Re: [time-nuts] Any reason not to use one power amplifier and splitter for distribution amplifier?
Dave wrote: I was looking to make a 10 MHz distribution amp to feed test equipment with the output of a GPSDO. * * * 16-way Minicircuits splitter on eBay which I got for $40. I guess the loss is around 12 dB. Is there any reason not to just drive that with 22 dBm or so of power to get 10 dBm at each of 16 ports? Is 10 dBm an optimal value? I see several distribution amp designs witb one amplifier on each output, but is it just a lot less hassle to split a higher power amp. It all depends on what you need. If the job is feeding the time base inputs of test equipment from a GPSDO, the splitter approach should work fine if you bear a few things in mind. First, the splitter achieves its rated isolation only if it is matched well at the input and *all* outputs. That at least means using dummy loads on unused outputs, but consider that the REF inputs of most instruments are not 50 ohm loads (usually ~ 1k ohm). So, you would need to provide proper termination for the in-use outputs, too. Ideally, it would be in the form of a 52.6 ohm pass-through load at the instrument, so the coax is terminated in 50 ohms at the load (this assumes the instrument has a 1k ohm input -- if not, the pass-through terminator would need to be recalculated -- but note that only 50 and 75 ohm pass-through terminators are likely to be available as commercial items). Second, the amplifier should put out about 25dBm from a 50 ohm source, so each load will receive the standard 1Vrms = 13dBm (10dBm would probably work OK for most instruments, but they usually are fed 13dBm). If the amplifier is not naturally matched to 50 ohms, there will be additional loss in the matching network. Amplifiers that put out 25-35dBm with harmonics below, say, -50dBc are not trivial to design or build. (Not terribly difficult, but not trivial.) I used the splitter topology for the multicoupler that multiplexes antennas to eight receivers. In that case, an amplifier with extremely low noise and high dynamic range, with a natural 50 ohm output -- the sort of amplifier people use these days for post-mixer amps in HDR receivers -- works very well. But the radios are all 50 ohm loads to begin with, so I didn't need to muck about with odd value pass-through terminators. For distributing 10MHz to test equipment, I find it much easier to get good results with a distributed amplifier approach. The circuit I posted back on Nov. 26 is about as simple as it gets, but can be made even simpler. As drawn, each stage uses a 1:1:1 transformer, with the output taken from one of the windings. If the output winding is deleted, the transformer becomes a simple 1:1 and the output is taken through a 10nF blocking capacitor straight from the collector. 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] Rubidium FE-5680b 1pps to 10Mhz
Hello All: I know there is a million variations of this Rubidium Standard. Curious if anyone had any success or insight in converting the 1 pps to a 10Mhz output by some means of hacking. http://www.ebay.com/itm/FEI-fe-5680-Series-fe-5680b-rubidium-oscillator-With-1pps-20mhz-output-ONLY-/291273421415?pt=US_Ham_Radio_Receivershash=item43d13fb267 Some info on converting to 10Mhz by tracing a 20Mhz output on the board and sending to a divider from the Ebay listing. http://www.eevblog.com/forum/testgear/fe-5680b-1pps-to-10mhz/msg557064/#msg557064 Thank you -=Bryan=- ___ 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] Any reason not to use one power amplifier and splitter for distribution amplifier?
On Sunday, January 04, 2015 03:39:48 AM Charles Steinmetz wrote: Dave wrote: I was looking to make a 10 MHz distribution amp to feed test equipment with the output of a GPSDO. * * * 16-way Minicircuits splitter on eBay which I got for $40. I guess the loss is around 12 dB. Is there any reason not to just drive that with 22 dBm or so of power to get 10 dBm at each of 16 ports? Is 10 dBm an optimal value? I see several distribution amp designs witb one amplifier on each output, but is it just a lot less hassle to split a higher power amp. It all depends on what you need. If the job is feeding the time base inputs of test equipment from a GPSDO, the splitter approach should work fine if you bear a few things in mind. First, the splitter achieves its rated isolation only if it is matched well at the input and *all* outputs. That at least means using dummy loads on unused outputs, but consider that the REF inputs of most instruments are not 50 ohm loads (usually ~ 1k ohm). So, you would need to provide proper termination for the in-use outputs, too. Ideally, it would be in the form of a 52.6 ohm pass-through load at the instrument, so the coax is terminated in 50 ohms at the load (this assumes the instrument has a 1k ohm input -- if not, the pass-through terminator would need to be recalculated -- but note that only 50 and 75 ohm pass-through terminators are likely to be available as commercial items). Second, the amplifier should put out about 25dBm from a 50 ohm source, so each load will receive the standard 1Vrms = 13dBm (10dBm would probably work OK for most instruments, but they usually are fed 13dBm). If the amplifier is not naturally matched to 50 ohms, there will be additional loss in the matching network. Amplifiers that put out 25-35dBm with harmonics below, say, -50dBc are not trivial to design or build. (Not terribly difficult, but not trivial.) I used the splitter topology for the multicoupler that multiplexes antennas to eight receivers. In that case, an amplifier with extremely low noise and high dynamic range, with a natural 50 ohm output -- the sort of amplifier people use these days for post-mixer amps in HDR receivers -- works very well. But the radios are all 50 ohm loads to begin with, so I didn't need to muck about with odd value pass-through terminators. For distributing 10MHz to test equipment, I find it much easier to get good results with a distributed amplifier approach. The circuit I posted back on Nov. 26 is about as simple as it gets, but can be made even simpler. As drawn, each stage uses a 1:1:1 transformer, with the output taken from one of the windings. If the output winding is deleted, the transformer becomes a simple 1:1 and the output is taken through a 10nF blocking capacitor straight from the collector. A 10nF cap connected to the emitter winding avoids capacitively coupling collector power supply noise to the output (assuming that the collector supply isnt ground.). Bruce 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 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] Any reason not to use one power amplifier and splitter for distribution amplifier?
Hi On Jan 3, 2015, at 10:37 PM, paul swed paulsw...@gmail.com wrote: Dave I am sure there will be many answers. But yes indeed it will work fine. All of the outputs should have the same delay also and that may be useful. There really are the two approaches. The big power amp thats a 1/2 Watt you are talking and the many small amps as in the distributed mode. Whats interesting is the telcos always do the big amp splitter and the test equipment manufactures use precision distributed distribution amps. I guess its a pick your poison. Or maybe the test equipment manufacturers needed more isolation port to port. Or heavens maybe they could just sell them for more money. Would they do that? The telco types were used to the need to terminate all the lines correctly. It’s been part of their DNA for 100 years. They also are used to designing cable plants rather than just tossing wires around. They also have some needs like 20 year MTBF, so orderly is a good idea. If I see a properly terminated single drop standard line in a real working lab, it will be the first time I see one. BNC Tee’s seem to be a popular item when hooking up instruments in a typical lab. (Note - in this case the definition of “properly terminated” is 40 db return loss, so it’s as good as the splitter). More or less - the instrument guys opted for a “tap off multiple instruments” approach. The telco guys opted for a “individual run to each instrument” approach. Did every single outfit all over the world read the exact same book? Certainly not, the real world is never that orderly. Telco’s are not 100% fixed, labs are not 100% random wired. So what happens: Telco has a problem, it’s a fixed plant. They track it down and do what’s needed. The problem (hopefully) does not come back. Lab has a problem, It’s Bob over on the third bench from the end. They try to track it, Bob moves on in his troubleshooting. They never find it. Much oratory, very little labor. How often does that happen? Roughly three of four times a week where I work… We find it and fix it about half the time. The rest of the time it “just goes away” or people get tired of looking. Most common issue - can’t run a clean phase noise / ADEV / vibe plot with that silly gizmo running on (name deleted to protect Bob)’s bench. Less common issues - can’t get a clean counter reading on standard line #XXX. So yes, a real lab does go for more isolation and better protection that a telco. Undiagnosed / random problems from shorts and opens are very real in the lab, not so much in the telco. 10 MHz threat signals and 10 MHz standards are common in the lab, less so in the telco. Different systems, different needs, different solutions. At least in my basement, I’m a lot closer to a lab than a telco. I move stuff around, I turn gear on and off. I set things up and tear them down. I do indeed work on a lot of stuff that runs at 10 MHz. I have multiple 10 MHz sources running all the time. Troubleshooting every cable connection for issues is not much fun. Isolation does indeed matter in a situation like that. Even with all my junk, I don’t have a *need* for a 16 output system. I doubt I ever have more than a dozen taps running on my Spectracom at any one time. 16 boxes is a *lot* of stuff. Are there some exotic situations that come up - sure. What’s exotic to me might be normal to you. My typical might be your exotic. Do close in spurs matter to you? They do to me. Does a “burp” (phase shift) in all the standards when a cable is unplugged matter to you? It does to me. Do you run stuff 24/7 365 days a year? I do sometimes (yes yell at me for “sometimes and 365”). Do you need -175 dbc/Hz phase noise on your standard lines? I don’t. Do you need a range of standard frequencies (100K, 1M, 5M, 10M)? I do. Do you have some stuff (= almost everything) that’s fine at 1x10^-11 at 1 second wired one way and other stuff wired another? I do. How much do you listen to WWV at 5 or 10 MHz? Me - not so much. Again, different needs, will drive different solutions. Bob Humor aside each has a very good reason for doing the distribution and its driven by the requirements. I have several of those spitters and picked them up for $ 0 at hamfests. Seems no one had a use for them when all of the 900 Mhz gear came out of the sites. Mostly gone at this point. A 1/2 watt 10 Mhz amp is not that hard to build look at the many Ham sites we have a band close to 10 Mhz/ 30 Meter. Regards Paul WB8TSL On Sat, Jan 3, 2015 at 6:09 PM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: I was looking to make a 10 MHz distribution amp to feed test equipment with the output of a GPSDO. I see this http://m.ebay.com/itm/201244302355 16-way Minicircuits splitter on eBay which I got for $40. I guess the loss is around 12 dB. I actually bought another for $35 which was similar but one of them, the
[time-nuts] HP 58503A Com 4 conflict
My new old HP58503A wants to connect to my PC on Com 1-4. Other PC devices are already using those 4 Com ports. Is there any way to connect it to a Com port other than one of those 1 to 4? I currently use an Edgeport USB-to-Serial Converter which works very well to communicate with the PC and to assign Com ports to my various GPS units. But, as far as I know, the chosen Edgeport Com port must fall within the range of Com ports which for which the device is designed. If this has been answered, please point me to the discussion. Many thanks. And, Happy New Year to all, with wishes for a more peaceful (and timely - couldn't resist) year. Jim Robbins N1JR ___ 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] Any reason not to use one power amplifier and splitter for distribution amplifier?
Friends in Time, There's been a large amount of discussion about distribution amps on this list. People may be using them just because that's what's done. So I ask you: What are we trying to isolate? The destination devices do not generate an interfering signal, n'est ce pas? The receiving devices do not need to have 50 ohms input impedance if the source cable is properly terminated, no? If I use high impedance receivers tapped off a terminated line, how is this different from 10 base T? Yes, there will be cable delay between receivers, but how were you going to avoid that with your distribution amp? Put another way, why do counters like the Racal 1992 allow you to choose 50 ohm or high impedance at the input? Please, no take it on faith audiophile answers. HNY. Bill Hawkins ___ 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] Any reason not to use one power amplifier and splitter for distribution amplifier?
Almost all frequency counters have an internal source which is a potential means of injection locking an external reference if the isolation between the internal source and the external source is inadequate. High impedance taps on a single terminated line ensure that the isolation between such internal sources and the shared line is limited by the isolation afforded by the internal source selection gating/switching of each device.adding or removing a tap invariably changes the phase shift between the source and each of the other receivers.The minimum isolation required can be estimated from the maximum acceptable frequency shift, the resonator Q and internal reverse isolation between the source output and the resonator Q. Frequency distribution systems like the Spectracom 8140 with wide range ADC tend to degrade the source phase noise significantly with respect to non agc distribution systems. Bruce On Sunday, 4 January 2015 9:41 PM, Bill Hawkins b...@iaxs.net wrote: Friends in Time, There's been a large amount of discussion about distribution amps on this list. People may be using them just because that's what's done. So I ask you: What are we trying to isolate? The destination devices do not generate an interfering signal, n'est ce pas? The receiving devices do not need to have 50 ohms input impedance if the source cable is properly terminated, no? If I use high impedance receivers tapped off a terminated line, how is this different from 10 base T? Yes, there will be cable delay between receivers, but how were you going to avoid that with your distribution amp? Put another way, why do counters like the Racal 1992 allow you to choose 50 ohm or high impedance at the input? Please, no take it on faith audiophile answers. HNY. Bill Hawkins ___ 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 58503A Com 4 conflict
Hi Ok, off into serial land …. The GPSDO does not really know or care what port it’s on. It will be just as happy on port 119 as on port 4. It (by design) does care about the baud rate / data bits / parity / stop bits. This is as true with a USB to serial as with a direct serial card. That’s the good news. Now for the rest of the news. If your computer operating system is old enough, you may only *have* 4 com ports. Bad news there = upgrade the computer. Typically this is a Windows 95 and earlier issue. If the software running on the computer is old enough it may only *know* how to use 4 com ports. Bad news is same = upgrade the software. Typically this is a Windows 95 era (mid 90’s) issue. If the drivers on the serial to usb converter are old enough, they may only talk as 4 com ports (I’ve never seen this on a modern OS). Same news = upgrade the driver. All this relates to Windows. The cutoff times and versions for other OS’s are a bit more obscure. The same basic details apply. If you are running on an XP or newer machine, you should have far more than 4 com ports available. If you are running any of the newer ( = past 2000) software to talk to the box, it should be quite happy to deal with more than 4 com ports. My *guess* is that you need a different piece of software. Exactly what you are doing will determine which one you need. ( = more info required). - On Jan 4, 2015, at 10:50 AM, James Robbins jsrobb...@earthlink.net wrote: My new old HP58503A wants to connect to my PC on Com 1-4. Other PC devices are already using those 4 Com ports. Is there any way to connect it to a Com port other than one of those 1 to 4? I currently use an Edgeport USB-to-Serial Converter which works very well to communicate with the PC and to assign Com ports to my various GPS units. But, as far as I know, the chosen Edgeport Com port must fall within the range of Com ports which for which the device is designed. If this has been answered, please point me to the discussion. Many thanks. And, Happy New Year to all, with wishes for a more peaceful (and timely - couldn't resist) year. I have this terrible urge to start a calendar thread revolving around “new” years … so far I’ve resisted the urge. It’s *very* difficult ….arhhh…. Bob Jim Robbins N1JR ___ 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] Lucent KS-24361 / Z3810A : problem with Z3812A/REF 0 unit power up?
Hello, I just received my Lucent KS-24361 and set it up on my bench to power it up. I connected the Z3809A interconnect cable between the two units (Z3811A/REF 1, and Z3812A/REF 0) and applied +24VDC to the appropriate pins on the two DE-9 connectors. The Z3811A/REF 1 ran through a sequential test of the four LEDS and then after a few seconds it settled in with the amber NO GPS and the red FAULT LEDs illuminated. Meanwhile, the Z3812A/REF 0 unit never lit a single LED and is still sitting there with all LEDs dark. Both units are drawing current: the Z3811A/REF 1 draws about 700 mA steady state, and the Z3812A/REF 0 draws only slightly less: 600 mA steady state. So far, I've swapped power connectors between the units and saw no difference, and I tried to power up the Z3812A/REF0 alone, but still no joy. Am I missing something about the setup, or do I have a defective Z3812/REF 0 unit? Thanks, Stan ___ 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] Lucent KS-24361 / Z3810A : problem with Z3812A/REF 0 unit power up?
Wiggle the 15 pin interconnect several times if they do not make good contact I think this is what happens. Regards Paul WB8TSL On Sun, Jan 4, 2015 at 5:42 PM, Stan swp...@earthlink.net wrote: Hello, I just received my Lucent KS-24361 and set it up on my bench to power it up. I connected the Z3809A interconnect cable between the two units (Z3811A/REF 1, and Z3812A/REF 0) and applied +24VDC to the appropriate pins on the two DE-9 connectors. The Z3811A/REF 1 ran through a sequential test of the four LEDS and then after a few seconds it settled in with the amber NO GPS and the red FAULT LEDs illuminated. Meanwhile, the Z3812A/REF 0 unit never lit a single LED and is still sitting there with all LEDs dark. Both units are drawing current: the Z3811A/REF 1 draws about 700 mA steady state, and the Z3812A/REF 0 draws only slightly less: 600 mA steady state. So far, I've swapped power connectors between the units and saw no difference, and I tried to power up the Z3812A/REF0 alone, but still no joy. Am I missing something about the setup, or do I have a defective Z3812/REF 0 unit? Thanks, Stan ___ 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] Lucent KS-24361 / Z3810A : problem with Z3812A/REF 0 unit power up?
The interface jumper cable has several short pins that sometimes do not make a good connection. You might check that it is fully plugged in on both ends and that all 15 pins look ok. The cable crosses over the pins such that pin 1 of one end goes to pin 15 of the other and so on. There are some power supply test points on the top of the board that you can get to with the cover removed. There should be +5, +15, and -15 volts in there. Do you have an amplified antenna connected to the GPS Rx input? The antenna should use +5 volts. Regards - Original Message - From: Stan swp...@earthlink.net To: time-nuts@febo.com Sent: Sunday, January 04, 2015 5:42 PM Subject: [time-nuts] Lucent KS-24361 / Z3810A : problem with Z3812A/REF 0 unit power up? Hello, I just received my Lucent KS-24361 and set it up on my bench to power it up. I connected the Z3809A interconnect cable between the two units (Z3811A/REF 1, and Z3812A/REF 0) and applied +24VDC to the appropriate pins on the two DE-9 connectors. The Z3811A/REF 1 ran through a sequential test of the four LEDS and then after a few seconds it settled in with the amber NO GPS and the red FAULT LEDs illuminated. Meanwhile, the Z3812A/REF 0 unit never lit a single LED and is still sitting there with all LEDs dark. Both units are drawing current: the Z3811A/REF 1 draws about 700 mA steady state, and the Z3812A/REF 0 draws only slightly less: 600 mA steady state. So far, I've swapped power connectors between the units and saw no difference, and I tried to power up the Z3812A/REF0 alone, but still no joy. Am I missing something about the setup, or do I have a defective Z3812/REF 0 unit? Thanks, Stan ___ 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] Lucent KS-24361 / Z3810A : problem with Z3812A/REF 0 unit power up?
Hi Stan, Is there a green LED lit on the board near the power block, or are both red and green very dim or not on at all? I have a unit with the same symptoms as yours. Both output voltages are extremely low from the power block. Unless the green LED is lit or flashing, I'd send it back. Bob - AE6RV From: Stan swp...@earthlink.net To: time-nuts@febo.com Sent: Sunday, January 4, 2015 4:42 PM Subject: [time-nuts] Lucent KS-24361 / Z3810A : problem with Z3812A/REF 0 unit power up? Hello, I just received my Lucent KS-24361 and set it up on my bench to power it up. I connected the Z3809A interconnect cable between the two units (Z3811A/REF 1, and Z3812A/REF 0) and applied +24VDC to the appropriate pins on the two DE-9 connectors. The Z3811A/REF 1 ran through a sequential test of the four LEDS and then after a few seconds it settled in with the amber NO GPS and the red FAULT LEDs illuminated. Meanwhile, the Z3812A/REF 0 unit never lit a single LED and is still sitting there with all LEDs dark. Both units are drawing current: the Z3811A/REF 1 draws about 700 mA steady state, and the Z3812A/REF 0 draws only slightly less: 600 mA steady state. So far, I've swapped power connectors between the units and saw no difference, and I tried to power up the Z3812A/REF0 alone, but still no joy. Am I missing something about the setup, or do I have a defective Z3812/REF 0 unit? Thanks, Stan ___ 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] Lucent KS-24361 / Z3810A : problem with Z3812A/REF 0 unit power up?
Hi More or less in order of probability : 1) The most likely case is the interconnect cable. A couple of plug / unplug cycles on both ends is well worth the trouble. Also a bit of flexing of the cable may be in order. No it’s not good that the cable is bit flaky, it’s an easy part to replace if it dies later. It’s also a part that goes away once you (if you) rewire the units. 2) Next up is a check of the GPS antenna. If the “No GPS” LED flashes, that’s an antenna fault. Best bet - your REF-0 does have a problem. For entertainment value, you can hook up an RS-422 serial to the Diag port and see what (if anything) the log has to say about the issue. Bob On Jan 4, 2015, at 5:42 PM, Stan swp...@earthlink.net wrote: Hello, I just received my Lucent KS-24361 and set it up on my bench to power it up. I connected the Z3809A interconnect cable between the two units (Z3811A/REF 1, and Z3812A/REF 0) and applied +24VDC to the appropriate pins on the two DE-9 connectors. The Z3811A/REF 1 ran through a sequential test of the four LEDS and then after a few seconds it settled in with the amber NO GPS and the red FAULT LEDs illuminated. Meanwhile, the Z3812A/REF 0 unit never lit a single LED and is still sitting there with all LEDs dark. Both units are drawing current: the Z3811A/REF 1 draws about 700 mA steady state, and the Z3812A/REF 0 draws only slightly less: 600 mA steady state. So far, I've swapped power connectors between the units and saw no difference, and I tried to power up the Z3812A/REF0 alone, but still no joy. Am I missing something about the setup, or do I have a defective Z3812/REF 0 unit? Thanks, Stan ___ 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] Lucent KS-24361 / Z3810A : problem with Z3812A/REF 0 unit power up?
Am 04.01.2015 um 23:42 schrieb Stan: I just received my Lucent KS-24361 and set it up on my bench to power it up. I connected the Z3809A interconnect cable between the two units (Z3811A/REF 1, and Z3812A/REF 0) and applied +24VDC to the appropriate pins on the two DE-9 connectors. The Z3811A/REF 1 ran through a sequential test of the four LEDS and then after a few seconds it settled in with the amber NO GPS and the red FAULT LEDs illuminated. Meanwhile, the Z3812A/REF 0 unit never lit a single LED and is still sitting there with all LEDs dark. Both units are drawing current: the Z3811A/REF 1 draws about 700 mA steady state, and the Z3812A/REF 0 draws only slightly less: 600 mA steady state. So far, I've swapped power connectors between the units and saw no difference, and I tried to power up the Z3812A/REF0 alone, but still no joy. Am I missing something about the setup, or do I have a defective Z3812/REF 0 unit? That's normal. The pair goes ON only when it sees GPS for quite some time. BTW the POWER consumption is fixed. If you have more voltage, the current will drop. regards, Gerhard ___ 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] schematics of frequency counter
hi Neil, TPS79333 is quite cheap and adm7150 is 60 times the price of it. These 2 ldo has different package, it not easy to replace it directly. I have tried power the system with 18650 battery, the performace is almost the same with 5v from laptop USB port. So I think psrr might not be a issue. If the noise generated by LDO is the problem, can I filter it out by puting more caps? Neil Schroeder gign...@gmail.com于2015年1月3日星期六写道： I would reconsider the LDOs while you have some time to play with them. The TPS79333DBVR is not even remotely ultralow noise at most offsets, despite what TI may say. For 5V5 and under up to about 600ma, I would suggest you take a look at the ADM7155 (adjustable) or ADM7154 (fixed). If you need 800ma, the 7150 is here for you. http://www.analog.com/en/power-management/linear-regulators/adm7155/products/product.html http://www.analog.com/en/power-management/linear-regulators/adm7150/products/product.html The TI part has nearly 35 uVRMS of noise at just 2.8a with not very good PSRR. The 7155 will produce less than 1.0 μVRMS Total Integrated Noise from 100 Hz to 100 KHz and 1.6 from 10 to 100 KHz,and that's without an RC noise compensation network. Its a fabulous part for a sensitive application like yours. I'm hoping I am right in assuming that the noise performance of the LDOs is a concern, and don't mean to even dare suggest that you've done anything but a great job! :-) NS On Sat, Dec 27, 2014 at 5:34 AM, Li Ang lll...@gmail.com wrote: Hi Charles, In my circuit, the VCC is 5v. I've noticed my bias and emitter resistor is something need to be changed. I will play with the resistors and see if it improves. Thanks. 2014-12-27 6:42 GMT+08:00 Charles Steinmetz csteinm...@yandex.com: Li Ang wrote: RF pnp transistor is harder to get. I would like the front end works at 300MHz. My questions: 1) why the difference of DC bias of the 2 NPN matters? I thought only the frequency part is useful to a counter, amplitude information is useless right? You want the circuit to switch near the mid-point of the input sine wave, and at exactly the same place every time. How you bias the transistors determines how well this is accomplished. You also want the output to switch fast and cleanly between a low voltage very near 0v (ground) to a high voltage very near 3v (Vcc, logic high). An NPN cannot do that, biased the way that you have them connected (the emitter of the output transistor Q301 can only pull the output down to a little less than 1v due to R315, which may sort of work but is not a proper way to run 3v logic). This operation also saturates Q301, which is bad for performance. See simulated results below. In order for an NPN to provide a useful output for 3v logic, (i) its emitter must be grounded, and (ii) it must either be run into saturation or use a Baker clamp. Running the transistor into saturation must be avoided, particularly if you want to reach 300MHz, and a Baker clamp raises the logic low output voltage to 0.5v (not a good thing with 3v logic). So, it is very much better to use a PNP differential pair. For a 300MHz circuit, I would use BFT93 (and even that barely gets you to 300MHz). 2) what's is the C4 in your circuit for? C4 makes Q1 and Q2 a differential (emitter-coupled) pair at RF frequencies, but not at DC. So, the circuit has no gain at DC and therefore the DC errors between Q1 and Q2 cause much less output error than they would if the emitters were connected directly together. 3) If the noise is more important than the gain, what kind of transistor should I choose? The Ft near 300MHz ones(BFS17, 2SC9018) or Ft far beyond 300MHz ones(BFP420, BFP183,BFR93) ? Far beyond. The Ft is the frequency where a transistor completely runs out of gain. You want to operate at a much lower frequency where the transistor still has substantial gain, particularly with fast RF transistors, which generally have much lower DC hfe than general-purpose transistors like 3904 and 3906. Note that the simulation of the circuit you published (simulated results below) barely works at even 20MHz. As I noted above, even the BFT93 barely gets you to 300MHz with a 1Vrms input. 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 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] Frequency doubler 5/10 and distribution amplifier forLucent KS-24361
Good job on the doubler/distribution amp, Gerhard! Which PCB design software did you use to make the PC board? Could you share the files for it? Dave M Gerhard Hoffmann wrote: Hi, all, over the Christmas season, I have designed and built a frequency doubler from 5 to 10 MHz and a distribution amplifier for the Lucent KS-24361. A preliminary writeup is under http://www.hoffmann-hochfrequenz.de/downloads/DoubDist.pdf It features 4 or 5 10 MHz 10 dBm outputs and an optional 1PPS on SMA with CMOS levels into 50 Ohm. It is a small board to be mounted inside the KS-24361. Comments invited. regards, Gerhard ___ 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] Any reason not to use one power amplifierand splitter for distribution amplifier?
Thanks, Bruce. That does clear it up, although pulling an oscillator through a FET gate to a 50 ohm cable seems a stretch. If things are not that simple, e.g., a wiring harness to a front panel selector switch, then maybe. I'm assuming the source oscillator is well buffered against the world outside the oven can. I should have said 10base2, not T, meaning coaxial cable with BNC connectors and T connectors at the receivers, terminated at the far end. The allusion to audiophiles had to do with people who pay hundreds of dollars for a line (mains) cord that has special properties to make the sound from their amplifier somehow more pleasant. They do this because marketing told them so, ignoring what goes on in the house wiring to the wall outlet. There are people who need to handle time distribution very carefully (lest they get FTL neutrinos), but most of the list seems to buy their equipment from eBay. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bruce Griffiths Sent: Sunday, January 04, 2015 3:39 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Any reason not to use one power amplifierand splitter for distribution amplifier? Almost all frequency counters have an internal source which is a potential means of injection locking an external reference if the isolation between the internal source and the external source is inadequate. High impedance taps on a single terminated line ensure that the isolation between such internal sources and the shared line is limited by the isolation afforded by the internal source selection gating/switching of each device.adding or removing a tap invariably changes the phase shift between the source and each of the other receivers.The minimum isolation required can be estimated from the maximum acceptable frequency shift, the resonator Q and internal reverse isolation between the source output and the resonator Q. Frequency distribution systems like the Spectracom 8140 with wide range ADC tend to degrade the source phase noise significantly with respect to non agc distribution systems. Bruce On Sunday, 4 January 2015 9:41 PM, Bill Hawkins b...@iaxs.net wrote: Friends in Time, There's been a large amount of discussion about distribution amps on this list. People may be using them just because that's what's done. So I ask you: What are we trying to isolate? The destination devices do not generate an interfering signal, n'est ce pas? The receiving devices do not need to have 50 ohms input impedance if the source cable is properly terminated, no? If I use high impedance receivers tapped off a terminated line, how is this different from 10 base T? Yes, there will be cable delay between receivers, but how were you going to avoid that with your distribution amp? Put another way, why do counters like the Racal 1992 allow you to choose 50 ohm or high impedance at the input? Please, no take it on faith audiophile answers. HNY. Bill Hawkins ___ 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.
