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100 MHz Crystal
"PDRUNEN" wrote in message ... Hi Group, I have a crystal marked 100MHz, it the smaller package found in the CBs. What I want to do is connect this up to a ECL or Fast TTL and get a 0 to 5 Volt square wave output that can drive 50 ohms with 2.5 volts or more. Anyone have a good circuit or suggestions? Tnx de KJ4uo It will oscillate at the fundamental, not the marked 100 MHz overtone frequency. At 100 MHz, I'd guess that's a 7th or 5th overtone cut. Most likely 7th, 20 MHz is about the limit for fundamental crystals. Pete |
" Uncle Peter" wrote in message
news:o0bZc.124585$Lj.108231@fed1read03... "PDRUNEN" wrote in message ... Hi Group, I have a crystal marked 100MHz, it the smaller package found in the CBs. What I want to do is connect this up to a ECL or Fast TTL and get a 0 to 5 Volt square wave output that can drive 50 ohms with 2.5 volts or more. Anyone have a good circuit or suggestions? Tnx de KJ4uo It will oscillate at the fundamental, not the marked 100 MHz overtone frequency. At 100 MHz, I'd guess that's a 7th or 5th overtone cut. Most likely 7th, 20 MHz is about the limit for fundamental crystals. That used to be the case, but 40 MHz fundamental crystals have been available for some time. I've got some. Leon |
On Tue, 31 Aug 2004 23:05:53 -0400, " Uncle Peter"
wrote: It will oscillate at the fundamental, not the marked 100 MHz overtone frequency. At 100 MHz, I'd guess that's a 7th or 5th overtone cut. Most likely 7th, 20 MHz is about the limit for fundamental crystals. So how does one tell if the xtal is fundamental or overtone? Not for xtals marked 100Mhz, obviously, but for much lower frequencies which could be either.. -- "What is now proved was once only imagin'd." - William Blake, 1793. |
"Leon Heller" a écrit dans le message de ... " Uncle Peter" wrote in message news:o0bZc.124585$Lj.108231@fed1read03... It will oscillate at the fundamental, not the marked 100 MHz overtone frequency. At 100 MHz, I'd guess that's a 7th or 5th overtone cut. Most likely 7th, 20 MHz is about the limit for fundamental crystals. That used to be the case, but 40 MHz fundamental crystals have been available for some time. I've got some. I guess this is not for the garden variety crystals, but I've seen (can't remember where) that IC etching technology has been applied to crystals manufacturing which resulted in crystals of over 200MHz fundamental frequency. -- Thanks, Fred. |
Paul Burridge wrote in message . ..
On Tue, 31 Aug 2004 23:05:53 -0400, " Uncle Peter" wrote: It will oscillate at the fundamental, not the marked 100 MHz overtone frequency. At 100 MHz, I'd guess that's a 7th or 5th overtone cut. Most likely 7th, 20 MHz is about the limit for fundamental crystals. So how does one tell if the xtal is fundamental or overtone? Not for xtals marked 100Mhz, obviously, but for much lower frequencies which could be either.. Easy. Look for resonances near 33.3MHz, 20MHz and 14.3MHz. Or...put it in an oscillator circuit which favors fundamental mode and see where it oscillates. Cheers, Tom |
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"Paul Burridge" wrote in message ... On Tue, 31 Aug 2004 23:05:53 -0400, " Uncle Peter" wrote: It will oscillate at the fundamental, not the marked 100 MHz overtone frequency. At 100 MHz, I'd guess that's a 7th or 5th overtone cut. Most likely 7th, 20 MHz is about the limit for fundamental crystals. So how does one tell if the xtal is fundamental or overtone? Not for xtals marked 100Mhz, obviously, but for much lower frequencies which could be either.. I have used fundamental cut crystals on their overtones and overtone crystals on their fundamental. NOTE, the frequencies will NOT be exact harmonics/multiples. Somewhere I have information giving the typical differences. The crystal Colpitts is one sure bet. Stay away from circuits with inductors and tuned circuits for a fundamental oscillator. Some IC oscillators can give misleading results. They can pound the rock too hard. here's some circuits thanks to GOOGLE: This type is my favorite. Used in just about all Motorola channel elements of Motrac through Micor and probably beyond. http://homepage.tinet.ie/~ei9gq/tx_circ.html Though seems to me, the lower cap should be 100 rather than 220pf, but they are REALLY non critical. One page I found had them both at 1000pf. Fig 7 looks the same: http://www.northcountryradio.com/PDFs/column007.pdf Discover Circuits also has a lot of circuits. http://www.discovercircuits.com/O/o-crystal.htm -- Steve N, K,9;d, c. i My email has no u's. P.S. the Educypedia has lots of circuit ideas, in general http://users.telenet.be/educypedia/e...osciltypes.htm If you do your own search, THIS is NOT a Colpitts crystal osc... http://www.designnotes.com/CIRCUITS/colpitts.htm |
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"Paul Burridge" a écrit dans le message de ... On 1 Sep 2004 14:14:12 -0700, (Mike Monett) wrote: Frequency multiplication tends to increase jitter as well as frequency, however. To minimize jitter at the gigahertz level, equipment builders have to start with super-low-jitter reference oscillators. But the higher the reference frequency climbs, the lower the final gigahertz signal's jitter. Very interesting, Mike. By "jitter" do you mean phase noise? No. Jitter is jitter is jitter, but is related to phase noise that is phase noise that is phase noise. -- Thanks, Fred. |
Paul Burridge wrote in message . ..
On 1 Sep 2004 14:14:12 -0700, (Mike Monett) wrote: Frequency multiplication tends to increase jitter as well as frequency, however. To minimize jitter at the gigahertz level, equipment builders have to start with super-low-jitter reference oscillators. But the higher the reference frequency climbs, the lower the final gigahertz signal's jitter. Very interesting, Mike. By "jitter" do you mean phase noise? Hi Paul, Actually, I didn't write that. Those were excerpts from various sites that discussed the pros and cons of inverted mesa crystals. The main advantage of inverted mesa crystals is lower jitter (or phase noise,) especially when you have to multiply to higher frequencies such as the Ghz region. Inverted mesa crystals allow you to start at a higher frequency, which reduces the multiplication factor needed. To answer your question, yes, phase noise and jitter are closely related. Jitter is measured in the time domain and has units of time, where phase noise is measured in the frequency domain and has units of dBc. You can convert from phase noise to jitter by integrating the phase noise curve. There are many articles that discuss phase noise and jitter. Perhaps the best are by Hajimiri and Lee: Ali Hajimiri and Thomas H. Lee, "A General Theory of Phase Noise in Electrical Oscillators", IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 33, NO. 2, FEBRUARY 1998 http://www.chic.caltech.edu/Publicat...neral_full.PDF (441k pdf) Thomas H. Lee, Ali Hajimiri, "Oscillator Phase Noise: A Tutorial", IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 35, NO. 3, MARCH 2000, http://www.chic.caltech.edu/Publicat...hase_tutor.pdf (212k pdf) Dean Banerjee also discusses this in his book "PLL Performance, Simulation and Design" https://www.national.com/appinfo/wir...sBook_4_01.pdf There is a worked example in "Measuring / Specifying Jitter in crystal oscillators": http://tinyurl.com/4jzfc Wenzel has an Excel spreadsheet to calculate Allan Variance from Phase Noise: "This spreadsheet calculates the Allan Variance from supplied phase noise intercepts. Total RMS jitter over the specified bandwidth is also calculated." http://www.wenzel.com/documents/spread.htm Boris Drakhlis had two articles titled "Calculate Oscillator Jitter By Using Phase-Noise Analysis," Microwaves & RF, Jan. 2001 pp. 82-90 and p. 157, but they seem to have disappeared from the web. I could email them to you if you are interested, but they basically duplicate the above info. Ken Kundert also has some info on noise and jitter on his home page: http://home.pacbell.net/kundert/ Most exciting to me is Rohde has found a way to significantly reduce the phase noise in wideband vco's, which was previously dominated by varactor noise. I keep searching for more information, but there seems to be nothing in the USPTO or on the web. He sells modules but I don't have the url handy. Maybe some info will appear as time goes on and more people use them. Best Regards, Mike |
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Generally speaking. it is the part of the blank which is directly under the electrodes, and very near to the edges of the electrodes, that determine the frequency. I was close to some 135 MHz crystal filter some years ago, but wasn not aware of the technology useed -- it wasn't used in the final design. -- Steve N, K,9;d, c. i My email has no u's. |
Paul Burridge wrote:
[excellent references snipped] Thanks, Mike. That lot ought to keep me quiet for a while! p. Now, watch you don't get too smart! I enjoy the discussions you raise and usually end up learning something - which is more than I can say for some of the self-appointed experts in other newsgroups;) Best Wishes, Mike Monett |
"Jim Adney" wrote in message
... On 1 Sep 2004 09:59:49 -0700 (Tom Bruhns) wrote: Suggestion: just get a 100MHz TTL oscillator. I believe Harold offered you one last time you posted about 100MHz xtals a couple years ago. ECL won't have 2.5V output, but I could supply you with a nice little PECL 100MHz VCXO that you could easily trim to "exactly" 100MHz. It will deliver about 800mV p-p into 50 ohms. What is PECL? Plessey emitter-coupled logic, like MECL, which is made by Motorola. Leon |
From: "Leon Heller"
Newsgroups: rec.radio.amateur.homebrew References: Date: Fri, 3 Sep 2004 08:44:37 +0100 X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1437 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441 Lines: 17 Message-ID: NNTP-Posting-Date: 03 Sep 2004 07:44:36 GMT NNTP-Posting-Host: 81-178-232-132.dsl.pipex.com X-Trace: 1094197476 news-text.dial.pipex.com 20252 81.178.232.132:3125 X-Complaints-To: "Jim Adney" wrote in message .. . On 1 Sep 2004 09:59:49 -0700 (Tom Bruhns) wrote: Suggestion: just get a 100MHz TTL oscillator. I believe Harold offered you one last time you posted about 100MHz xtals a couple years ago. ECL won't have 2.5V output, but I could supply you with a nice little PECL 100MHz VCXO that you could easily trim to "exactly" 100MHz. It will deliver about 800mV p-p into 50 ohms. What is PECL? Plessey emitter-coupled logic, like MECL, which is made by Motorola. Leon PECL is ECL run from a positive supply. ECL is normally run from a negative supply respect to ground. So, they have the sme swings, but different "bias" levels. Jure Z. |
PECL = positive-supply ECL. It's set up to run from a +5V supply
(with the metal case grounded), instead of the usual -5.2V for ECL. Has nothing to do with Plessey. I believe it's spec'd +/-20ppm total from -40C to +85C. It uses a standard AT-cut crystal, I believe, so one could find a zero-slope operating temperature and it'd be quite stable. Cheers, Tom Jim Adney wrote in message . .. On 1 Sep 2004 09:59:49 -0700 (Tom Bruhns) wrote: Suggestion: just get a 100MHz TTL oscillator. I believe Harold offered you one last time you posted about 100MHz xtals a couple years ago. ECL won't have 2.5V output, but I could supply you with a nice little PECL 100MHz VCXO that you could easily trim to "exactly" 100MHz. It will deliver about 800mV p-p into 50 ohms. What is PECL? What kind of stability and aging could I expect from this oscillator? - ----------------------------------------------- Jim Adney Madison, WI 53711 USA ----------------------------------------------- |
"Tom Bruhns" wrote in message
m... PECL = positive-supply ECL. It's set up to run from a +5V supply (with the metal case grounded), instead of the usual -5.2V for ECL. Has nothing to do with Plessey. Yes, you are correct. Plessey used to make it. Please excuse my confusion. Leon |
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