#58: How to zero-beat WWV to check or adjust a Frequency Counter's accuracy

[@aeromojito]

You can use an inexpensive SDR dongle to do this too. I used AM mode. The waterfall will show you the interval of the beats. I calibrated an OCXO module and use it as a reference for a handheld counter and signal generator.

[@patrickoneillnl1966]

Thank you Alan for such a wonderful video. It takes someone like you who has all the equipment to offer such demonstrations. BTW I just passed the Canadian Basic HAM exam with honours and I think at least two or three of your videos helped explain some of the concepts I struggled with last month. I am now studying for my Advanced Exam and enjoying this journey which is what brought me to your channel once more. 73 VO1PST

[@SixWildKids]

Great video, as usual. Got my Si5351 board tuned to less than 1 Hz using this method. Saved me time building a GPS disciplined oscillator. Oh, who am I really kidding? I'm still gonna build one anyway because that's what we do...

[@KX4UL]

These are the kind of useful tips I love to learn! Reminds me of how I calibrated the frequency dial on my first HF rig. It was a Kenwood TS520S hybrid with only an analog readout dial. The band selector switch had a pre-setting for WWV just for calibrating. Thanks for this video demo.

[@ruhnet]

I never thought of using the S-meter like that. Thanks for this video!

[@thevacuumtubejunky9774]

Thank you for bringing this subject to light. My Father was a Ham operator dating back to the early 30's and would use a bc 348 signal corps radio set for the WWV carrier as well as a set of tuning forks for calibrating his test and radio equipment. Certainly a lost radio equipment testing skill set. Thanks for sharing! Kind regards,Eric Dee.

[@rickf2061]

EXCELLENT explanation and demonstration ! Very well done. Thanks for posting this video.

[@jaa93997]

The amount of old school in you is too damn awesome! Keep it up please!

[@wadepatton2433]

Old guys know stuff. Young folks _who listen_ get to know stuff too (but hormones can interfere with learning). the Mega cycle?

[@BootstrapWorkbench]

Alan, your videos are really the best of KZbin. I'm putting together an electronics bench, out what I can find cheaply, like old Nixie tube counters and Tektronix CROs, and your videos help greatly. Thanks for the knowledge!

[@dewdude]

Thank you. I was pretty sure I knew what zero-beating was and how it worked; but this simple visual totally explained it.

[@erin19030]

Love that vintage nixie display frequency counter.

[@1ebutuoy2]

I built a 10 MHz TRF receiver with a 10 MHz crystal in the front end for selectivity. Only 3 transistors gives a very useable output. I use the oscillator under test to trigger a scope and connect the WWV signal to the vertical. It's easy to get down to .1 Hz if you have a fine adjustment on the oscillator. Much better is possible if propagation from Fort Collins is very good, I think.

[@user-uv4xe3cq2y]

Very interesting. This is the stuff that keeps me up late. Thanks.

[@TheBandScanner]

Excellent. I've been doing this since 1982, at a remote military station as the radio technician.

[@justicelut]

Thanks for the info, very interesting.

[@glenwoofit]

WoW I didn't know that. When you explained it I was D'oh that's so obvious but it's never crossed my mind. Another Top Tip, Thanks.

[@Homer19521]

Just used my TS-830S & checked my Racal Dana 1992 w/OCXO & it was within a hertz or 2. Thanx! We had a QSO a few years back. 73

[@EdWatts]

I check my radios by tuning in WWV and then selecting USB then LSB and setting the receiver so that the pitch of the audio is the same on each. The receiver is then tuned exactly to the carrier frequency -- yeah, I have a good ear. Most are off by a little bit, but usually less than 3 ppm. Your video shows a good system of setting signal generators and counters.

[@stargazer7644]

I use a digital musical instrument tuning indicator listening to the WWV audio coming out of the speaker to do the same thing. I get 100th of a hz resolution.

[@ki4dbk]

Thank you Alan, I know I had a hand in stimulating the production of this great video. I tried to do this yesterday in my lab/shack, and was having several problems. I wish you had shown the exact coupling you used into the coax, since mine tended to be either too loose, or to tight (too strong of a carrier). Also, I am in the middle of an antenna crisis (broken compromised dipole) plus lots of storms here. You cheated with the Tek counter of course, but it was good to see. Thanks for this!

[@jennifer86010]

My comment below describes the method that aural Piano Tuners have used for centuries to tune pianos. It is a method of listening to two tones, one of which is tuned to an accurate tuning fork, and one of which is not. The piano tuner listens to both strings as he strikes a note on the keyboard. He uses his tuning wrench (hammer) to adjust the second string to the in-tune string. When they get close to being in tune with each other, he hears a wavering sound called "beats". As he slowly adjusts the string, the beats eventually slow down and then disappear when both strings are in perfect tune. Airplane pilots who fly smaller twin engine airplanes use this same technique. If both engines are revolving at different R.P.M.s, it causes a great deal of noise and vibration to the aircraft. The pilot adjust one engine to the speed and desired R.P.M., then slowly adjusts the second engine until the heard "beats" slow way down, and eventually disappear into only a single sound. At that point, both engines are in perfect sync, revolving at exactly the same R.P.M.

[@233kosta]

What a gorgeous nixie display on that counter!

[@bigsky1970]

As an aside, it's amazing what sort of applications can be utilized with WWV, I've even read that pianos can be tuned with WWV as the reference tone. They transmit 440 Hz at 2 minutes after each hour and at one minute after the hour on WWVH, and 440 Hz is musical note A above middle C. Once that note is calibrated, the rest of the piano can be tuned.

[@cny02253]

Great video! This is a really powerful aid for calibration a lot of people don't seem to know about. Would perhaps be helpful to show how it is done with no S-meter and on a simple SW digital display RX on AM? (not ssb- I think that is adding an element of confusion) You could also show in a little more detail how to couple? I know its basic, but many experimenters are not hams or all that familiar with coupling RF, etc.

[@ki4dbk]

It is. After a reexamination of the manual, and also looking at a picture of the plugin removed. I realized my first assumption about the origin of the rear panel reference signal was incorrect. I do indeed have access to the counter's reference, and not only that, I can switch it from 1hz, all the way up to 10Mhz in decade steps! I wish I had your new Tek counter to check this, but now there is even more motivation to get the WWV technique working here. This may require an 10Mhz antenna.

[@RadioHamGuy]

Another great tutorial, thanks!

[@fshrofmn]

Great video Alan. Thanks a bunch

[@W1RMD]

Great informative video. Also, it's nice to have a vfd and nixie display in the same screen shot! I miss the old Kenwoods with their vfd readouts. Replaced by liquid crystal displays. (UG!)

[@ki4dbk]

On the back of my HP5245L counter are two BNC's. However, on the back of the HP5262A Time Interval Plugin is a Reference Oscillator Output. It can be set for a variety of frequencies, including 10 MHz! I will have to investigate that and reply with a video, as well as another one demonstrating success with WWV and my equipment. Tnx again!

[@TommyMartin]

Interesting and informative. Thanks.

[@paulscats17]

Interesting video. This may be a dumb question but pleas bear with me. Exactly how do you attatch your test wire to the antenna?

[@w2aew]

Just by proximity, no physical connection.

[@paulscats17]

Ok. Thank You!

[@ki4dbk]

Saturday, when I was attempting this, I seemed to lose a lot of signal (or gain QRM/N) whenever I exposed the center conductor on my PL-259. Unfortunately I was averaging about a 579 WWV signal strength on the meter on 10Mhz. I may be able to try again later tonight, this time using my HP counter's 10Mhz reference instead of my sig gen. That may make it simpler as seen in your video.

[@TonyButchT]

Very, Very Interesting! Thank You!

[@neira.francisco]

Great practical explanation. TNX!

[@ki4dbk]

Sorry to post again but I meant to say there are two BNC's labeled "AUX" on the HP counter, but no reference output, except on the rear of the Time Interval Plugin.

[@KandiKlover]

Hey a Nixie tube frequency counter. Very nice.

[@w2aew]

Yeah, I love those nixies!

[@ChrisWilson5006]

Another excellent video, thank you, but may I ask for more detail on the safe means to couple the output from the counter to the antenna of the receiver? I am a bit jittery about ramming signals into my receiver antenna socket willy nilly :) Could this zero beating be done on a `scope in some way? Cheers Alan!

[@jimerickson1809]

We used to do this at the old MARS station in the Army.

[@eie_for_you]

Yup. Just checked all of my stuff and they appear to be dead on. Unfortunately, none of them have a place to adjust from the outside even if they were off. I'd have to crack open the case, I suppose. On the other hand, they all allowed for an external standard. So, if I could secure that GPS standard thingy my friend speaks of, then I could use that if I needed better accuracy. Thanks!

[@w2aew]

One thing you could do is use the siggen output to check zero-beat against WWV, then you could make small adjustments to see the "beat", or if it was off a little, you'd be able to see how much. Once you've verified one (like the siggen), you could then put the Reference Output signals from the siggen and the spectrum analyzer onto your scope, trigger on one of them, and then see how much the other "walks" with respect to the triggered one.

[@eie_for_you]

@@w2aew We used to use the Lissajous patterns to adjust stuff in the USAF. Always a cool way.

[@w2aew]

@@eie_for_you Yep, I have a video on them too!

[@MauriatOttolink]

Good stuff.. It would have been additionally helpful to point out that the freq read out of the RX during this exercise, was totally irrelevant. The role of the receiver was simply to acquire the 10 Mhz sig. from WWV..what ever the reading on the RX.. It might have no digi readout! Its entire purpose was simply to connect into WWV on 10 Mhz..If the dial said "600 fluid oz. or two feet, it wouldn't matter. We'll deal with the Rx later!

[@wadepatton2433]

Thanks I got "hung up" on that aspect. It's a start for my "haven't built a kit yet" practical ham knowledge.

[@12DGJB21]

How is the Leader frequency counter coupled to the WWV receiver? Is the output of the frequency counter directly connected to the antenna input on the back of the receiver? Or is it more loosely coupled?

[@w2aew]

The Leader's 10MHz reference output is loosely coupled via a wire "antenna" to the receiver, so that its signal combines with the WWV broadcast signal being received via another antenna.

[@famossfla]

Alan I'm trying to duplicate your setup here but not getting the pulsating deviation on my S-meter like you show. How did you couple the blue wire into the receiver to get the beat signal ?Was it just loosley coupled ? My counter 10mhz reference out should only be a couple hz off. Thanks

[@w2aew]

yes, just loosely coupled by bringing the 'blue' wire close to one side of the 450ohm ladder line feedline that runs up to the antenna.

[@1903A3shooter]

OK! on the two signals still being at 10 meg. Had me going there for a bit. I thought you were putting in a 500hz off set. Hi. I use to use a 5 meg. osc in a old unit and beat it against 20 meg. wwv. 4th. Set the two signals to zero using a scope to watch the signal when it got so low I could not hear it anymore. Then used the 20 meg.output to adjust the counter. I dont know if that got me closer or not, I think I got the 5 very close but dont know if using the 20 meg.out was better or worse.

[@1903A3shooter]

Great but I got lost with the receiver being 500 Hz high. I understand the resulting tone but not the beating at that point. Dave W4GSM

[@GSR600Relaxed]

Great video. Thanks!

[@PelDaddy]

Another great (if older) video. Thanks. Question: Not being a ham (yet anyway) I do not have a fancy radio. I do, however have an old AM/SW receiver tube based I restored myself (Echophone EC-1). It does not have an S-Meter, but it does do AM. Could I do this by sound? Would it be any less accurate by sound? I am familiar with zero beating, as the EC-1 has a BFO. Thanks.

[@w2aew]

+PelDaddy Sure, you can zero-beat by ear. It won't be as accurate because you can't hear below 20 or 30Hz generally, but you should be able to get pretty close.

[@PelDaddy]

+w2aew Thanks for the reply. Silly me for not thinking of that, but it, of course, makes sense. Not ideal for fine tuning equipment. Perhaps a VTVM on the AGC circuit or similar would give me an adequate visual representation for a more accurate zero beat. Might be fun to do...

[@MM0SDK]

Does that Tektronix frequency counter really have a 100uHz resolution?

[@whatspapadoingnow6197]

How did you couple the frequency reference from the counter (blue wire) to the receiver? Is it simply loosely coupled to the antenna jack of the radio? If you have a shielded coax cable already connected to the radio antenna jack will this still work?

[@w2aew]

The blue wire basically acted like an antenna and put enough signal into the air to be picked up by my HF antenna, the same one that was receiving WWV.

[@DumbledoreMcCracken]

Is it possible to construct a sine from a phase modulated signal?

[@w2aew]

Can you re-phrase your question? It doesn't make sense to me.

[@DumbledoreMcCracken]

@@w2aew I thought of a way. If I were to rectify the phase modulated signal, that would create a half wave representation, not a sine wave, but closer to what I think I want.

[@dmottern1952]

Great Info!!

[@SDsailor7]

Is that WWV signal on a regular stereo receiver? And on the am dial? Anyone know? Thank you

[@w2aew]

No. WWV transmits on 2.5MHz, 5MHz, 10MHz, 20MHz and 25MHz. All of these lie between the AM broadcast band and the FM broadcast band.

[@SDsailor7]

@@w2aew Ah. I see. So you need a different type of receiver then?

[@w2aew]

Yes, a shortwave receiver, or what is commonly called a general coverage HF receiver.

[@SDsailor7]

@@w2aew Thank you, I will look for one of those, should not be hard to find. Cheers

[@jennifer86010]

If you want to Zero-Beat an H.F. receiver using WWV or WWVH, put your receiver or transceiver into LSB or USB mode. Tune to 5 or 10 Mhz. Listen for the broadcasted solid tone along with the tick/tocks. If you hear two tones, carefully adjust your frequency tuning knob until only one tone is heard. Now note your frequency readout on the dial. If it reads anything other than exactly 5 or 10 Mhz, it shows how far off frequency your receiver actually is.

[@SDsailor7]

Is this WWV on a regular stereo receiver or on a special receiver?anyone know?Thank you I need to calibrate my frequency counter.

[@w2aew]

You need something that can receive 10MHz, such as a ham or shortwave receiver.

[@SDsailor7]

@@w2aew Thsnk you gor the fast reply. I do not have one of those. Could i use my function generator instead?

[@SDsailor7]

@@w2aew Sorry meant to say Thank you.

[@w2aew]

@@SDsailor7 A function generator can only be used to calibrate your frequency counter if you already KNOW that the accuracy of the function generator is much better than the counter.

[@ki4dbk]

I meant 539 WWV sig.

[@OfficialDPTheRealDeal]

Where do I buy the adjustment tools??

[@w2aew]

Most electronics distributors carry non-metallic alignment tools, like this: www.mouser.com/ProductDetail/Jonard-Industries/TK-AT5/?qs=sGAEpiMZZMuqHt7hmXVVHp4IeFI6fmRqLq7buOsdS8o%3d

[@wadepatton2433]

Shave down a chopstick into non-metallic, flat screwdriver. Will still operated as chopstick too.

[@stdorn]

Is you frequency counter nixie tube? If so cool!

[@w2aew]

Yep - it's got nixie tubes.

[@gipgipson1185]

How did you know carrier for wwv is 500 Hz off and not 700 Hz. On 10 MHz. Lloydgip51

[@w2aew]

I could have tuned to 700Hz if I wanted to, and heard a 700Hz audio beat tone instead.

[@ki4dbk]

I would happily engage someone in a rhetorical "word war" any time.

[@gipgipson1185]

HOW DID U KNOW TO GO 5 HTZ OFF TO GET THE RIGHT SIGNAL OFF OF YOUR VIDEO ON WWV. 10 MGHZ I WATCH YOUR TWO VIDEOS. U EXPLAINED THEM VERY WELL. ,,,,,, THANKS FOR YOUR TIME,,,,, ON YOUR VIDEOS FOR US NOT SO SMART ONES. LLOYDGIP51. ILL BE LOOKING FOR YOUR RESPONSE. I GUESS U HAVE A WEB PAGE

[@stargazer7644]

It was 500 Hz off, not 5 Hz. He just moved it off far enough to hear the carrier hetrodyne tone. At 500Hz, you'll hear a 500 Hz carrier tone. The exact offset isn't important, you can use any offset that creates a tone you can hear.

[@denniswage9748]

Isn't using a radio unreliable as being accurate?

[@w2aew]

I'm using the radio to RECEIVE an accurate frequency from WWV. I am NOT using the receiver's frequency display to determine the frequency accuracy. I am summing the accurate WWV signal at 10MHz with the reference output of the counter (also 10MHz). If these two signals are very close in frequency, they will "beat" with each other (constructively or destructively add, depending on the phase), and the resulting sum will be indicated on the receiver's signal strength meter. The receiver doesn't have to be calibrated to do this - we're only using it as a power indicator of the summed signals.

[@avt3216]

OOPS... you weren't ever at exactly 10.000500 MHz on your receiver... you had 1 digit of precision, could have been +-50 Hz (roundoff). I could HEAR the difference between the two times you played 10.000500 MHz, guessing it was off the second time by 20-30 Hz,. So, don't depend on the readout!

[@w2aew]

There was never any reason to be at exactly 10.0005MHz. The only thing that was important was to put the WWV carrier within the passband of the SSB receiver. Once this is done, the reference oscillator is then beat against the WWV carrier and observed on the receiver’s s-meter.

[@kemonoyama2084]

WOW! Nice Shack!