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Hi, everybody.
I keep my (Leo Bodnar) GPS-disciplined oscillator running continuously, and I have its output going to a?BG7TBL distribution amp (yes, I could have designed and built my own distribution amp easily, but for <$100, it's not worth the time, since I'm not retired yet) .? So far, the only instruments I own that can use the 10 MHz from the GPSDO are an 8566A spectrum analyzer and a 5343A frequency counter.? Now the distribution amp puts out 4 Vp-p unterminated and 2 Vp-p = +10 dBm into 50 ohms, and I'm wondering if I should keep the outputs of the distrib amp running continuously into the spec an and freq counter.
Maybe I'm just extra cautious, but ISTR blowing something up early in my career by putting hot signals into something not powered up.??I keep the 8566A and 5343A powered up and in Standby mode at all times.?Perhaps we have the designers of said HP equipments in the group?? Or at least somebody familiar with the innards of one and/or the other piece of gear.? Magnificent stuff, BTW!
Thanks.
Jim Ford
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I've had a lab" with several 8566s, two 8510c,and (probably) 5 5345As + numerous HP equipment with the distributio amp feeding everything all the time. Don't believe my amp puts out quite 4v (think it is more like 1.5 - 2.0, but I've never had a problem.
Quoting Jim Ford <james.ford@...>:
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Hi, everybody.
I keep my (Leo Bodnar) GPS-disciplined oscillator running continuously, and I have its output going to a BG7TBL distribution amp (yes, I could have designed and built my own distribution amp easily, but for <$100, it's not worth the time, since I'm not retired yet) . So far, the only instruments I own that can use the 10 MHz from the GPSDO are an 8566A spectrum analyzer and a 5343A frequency counter. Now the distribution amp puts out 4 Vp-p unterminated and 2 Vp-p = +10 dBm into 50 ohms, and I'm wondering if I should keep the outputs of the distrib amp running continuously into the spec an and freq counter.
Maybe I'm just extra cautious, but ISTR blowing something up early in my career by putting hot signals into something not powered up. I keep the 8566A and 5343A powered up and in Standby mode at all times. Perhaps we have the designers of said HP equipments in the group? Or at least somebody familiar with the innards of one and/or the other piece of gear. Magnificent stuff, BTW!
Thanks.
Jim Ford
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Agree with Bruce,
Been running my 10 MHz 24x7 into a HP-5342A, HP-8901B and Fluke 6060A/AN for years with no ill effects.
Regards
Lou
VK3ALB
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Thanks, Bruce and Lou.
I figured as long as the units were powered up everything should be OK.? Just paranoid I guess.
Jim
Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message -------- From: Lou Blasco <vk3alb@...> Date: 4/12/20 9:02 PM (GMT-08:00) Subject: Re: [HP-Agilent-Keysight-equipment] GPSDO connected to external ref inputs
Agree with Bruce, Been running my 10 MHz 24x7 into a HP-5342A, HP-8901B and Fluke 6060A/AN for years with no ill effects. Regards Lou VK3ALB
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I have a GPSDO going to a 4 port distribution amp which is connected to a HP 8920A, HP 8594E, 8656B, and HP 53131A. The Ref signal is never turned off but the equipment is turned off daily. Never had a problem
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No problem - I do think 4v is a bit high though - any radiation problems?
Cheers!
Quoting Jim Ford <james.ford@...>:
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Thanks, Bruce and Lou.I figured as long as the units were powered up
everything should be OK.? Just paranoid I guess.JimSent from my
Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Lou Blasco
<vk3alb@...> Date: 4/12/20 9:02 PM (GMT-08:00) To:
[email protected] Subject: Re:
[HP-Agilent-Keysight-equipment] GPSDO connected to external ref
inputs Agree with Bruce,Been running my 10 MHz 24x7 into a HP-5342A,
HP-8901B and Fluke 6060A/AN for years with no ill
effects.RegardsLouVK3ALB
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Thanks, Clif.? One more data point on the curve.
Jim
Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message -------- From: Clif Holland <clif@...> Date: 4/13/20 5:08 AM (GMT-08:00) Subject: Re: [HP-Agilent-Keysight-equipment] GPSDO connected to external ref inputs
I have a GPSDO going to a 4 port distribution amp which is connected to a HP 8920A, HP 8594E, 8656B, and HP 53131A. The Ref signal is never turned off but the equipment is turned off daily. Never had a problem
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Jim,
?
I have a HP 5087A distribution amp feeding output from an older HP Z3816 GPSDO to several pieces of equipment.? These include:
?
Agilent E4425B signal generator
Agilent 8714ET network analyzer
EIP 548A microwave frequency counter
HP 3575A gain/phase meter
HP 5335A counter
HP 8920A RF communication test set
HP 53310A modulation domain analyzer
HP K34-9991A phase comparator
PTS 250 frequency synthesizer
Tracor 527E frequency difference meter
Tracor 895A linear phase/time comparator
Wayne Kerr PSG2400L signal generator
?
Except for the Z3816/5087 units most of the driven equipment is in a power-down state unless needed.? The port on the 527E is switchable to an external connector on the bench for other test applications.? In all, I feed one volt p-p or less to all of the equipment and it stays happy.? The advantage with the 5087A is that each output is individually adjustable to suit the needs of the attached hardware.
?
If any of your units cannot tolerate a 4V amplitude I suggest that you pick up an in-line 50 ohm attenuator either from your favorite auction site or from Mini-Circuits (no affiliation however I rely on them for their low-cost high-quality products).? 4 volts does seem a little excessive for most external reference inputs since I am assuming you are referring to RMS amplitude and not peak-to-peak value.
?
Greg
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The output of my x10 dist amp was running at about +12 dBm driving two radios and seven TE.? I put a 10dB pad on the input side because my Icom IC-9700 was complaining about the high level.? e.g.,?? Your +10 dBm is about 5 dB higher than normal practice but definitely won't hurt anything even if not mitigated.
best regards....
Frank Mackowick / WA3NHK
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That's 4 Volts peak to peak unterminated. 2 Volts peak to peak or +10 dBm into 50 ohms, which I assume the 5343A and 8566A have.
As to radiation, not as far as I know. I've not tried to work the HF band that I hear gets obliterated by stray 10 MHz from distribution systems. Unless one takes care with double shielded coax and terminators on all unused outputs. Not there with the ham radio gear yet (will take recommendations on a 70 cm capable rig, though).
Thanks.
Jim
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------ Original Message ------ From: "Bruce" <bruce@...> To: [email protected]Sent: 4/13/2020 9:25:03 AM Subject: Re: [HP-Agilent-Keysight-equipment] GPSDO connected to external ref inputs No problem - I do think 4v is a bit high though - any radiation problems?
Cheers!
Quoting Jim Ford <james.ford@...>:
Thanks, Bruce and Lou.I figured as long as the units were powered up
everything should be OK. Just paranoid I guess.JimSent from my
Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Lou Blasco
<vk3alb@...> Date: 4/12/20 9:02 PM (GMT-08:00) To:
[email protected] Subject: Re:
[HP-Agilent-Keysight-equipment] GPSDO connected to external ref
inputs Agree with Bruce,Been running my 10 MHz 24x7 into a HP-5342A,
HP-8901B and Fluke 6060A/AN for years with no ill
effects.RegardsLouVK3ALB
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------ Original Message ------
Sent: 4/13/2020 10:55:53 AM
Subject: Re: [HP-Agilent-Keysight-equipment] GPSDO connected to external ref inputs
The output of my x10 dist amp was running at about +12 dBm driving two radios and seven TE.? I put a 10dB pad on the input side because my Icom IC-9700 was complaining about the high level.? e.g.,?? Your +10 dBm is about 5 dB higher than normal practice but definitely won't hurt anything even if not mitigated.
best regards....
Frank Mackowick / WA3NHK
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A mostly-related question:
I have an older GPS module (Navsync CW12-TIM) that (apparently) functions as a GPSDO. The output freq is programmable, up to 30 MHz.
The CW12 doc includes (for example) the following: "The graph below demonstrates the ability of the CW12-TIM GPS to continue to provide a GPS disciplined output frequency with the GPS aerial located completely inside a building...". The doc also says the CW12-TIM was designed to meet the form and functionality of the Motorola M12+.
I have limited knowledge of these things.
My question is this: Is this module producing a signal that is equivalent to what you folks are talking about earlier in this thread? Or is there more to it?
Would it be correct to say that my GPS module outputs a signal that has excellent long-term "accuracy", but the short-term "precision" (including jitter and such) may not be so good?
Thanks,
Pete
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If it has a Motorola M12 GPS receiver installed, that receiver is capable of providing the 1 Pules per Second (PPS) required by most GPSDOs - It does not produce the 10MHz signal however, that comes from the GPSDO. The 1PPS is the discipline part of the GPSDO. I (the M12)t has a TTL output 1PPS signal - I have the specs somehwere if you can't find them on line. The M12 was (and apparently is) distributed by - see this page for a pointer to the M12 and its documentation. I used one for a number of years and it was a fine GPS timing source for a DO. I now use a RUDO (Rubidium disciplined oscillator) with a built in GPS Rx. Cheers! Bruce Quoting "saipan59 (Pete)" < [email protected]>:
A mostly-related question:
I have an older GPS module (Navsync CW12-TIM) that (apparently) functions as a GPSDO. The output freq is programmable, up to 30 MHz.
The CW12 doc includes (for example) the following: "The graph below demonstrates the ability of the CW12-TIM GPS to continue to provide a GPS disciplined output frequency with the GPS aerial located completely inside a building...". The doc also says the CW12-TIM was designed to meet the form and functionality of the Motorola M12+.
I have limited knowledge of these things.
My question is this: Is this module producing a signal that is equivalent to what you folks are talking about earlier in this thread? Or is there more to it?
Would it be correct to say that my GPS module outputs a signal that has excellent long-term "accuracy", but the short-term "precision" (including jitter and such) may not be so good?
Thanks,
Pete
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Based on the rest of your - email you seem to have a compete GPSDO system and just need to know how to program it for 10MHz (or 5Mhz) output. Cheers! Quoting "saipan59 (Pete)" < [email protected]>:
A mostly-related question:
I have an older GPS module (Navsync CW12-TIM) that (apparently) functions as a GPSDO. The output freq is programmable, up to 30 MHz.
The CW12 doc includes (for example) the following: "The graph below demonstrates the ability of the CW12-TIM GPS to continue to provide a GPS disciplined output frequency with the GPS aerial located completely inside a building...". The doc also says the CW12-TIM was designed to meet the form and functionality of the Motorola M12+.
I have limited knowledge of these things.
My question is this: Is this module producing a signal that is equivalent to what you folks are talking about earlier in this thread? Or is there more to it?
Would it be correct to say that my GPS module outputs a signal that has excellent long-term "accuracy", but the short-term "precision" (including jitter and such) may not be so good?
Thanks,
Pete
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On Mon, Apr 13, 2020 at 06:54 PM, Bruce wrote:
If it has a Motorola M12 GPS receiver installed, that receiver is capable of providing the 1 Pules per Second (PPS) required by most GPSDOs - It does not produce the 10MHz signal however, that comes from the GPSDO. The 1PPS is the discipline part of the GPSDO.
Thanks for your comments! To clarify a bit:? The module has both a freq output, and a 1 PPS output. I know how to program the freq output (it defaults to 10 MHz, but I can change it to all sorts of values). It has a small connector for an active antenna. Some years ago, I bought a mag-mount "turtle" with a few feet of cable, from a Chinese vendor. I hooked it up to a little MCU board to send/receive serial data. The module has a couple of LEDs that indicate the status of GPS lock and such (it even does a blinking pattern to show how many satellites are acquired). All seems to work. But what I'm asking is: What is the "quality" of the freq output from this thing likely to be? The NavSync docs don't seem to address this aspect, other than to compare it to a Cesium source and such - it doesn't describe specs such as jitter, which I (think) understand is a key measurement of short-term performance. The docs do say that the 1 PPS edge is +/- 30 nS from UTC. Another way to phrase the question: What does the OP's "Leo Bodnar" box do that is "better", when it comes to "signal quality" for a basic 10 MHz reference?? A third way to phrase the question: If I use this module as a reference for my HP5345A counter, is it "better" than the internal reference? Thanks again, Pete
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Here's a pic. Note that there's also a battery backup capability. 
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On 4/13/20 9:28 PM, saipan59 (Pete) wrote: Thanks for your comments! To clarify a bit:?
The module has both a freq output, and a 1 PPS output. I know how to
program the freq output (it defaults to 10 MHz, but I can change it to
all sorts of values). It has a small connector for an active antenna.
Some years ago, I bought a mag-mount "turtle" with a few feet of cable,
from a Chinese vendor. I hooked it up to a little MCU board to
send/receive serial data. The module has a couple of LEDs that indicate
the status of GPS lock and such (it even does a blinking pattern to show
how many satellites are acquired). All seems to work.
But what I'm asking is: What is the "quality" of the freq output from
this thing likely to be? The NavSync docs don't seem to address this
aspect, other than to compare it to a Cesium source and such - it
doesn't describe specs such as jitter, which I (think) understand is a
key measurement of short-term performance. The docs do say that the 1
PPS edge is +/- 30 nS from UTC.
Another way to phrase the question: What does the OP's "Leo Bodnar" box
do that is "better", when it comes to "signal quality" for a basic 10
MHz reference??
A third way to phrase the question: If I use this module as a reference
for my HP5345A counter, is it "better" than the internal reference? The long-term stability is likely to be very good. But without knowing more about the architecture of the device, anything else is hard to say. It's probably a PLL-based frequency synthesizer, so, phase noise...but how much and where? You can measure it, but not without something "better" than your board is likely to be. You are standing on the precipice of becoming a Time Nut. Fair warning. ;) -Dave -- Dave McGuire, AK4HZ New Kensington, PA
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On Mon, Apr 13, 2020 at 08:08 PM, Dave McGuire wrote:
You are standing on the precipice of becoming a Time Nut. Fair
warning. ;)
Thanks Dave! I'm sorta already there, although my focus is "obsolete gear that I'm unlikely to ever use". For example, the super-cool HP115AR Clock, with its mechanical display, and really awkward startup procedure... Here is a very short video of it running, working with the audio from WWV on a Hammarlund SP-600 rcvr (not shown), signal displayed by an HP122AR scope, and comparing the WWV timing to the oscillator in an HP5245L (not shown). But I'm thinking I'll set up this GPSDO in a little box, so that I can point to it and say "the output of that thing is really accurate". Pete
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That's sorta my attitude, too.? For less than $250, I have a frequency reference that is better than I will ever need, and I don't have the time to fool with anything better.? Now, if they were to give me that rubidium frequency standard that crapped out at work, I would try to revive it with a hair dryer or heat gun.? Just to have holdover.? It's really embedded in a rack, though, and not easy to get out, so I haven't volunteered to remove it.? ?Yes, I live on the Time Nut Precipice, the TNP for short!
Jim Ford?
Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message -------- Date: 4/13/20 8:02 PM (GMT-08:00) Subject: Re: [HP-Agilent-Keysight-equipment] GPSDO connected to external ref inputs
On Mon, Apr 13, 2020 at 08:08 PM, Dave McGuire wrote:
You are standing on the precipice of becoming a Time Nut. Fair
warning. ;)
Thanks Dave! I'm sorta already there, although my focus is "obsolete gear that I'm unlikely to ever use". For example, the super-cool HP115AR Clock, with its mechanical display, and really awkward startup procedure... Here is a very short video of it running, working with the audio from WWV on a Hammarlund SP-600 rcvr (not shown), signal displayed by an HP122AR scope, and comparing the WWV timing to the oscillator in an HP5245L (not shown). But I'm thinking I'll set up this GPSDO in a little box, so that I can point to it and say "the output of that thing is really accurate". Pete
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With a disciplined oscillator, the crystal oscillator will determine the short term characteristics of the output; the GPS will determine the "long term stability".
If you use a poor crystal oscillator, you will have jitter and most likely poor phase noise performance.
The same applies with the Rb standards. The short term performance is that of the crystal oscillator. The Rb device is not a primary standard with so so short term stability; That is why they contain to good quality crystal oscillator. In addition you still have to calibrate it once in a while. With GPS that isn't necessary.
A disciplined oscillator, using GPS should result in about 100 times better stability than that of the crystal oscillator alone. Again, if you use a poor crystal oscillator, the performance will not be too great.
Mine use SC crystal oscillators in ovens.
I use two different disciplined oscillators in two location at home. I have compared them using a vector voltmeter and can see some phase changes now and again, but I don't think that for my purposes that is important.
Stuart K6YAZ
Los Angeles, USA
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saipan59 (Pete)
Dave McGuire