Magnus Good afternoon. I am having a hard time following this. Conflicting data I believe.. Using the FRS-C because its the clearest. On page 3-14 it says +/- 1E-9 for 5V (5V is later in the book) Wouldn't that be 2E-9th for 5V? The 10811 is far more difficult to pin down as several articles from TVB and others say the 10811 actually has a wider control range then the standard. Something like 10 Hz over 10V. Traditional is 1 Hz over 10 V. But as I say seems to be different answers depending on what you read.
When these details are settled you then came up with the need for a gain of 8. Did you use a rule of thumb? Thanks Paul WB8TSL On Fri, Dec 30, 2016 at 9:06 AM, Magnus Danielson <[email protected]> wrote: > I think the numbers given for 10811 sensitivity was grossly incorrect from > the source I had, so it should be +/- 1E-6 for +/- 5V, thus giving 2E-6 > over 10V thus giving a sensitivity of 2E-7/V. Compare to 4E-10/V fro the > FRS-C and just redo the work. > > I thought the numbers where funny but too tired to do extensive digging, > but I just wanted to show the general idea. > > Cheers, > Magnus > > > On 12/30/2016 04:05 AM, paul swed wrote: > >> Been interesting. >> Did increase the gain to 8 and remove the attenuation 10:1 needed for >> the piezo ocxo. Not sure I would say the system locks but it certainly >> slows the drift down to 10ns/30 minutes. I also added an offset after >> the amplifier. This allowed the Z3801 EFC to set its range more towards >> 50%. >> Though the FRS manual says the range is 0-5V for EFC the FRS is clearly >> offset with age to the +1.7V for center. (The other FRS was +.6V) >> >> Its interesting to see at the startup of the Z3801 the EFC range in the >> RB. Nice steps down towards a fairly low angle line according to Lady >> Heather. >> >> Have had to stop the experimentation late today to give a hand to a >> fellow on a HP 70-110GHz signal source. Till today I was a 10 GHz sort >> of guy. >> Regards >> Paul >> WB8TSL >> >> >> >> On Wed, Dec 28, 2016 at 6:51 PM, Magnus Danielson >> <[email protected] <mailto:[email protected]>> wrote: >> >> Hi, >> >> Well, that was the data I was able to find (and I referred to TvBs >> page where I found it). If you have more accurate data, please share >> so we can get the numbers right. >> >> The Z3801A will do a least square estimate of frequency error and then >> translate that into an initial DAC setting assuming it knows the EFC >> sensitivity, and the loop will work out the rest from there >> (hopefully). >> Getting EFC in the right neighborhood is probably wise for this >> reason. >> >> Cheers, >> Magnus >> >> >> On 12/29/2016 12:32 AM, Bob Camp wrote: >> >> Hi >> >> Ummm ….. errrrr …. >> >> The 10811 that is used in the Z3801 has a *larger* electrical >> tuning range than the standard >> 10811 not a smaller one. It’s tuning range and the TBolt OCXO’s >> tuning range are >> very similar. >> >> Bob >> >> On Dec 28, 2016, at 6:22 PM, Magnus Danielson >> <[email protected] >> <mailto:[email protected]>> wrote: >> >> Paul, >> >> We just want to help you with that curiosity, it sounds like >> a fun little project. :) >> >> The FRS-C [1] has a range of +/- 1E-9 over 0-5V, so EFC >> sensitivity is 4E-10/V. >> >> The Z3801A has a range of 5.20E-10 [2] over -5V to +5V [3], >> so EFC sensitivity is 5.2E-11/V. >> >> So, it looks like you need to have a gain of 8 and raise the >> EFC 2.5 V. >> >> Cheers, >> Magnus >> >> [1] http://www.to-way.com/tf/frs.pdf >> <http://www.to-way.com/tf/frs.pdf> >> >> [2] http://www.leapsecond.com/pages/z3801a-efc/ >> <http://www.leapsecond.com/pages/z3801a-efc/> >> >> [3] http://www.realhamradio.com/joe-geller.htm >> <http://www.realhamradio.com/joe-geller.htm> >> >> On 12/28/2016 11:42 PM, paul swed wrote: >> >> Magnus and Bob, >> Thank you for your response. As far as the original HO >> 10811 oscillator >> goes there is some well written details on it behavior >> and sensitivity. It >> was not the same as a standard 10811. A far smaller >> range as I recall. But >> the data is there. >> Its funny on the RB I have the EFC range from the spec >> sheet. It really >> tunes from 0-5V. But I find it interesting that the best >> alignment with >> other references is sub 1V. Its an old FRS C and I have >> others that may >> present a more centered range. >> >> I'll have to compare the detials that I have on the >> 10811 and FRS C. But I >> actually pulled out a 100:1 antenuator I was using on >> the Piezo crystal >> that indeed does lock. >> >> Goal in all of this is nothing special simply curiosity. >> Thanks again. When I have some real numbers to share I >> will. >> Regards >> Paul >> WB8TSL >> >> On Tue, Dec 27, 2016 at 10:26 PM, Bob Camp >> <[email protected] <mailto:[email protected]>> wrote: >> >> Hi >> >> The loop gain (as Magnus mentions) needs to be >> “correct” for the Rb. Since >> the firmware was written for an OCXO with a PPM(ish) >> trim range, tacking it >> on to a PPB(ish) Rb will require everything to scale >> by 1000:1. That’s 10 >> bits. >> You may (or may not) have enough resolution in the >> math to handle that wide >> a range of gains. >> >> If it really locks, the next challenge is to get it >> to run out to ~ 4 days >> or more on >> the loop. Again, the firmware may or may not be able >> to do this. Unless it >> does, >> the Rb really will not lock as well as it could. >> >> With the Rb correctly locked, you still have the >> issue that the Rb is a >> 2x10^-11 >> device (ADEV) at 1 second and the OCXO probably is >> 2x10^-12 (or better). >> For >> driving a counter with a normal gate, the Rb may not >> show much (if any) >> improvement. >> There is the slight chance the ADEV will get the >> firmware confused….. >> >> Since the firmware source is running around >> somewhere, you *could* dig into >> all of this wonderful stuff :) >> >> Bob >> >> >> On Dec 27, 2016, at 8:33 PM, paul swed >> <[email protected] >> <mailto:[email protected]>> wrote: >> >> OK so could not resist. The replacement of the >> HP 10811 with a PIEZO ocxo >> went very well. So in for a penny in for a >> pound. Why not an RB. Having a >> few around. Choice efratom FRS-c. Lot of thought >> went into this choice. >> >> Not >> >> really it was there. It has a inverse frequency >> to EFC voltage just like >> the piezo and opposite the HP 10811. >> Well it connects runs and locks using the simple >> 1 opamp level ofset and >> and phase inverter. >> But locked is a funny comment. According to >> HPsatstat and LH. Its pll is >> locked. But both scope and the LH graph shows a >> very slow frequency drift >> that with the offset I can make positive or >> negative. A cycle at 10 ns >> takes quite some time about an hour compared to >> a TBolt and another non >> modified Z3801. At this level of resolution some >> things start to become >> questionable. >> >> I almost wonder if the modified z3801 under some >> level of drift assumes >> everything is locked and fine. Can it be pushed >> beyond expectations. I >> suspect it can. >> Anyhow as I say a bit of GPSDO fun. >> Regards >> Paul >> WB8TSL >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> <mailto:[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] >> <mailto:[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] >> <mailto:[email protected]> >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> <https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> >> and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> <mailto:[email protected]> >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> <https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> >> and follow the instructions there. >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> <mailto:[email protected]> >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> <https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> >> and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] <mailto: >> [email protected]> >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> <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.
