Perhaps this is useful Microwave oscillators will change in both power output and frequency as a function of the load impedance. This was first used to characterize magnetrons and klystrons. When plotted on a Smith Chart it is called a Rieke Diagram. I later used it with Gunn Diodes. You can make a considerable difference in the power output and immunity to load pulling of the frequency by adjusting the output coupling from the waveguide cavity. I used thin irises of varying diameter inserted between waveguide flanges to do this easily. When the power is greatest, the load pull is worst. If you provide a perfect match with a slide screw tuner, you get all the power you can, and then there is not enough left in the cavity to sustain oscillation. Guess what - it stops.
I believe what you are seeing can be explained by the differing effects of changes in load impedance upon the oscillators. These will always be present of with any form of summing device unless a ferrite isolator with a very high degree of isolation (40+ dB) is used on each source before the summing device. john c roos k6iql -----Original Message----- From: time-nuts-request <[email protected]> To: time-nuts <[email protected]> Sent: Sat, Oct 11, 2014 11:50 am Subject: time-nuts Digest, Vol 123, Issue 42 Send time-nuts mailing list submissions to [email protected] To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to [email protected] You can reach the person managing the list at [email protected] When replying, please edit your Subject line so it is more specific than "Re: Contents of time-nuts digest..." Today's Topics: 1. locking oscillators - an increase in power and/or stability ? ([email protected]) 2. Re: locking oscillators - an increase in power and/or stability ? (Dr. David Kirkby (Kirkby Microwave Ltd)) 3. Re: Digital Mixing with a BeagleBone Black and D Flip Flop (Simon Marsh) 4. Re: HP10811-60212-B Pinouts. ([email protected]) 5. Re: GPS jump (Jim Lux) 6. Re: locking oscillators - an increase in power and/or stability ? (Jim Lux) 7. Re: HP10811-60212-B Pinouts. (Bob Stewart) ---------------------------------------------------------------------- Message: 1 Date: Sat, 11 Oct 2014 09:00:28 -0700 From: <[email protected]> To: [email protected] Subject: [time-nuts] locking oscillators - an increase in power and/or stability ? Message-ID: <[email protected]> Content-Type: text/plain; charset=us-ascii Came across this. Might be relevant. Cheers, Corby http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930008868.pdf a) Greater than 100% power combining efficiencies have been realized as predicted. This implies that the output power from the combiner is typically greater than the sum of the power available from individual devices. ------------------------------ Message: 2 Date: Sat, 11 Oct 2014 17:41:12 +0100 From: "Dr. David Kirkby (Kirkby Microwave Ltd)" <[email protected]> To: Discussion of precise time and frequency measurement <[email protected]> Subject: Re: [time-nuts] locking oscillators - an increase in power and/or stability ? Message-ID: <canx10hdwpkrjuachzbd1r3hdqvwhwo5ezq1ykvpysuhdakh...@mail.gmail.com> Content-Type: text/plain; charset=UTF-8 On 11 Oct 2014 16:25, "Didier Juges" <[email protected]> wrote: > If I could get 1200W by combining two 300W amplifiers, I would now be retired and very wealthy indeed. > > Unfortunately, there is no free lunch and unless somehow the Gun oscillators were delivering more power when connected to the magic T (maybe because of better matching) than when measured individually, combining two X W sources will only give you, at best, 2xX W, or 3dB more power. I see you don't get something for nothing - we are not taking about perpetual motion. I can see a few possible explanations. 1) Instrumentation error. 2) Better match - but that seems unlikely as I would have expected people to have tried countless way to improve that. 3) Injection locking causes the Gunn diode to oscillate in a different way, perhaps using different energy levels in the doped semiconductor. The fact that they have become frequency locked, indicates that their mode of operation has changed - they are not operating in the way the text books say that they do. About 2 decades ago I did an MSc in microwaves & optoelectronics. At that time I had a pretty good understanding of how Gunn diodes worked, but I have since forgotten the details. But it doesn't seem totally impossible that the mode of operation changes to one which is more efficient. > It does not matter what the combining structure is, magic T, coupler or else. I understand what you are saying, but it is hard to dismiss the possibility it is true given several people have observed this. Just because it doesn't fit into our established theories, doesn't mean it can not happen. It is not breaking any laws of physics - the overall efficiency is well below 100%. > Didier KO4BB Dave G8WRB. ------------------------------ Message: 3 Date: Sat, 11 Oct 2014 16:17:37 +0100 From: Simon Marsh <[email protected]> To: [email protected] Subject: Re: [time-nuts] Digital Mixing with a BeagleBone Black and D Flip Flop Message-ID: <[email protected]> Content-Type: text/plain; charset=UTF-8; format=flowed In this case, it seems reasonable that these multiple transitions are to be expected as there isn't any filtering that takes place in hardware prior to samples being captured by the BBB. The equivalent of the filtering/zero crossing detection takes place in software in the edge detection routine. Cheers Simon On 11/10/2014 15:19, Bob Camp wrote: > Hi > > If you are looking at the low frequency beat note out of a mixer and seeing multiple transitions on an edge - you filtering or your limiter are not up to the task. In most cases it’s the filter, but it can be either. > > Bob > > On Oct 11, 2014, at 9:10 AM, Robert Darby <[email protected]> wrote: > >> Simon, >> >> Welcome to the tangential world. >> >> I'm sure the clean edge I saw was an aberration, perhaps analogous to phase locking in oscillators; I don't think it's desirable because common sense tells you that with imperfect clocks and small phase differences there are bound to be some number of glitches at each transition. I did nothing specific to eliminate the glitches, it just happened that the positive going transition was very clean but there's no reason I am aware of to suggest that one transition should be better in this respect than another. Perhaps the flip flop I was using had a shorter set-up time on negative to positive transitions than vice versa; the smaller the set-up time the more likely one is to capture borderline events? >> >> I seem to recall that Didier Juges and Bruce Griffiths had some discussions re DDMTD's (although I can't find it in the archives) but in any event you could do far worse than dropping them a note directly to ask them about their thoughts on the matter. I'm sorry I can't provide any analysis of your data; just not in my skill set. >> Perhaps Marcus or TVB could comment. >> >> Bob Darby >> >> On 10/10/2014 3:46 PM, Simon Marsh wrote: >>> Bob, >>> >>> It's good to know someone else is trying this and it's not just me going >>> off on a tangent somewhere. I'd be very interested in understanding how you'd set this up and how you'd got a nice clean rising edge. >>> >>> My understanding is that the 'glitches' occur because the clocks are being sampled at a higher resolution than the cycle to cycle noise inherent in both the clocks and the setup. Certainly, I don't expect any of the oscillators I have available to be perfectly stable at ~1E-12 resolution, I'm sure they are all over the place The clock phase noise shows up as fast transitions near the actual beat edge as the clocks wander backwards and forwards over a few cycles. I'm sure analysis of the glitches themselves would probably say quite a lot about the cycle to cycle noise. >>> >>> I've attached an example of the transitions near an edge for a random TCXO. The edge goes from 0 at the start to 1 at the end and shows noise over about 180 samples (@10mhz). This corresponds to about ± 5E-11. The crossing line of the zero & one counts is where the edge is measured from the software point of view. ± 50ps sounds high to me, but I'm open to views as to whether that seems reasonable or just shows my shoddy setup ? >>> >>> For fun, also attached is plot of the transitions for a UBLOX8 GPS module outputing 10mhz. Compared to the TCXO that has about 10k transitions in a second's worth of data, the UBLOX module has over 1.3M (this is with a beat frequency of ~60hz). I think this is down to how the gps module is inserting/removing cycles to get 10mhz from its internal clock frequency (as has been discussed on here recently). >>> >>> Unfortunately, I don't have any expensive counters, that's part of my motivation for doing this, so I'm interested in ways that I can understand the noise floor. >>> >>> I tried passing one clock through a 74AC hex inverter and then measuring >>> the phase between the inverted/non-inverted signals on the basis that this should be more or less constant and what I'd be measuring was noise. It's certainly a good way of measuring how long the wire was that I used to make the connection This seems to yield an ADEV of 5.92E-11 @ 1 sec, plots also attached. >>> >>> Interestingly the phase seems to drift over the measurement interval, I'm open to suggestions on this, but guess this may be temperature related ? (open on bench, non-airconditioned etc) >>> >>> If the plots don't come through as attached, they are also on google drive here: >>> >>> https://drive.google.com/open?id=0BzvFGRfj4aFkSEdYV3lXcmZIVTA&authuser=0 >>> >>> Cheers >>> >>> >>> Simon >>> >>> On 10/10/2014 02:01, Robert Darby wrote: >>>> Simon, >>>> >>>> I breadboaded a set-up in March using 74AC74's and two 10 MHz Micro >>>> Crystal oscillators (5V square wave), one as the coherent source and one as the 10Hz offset clock. I had no glitch filtering as described in the article you cite (CERN's White Rabbit Project, sub nanosecond timing over ethernet) but found the positive zero crossing was very clean. The negative crossing not so much; no idea why one edge was clean and the other not. To ensure I only measured the rising clock edge and not the noise on the falling clock, I programmed ATiny's (digital 555?) to arm the D-flops only after a period of continuous low states. >>>> >>>> In any event, the lash up, as measure by a 5370, produced a clean linear noise floor of 8e-12 at 1s. I regret to note that's very slightly better than my results from the Bill Riley DMTD device. That's an indictment of my analog building skills, not his design. It's also nicely below a 5370 on it's own and needs only a simple 10 MHz counter for output. The zero crossing detectors for sine wave oscillator input will perhaps be more critical. >>>> >>>> This was encouraging enough that I thought I'd try to build an FPGA >>>> version of the same. The DDMTD is temporarily on back burner while I try to get a four channel 1ns resolution time tagger running on the FPGA to use with the DMTD. Almost there. I look forward to hearing your results with the BBB; keep us posted. >>>> >>>> Bob Darby >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ------------------------------ Message: 4 Date: Sat, 11 Oct 2014 12:57:12 -0400 From: [email protected] To: [email protected] Subject: Re: [time-nuts] HP10811-60212-B Pinouts. Message-ID: <[email protected]> Content-Type: text/plain; charset=UTF-8; format="flowed" Hi All, Yeah, that's the oscillator. The cables match the connector labels on the board. Same blue coax cables. Anyway, as this unit is missing the external oven controller, Is anyone aware of an aftermarket controller or a good reference for the controller required? I'm sure one can always build a controller, but buying something ready to go would be a better option! Thanks! Dan > [email protected] said: > > I found a picture that looks like your OCXO on Brooke Clarke's website. > > Maybe he has a schematic or pinouts for the oscillator. > > http://www.prc68.com/I/Images/Z3805A07b.jpg More info here: > http://www.prc68.com/I/Z3805A.html > > The Z3805A is very similar to the Z3801A > > > Brooke: > typo in http://www.prc68.com/Alpha.shtml > Down at the bottom, the link to the Z3805A page goes to > file:///C:/Webdocs_Hosted/I/Z3805A.html ------------------------------ Message: 5 Date: Sat, 11 Oct 2014 10:18:45 -0700 From: Jim Lux <[email protected]> To: [email protected] Subject: Re: [time-nuts] GPS jump Message-ID: <[email protected]> Content-Type: text/plain; charset=UTF-8; format=flowed On 10/11/14, 8:08 AM, Bob Camp wrote: > Hi > > To the extent that anything *is* locked, it’s been done for a lot longer than the 1980’s. Long before common view GPS, Loran-C observations (and corrections via clock trips) were used. You can look at it as a PLL, just a *very* fancy one with *very* long time constants. > > Bob > > It also depends on whether you need "lock in real time" or "lock in post processing". VLBI is a good example of the latter, and was done in the early 70s to determine the position of the moon rover, for example. ------------------------------ Message: 6 Date: Sat, 11 Oct 2014 10:22:55 -0700 From: Jim Lux <[email protected]> To: [email protected] Subject: Re: [time-nuts] locking oscillators - an increase in power and/or stability ? Message-ID: <[email protected]> Content-Type: text/plain; charset=UTF-8; format=flowed On 10/11/14, 9:00 AM, [email protected] wrote: > Came across this. > Might be relevant. > Cheers, > Corby > > http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930008868.pdf > a) Greater than 100% power combining efficiencies have been realized as > predicted. This implies that the output power from the combiner is > typically greater than > the sum of the power available from individual devices. > Those are Indium Phosphide Gunn Oscillators which are highly nonlinear and have significant dynamic component to their Z. So you can't expect all the usual combining rules (which are typically based on constant impedances, etc.) This might be one of those "optimize the dynamic match to suck more power out of the device" kind of things. ------------------------------ Message: 7 Date: Sat, 11 Oct 2014 10:46:40 -0700 From: Bob Stewart <[email protected]> To: Discussion of precise time and frequency measurement <[email protected]> Subject: Re: [time-nuts] HP10811-60212-B Pinouts. Message-ID: <[email protected]> Content-Type: text/plain; charset=us-ascii Hi Dan, Didier's site is back up and this should give you a start: http://www.ko4bb.com/manuals/index.php?dir=05%29_GPS_Timing/Z3801/Z3801A_Schematic Bob ________________________________ From: "[email protected]" <[email protected]> To: [email protected] Sent: Saturday, October 11, 2014 11:57 AM Subject: Re: [time-nuts] HP10811-60212-B Pinouts. Hi All, Yeah, that's the oscillator. The cables match the connector labels on the board. Same blue coax cables. Anyway, as this unit is missing the external oven controller, Is anyone aware of an aftermarket controller or a good reference for the controller required? I'm sure one can always build a controller, but buying something ready to go would be a better option! Thanks! Dan ------------------------------ Subject: Digest Footer _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts ------------------------------ End of time-nuts Digest, Vol 123, Issue 42 ****************************************** _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
