Re: [time-nuts] Austron 1250A Tuning tool
I adjusted my 1250A using a 1/8 brass rod that I got from the hardware store. I filed down the end to make it into a screwdriver. This worked fine. I could tell when the tip was engaged with the screw in the oscillator by feeling it fall into place and then I could make the adjustment. The brass didn't have any effect on the frequency. When I removed the tool the frequency didn't change. A metallic tool is needed since the adjustment screw needs some torque to make it turn. -Original Message- From: Ole Petter Ronningen Sent: Saturday, February 21, 2015 1:07 AM To: time-nuts@febo.com Subject: [time-nuts] Austron 1250A Tuning tool Hello My 1250A has drifted outside the range of the front panel control, so the coarse adjust needs some fiddling. The manual makes mention of a special tool to be used for this. I don't have the tool, the closest I can get is a 10 bamboo stick that I cunningly liberated from my wifes sushimaking mat! I wondered if anyone else on the list has this tool, and can send me a description/photo of the tip? I tried widdling the tip of my stick to various shapes, but not knowing what it is supposed to mate with, it is a bit frustrating.. Thank you all ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NAA experiments as a reference
I am able to phase track NAA using the following method: Reception using active whip antenna input into HP 3581C selective vm, tuned to 24 KHz using its 300 Hz bandpass filter. Output is taken from Restored connection on back panel and input into the squaring chip AD835, set up on a breadboard. If the output of the AD835 is looked at with a dynamic signal analyzer, I see two monochromatic signals at 48.1 KHz and 47.9 KHz. I am able to phase lock on either of these using the Tracor 599J if they are input into it. The lock seems to agree with the tracking I got with WWVB over the 15 minutes or so that I let it lock. I have also looked at some of the other Navy MSK signals, but this morning they were too weak. I could see hints of the monochromatic signals with NLK but there were too weak to lock on. John, KA5QEP -Original Message- From: paul swed Sent: Saturday, September 13, 2014 6:18 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] NAA experiments as a reference Thats what I am trying to understand. How good is good. Is it a useful replacement for wwvb. Certainly kicks butt in signal strength. Regards Paul WB8TSL On Sat, Sep 13, 2014 at 2:03 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: The underlying NAA reference is UTC(USNO). How close they track it I don't know. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Tracor Now Tracking
A while ago I asked about dephasing WWVB. Since them I have tried many things and finally found one that works. I use my WWVB trf receiver with the squaring chip at its output. This gives me a dephased 120 KHz signal. In reading the Tracor manual about their MSK converter I discovered that they do a frequency conversion first using the 100 KHz coherent output at the Tracor’s rear panel. I did the same trick with the 120 KHz signal using a MiniCircuits mixer, which outputs the 20 KHz difference frequency. Then this can be used as input for the Tracor. Tracor is happy with this signal and is tracking fine. 73, John, KA5QEP ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Dephasing WWVB
First on the Schmidt trigger - The problem is that at the start of each bit that WWVB transmits the squared 60 KHz signal is essentially dead and the trigger must pick a new starting point. This point seems to be random and can apparently end up as a positive or negative, so you end up with phase changes of 180 after the flip flop. No trigger can fix this. The system has to have some memory of the phase and this is why the Costas loop works. I thought about getting rid of the 100 KHz front end filter in the Tracor and seeing if I could modify it by squaring the LO signal. This isn't straightforward either. The Tracor has a complex method of generating the IF signal. I wasn't aware that 60 KHz crystals are available. I would have used these instead of the LC filters. I had some old telephone loading ferrite toroid coils, so most of the hardware was available. Thanks for all the comments on this. At least I understand the problem now, and why the solution will take some work. John -Original Message- From: paul swed Sent: Monday, June 30, 2014 9:49 AM To: Martin VE3OAT ; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Dephasing WWVB Many of the old receivers use them spectracoms come to mind. They are big units and +- 40 Hz BW and I am totally unaware that they can be found today. That also goes for nice transformers and inductors to build higher Q circuits. I built a opamp chain and it worked well but those crazy amps do draw power. I like the ua consumption level. But thats a personnel preference. I used the 60 KHz watch Xtals and its in the schematics of the WWVB rcvr I released to time-nuts a year ago. These little crystals are interesting to work with and available from China 25 xtals for a few $ at the pay site. I purchased 2 packs so that I could sift through them. The trick is to very very lightly load them. I could learn much more about them actually. They seem useful overall. The first re-modulator used them directly as the 60 KHz source. I stepped up to the 15.360 MHz osc only because I believed they were not accurate enough and that turned out not to be the case as I found. The other comment to note is that these xtals cause an actual signal gap at the phase transition. Because at that point the signal is actually 2 X 60 Khz. The crystal gaps for at least 8 cycles from what I have seen. Regards Paul WB8TSL On Sun, Jun 29, 2014 at 6:39 PM, Martin VE3OAT ve3...@storm.ca wrote: John Reed wrote : By the way, my 5 section synchronous filter is an LC with op-amps between each stage to bring the gain up for the squaring chip. It has a 2 KHz -6 dB bandwidth at 60 KHz. John, have you thought of using a single 60.0 kHz crystal as a bandpass filter? I can't remember which receiver it was, but I think one of the old commercial WWVB receivers used a crystal as the tuning element. ... Martin VE3OAT ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Dephasing WWVB
Thanks Paul. I thought that this would be a simple project. But, I'm seeing that random phase jump problem on every method I've tried so far. My first attempt was a 2N that would go into saturation on the plus cycle, then into a flip-flop. I ended up with the phase problem on the 60 KHz output. Then I tried using a pulse generator into a flip-flop. Same problem. The puzzling thing is the 120 KHz output from the 2N or pulse generator look fine, but the 50 KHz output of the flip-flop is not. By the way, my 5 section synchronous filter is an LC with op-amps between each stage to bring the gain up for the squaring chip. It has a 2 KHz -6 dB bandwidth at 60 KHz. John -Original Message- From: paul swed Sent: Sunday, June 29, 2014 9:34 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Dephasing WWVB John welcome to time nuts. This won't be a super long post have other things to do. Search for d-psk-r and you can see a few of my exploits. Summation. It ain't easy. It appears to be really easy unless you are far away like the east coast. Then the propagation gods enter into the picture along with the 60 KHz station in England that shows up most nights. The simplest of approaches was indeed the old doubling trick and the many flavors of it. I built most along with regenerative dividers and other trickery. Fact is it simply drops a count and that flips the phase quite annoying. I finally created two approaches. One specifically for spectracom devices essentially adding a third mixer and checking for the flip. Works but requires internal hacking of the spectracom. The other pretty much a freestanding receiever using a classic costas loop approach. All details were released to time nuts over a year ago. My next stab is more of a digital approach using the STM discovery board. Have to say I seem to get lost in some of the basics of getting all of the crazy registers set. However its value is it can run very very fast. So you can do some nice sampling. Regards Paul WB8TSL On Sat, Jun 28, 2014 at 5:38 PM, Charles Steinmetz csteinm...@yandex.com wrote: John wrote: I discovered an article on the web that uses an AD835 multiplier chip to square the WWVB signal * * *. I built a five section synchronous filter tuned to 60 KHz to get rid of interference and its output feeds the 835 chip. This all works fine. * * * the 599J won't tune that high so I have to divide this 120 KHz frequency by 2. * * * I've tried to generate a pulse train from the 120 KHz signal and then use a flip-flop to divide the frequency. This does not work well. Apparently generating the pulse train picks up noise and I end up with a 60 KHz signal with fluctuating phase. Now I'm trying to get a Miller frequency divider working Why are you trying to generate pulses, rather than just squaring (clipping) the output of the 835 in a saturated amplifier? Pulses have less energy and therefore higher noise. All you need is a signal-conditioning squarer matched to the level coming out of the 835 (see Bruce Griffith's pages at ko4bb.com for ideas, as well as the Wenzel site and any number of illustrations in Experimental Methods in RF Design -- for example, both Figures 5-46 and 4-45 show complete simple squarers with FF dividers). Even a CMOS gate biased to half-voltage should work fine. I like the NC7SZ74 Dflop for the divider. Half of a 74HC74 works fine, too. This should be the kind of thing you throw together in 15 minutes and it works first time. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Dephasing WWVB
Hi guys, This is my first posting. I think I’m a Time Nut, at least my friends tell me I am. I’m trying to get my old Tracor 599J phase locking receiver working again. It used to work great, but since 2012 has not worked, as you all are probably aware. I discovered an article on the web that uses an AD835 multiplier chip to square the WWVB signal which gets rid of that added phase. I built a five section synchronous filter tuned to 60 KHz to get rid of interference and its output feeds the 835 chip. This all works fine. Now I have a 120 KHz signal that’s phase free. The problem is that the 599J won’t tune that high so I have to divide this 120 KHz frequency by 2. So far I haven’t had any luck with doing this. I’ve tried to generate a pulse train from the 120 KHz signal and then use a flip-flop to divide the frequency. This does not work well. Apparently generating the pulse train picks up noise and I end up with a 60 KHz signal with fluctuating phase. Now I’m trying to get a Miller frequency divider working, but that’s not operational right now. Anyone have any other ideas? John Reed ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
