Re: [time-nuts] HP 8566B repair
I don't think much of the idea of shotgun-replacing these particular caps. There are a great many of them, they're not *that* unreliable, and unlike the notorious radial-lead tantalums, they tend to fail open, not shorted, so they're unlikely to damage other parts when they fail. On the other hand there are definite risks, from ESD to human error, associated with unsoldering and resoldering a bunch of parts unnecessarily. Just be prepared to open it up once every couple of years to track down the next one. Nothing to be afraid of inside the 8566s. You could rebuild the whole thing from scratch with HP's docs, if you had to. -- john, KE5FX > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Behalf Of Jeff Mock > Sent: Thursday, December 06, 2007 7:55 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] HP 8566B repair > > > Thanks so much, that's just the encouragement I need to crack open the > RF section. I'll take a look at the electrolytic caps you suggest. > Assuming that I find something, do you think it's worth replacing other > caps in the area figuring that they will also go bad soon enough? > > jeff > > ___ 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] HP 8566B repair
Jeff Mock wrote: > Does anyone have any suggestions or advice about 8566B repair? > > I've had an 8566B for 7-8 years, it's been a faithful tool, never had a > problem with it. It's reasonably clean unit that's never seen a tough > life. It sits in the storeroom 90% of the time and is on my bench maybe > 10% of the time. > > So, this week, after a 4 month hiatus, I've been using it on the bench > and it starting producing a "YTO UNLOCK" message, the trace seems to > basically work properly but is clearly unlocked and the trace will > randomly slide to the left or right. The Yttrium oscillator is clearly > unlocked. I'm hopeful that the problem is in one the control loops > outside the oscillator module. > > I read the repair guide that Agilent kindly keeps on their website, they > have some good instructions and narrow the problem to 3-4 modules, but > I've never opened up the instrument and am a little apprehensive about > making things worse. My hunch is that the problem is an electrolytic > cap that has dried out over the years and has failed. > > Any suggestions for either self repair or outside repair and > re-calibration is appreciated... > > In full disclosure, I also have a 70908A based spectrum analyser that > that has much better specs, especially in microwave. It can completely > replace the 8566B, but I'm quite fond of the 8566B, I can operate it > blind folded, it's like an old friend and I would really like to fix it. > > jeff > > > ___ > 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. > This document is very helpful in dealing with YIG oscillators. http://www.vhfcomm.co.uk/pdf/A%20Simple%20Approach%20tyo%20YIG%20Oscil.pdf YIG oscillators should be quite reliable, and I would expect that it is just an electrolytic cap or similar as you mentioned. The oscillator portion clearly works, so the only thing that could be wrong with the oscillator itself is a burned out FM coil which is unlikely. The oscillator would not oscillate at all without main coil current assuming it is not a PMYTO, which is extremely unlikely in an older unit. I would expect that the FM coil (fine tune, driven by the PLL) current is pegged to either side or the FM coil is not being driven. It could be as simple as adjusting a pot on the main coil (course tune) driver. The PLL and FM coil may have as small of a tuning range as 10 MHz. Darrell Harmon ___ 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] HP 8566B repair
Thanks so much, that's just the encouragement I need to crack open the RF section. I'll take a look at the electrolytic caps you suggest. Assuming that I find something, do you think it's worth replacing other caps in the area figuring that they will also go bad soon enough? jeff John Miles wrote: > Never fear. I have seen this a few times, in a couple of 8566Bs that I have > owned as well as in some others. The YTO UNLOCK error always seems to come > down to an open electrolytic on the YTO driver or pretune DAC boards, under > the hinged plastic cover toward the rear of the RF section. > > Check power supply voltages first, then check ESR of all of the axial-lead > electrolytics on all boards under that cover. Then, if those areas are both > OK, go through the YTO calibration procedure in the manual until you either > successfully recalibrate the pretune/driver system, or reach a particular > step that you can't complete. > > -- john, KE5FX > >> -Original Message- >> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] >> Behalf Of Jeff Mock >> Sent: Thursday, December 06, 2007 7:38 PM >> To: Discussion of precise time and frequency measurement >> Subject: [time-nuts] HP 8566B repair >> >> >> Does anyone have any suggestions or advice about 8566B repair? >> >> I've had an 8566B for 7-8 years, it's been a faithful tool, never had a >> problem with it. It's reasonably clean unit that's never seen a tough >> life. It sits in the storeroom 90% of the time and is on my bench maybe >> 10% of the time. >> >> So, this week, after a 4 month hiatus, I've been using it on the bench >> and it starting producing a "YTO UNLOCK" message, the trace seems to >> basically work properly but is clearly unlocked and the trace will >> randomly slide to the left or right. The Yttrium oscillator is clearly >> unlocked. I'm hopeful that the problem is in one the control loops >> outside the oscillator module. >> >> I read the repair guide that Agilent kindly keeps on their website, they >> have some good instructions and narrow the problem to 3-4 modules, but >> I've never opened up the instrument and am a little apprehensive about >> making things worse. My hunch is that the problem is an electrolytic >> cap that has dried out over the years and has failed. >> >> Any suggestions for either self repair or outside repair and >> re-calibration is appreciated... >> >> In full disclosure, I also have a 70908A based spectrum analyser that >> that has much better specs, especially in microwave. It can completely >> replace the 8566B, but I'm quite fond of the 8566B, I can operate it >> blind folded, it's like an old friend and I would really like to fix it. >> >> > > > ___ > 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] HP 8566B repair
Never fear. I have seen this a few times, in a couple of 8566Bs that I have owned as well as in some others. The YTO UNLOCK error always seems to come down to an open electrolytic on the YTO driver or pretune DAC boards, under the hinged plastic cover toward the rear of the RF section. Check power supply voltages first, then check ESR of all of the axial-lead electrolytics on all boards under that cover. Then, if those areas are both OK, go through the YTO calibration procedure in the manual until you either successfully recalibrate the pretune/driver system, or reach a particular step that you can't complete. -- john, KE5FX > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Behalf Of Jeff Mock > Sent: Thursday, December 06, 2007 7:38 PM > To: Discussion of precise time and frequency measurement > Subject: [time-nuts] HP 8566B repair > > > Does anyone have any suggestions or advice about 8566B repair? > > I've had an 8566B for 7-8 years, it's been a faithful tool, never had a > problem with it. It's reasonably clean unit that's never seen a tough > life. It sits in the storeroom 90% of the time and is on my bench maybe > 10% of the time. > > So, this week, after a 4 month hiatus, I've been using it on the bench > and it starting producing a "YTO UNLOCK" message, the trace seems to > basically work properly but is clearly unlocked and the trace will > randomly slide to the left or right. The Yttrium oscillator is clearly > unlocked. I'm hopeful that the problem is in one the control loops > outside the oscillator module. > > I read the repair guide that Agilent kindly keeps on their website, they > have some good instructions and narrow the problem to 3-4 modules, but > I've never opened up the instrument and am a little apprehensive about > making things worse. My hunch is that the problem is an electrolytic > cap that has dried out over the years and has failed. > > Any suggestions for either self repair or outside repair and > re-calibration is appreciated... > > In full disclosure, I also have a 70908A based spectrum analyser that > that has much better specs, especially in microwave. It can completely > replace the 8566B, but I'm quite fond of the 8566B, I can operate it > blind folded, it's like an old friend and I would really like to fix it. > > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] HP 8566B repair
Does anyone have any suggestions or advice about 8566B repair? I've had an 8566B for 7-8 years, it's been a faithful tool, never had a problem with it. It's reasonably clean unit that's never seen a tough life. It sits in the storeroom 90% of the time and is on my bench maybe 10% of the time. So, this week, after a 4 month hiatus, I've been using it on the bench and it starting producing a "YTO UNLOCK" message, the trace seems to basically work properly but is clearly unlocked and the trace will randomly slide to the left or right. The Yttrium oscillator is clearly unlocked. I'm hopeful that the problem is in one the control loops outside the oscillator module. I read the repair guide that Agilent kindly keeps on their website, they have some good instructions and narrow the problem to 3-4 modules, but I've never opened up the instrument and am a little apprehensive about making things worse. My hunch is that the problem is an electrolytic cap that has dried out over the years and has failed. Any suggestions for either self repair or outside repair and re-calibration is appreciated... In full disclosure, I also have a 70908A based spectrum analyser that that has much better specs, especially in microwave. It can completely replace the 8566B, but I'm quite fond of the 8566B, I can operate it blind folded, it's like an old friend and I would really like to fix it. jeff ___ 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] Cesium Oscialltors and Low Phase Noise Frequency Standard
It sounds like a really nice oscillator. I'm sure that everyone would love to hear about the challenges and tradeoffs in designing such a high performance quartz oscillator. Do you guys cut your own crystals? How much of the improvement comes from a better SC-cut crystal and how much from better electronics or better ovens? I could go on and on, you wouldn't want to sit next to me on a plane. jeff Martyn Smith wrote: > Hi, > > Is there anyone out there clever enough to design me a cesium frequency > standard?? > > There's only two manufacturers that I know of and there's room for another > supplier. > > Also you may be interested to read we have just developed what we believe to > be the worlds lowest close-in phase noise 10 MHz oscillator. > > It makes -121 dBc/Hz @ 1 Hz. Noise floor is only -162 dBc/Hz at the moment, > but we are working on reducing this a further 5 to 10 dB. > > Enter your order number here.. > > Best Regards > > Martyn > > This Email is from: > > Martyn Smith > Precision Test Systems LTD > Tel: +44 (0) 1245 329608 > Email: [EMAIL PROTECTED] > Web: www.ptsyst.com > > ___ > 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] Cesium Oscialltors and Low Phase Noise Frequency Standard
Martyn Smith wrote: > Hi, > > Is there anyone out there clever enough to design me a cesium frequency > standard?? > > There's only two manufacturers that I know of and there's room for another > supplier. > > Also you may be interested to read we have just developed what we believe to > be the worlds lowest close-in phase noise 10 MHz oscillator. > > It makes -121 dBc/Hz @ 1 Hz. Noise floor is only -162 dBc/Hz at the moment, > but we are working on reducing this a further 5 to 10 dB. > > Enter your order number here.. > > Best Regards > > Martyn > > The Oscilloquartz 8607 is a few dB better than that at 1Hz offset. Bruce ___ 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] Cesiums's
Rick, Your just the person I need Any chance of a cesium before Christmas? Seriously, I do know how complicated they are. Although we supply hydrogen masers, everyone prefers cesium's. Also I hear there's a large inquiry out there for tens of units. Maybe 100's. The goods news on our ULN oscillator is the phase noise. The bad news is that its not a finished product, only a prototype. We still have to temperature compensate it and build proper output amplifiers. A long way off. But hopefully we will get there some day. Best Regards Martyn ___ 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] Cesium Oscialltors and Low Phase Noise Frequency Standard
Why do you say there's room for another supplier? 5 years ago there were 3 suppliers, but Agilent sold out to Symmetricom. What unmet need are you proposing to fill? What is the short term stability (sigma-sub-y-of-tau) of your world class oscillator? Rick Karlquist (RF designer for the 5071A Cesium standard) Martyn Smith wrote: > Hi, > > Is there anyone out there clever enough to design me a cesium frequency > standard?? > > There's only two manufacturers that I know of and there's room for another > supplier. > > Also you may be interested to read we have just developed what we believe to > be the worlds lowest close-in phase noise 10 MHz oscillator. > > It makes -121 dBc/Hz @ 1 Hz. Noise floor is only -162 dBc/Hz at the moment, > but we are working on reducing this a further 5 to 10 dB. > > Enter your order number here.. > > Best Regards > > Martyn > > This Email is from: > > Martyn Smith > Precision Test Systems LTD > Tel: +44 (0) 1245 329608 > Email: [EMAIL PROTECTED] > Web: www.ptsyst.com > > ___ > 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] Modulation on Rb sources
At 9:56 PM -0800 12/5/07, Jeff Mock wrote: >I have a couple of Rb sources and went looking for spurs close to the >carrier. One was particularly surprising. First is a GPS disciplined >Rb oscillator from Berkeley Varitronics. I'm not a big fan of this box, >but that's another story. > >Here's plot of 500Hz around 10MHz, it looks like the 10MHz signal is AM >modulated with a 128Hz signal, the spurs are about -75dBc. I did the >plot twice, once during normal operation, and once with the GPS control >loop disabled from the front panel. The plots were identical. So, my >question is whether this modulation is part of the Efratom module or >introduced by the Berkeley Varitronics box? > > http://www.mock.com/test/rhinoii/am-128hz.png > >Here's a similar plot of an LPRO-101. This is just the module with a >semi-crappy power supply. There's a little 60Hz (+harmonics) that I >figure is power supply related leaking through the mixer. The 10MHz >signal is +8dBm, so the 60Hz spurs are at least 98db below the carrier, >much better than the previous graph and more like what I expected. > > http://www.mock.com/test/lpro-101/am60hz.png > >Does anyone know what's going on with the first box? > >jeff Jeff, The modulation is how the device maintains lock. Read the manual for more info. Yours could have too high a modulation level. I don't know what the close-in spur level is supposed to be, but I could drag my FRS-N into the lab and measure it if you're interested. Just not this month since there's too much real work going on. -- --David Forbes, Tucson, AZ http://www.cathodecorner.com/ ___ 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] Cesium Oscialltors and Low Phase Noise Frequency Standard
Hi, Is there anyone out there clever enough to design me a cesium frequency standard?? There's only two manufacturers that I know of and there's room for another supplier. Also you may be interested to read we have just developed what we believe to be the worlds lowest close-in phase noise 10 MHz oscillator. It makes -121 dBc/Hz @ 1 Hz. Noise floor is only -162 dBc/Hz at the moment, but we are working on reducing this a further 5 to 10 dB. Enter your order number here.. Best Regards Martyn This Email is from: Martyn Smith Precision Test Systems LTD Tel: +44 (0) 1245 329608 Email: [EMAIL PROTECTED] Web: www.ptsyst.com ___ 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.
