp it's still pretty much a gas but too much in the cell makes it opaque to the required light from the lamp. HP describes a routine to deflood the cell if that happens. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] EFOS Maser prototype display
Check the picture out here: https://www.eevblog.com/forum/metrology/efos-maser-prototype-in-museum-di splay/new/#new Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Used Hydrogen Maser
Perrier, Hi! Depends on the type and model, Active or Passive Maser etc. I believe new active Masers run in the 1/4 million dollar range. T4 science offers some nice Passive Masers but I don't know the cost. pH Maser 1008 https://www.t4science.com/products/phmaser-1008/ On the basis of just a few examples (they are very rare) a used active Maser can be found for 30-40 Thousand dollars. This for a demonstrated working unit less transport costs which won't be cheap! Expect to pay $1000.00 every 4-5 years on ion pump repair, electricity costs for 24/7 operation, air-con costs to keep it happy, cost of a vacuum turbopump station and ion pump controller for the ion pump repairs. (and don't forget a place to park a small refrigerator sized instrument.) The older Masers are more serviceable than some newer vintages, however getting some specialized parts may be impossible. Some newer Masers use getter packages as the main Hydrogen waste pump and make it very difficult to service the vacuum system. Also some do not make provision for easy field replacement of the ion pumps. Hope this helps and good luck on the lottery! If you do win I would suggest the MHM 2010 https://www.microsemi.com/product-directory/active-hydrogen-maser/4123-mh m-2010-active-hydrogen-maser Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] It is possible to "recharge" a hydrogen maser?
Luiz, Ch1-75 Hydrogen storage details. The compound LaNi5H, is used for storing molecular hydrogen. The LaHi5H, is characterized by high hydrogen partial pressure (2 to 5 atmospheres) at +(20-50) degrees C. 250 grams of the compound contains 18 liters of hydrogen at normal pressure. It is sufficient for maser continuous operation for more than 40 000 hours. I believe that the container holding the LaHi5H is heated and thermostatically controlled to maintain the proper pressure into the purifier. First you should be able to power up the maser just far enough so that the ion pumps can operate. Monitor their current and it should drop down to almost zero within a few hours. If not you may need to get the ion pumps rebuilt. There are commercial outfits that can rebuild them but if there are not isolation valves to close and isolate the Maser when you remove the ion pumps you will not be able to proceed! Since the Russian Masers also use a getter pump in concert with the ion pumps, opening up the vacuum system will contaminate the getter pump. The process of clearing the getter is very detailed and involves temperatures of up to 800 degrees C, and without careful instructions on how to do it you risk damaging other portions of the Maser! If the pressure does drop down, then you need to determine if there is any Hydrogen left. I know that some Russian Masers will give you an alarm that tells you if you are out, and some have a mechanical pressure gage, but Im not sure about the CH1-75. You will need to check the manuals. If it does not provide an alarm or have a gage then see if the HFO oscillator is working and if the discharge bulb is lighting up. If it lights up you are not out of Hydrogen! If it does not light and you have determined that the lack of Hydrogen is indeed the problem you will need to locate the LaHi5H container. After you locate it make sure it is being heated, this could cause an apparent lack of Hydrogen! Then see how it is connected to the discharge bulb. Hopefully it will be a threaded connection. This connection is on the high pressure side of the purifier and can be removed without compromising the vacuum. You will need to remove the container and recharge it. I would instead replace it with a small compressed hydrogen cylinder and regulators. Use ultra-high purity dry Hydrogen and make sure you purge the line going to the purifier. The purifier will block other gases from getting into the Maser but in the process too much foreign gas can contaminate and damage the purifier! Once you manage to locate the container some pictures on where its hiding would be nice! Good luck with your efforts! Cheers, Corby Dawson ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Are there any company selling refurbished/reconditioned Cesium tubes?
When evaluating an instrument with a used tube the beam current is not the best indicator to look at! For an HP instrument If the tube label has the EM voltage listed then with the beam current set to it's proper level check the current EM voltage. As the tube ages you will require more and more EM voltage to bring the gain back to nominal. Also performing a SN test on the tube or even a quick look at the peak/valley/background levels is helpful. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] It is possible to "recharge" a hydrogen maser?
Luiz, Once I know the model number of the Maser I can give some advice. I recharged the Hydrogen bottle of the EFOS2 Maser 4 times in the past with no problem. Really depends on the method of Hydrogen storage and if they made provision for field repair, I.E. threaded fittings vice welded joints. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Frequency Standard in personal lab
Taka, I'm assuming you meant an HP 53132A? Anyway to make meaningful measurements you need a DMTD setup or some other resolution expanding scheme. An HP 5065A would be your best bet to add to your stable! Between a good cherry picked Quartz and the 5065A you could cover most bases easily! Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Neat looking DMTD unit on eBay
Hi, A friend directed me to this listing. Nice looking DMTD unit. Low power and compact! Has anyone played with one of these yet? https://www.ebay.ca/itm/123728915157?ul_noapp=true Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Passive Hydrogen Maser
Anton, What you describe sounds promising however more info would be needed to troubleshoot. Not sure what monitoring provisions the CH1-76 has, I think there are a couple time-nuts with that unit that could comment. There are a lot if causes for a loss of IF in an active Maser and a few extra thrown in with a passive Maser! Good Luck! Corby Dawson ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] GPS week rollover
Are we expecting any week rollover problems with the receivers we time nuts like to play with??? Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Help needed with Tracor 308A Rubidium Frequency Standard
Heinz, The relay you hear "clicking" is the relay that generates the HV start pulse for the lamp. Once the lamp starts and is detected by the preamp circuit the relay stops cycling. You can pull the OMU and leave it connected up. Pull the covers off the lamp end of the OMU and the metal rectangular cover screwed onto the lamp module. You will see a cylindrical HV pulse transformer. Lay an insulated screwdriver touching the lamp module case so that it comes very close to the HV stud of the TX. You should see a spark every time the relay clicks. Forcing this spark sometimes will sometimes start the lamp for you. No spark troubleshoot the circuit that generates the pulse into the TX. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP5065A on eBay WARNING
Hi, Wanted to warn about the 5065A that has now sold twice on eBay. (Jan 18 and Feb 2) When it first listed I contacted the seller and told him the optical unit was missing (A12) and he should not call it "fully functional" Anyway he sold it for his asking price and now it looks like he just sold it again. If he has it returned and lists it again just be aware its not all there! Not really worth the price with no A12! Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] PPS clock module
John, The clock modules from the 5061A and 5065A take a 1PPS input! I have several I can sell. However they are not suitable for a portable app as they are power hogs! Although they do have a circuit that kills the display if the standard is on battery power, you can then push the button on the front to momentarily read the time. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] RF Isolation Amplifier ...
Thanks for the inputs. Attached is the blurb from the manual on the 5Mhz isolation amps. I don't want to redesign as the 3 amps are matched for delay and temp and run at 45 degrees C. I'll check the output of the amp with a spec-A and select the capacitor as appropriate. Cheers, Corby___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] RF isolation amplifier question
Hi, I removed this amp from the EFOS2 Maser as it was intermittent. Of course now I can't get it to fail on the bench! I have fabricated a new PC board to replace it and have the components on hand. Note the 12pfd cap on the collector . Some notes I have indicate is select at test and that is it a glass capacitor. The as built unit has a johansen 50pf that looks to be an early version of surface mount with leads soldered on. How do I determine what value to install on the new amplifier? Cheers, Corby___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP5065A Step Recovery Diode, what part#?
Hi, I'll throw my two bits in! Diodes from Efratom FRS, FRK, and M100 are made for 60Mhz drive and probably would be a good fit. I'll take a look and see if I have any junkers. All diodes used in Rubidiums are inside the cell oven so operate at a high temp anyway. I agree with Ed, swapping A3 modules requires retuning. One tidbit, make sure the two trim caps are actually rotating! The top rotor can get stuck and if you force it the screw connection will break. Then you have a fixed capacitor, not a variable anymore. If you check ahead of time you can break the rotor free by levering a tool against it laterally. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP 5065A fault
John, I have repaired several with this problem. If you want I'll contact you off list with the details and PIX. Very basically: Dig out potting (don't start until I send details!) remove oven cylinder rewind oven coil add new thermistor if needed install and wire new oven measure temp and select matching value for the A11 resistor Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] EFOS2 Maser acting up :(
Well finally caught it while it was acting up again! Had to add an audible alarm to help me catch it. The 1st L.O. (1440Mhz) dies completely and also the 20Mhz TTL front panel output dies. Both the 1440Mhz and 20Mhz are derived from the 180Mhz signal. So now need to see if the 5Mhz input to 180Mhz multiplier is OK during a failure. That should point me to the correct subassy. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] EFOS2 Maser acting up :(
Forgot to mention that with the problem occurring, and at the same time I observed the good cavity output on the spec-A, feeding a signal from an 8660D synthesizer into the LNA showed a zero IF level also. So it's downstream from there. Dana, I have found that "watchful waiting" before jumping in to troubleshoot is the BEST advice. This problem however after a week or so was not correcting! The EFOS2 Maser does not servo the IF level to the Hydrogen pressure. You set the pressure you want and it does servo the Palladium leak to maintain that pressure. I do have a log of readings and when the problem is occurring they all (30 parameters) read nominal! This included the requested Hydrogen pressure value and the measured Hydrogen pressure value. Ole, Yes the 5.7Khz I.F. amplitude monitor. As I mentioned above feeding in an external signal also gave a zero I.F. amplitude reading. Of course now that I'm set up to monitor the L.O. it's not messing up! A watched Maser never fails??? Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP 5065A HP5061A clock module on ebay
Hi, See https://www.ebay.com/itm/digital-clock-module-for-HP5065A-or-HP5061A-freq uency-standard-working/323360298547 Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] FTS 1000A-100 on Ebay
Hi, I just listed an FTS 1000A-100 oscillator on eBay. Fully tested, see plot in listing. Also will be listing some 10811 (various types) and some FE405B soon. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Phase combined HP 5065As!!!
Well I'm trying this out again. I have two "enhanced" NOT "Super" HP 5065As I'm working on and decided to ensemble them together, if that's applicable to only two units? Attached is a plot against my FTS 1200 and Maser. Pretty neat. I'm working on an easy way to lock them together for such work. Now if I only had that 8607 option 8 or the Rakon HSO14 option 8 for my lower Tau (< 32 Sec.) Cheers, Corby___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Need help machining an Aluminum cylinder
Hi, I remember a few that had machine shops volunteering to help with machining last year but can't remember who! I have a 2 and 3/8" diameter cylinder 1.45" long. It needs nine 1/6" deep X 1/16" wide grooves machined in the circumference and adding some length to a slot already existing running down the side. This is to try another way to rebuild the HP 5065A Lamp oven. Can anyone help? Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP 5065A A1 replacement with DDS
Bert, Yes the 5062C also used the same synthesizer style as the 5065A and 5061A/B. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to https://lists.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] HP 5065A A1 replacement with DDS
Hi, My purpose was to provide an inexpensive (<$30.00) and simple way to replace a defective A1 without degrading the performance the original A1 gave. The Chinese DDS allows this without having to solder all those tiny pins! Both styles actually performed better than the original, and the same in a "super" mod unit. I was not claiming "theoretical" perfect performance and rejected more complex schemes on purpose. Also the current drawn by the A1 is part of the current budget for the TED so an A1 replacements current draw should be between 100 and 150 mA! Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to https://lists.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Want info on Bliley NV26T992 oscillator
Hi, Anyone have hookup info for the Bliley NV26T992 https://www.ebay.com/itm/Bliley-Technologies-Crystal-Oscillator-10-0MHz-N V26T992/181179304420?epid=19019617029&hash=item2a2f20c9e4:g:opQAAOxyOnRR6 T04 Looks to be a cute cleanup oscillator but I can't find any seller that has pinout info. and power hookup. Cheers, Corby___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to https://lists.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] HP cesium beam tube life
The "shelf life" referred to is only related to tube vacuum without pumping occasionally. It was derived from an estimate of how badly a worst case tube would leak. Most tubes have an almost perfect vacuum seal and this "shelf life" is indefinite. Leaving a 5061A/B on and in the Cs-off mode keeps the ion pump on. The actual life of a continuously working tube is conservatively estimated by the warranty lengths HP assigned to the various tube styles. Cheers, Corby ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to https://lists.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
