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]> > 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 > > [2] http://www.leapsecond.com/pages/z3801a-efc/ > > [3] 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]> 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]> 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] >>>> 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. >> > _______________________________________________ > 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.
