Re: [time-nuts] HP 10811A failure
On 10/13/2012 8:30 AM, Adrian wrote: 12V for the oven because inside the outer oven lives a 10811-60158 ( see http://www.realhamradio.com/GPS-oven-journey.htm ) that, as by the specs sheet, is specified 12 to 30 V DC, 11 W max. at turn on (mine draws some 9 W), and Steady state power drops to approximately 2 W at 25°C in still air at 20 V (mine draws some 1.9 W at 12 V without powering the outer oven). This is surprising to me. Can you give us a citation to this spec? AFAIK, all 10811 ovens are the same, and the ones I have looked at sort of work at 15V, but they don't really work properly on 12V. One source of confusion is the case of the 5334A counter. The power supply IMHO is poorly designed and the voltage sags down to 12V during 10811 warm up. (All 10811's and 10544's are guaranteed not to draw more current than a 47 ohm resistor). It turns out that you can count on the 10811 oven to function sufficiently at 12V to turn on the heater transistors and get the oven warmed up. After the oven warms up, the current drops back and the 5334A power supply voltage gets back up over 20V. This is different than saying that it is OK to just connect a 10811 heater to a constant 12V supply. When I was project manager of the 5334B version (a cost reduction exercise), I took the opportunity to redesign the power supply so that it worked correctly, in my opinion, meaning that the voltage did not have a huge sag. I don't like design shenanigans. Rick Karlquist N6RK ___ 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 10811A failure
Sounds like another source of this confusion is that there is more than one version of the HP10811 inner heater circuit. Where as most 10811's start loosing performance at around 15 volts on their inner oven. I have one 10811, that was taken out of a dual oven version, that maintains full temperature regulation with under 10 volts on its inner oven circuit. When I opened them up, the main difference I saw was: On the unit that needs the higher heater voltage, the circuit is as shown in the manual's schematic, U2 = 10 V and R17 = 10K. R17 is used to reduce the bridge voltage to ~ 5V. On the unit that works at lower heater voltages, R17 = 0 Ohms, and U2 has a 5V output. Both circuits give the same 5 volts across the bridge, and both where set to operate at approximately the same temperature and both had similar factory temperature trim resistors in them. BTW the 10811's outer oven will work fine with under 10 Volts on it. I drive mine from a simple home built linear temperature controller. ws ** On 10/14/2012 1:19 PM 8:30 AM, Richard (Rick) Karlquist wrote: 12V for the oven because inside the outer oven lives a 10811-60158 ( see http://www.realhamradio.com/GPS-oven-journey.htm ) that, as by the specs sheet, is specified 12 to 30 V DC, 11 W max. at turn on (mine draws some 9 W), and Steady state power drops to approximately 2 W at 25°C in still air at 20 V (mine draws some 1.9 W at 12 V without powering the outer oven). This is surprising to me. Can you give us a citation to this spec? AFAIK, all 10811 ovens are the same, and the ones I have looked at sort of work at 15V, but they don't really work properly on 12V. One source of confusion is the case of the 5334A counter. The power supply IMHO is poorly designed and the voltage sags down to 12V during 10811 warm up. (All 10811's and 10544's are guaranteed not to draw more current than a 47 ohm resistor). It turns out that you can count on the 10811 oven to function sufficiently at 12V to turn on the heater transistors and get the oven warmed up. After the oven warms up, the current drops back and the 5334A power supply voltage gets back up over 20V. This is different than saying that it is OK to just connect a 10811 heater to a constant 12V supply. ... ___ 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 10811A failure
Hi All, both of my double oven 10811A's have been running flawlessly until now when I noticed that the output power has dropped by about 3 dB (measures only 4...4.5 dBm at 50 Ohm load), and the noise floor has gone up by about 20 dB, while the frequency is still spot on. I used them for various mesurements, so I can unfortunately not remember what might have caused the failure. Only the 12V linear lab power supply that fed the heaters had developed a completely dead filter cap, so the feeding voltage was a 100 Hz sawtooth rather than DC. The heaters appear to be still working though. I'm only using the internal heater. They draw some 700 mA at power up and drop to around 150 mA each when warm. So the oscillators are unlikely to be cooked inside. Something must have happened to the 10 MHz output, possibly an ESD issue? Before I start taking them apart, can anyone tell what has happened or what to look for first? Regards, Adrian ___ 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 10811A failure
Sounds like another dead cap. Thomas Knox Date: Sat, 13 Oct 2012 14:51:54 +0200 From: rfn...@arcor.de To: time-nuts@febo.com Subject: [time-nuts] HP 10811A failure Hi All, both of my double oven 10811A's have been running flawlessly until now when I noticed that the output power has dropped by about 3 dB (measures only 4...4.5 dBm at 50 Ohm load), and the noise floor has gone up by about 20 dB, while the frequency is still spot on. I used them for various mesurements, so I can unfortunately not remember what might have caused the failure. Only the 12V linear lab power supply that fed the heaters had developed a completely dead filter cap, so the feeding voltage was a 100 Hz sawtooth rather than DC. The heaters appear to be still working though. I'm only using the internal heater. They draw some 700 mA at power up and drop to around 150 mA each when warm. So the oscillators are unlikely to be cooked inside. Something must have happened to the 10 MHz output, possibly an ESD issue? Before I start taking them apart, can anyone tell what has happened or what to look for first? Regards, Adrian ___ 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 10811A failure
And, why 12V for the oven? The 10811A manual states from 20V to 30V for the oven. 12V for the oscillator itself. On Sat, Oct 13, 2012 at 4:34 PM, Tom Knox act...@hotmail.com wrote: Sounds like another dead cap. Thomas Knox Date: Sat, 13 Oct 2012 14:51:54 +0200 From: rfn...@arcor.de To: time-nuts@febo.com Subject: [time-nuts] HP 10811A failure Hi All, both of my double oven 10811A's have been running flawlessly until now when I noticed that the output power has dropped by about 3 dB (measures only 4...4.5 dBm at 50 Ohm load), and the noise floor has gone up by about 20 dB, while the frequency is still spot on. I used them for various mesurements, so I can unfortunately not remember what might have caused the failure. Only the 12V linear lab power supply that fed the heaters had developed a completely dead filter cap, so the feeding voltage was a 100 Hz sawtooth rather than DC. The heaters appear to be still working though. I'm only using the internal heater. They draw some 700 mA at power up and drop to around 150 mA each when warm. So the oscillators are unlikely to be cooked inside. Something must have happened to the 10 MHz output, possibly an ESD issue? Before I start taking them apart, can anyone tell what has happened or what to look for first? Regards, Adrian ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 10811A failure
At least not a power supply cap. No change on a different PS. Do you mean the oscillator output coupling cap? 12V for the oven because inside the outer oven lives a 10811-60158 ( see http://www.realhamradio.com/GPS-oven-journey.htm ) that, as by the specs sheet, is specified 12 to 30 V DC, 11 W max. at turn on (mine draws some 9 W), and Steady state power drops to approximately 2 W at 25°C in still air at 20 V (mine draws some 1.9 W at 12 V without powering the outer oven). Adrian Azelio Boriani schrieb: And, why 12V for the oven? The 10811A manual states from 20V to 30V for the oven. 12V for the oscillator itself. On Sat, Oct 13, 2012 at 4:34 PM, Tom Knox act...@hotmail.com wrote: Sounds like another dead cap. Thomas Knox Date: Sat, 13 Oct 2012 14:51:54 +0200 From: rfn...@arcor.de To: time-nuts@febo.com Subject: [time-nuts] HP 10811A failure Hi All, both of my double oven 10811A's have been running flawlessly until now when I noticed that the output power has dropped by about 3 dB (measures only 4...4.5 dBm at 50 Ohm load), and the noise floor has gone up by about 20 dB, while the frequency is still spot on. I used them for various mesurements, so I can unfortunately not remember what might have caused the failure. Only the 12V linear lab power supply that fed the heaters had developed a completely dead filter cap, so the feeding voltage was a 100 Hz sawtooth rather than DC. The heaters appear to be still working though. I'm only using the internal heater. They draw some 700 mA at power up and drop to around 150 mA each when warm. So the oscillators are unlikely to be cooked inside. Something must have happened to the 10 MHz output, possibly an ESD issue? Before I start taking them apart, can anyone tell what has happened or what to look for first? Regards, Adrian ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts 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 10811A failure
I am sorry I assumed you had resolved your PS issues, I should have been clearer, I meant bad cap in the oscillator. I would temporarily solder a number of leads internally and check the different voltages for noise. Good luck on the repair. Thomas Knox Date: Sat, 13 Oct 2012 17:30:27 +0200 From: rfn...@arcor.de To: time-nuts@febo.com Subject: Re: [time-nuts] HP 10811A failure At least not a power supply cap. No change on a different PS. Do you mean the oscillator output coupling cap? 12V for the oven because inside the outer oven lives a 10811-60158 ( see http://www.realhamradio.com/GPS-oven-journey.htm ) that, as by the specs sheet, is specified 12 to 30 V DC, 11 W max. at turn on (mine draws some 9 W), and Steady state power drops to approximately 2 W at 25°C in still air at 20 V (mine draws some 1.9 W at 12 V without powering the outer oven). Adrian Azelio Boriani schrieb: And, why 12V for the oven? The 10811A manual states from 20V to 30V for the oven. 12V for the oscillator itself. On Sat, Oct 13, 2012 at 4:34 PM, Tom Knox act...@hotmail.com wrote: Sounds like another dead cap. Thomas Knox Date: Sat, 13 Oct 2012 14:51:54 +0200 From: rfn...@arcor.de To: time-nuts@febo.com Subject: [time-nuts] HP 10811A failure Hi All, both of my double oven 10811A's have been running flawlessly until now when I noticed that the output power has dropped by about 3 dB (measures only 4...4.5 dBm at 50 Ohm load), and the noise floor has gone up by about 20 dB, while the frequency is still spot on. I used them for various mesurements, so I can unfortunately not remember what might have caused the failure. Only the 12V linear lab power supply that fed the heaters had developed a completely dead filter cap, so the feeding voltage was a 100 Hz sawtooth rather than DC. The heaters appear to be still working though. I'm only using the internal heater. They draw some 700 mA at power up and drop to around 150 mA each when warm. So the oscillators are unlikely to be cooked inside. Something must have happened to the 10 MHz output, possibly an ESD issue? Before I start taking them apart, can anyone tell what has happened or what to look for first? Regards, Adrian ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts 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 10811A failure
Perhaps a silly question, but as I get the impression that both seem to have failed simultaneously with the same fault I'm just wondering if you're sure it isn't what you're checking them with that's developed a problem? Regards Nigel GM8PZR In a message dated 13/10/2012 13:52:46 GMT Daylight Time, rfn...@arcor.de writes: Hi All, both of my double oven 10811A's have been running flawlessly until now when I noticed that the output power has dropped by about 3 dB (measures only 4...4.5 dBm at 50 Ohm load), and the noise floor has gone up by about 20 dB, while the frequency is still spot on. I used them for various mesurements, so I can unfortunately not remember what might have caused the failure. Only the 12V linear lab power supply that fed the heaters had developed a completely dead filter cap, so the feeding voltage was a 100 Hz sawtooth rather than DC. The heaters appear to be still working though. I'm only using the internal heater. They draw some 700 mA at power up and drop to around 150 mA each when warm. So the oscillators are unlikely to be cooked inside. Something must have happened to the 10 MHz output, possibly an ESD issue? Before I start taking them apart, can anyone tell what has happened or what to look for first? Regards, Adrian ___ 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 10811A failure
A very good point! I checked the output amplitude with a spectrum analyzer, a power meter and a scope, the latter with a 50 ohm load to the input. I re-checked the power supply connections and can confirm they are the same as before. I used three different power supplies for the oscillators and two for the heaters, still no difference. But... To make it short, your comments helped to get me back on track. Both beauties escaped unnecessary dismantling and are now working as they should. Actually, the problem was caused by a long-term misunderstanding. I was always wondering why 'HP used simple stranded wire' and not coaxial cable on the 10 MHz output and EFC. As long as I connected them on the bench, I replaced the 'missing' ground connection with a short wired croc clamp between coax and ground. Today I realized that the thin blue wire IS actually coax cable, so I should have connected the coax shield to the BNC ground on my newly built 2x 10811 enclosure. With the new wiring, the output ground had just become much more inductive, up to a point where the nominal source impedance of 50 ohms had increased to over 120 ohms, causing the amplitude loss of some 3 dB and capturing noise. Btw. the Sprague 6800 uF / 40 V from my RS NGA power supply has indeed died, but independently of the osc. problem. Adrian gandal...@aol.com schrieb: Perhaps a silly question, but as I get the impression that both seem to have failed simultaneously with the same fault I'm just wondering if you're sure it isn't what you're checking them with that's developed a problem? Regards Nigel GM8PZR In a message dated 13/10/2012 13:52:46 GMT Daylight Time, rfn...@arcor.de writes: Hi All, both of my double oven 10811A's have been running flawlessly until now when I noticed that the output power has dropped by about 3 dB (measures only 4...4.5 dBm at 50 Ohm load), and the noise floor has gone up by about 20 dB, while the frequency is still spot on. I used them for various mesurements, so I can unfortunately not remember what might have caused the failure. Only the 12V linear lab power supply that fed the heaters had developed a completely dead filter cap, so the feeding voltage was a 100 Hz sawtooth rather than DC. The heaters appear to be still working though. I'm only using the internal heater. They draw some 700 mA at power up and drop to around 150 mA each when warm. So the oscillators are unlikely to be cooked inside. Something must have happened to the 10 MHz output, possibly an ESD issue? Before I start taking them apart, can anyone tell what has happened or what to look for first? Regards, Adrian ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP 10811A failure
Hi Adrian Glad to hear you're back on track and that all is now well I can understand that very thin coax being quite deceptive, it's certainly amongst the thinnest I've ever come across. I've got a couple of double oven10811s bought from one of the usual Chinese Ebay sellers a few years ago as potential spares for my Z3801As and both have one of the coax connectors chopped off, can't remember now whether it's the 10MHz output or the EFC input. Either way, should they ever be needed in anger I'm keeping my fingers crossed that the leads can be swapped over, cos fitting another connector sure don't look to be a very user friendly option:-) Regards Nigel GM8PZR In a message dated 14/10/2012 00:27:23 GMT Daylight Time, rfn...@arcor.de writes: A very good point! I checked the output amplitude with a spectrum analyzer, a power meter and a scope, the latter with a 50 ohm load to the input. I re-checked the power supply connections and can confirm they are the same as before. I used three different power supplies for the oscillators and two for the heaters, still no difference. But... To make it short, your comments helped to get me back on track. Both beauties escaped unnecessary dismantling and are now working as they should. Actually, the problem was caused by a long-term misunderstanding. I was always wondering why 'HP used simple stranded wire' and not coaxial cable on the 10 MHz output and EFC. As long as I connected them on the bench, I replaced the 'missing' ground connection with a short wired croc clamp between coax and ground. Today I realized that the thin blue wire IS actually coax cable, so I should have connected the coax shield to the BNC ground on my newly built 2x 10811 enclosure. With the new wiring, the output ground had just become much more inductive, up to a point where the nominal source impedance of 50 ohms had increased to over 120 ohms, causing the amplitude loss of some 3 dB and capturing noise. Btw. the Sprague 6800 uF / 40 V from my RS NGA power supply has indeed died, but independently of the osc. problem. Adrian gandal...@aol.com schrieb: Perhaps a silly question, but as I get the impression that both seem to have failed simultaneously with the same fault I'm just wondering if you're sure it isn't what you're checking them with that's developed a problem? Regards Nigel GM8PZR In a message dated 13/10/2012 13:52:46 GMT Daylight Time, rfn...@arcor.de writes: Hi All, both of my double oven 10811A's have been running flawlessly until now when I noticed that the output power has dropped by about 3 dB (measures only 4...4.5 dBm at 50 Ohm load), and the noise floor has gone up by about 20 dB, while the frequency is still spot on. I used them for various mesurements, so I can unfortunately not remember what might have caused the failure. Only the 12V linear lab power supply that fed the heaters had developed a completely dead filter cap, so the feeding voltage was a 100 Hz sawtooth rather than DC. The heaters appear to be still working though. I'm only using the internal heater. They draw some 700 mA at power up and drop to around 150 mA each when warm. So the oscillators are unlikely to be cooked inside. Something must have happened to the 10 MHz output, possibly an ESD issue? Before I start taking them apart, can anyone tell what has happened or what to look for first? Regards, Adrian ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts 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.
