Methods for improving 60kHz RF signal (WWVB)?

A Costas loop, or failing that, a squaring loop as in the article.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
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I would do that sometimes to save time. it's not a required step.

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Quenching usually makes metals hard and brittle.

You can also just get Type K copper tubing.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

Or a Thompson magical loop ;-) ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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I love to cook with wine.     Sometimes I even put it in the food.

I think that was first invented by Dr. Fred M'Bogo.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

My understanding is, it's veeeeeeeeery slightly softer (like a percent or a few) quenched, but it basically doesn't matter.

If "usually" is by tonnage, that's about right. A36 is the most common grade I think, and ranges from ~1020 to "floor sweepings". More than a few blacksmiths have been burned by that.

IIRC, only martensitic type systems (Fe-C being the most important) are prone to quench hardening, which by the periodic table, aren't very common I think. Of course, the rest of the periodic table is too reactive or soft or low melting to be of structural value (e.g., cerium, lead, sodium..), or just too damn rare and expensive (there are probably some awesome scandium alloys yet to be discovered, but..).

Bend the bendable stuff? You must be joking! :-)

It even comes in a coil, so open the box, stretch it out and you've got one hell of an RFC for that megawatt vacuum tube final you always wanted.

Tim

--
Seven Transistor Labs 
Electrical Engineering Consultation 
Website: http://seventransistorlabs.com

The problem these days is that a house is surrounded by electric "smog" due to all active electronics such as VFDs.

If you are used some small untuned whip antenna close to the house as in many pictures in that article and links, you are going to have a

1-10 pF connection from the in-house wiring to that whip and hence have a strong connection interference from the mains to the whip.

Typically a simple active is just not much more a high input resistance FET drain follower that probes the voltage in the whip and drives the 50 ohm coax with significant current gain.

Since the short antenna is highly reactive (some pF capacitance from the "ether" to the whip) there is going to be a capacitive voltage divider to ground, either through the FET gate-source capacitance or a huge attenuation due to the coaxial cable capacitance, if such short antenna is connected directly to a coax to avoid indoor noise pickup.

Since some of the link were broken, I don't know if this whip was actually tuned, i.e. used some kind of loading coil to make the antenna look like a resistive source to the amplifier ?

In my experiments I have used a few meters of wire suspended into some trees in the garden, connected to a LC tank top through a 10 pF capacitor. The inductance consisted of several coils in series and selected by the band and the voltage at the lowest coil (relatively low impedance), went through a darlington voltage follower to a short

50 ohm coax. The capacitance was tunable with mechanical multi section capacitor. The short coax was required to avoid spurious radiation from the receiver synthesizer to the antenna :-). The whole setup was operated from a 12 V car battery.

With this setup, the 16 kHz Rugby UK station (nearly 2000 km away) could heard with good SNR even during summer days. Of course this setup with mechanical variable capacitors made sense only during warm summer days :-).

Running an mains extension cord across the garden without connecting the charger, increased the noise level.

Small magnetic loop antennas have some advantage compared to small electric (capacitive) antennas in the near field due to the cube/square relationship.

For ferrous metals, yes.

The size of the quenching effect varies with specific alloy. For instance, steel containing 1% carbon gets very hard, while steel containing 0.18% carbon is not much affected by quenching.

For non-ferrous metals, no, it anneals them.

Copper alloys have variations in quenching effect, but I don't offhand know which is which. Likewise, silver - I first heard the quench- to- anneal story when taking jewelry making class in the 1970s. We would combine quenching with firescale (oxide) and flux removal by quenching in a dilute mineral acid after hard soldering.

Yes, but that's cheating. You should be drawing your own tubing from billet.

Joe Gwinn

Ouch!

Ouch! again. Did you get a manual with it? ( Hm. I'd better make sure I can locate _mine_ before I make any offers. )

Thanks. Now I can find a replacement movement if I need one.

Oh, and if any of our readers are interested in making their own

3"-tall nixie-ish displays from EL wire:

Okay. Thanks for the reassurance -- I thought I was going crazy. ( Okay, crazier. )

Another page I hadn't noticed the last time I visited c-max. Thanks

Vines... vines... how about that adorable plant named Audrey II from "Little Shop of Horrors"?

A-hum. I knew that... it's my spelling checker's fault!

Thanks. I've been looking at USB audio interfaces that would (a) work with Ubuntu Linux and (b) sample at greater than 2x60kHz, and while there are a lot of inexpensive ones out there, it's really hard to tell what their spec's are. Punchline? I finally got around to checking the specifications on my laptop's built-in audio... and found that Dell dropped an STAC9205 into this D630... and that chip says it can deliver 24-bit samples at 192kHz. ( Now I have to verify that the Linux drivers can reliably deliver this. That should not be taken as a jab at Linux, merely an exposure of my own inexperience. )

Sounds like a good time for lunch.

Thanks again. It'll probably be a few weeks before I have any progress, but I'll post something back when I have results.

Frank

--
  How much easier it is to do things yourself than to teach other 
  people to do them! ...throughout my foolish life, there has been 
  that inner something or other that compelled me to teach people 
  how to do things, no matter how eccentric or unorthodox -- a sense 
  of some great event ahead that would need every talent I could 
  develop in all who came under my influence.  That strange urge was 
  behind every decision of policy in our medical work, in our 
  nurses' training; behind acceptance of duties for which I was 
  poorly trained: an urge to learn first, how to do the thing 
  myself, and then to find someone whom I could teach to do it for 
  me.                    -- Gordon S. Seagrave / Burma Surgeon

WWVB recently added a whole new modulation method that should stunningly improve their reception reliability.

Unfortunately, the new chips are half a year overdue and appear to be stuck in the pipe.

See

--
Many thanks, 

Don Lancaster                          voice phone: (928)428-4073 
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Thanks, but I have both the printed and scanned manuals. What I lack is time and incentive.

Yech. That's ugly. With real Nixie tubes, you can read all the digits instead of just the one up front. However, if you're using real Nixie tubes with a 60KHz receiver, you're going to have RFI problems from the usual switching high voltage power supply. I've seen it done, but it required lots of shielding and ferrite filters.

There are quite a few that offer 192KHz sampling rate. The problem is that the audio sections usually roll off at about 20KHz. I've found cards that will allegedly go to 90KHz, but they're expe$ive. For example: I have yet to find a USB version that does above 20KHz, but suspect that once can be found which might be modified. (Yet another project).

No, that's NOT the spec. The 192KHz is the sampling rate not the frequency response. If you want to go up to the Shannon limit, you theoretically can get about 80Khz for the upper frequency. You'll need to butcher the audio amplifier section of the sound card to do that. My guess(tm) is that's easier to add a mixer and downconvert the 60KHz RF to a lower frequency that's more easily digested by a sound card. That's the way DRM broadcasting is done from the 455KHz IF frequency of a receiver. With a working bandwidth of only about 5Hz, this should be easy (famous last words).

Good luck.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Yep.

See: I'm still waiting for samples from last year. No data sheets or tech info to be found. I'm wondering if the chip is for real.

Xtendwave did most of the work on the new WWVB system for the NIST. I don't know anything about the status of their licenses to other chip vendors. I suspect they want to make their own chips before licensing the IP to anyone else:

Patents and applications: and a whole bunch more patents and applications:

Hmmm... Looks like ownership is now in the hands of Grindstone Capital. Click "Legal Events" on most of the patents.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Understood.

[...]

Nice specs, but, as you say, a bit pricey.

Yes. Sampling rate. To directly sample a 60kHz signal the way I was describing ( and be able to reconstruct it ) one needs to sample faster than 120kHz. (Nyquist)

Yup. That's the part I overlooked in my excitement. The ADCs I've used before were on microcontrollers, and I didn't stop to think about what kind of filtering -- with all the best intentions -- a laptop manufacturer might put ahead of an ADC "intended" for audio input, even one capable of 192ksps.

Oops. My bad.

Before I read your reply I managed to get SpectrumLab installed (under Wine) and hooked up one end of a 30' microphone cable to the D630's Mic_In socket. In spite of whatever filters Dell has on its audio input, last night SpectrumLab reported two (FFT-averaged) "peaks" at

59940Hz and 60060Hz varying from 10 to 20dB above everything else. ( Right now I can barely pick out the same peaks from the surrounding "noise" (a.k.a. "Stuff I don't care about." )

I've got some other things I need to get done before I spend much more time on this. That will give me time to decide whether I'd rather solder up a downconverter or write code to have some microcontroller do the sampling at >120ksps for me. Decisions, decisions.

On the good side, it looks like we've finally gotten past the 2014 Groundhog's Curse. The sleet/freezing rain we got Monday and Tuesday will be replaced by sunny, high-60s weather by the weekend.

Frank

--
  ...the fact that some geniuses were laughed at does not imply that 
  all who are laughed at are geniuses. They laughed at Columbus, they 
  laughed at Fulton, they laughed at the Wright Brothers. But they 
  also laughed at Bozo the Clown.     -- Carl Sagan

Den torsdag den 13. marts 2014 15.51.15 UTC+1 skrev Frnak McKenney:

build one of these, control it from computer with NTP ;)

-Lasse