Re: [time-nuts] EFC divider resistors
Hi OCXO’s with separate ground for the oven have indeed been made. They do show up in catalogs and on data sheets. Customers don’t buy them….. The same is true of the other approach, which is to bring out a separate (isolated) EFC return. Bob On Jan 31, 2014, at 11:14 PM, Hal Murray hmur...@megapathdsl.net wrote: li...@rtty.us said: A 7805 has a *rated* temperature coefficient of 2 mv / C. Most parts do way better than this. The problem is knowing if you have a good part or not. On a 5V part, your reference could be running 400 ppm/C. Since the divider has no impact on this number, it over-rides what ever you do with the divider resistors. A good voltage reference will set you back about $50 or so. Plan B would be to keep the 7805 at a constant temperature. You commonly see a couple of mv of variation in the ground pin voltage with oven current depending on exactly where the pin is terminated. Any change in the ground setup can be an issue on an OCXO with the EFC in common with the oven (which is most parts). Again, plan B would be to keep the OCXO at a constant temperature so the heater current is (close) to constant and the offset on the ground pin due to heater current would be constant. - I've heard comments about offset due to a single ground pin for several/many years, so it's nothing new. Why are manufacturers not providing separate pins? Are there OCXOs (that I haven't noticed) with 2 ground pins? Is the problem backward compatibility? In that case, I'd expect there would be a pinout with a new second-ground pin that offered an interesting beat-this challenge to other vendors. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Replacement fan in SR620
Fellow time-nuts, I heard the fan in one of my SR620s and it didn't really was a nice sound. Has someone found a good replacement fan? Quieter would be nice. Considering performance checks and calibration this evening. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Replacement fan in SR620
Magnus I have a big collector of fans, mostly for Agilent equipment not that it matters, let me know the dimensions I will see what I have that is quiet. Cheers; Thomas Knox Date: Sat, 1 Feb 2014 18:56:48 +0100 From: mag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: [time-nuts] Replacement fan in SR620 Fellow time-nuts, I heard the fan in one of my SR620s and it didn't really was a nice sound. Has someone found a good replacement fan? Quieter would be nice. Considering performance checks and calibration this evening. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] EFC divider resistors
All, The REF 102 from TI is a +10 reference with a TC of 2.5PPM/max. Using two 1% 50 PPM metal film Xcion resistors on can make a +5 V regulator that is far superior to a 7805. Cost is about $7 from mouser. If one needs to have an adjustable resistor in a circuit perhaps one of the digital pots that are available will suffice. A question: would thermal cycling oscillators or reference boards be useful before starting a stability run? Regards, Perrier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Replacement fan in SR 620
Hi Jarl, On 01/02/14 21:47, Jarl Risum wrote: Hi Magnus, I recently sent the following comment to the Time-Nuts list, but it do not turn up. So I decided to send a copy directly to you: Thanks Magnus, In my SR620 the fan is a Delta DBF0624H which unfortunately seems no longer to be in production. It is a 60x60x25 mm fan, 24V /0.11A. As discussed previously on the list, the temperature controlled cooling of the SR620 is marginal. I have to remove the counter from it's cramped quarters on the shelf and place it on the table whenever I try to make critical measurements over a long time span. My room temperature is around 20 deg C. If you cannot get rid of the noise by oiling the original fan and you have to replace it I suggest you - just as a safety measure - to monitor the temperature of the right side panel of the SR 620 after replacing the fan and at the same time compare with the temperature of another, working and healthy, SR620 in similar surroundings. . If you find a generally available, silent replacement fan with sufficient cooling capacity, please let us know. Cheers, Jarl OK, I'm considering the EBM-Papst 614NGN, which is 60x60x25 24V radial fan. Your measures helped me to go straight to the search for a fan. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Replacement fan in SR620
Magnus, I took an EBMPabst 624. Pabst has a good reputation. The original fan is a Delta Electronics DFB0624 H, Dimensions are 60mm x 60mm x 25mm, DC24V 0.11A Volker Am 01.02.2014 18:56, schrieb Magnus Danielson: Fellow time-nuts, I heard the fan in one of my SR620s and it didn't really was a nice sound. Has someone found a good replacement fan? Quieter would be nice. Considering performance checks and calibration this evening. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Replacement fan in SR620
Jarl wrote: In my SR620 the fan is a Delta DBF0624H. It is a 60x60x25 mm fan, 24V /0.11A. Mine, too. Does anyone know the airflow rating of the Delta fan? It does not appear to move as much air as it should (at least not if the idea is to hold the interior at a fixed temperature) -- every SR620 I've used has the fan running at full speed by the time it's been on for 10 minutes, unless the ambient temperature is less than 17-18C. On the one hand, it would be nice to move more air so the internal temperature is more tightly regulated; but on the other hand, it would also be nice if the fan were quieter. It is unlikely we can have both. The fact that the original fan seems marginal counsels against replacing it with one that moves less air. The thermal design of the 620 is far from optimal. The thermistor is located in a tunnel between the interior of the instrument and the exterior, with the fan blowing directly across it through the tunnel. So, the fan startup is an ugly process of fits and starts as the instrument warms up. Also, the air inlets seem to be too small and the internal airflow was not properly designed to circulate cooling air where it needs to go. I have toyed with the idea of cutting a slot maybe 4 long and 1/8 tall in the right wall of the chassis at the rear, above the four TO-220 devices mounted there -- and perhaps another slot about the same size in the top cover above those devices. Also, maybe attaching some internal baffles to the top cover to channel airflow where it is needed. I installed a terminal strip on the GPIB connector mounting screw and relocated the thermistor there in my SR620s (in the general vicinity of the oscillators). (However, note that stabilizing the internal oscillator temperature is not really very important for most of us, because time nuts generally use an external time base. In that case, it is probably more important that the temperature of the triggers and interpolators is held constant.) With the thermistors relocated as I have described, the fans start up as they should (monotonically, speeding up smoothly from stopped to full speed without any fits and starts). They still reach full speed in 10 minutes or so, so at the end of the day I don't think I've really changed anything except the aesthetics of the fan startup. (IMO, the change is worth it just for that, but there does not seem to be any operational improvement.) Perhaps SRS did not intend to regulate the interior temperature of the SR620 -- maybe they just wanted it to warm up faster (if you did away with the thermistor and had the fan run full speed whenever the counter was on, it would presumably take longer to warm up). Anyway -- does anybody have an old Delta catalog or datasheet that specifies the airflow rating of the original Delta fan? Best regards, Charles ___ 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 Acquisition: HP-53132A
Hello The Net, I just got in the counter and the fan is always ON, even with the front panel switch OFF. I looked in the manual but could not find anyway to change this. The counter has the standard internal 10 MHz reference, but I will be using a Trimble T'bolt GPS/DO for the external reference. The fan is part of the power supply module. I can see a possible need for it if a premium ovenized reference is always ON. But I do not have the premium internal reference. Is there a way to only allow the fan to be ON, if the front panel switch is ON ? Possibly a jumper setting ? Are there any key strokes to determine the software version, other than a check sum ? I do not have the standard HP serial number, with the vintage (manufacturing date code) code first. The unit was manufactured in Korea. Stan, W1LE on Cape Cod z ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New Acquisition: HP-53132A
I know that with the ovenized oscillator the power supply (and therefore fan) are always on. Thomas Knox Date: Sat, 1 Feb 2014 22:50:13 -0500 From: stanw...@verizon.net To: time-nuts@febo.com Subject: [time-nuts] New Acquisition: HP-53132A Hello The Net, I just got in the counter and the fan is always ON, even with the front panel switch OFF. I looked in the manual but could not find anyway to change this. The counter has the standard internal 10 MHz reference, but I will be using a Trimble T'bolt GPS/DO for the external reference. The fan is part of the power supply module. I can see a possible need for it if a premium ovenized reference is always ON. But I do not have the premium internal reference. Is there a way to only allow the fan to be ON, if the front panel switch is ON ? Possibly a jumper setting ? Are there any key strokes to determine the software version, other than a check sum ? I do not have the standard HP serial number, with the vintage (manufacturing date code) code first. The unit was manufactured in Korea. Stan, W1LE on Cape Cod z ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New Acquisition: HP-53132A
Are there any key strokes to determine the software version, other than a check sum ? Hi Stan, Hold recall down as you press power-on to see the firmware version. It's a very nice counter. I use them all the time. Here's some light reading for you: http://cp.literature.agilent.com/litweb/pdf/53131-90055.pdf Agilent 53131A/132A 225 MHz Universal Counter Operating Guide http://cp.literature.agilent.com/litweb/pdf/53131-90044.pdf Agilent 53131A/132A 225 MHz Universal Counters Programming Guide http://cp.literature.agilent.com/litweb/pdf/53131-90039.pdf Agilent 53131A/132A/181A 225 MHz Counters Assembly-Level Service Guide http://cp.literature.agilent.com/litweb/pdf/5989-6308EN.pdf Agilent 53132A Component Level Information /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New Acquisition: HP-53132A
According to the manual (in several places): *It is normal operation for the fan in the Counter to continue to run after the Counter is* *placed in Standby mode. Power to the timebase is continuous to maintain long term* *measurement reliability, and the fan helps maintain timebase temperature stability.* perhaps a in-line AC switch? Michael On Sat, Feb 1, 2014 at 8:50 PM, stan, W1LE stanw...@verizon.net wrote: Hello The Net, I just got in the counter and the fan is always ON, even with the front panel switch OFF. I looked in the manual but could not find anyway to change this. The counter has the standard internal 10 MHz reference, but I will be using a Trimble T'bolt GPS/DO for the external reference. The fan is part of the power supply module. I can see a possible need for it if a premium ovenized reference is always ON. But I do not have the premium internal reference. Is there a way to only allow the fan to be ON, if the front panel switch is ON ? Possibly a jumper setting ? Are there any key strokes to determine the software version, other than a check sum ? I do not have the standard HP serial number, with the vintage (manufacturing date code) code first. The unit was manufactured in Korea. Stan, W1LE on Cape Cod z ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] How to open solder-sealed OCXOs?
What's the best way to open an OCXO in the typical solder-sealed tinned steel can? I don't mind destroying the can itself, as long as the innards are not harmed. The goal is to run some experiments with thermal impedance as discussed here last week, and to ovenize parts of the EFC controller for better stability. Cheers! --Stu ___ 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.
