[time-nuts] Re: NIST 60KHz message
On Sunday, March 14, 2021, 11:56:11 AM EDT, Jeffrey Pawlan wrote: > I have been using the new BPSK receiver for NIST. There are two strange > things that perhaps others can explain. I don't know if this has anything to do with what you are experiencing, but WWVB is currently undergoing an equipment upgrade to improve the reliability of the signal. According to the WWVB website (https://www.nist.gov/pml/time-and-frequency-division/time-distribution/radio-station-wwvb): In order to install this equipment, beginning on March 9, 2021 the WWVB signal may be operated on a single antenna at approximately 30 kW radiated power for periods up to several days in duration, and may have occasional outages. Periods of reduced power operation lasting longer than 30 minutes will be logged on the WWVB Antenna Configuration and Power web page (https://www.nist.gov/time-distribution/radio-station-wwvb/wwvb-antenna-configuration-and-power), and any outage longer than five minutes' duration will be recorded on the WWVB Outage web page (https://www.nist.gov/time-distribution/radio-station-wwvb/wwvb-station-outages). Upgrades are expected to be complete by March 31, 2021. As I write this (at 19:50 UTC on 14-Mar-2021), WWVB is off-the-air. They were on earlier this morning and afternoon. I believe Colorado received a substantial snowstorm over the past day or so as well... 73 de John, KD2BD ___ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
Re: [time-nuts] Time Interval Counter(?) for high-precision watch measurement
The 32768 Hz crystal oscillator can be received, amplified, and filtered outside the watch as described here: http://charliethompson.50megs.com/quartz.html I actually tried this once, and it worked quite well on every watch and clock I could get my hands on at the time. The first three transistors form an amplifier with around 100 dB of gain. The crystal filter is required to remove the broadband noise generated by the amplifier. I didn't include the final two transistor "squaring" output stage because I was interested in having a sinusoidal output to view on a scope. 73.000 de John, KD2BD ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] WWVB SDR discussion
I'm seeing more than 100mV p-p right now (7:09 PM) (2309 UTC) on the output of my preamp from the east coast of New Jersey, 1622 miles east of WWVB. During my early days of WWVB experimenting, I found the signal is easier to spot (since it's buried in noise) if the scope's horizontal sweep is externally triggered by a stable and variable oscillator running at some sub-multiple of 60 kHz. The sweep generator in my Tek 465 was just too unstable and difficult to control, otherwise. 73.000 de John, KD2BD ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] WWVB SDR discussion
On Tuesday, August 11, 2020, 07:14:12 PM EDT, Bob kb8tq wrote: > The problem with the crystal is that it has a temperature coefficient. As a > narrow band filter, it will have a *lot* of delay. Crystal resonance moves > (with temperature) and the delay changes. I agree. The crystal needs to be ovenized. ;-) That very concern led me in my design to derive nearly all my receiver selectivity at baseband (DC) using op-amps, forgo any crystal filters, and keep the Q of the loop antenna low. 73.000 de John, KD2BD ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] WWVB PM Time Questions
Greetings to the group! I've been an FMTer for years, and an occasional "lurker" here, but as I find my ears occasionally "whistling" from time to time, I thought it was time to join in. :-) > On Jul 22, 2020, at 3:51 PM, paul swed wrote: > > Ray watch out for my comment on the KD2BD solution. That oscillator isn't > available and I have not been able to map something else into it. Tried > several good grade Oven oscillators. Just be aware of that issue. > Would need to do more tinkering and simply don't have that time right now. > Also it would be great if the oscillator was something that could be > obtained at a reasonable cost. I do not believe at all it has to be a > OCXO as the older true time and spectracoms were not and they locked solid. > So its a case of getting the control voltages right. As Paul correctly stated, the Bomar VCTCXO used in my WWVB Frequency Standard is no longer available, at least in single quantities. Fortunately, there are MUCH better alternatives available, but they require a little "finagling". Hopefully, this information will help. I have successfully used a Taitien model TTEAMCSANF-10.00 High Precision VCTCXO in my frequency standard with excellent results. This oscillator operates on 3.3 volts, and produces about a 1 volt p-p clipped sinewave output. It has a +/- 5 ppm pulling range, and is controlled by a positive slope tuning voltage between 0.5 and 2.5 volts. I've used two of these oscillators so far (in different projects), and both seem to tune exactly to 10 MHz with a tuning voltage close to 1.551 volts. However, YMMV. Use these numbers as a guide if your oscillator should have different specs. The attached schematic shows the original circuit at the top with the modified circuit at the bottom. A 3.3 volt LDO powers the oscillator, and a simple MFP-102 JFET amplifies the output to drive the subsequent 5-volt CMOS logic. The original oscillator was temperature sensitive, and took several minutes to warm up and settle down. I often had to manually tune the oscillator on power-up using the front panel tuning control to get it in the ballpark where it would eventually lock to WWVB. Now when I turn it on, the new oscillator locks to WWVB in about 30 seconds, and just stays there. :-) Digikey carries it for $13.81. 73.000 de John, KD2BD___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
