Frequency counters for Alignment
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Frequency counters for Alignment
 
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I have a couple of frequency counters, and I know they are a little off.
When I went through the alignment the first time, they tell you how to adjust settings based on zero beating from another transceiver, but I wanted to calibrate one of these counters well enough to use one of them. I have a XG2 that I haven't built yet, and I see that it has a +/- 1khz accuracy. I was thinking of using that to at least get the counter (a Heathkit IM-2410) close enough so I don't have to use the other transceiver. The XG2 will work ok for this won't it? -- David Wilburn [hidden email] K4DGW K2 #5982 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: Frequency counters for Alignment
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Hi, David:
The best way to calibrate a frequency counter is to set its time base oscillator accurately. WWV is a great reference for doing that. Unfortunately, the Heath IM-2410 uses a 3.58 MHz time base so a harmonic of the time base won't hit a WWV frequency exactly (those crystals are cheap and plentiful for NTSC Color TV sets). If one of your counters uses a time base that multiplies to a WWV frequency, all you need do is tune in WWV using a hunk of wire stuck in your receiver's antenna socket (10 MHz is usually good daytimes all over the USA, and 5 MHz is good in most areas at night). You should hear signals coming from the counter's time base near 10 MHz. Move the wire around and they'll change in strength. Find a position that gives you a good, strong beat note. The divider chain in the counter's time base produces a wide spectrum of frequencies. You might find one that hits WWV's frequency by placing the antenna wire near the counter. An ordinary AM receiver is ideal for this, but if you're stuck using a modern CW/SSB receiver (like the K2) carefully adjust it for no beat note to avoid confusion. That is, put the BFO zero beat with the carrier frequency just as you'd do or SSB. You should hear the tones and voice announcements clearly. Adjust the trimmer cap on the time base of your counter and you'll hear the beat frequency between a harmonic of the time base and WWV's carrier change. Carefully adjust the trimmer for zero beat. As you get close, you'll hear a slow 'whoosh-whoosh-whoosh" as the two frequencies get within a fee HZ of each other. When that whoosh slows to a stop, you're zero beat. Now your counter will be dead on at any frequency within it's range, no matter what frequency. The beauty of the counter design is that its just a digital counter. There's no "range tracking" or other adjustments to make once the time base is exactly on. The other approach is to use a signal generator with enough output to drive your counter. If it's not perfectly calibrated, you can set it to 5 or 10 MHz and zero beat it with WWV, then note the frequency on your counter. If it's off, adjust the time base oscillator trimmer capacitor (C26 on the IM-2410) so the display reads exactly 10.000 (to however many digits it has) MHz. Ron AC7AC -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of David Wilburn Sent: Thursday, March 01, 2007 4:20 PM To: Elecraft Discussion List Subject: [Elecraft] Frequency counters for Alignment I have a couple of frequency counters, and I know they are a little off. When I went through the alignment the first time, they tell you how to adjust settings based on zero beating from another transceiver, but I wanted to calibrate one of these counters well enough to use one of them. I have a XG2 that I haven't built yet, and I see that it has a +/- 1khz accuracy. I was thinking of using that to at least get the counter (a Heathkit IM-2410) close enough so I don't have to use the other transceiver. The XG2 will work ok for this won't it? -- David Wilburn [hidden email] K4DGW K2 #5982 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Frequency counters for Alignment
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A word of caution ...
The zero beating to WWV should be done during a silent period so as to avoid zeroing to the tone-modulated carrier. If you are receiving a network ... as opposed to a local ... TV program, the 3579.5454 NTSC color burst signal from your TV will very accurate. It's locked to the network's frequency standard, which is in turn locked to the NBS standard in Boulder. 73! Ken Kopp - K0PP [hidden email] or [hidden email] _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Frequency counters for Alignment
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In reply to this post by dave.wilburn
David,
You need a better reference the XG2 is a great small crystal based signal generator based. But what is the reference? It all comes down to your targeted accuracy. Also keep in mind when you connect the XG2 to your counter the "pull" effect can easily adjust a few Hz. Zero Beat with a reliable broadcast station is still far better or ask a instrumentation shop to calibrate. An other alternative is to use a calibrated transceiver but my own experience with this that the large amount of RF energy can easily overload circuits and then your reference makes no sense. Rgds Arie ----- Original Message ---- From: David Wilburn <[hidden email]> To: Elecraft Discussion List <[hidden email]> Sent: Friday, March 2, 2007 9:19:39 AM Subject: [Elecraft] Frequency counters for Alignment I have a couple of frequency counters, and I know they are a little off. When I went through the alignment the first time, they tell you how to adjust settings based on zero beating from another transceiver, but I wanted to calibrate one of these counters well enough to use one of them. I have a XG2 that I haven't built yet, and I see that it has a +/- 1khz accuracy. I was thinking of using that to at least get the counter (a Heathkit IM-2410) close enough so I don't have to use the other transceiver. The XG2 will work ok for this won't it? -- David Wilburn [hidden email] K4DGW K2 #5982 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ____________________________________________________________________________________ Get your own web address. Have a HUGE year through Yahoo! Small Business. http://smallbusiness.yahoo.com/domains/?p=BESTDEAL _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: Frequency counters for Alignment
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In reply to this post by Ken Kopp-2
Ken and all,
What you say is true - but you can detect the transmitted tones sent by WWV with great accuracy. See http://tf.nist.gov/stations/iform.html#stdf for innformation about what tones are transmitted at what times. With the audio of a SSB receiver fed into the computer soundcard, and the computer running a program like Spectrogram, one can align the received tones with properly set Spectrogram markers and when the transmitted tones line up with the received tones, you can be certain that WWV is tuned precisely. This is actually more accurate than trying to listen for the carrier at zero frequency - neither the receiver audio nor the human ear can respond to zero frequency, and attempt to do so may be off by +/-30 Hz or more - detecting the tones with a graphic display will allow you to tune within a few Hz. 73, Don W3FPR > -----Original Message----- > > A word of caution ... > > The zero beating to WWV should be done during a silent period > so as to avoid zeroing to the tone-modulated carrier. > > If you are receiving a network ... as opposed to a local ... TV > program, the 3579.5454 NTSC color burst signal from your TV > will very accurate. It's locked to the network's frequency standard, > which is in turn locked to the NBS standard in Boulder. > > 73! Ken Kopp - K0PP > [hidden email] > or > [hidden email] > > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.5.446 / Virus Database: 268.18.5/706 - Release Date: > 2/28/2007 4:09 PM > No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.446 / Virus Database: 268.18.5/706 - Release Date: 2/28/2007 4:09 PM _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Frequency counters for Alignment
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Great suggestion, Don! I wouldn't have thought
about using the Spectrogram's markers to match the tones from WWV. Thanks! 73! Ken Kopp - K0PP [hidden email] or [hidden email] _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: Frequency counters for Alignment
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In reply to this post by dave.wilburn
Dave,
To calibrate a frequency counter, you must have an accuracy of 10 times greater than the lowest resolution on the counter. In other words, if your counter reads down to 1 Hz, then you must calibate it to within 1/10th Hz to assure that the last digit is accurate. +/- 1 kHz is just not sufficiently accurate for calibrating a frequency counter that I would want to use at my workbench. You can calibrate your K2 to within 20 Hz and use the K2 output to calibrate your counter. The K2 calibation can be done with no equipment other than the K2 itself with its counter probe. I do this on a daily basis on K2s that I have in for repair - it works. The method is available on the Elecraft website at http://www.elecraft.com/Apps/K2%20C22%20Adjust%20App%20Note.pdf . 73, Don W3FPR > -----Original Message----- > > I have a couple of frequency counters, and I know they are a little off. > When I went through the alignment the first time, they tell you how to > adjust settings based on zero beating from another transceiver, but I > wanted to calibrate one of these counters well enough to use one of them. > > I have a XG2 that I haven't built yet, and I see that it has a +/- 1khz > accuracy. I was thinking of using that to at least get the counter (a > Heathkit IM-2410) close enough so I don't have to use the other > transceiver. The XG2 will work ok for this won't it? > -- > > David Wilburn > [hidden email] > K4DGW > K2 #5982 > No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.446 / Virus Database: 268.18.5/706 - Release Date: 2/28/2007 4:09 PM _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Frequency counters for Alignment
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In reply to this post by Ken Kopp-2
Ken Kopp wrote: > > > If you are receiving a network ... as opposed to a local ... TV > program, the 3579.5454 NTSC color burst signal from your TV will very > accurate. It's locked to the network's frequency standard, which is > in turn locked to the NBS standard in Boulder. > > That was true at one time, but is it still the case? I recall reading that with the switch to digital video distribution color burst is locally generated and hence not tied to the NBS standards. Jack K8ZOA _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: Frequency counters for Alignment
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In reply to this post by Ken Kopp-2
Ken,
If you want an even more challenging and exotic use of Spectrogram, consider using a diode ring mixer and a signal generator to convert an RF signal down to baseband (audio), amplify it a bit with an op amp and you can feed the output to the soundcard to be used (with Spectrogram) as a narrow band spectrum analyzer. This is a realistic way to examine the close-in frequency spectrum, such as that of an SSB transmitter output. Feed the K2 with an Elecraft 2T-gen to examine the spectrum of the transmitter. The concept comes from The Measurements chapter of Experimental Methods in RF Design, so I calim no originality for the design - only the application with the 2T-gen. No, I have not yet written this up for my website. 73, Don W3FPR > -----Original Message----- > From: Ken Kopp [mailto:[hidden email]] > Sent: Thursday, March 01, 2007 8:58 PM > To: [hidden email]; Ron D'Eau Claire; 'Elecraft Discussion List' > Subject: Re: [Elecraft] Frequency counters for Alignment > > > Great suggestion, Don! I wouldn't have thought > about using the Spectrogram's markers to match > the tones from WWV. > > Thanks! > > 73! Ken Kopp - K0PP > [hidden email] > or > [hidden email] _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Frequency counters for Alignment
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In reply to this post by Jack Smith-6
--- Jack Smith <[hidden email]> wrote:
> That was true at one time, but is it still the case? I recall reading > that with the switch to digital video distribution color burst is > locally generated and hence not tied to the NBS standards. > > > Jack K8ZOA NBS Special Publication 432 used to describe this method back in the late 70s, early 80s, but as was pointed out, it is no longer valid. Personally, I have a homebrew 10 digit frequency counter (99% complete) combined with a homebrew frequency reference locked to WWVB (60 kHz) (also 99% complete) which is used as a timebase for the counter. I can measure WWV and CHU's HF signals, and resolve the Doppler shift that occurs as the signals from these stations propagate via the ionosphere. :-) I have discovered that AM radio stations that carry IBOC digital broadcasts have generally VERY accurate and stable carrier oscillators. Some are based on Rubidium oscillators tied to GPS clocks! If you use this method for testing / calibration, just make sure you're receiving groundwave (not skywave) because of the Doppler effects earlier described. 73, de John, KD2BD Visit John on the Web at: http://kd2bd.ham.org/ . . . . ____________________________________________________________________________________ Looking for earth-friendly autos? Browse Top Cars by "Green Rating" at Yahoo! Autos' Green Center. http://autos.yahoo.com/green_center/ _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: Frequency counters for Alignment
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As in all measurements, there's a point beyond which greater accuracy is a
waste of time. Knowing what accuracy is needed is the mark of the experienced technician or engineer. Certainly, the few Hz accuracy easily achieved by zero beating WWV is more than enough for HF use, even for most commercial applications, and few counters have the time base stability to hold even that calibration for very long. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: Frequency counters for Alignment
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Ron and all,
That is especially true with the K2. Attempting to obtain dial calibration of greater than 20 Hz is an effort in frustration and futility. That is close to the limit imposed by the digitizing resolution of the K2. Even the tuning steps are 10 Hz, so it is impossible to get any closer than that limit. 73, Don W3FPR > -----Original Message----- > > As in all measurements, there's a point beyond which greater accuracy is a > waste of time. > > Knowing what accuracy is needed is the mark of the experienced > technician or > engineer. > > Certainly, the few Hz accuracy easily achieved by zero beating WWV is more > than enough for HF use, even for most commercial applications, and few > counters have the time base stability to hold even that > calibration for very > long. > > Ron AC7AC > > No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.446 / Virus Database: 268.18.5/707 - Release Date: 3/1/2007 2:43 PM _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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