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#21
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Heterodyne conversion crystals
"JB" wrote in message news:g5Dwk.762 That's why they have to learn to seperate their hobby from the pecuniary interests of others. So they don't become a target for commercial interests. If some one or group should be buying or renting radios or systems because their entity has regular need for radio dispatch or communications of a non-hobby nature, they should seek professional help while it exists rather than exploiting the ham. Of course if we all join the Communist Party and the government volunteers to provide us with free food, housing, clothing, medical and other basic subsistence needs, we should do whatever they want after we finish our compulsory rice picking for the day. It was the same in broadcasting. There was always a person willing to DJ for free, just for the fun of it, at the smaller stations. Folks who were trying to make a meager living behind the mikes were at the mercy of hobbyists. |
#22
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Heterodyne conversion crystals
On Sep 4, 9:11 pm, raypsi wrote:
On Sep 3, 2:54 pm, Michael Black wrote: On Wed, 3 Sep 2008, raypsi wrote: Hey Gary, Rocks aren't cheap hehttp://www.icmfg.com/thruhole_crystals.html Maybe in 9 land they pave the streets with gold. Personally I'd go with a programmable divider or PLL. Maybe you like retro, then I'd get some old rocks the ones you can take apart and grind them down to git's the freq's you need. And you can't grind them unless they are quite close to the desired frequency. Grinding by hand will be too uneven, so the crystal will stop working if you try to grind it more than a tiny bit. It also relies on a big stock of crystals spread around so you can find one sufficiently close enough, something that did seem possible in the years after WWII, but after all this time attrition may have reduced the stock considerably. And realistically, they also have to be bulky FT-243 holders, since those you can open by removing screws, and the blank is held in place with pressure. More recent holder types require desoldering the case, and figuring out how to remove the blank and then get it back in place when it's soldered in place (or something like that I can't remember how the blank is connected). One of the odd things is that if one has to buy new crystals, a synthesizer will likely be far cheaper. In the early seventies, synthesizers made a big splash because everyone wanted lots of channels on 2m FM, and the need to have them ground to frequency (and to equipment) made it all very costly, so synthesizers despite their cost and bulk became the norm. Almost forty years later, a synthesizer for a handful of crystals would still be comparatively bulky, but would be even cheaper than in the early seventies. Michael VE2BVW Believe it or not I was making a living sell rocks HI HI back forty years ago. It was like there was a freaking crystal company on every corner. There was so much competition back then the prices was chump change. The crystal companies could have put the big hurt on PLL or programmable dividers. I know the real reason crystals took a back seat, and it;s not what anybody thinks happened. 73 OM n8zu You don't see any newbies on here making any rock controlled hets.. It's like vinyl records or CD's they is all gone. They don't want you to know about crystals there is to much power in that knowledge. They want everyone dumbed down so they can be controlled, that's why they did away with code, nobody will ever know it ever existed in 5 years time. 73 n8zu |
#23
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Heterodyne conversion crystals
On Sep 2, 4:12�pm, Gary@ removenospamandputkf9cm.com wrote:
I am looking for some Heterodyne conversion crystals for a receiver I am making. The frequencies a 5 MHz, 7 MHz, 10.5 MHz, 13.5 MHz, �17.5 MHz and 21.5 MHz. The variable mixing frequency will be from 3 to 3.5 MHz. I would prefer all the same type holder. Once source of crystals is eBay. Another is AF4K (google his call), he has quite a stock in various holders. But be prepared to pay more than a few dollars per crystal! Actually, when you adjust for inflation, crystals cost about as much now as they did 30-40 years ago. Three dollars back in 1965 is the equivalent of about twenty dollars today. You can also do things like use harmonics and overtones of the crystals to get the higher frequencies. -- But before you start building, I suggest you reconsider that mixing scheme. As I understand it, the receiver will consist of a tunable section that covers 3 to 3.5 MHz, and a converter section which converts the various ham bands to that tuning range. So for 160, you would take the 2 to 1.5 MHz range, subtract it from 5 MHz, and get 3 to 3.5 MHz For 80, you would take the 4 to 3.5 MHz range, subtract it from 7 MHz, and get 3 to 3.5 MHz For 40, you would take the 7.5 to 7 MHz range, subtract it from 10.5 MHz, and get 3 to 3.5 MHz For 30, you would take the 10.5 to 10.0 MHz range, subtract it from 13.5 MHz, and get 3 to 3.5 MHz For 20, you would take the 14.5 to 14 MHz range, subtract it from 17.5 MHz, and get 3 to 3.5 MHz For 17, you would take the 18.5 to 18 MHz range, subtract it from 21.5 MHz, and get 3 to 3.5 MHz I guess you don't plan on 15, 12 or 10 meters. The main problem I see with this design is on 80 meters. On that band, the tunable frequency is too close to the band being covered, and you'll likely have troubles with feedthrough. For example, when you are trying to listen to a signal on, say, 3.6 MHz, the tunable section will be on 3.4 MHz, and the front-end selectivity probably won't be able to stop strong signals from leaking through. I suggest you look at other heterodyne schemes, because 80 meter operation will be compromised using the scheme you describe. Here's one to consider, from G2DAF: Tunable range is 5 to 5.5 MHz For 160, you would take the 2 to 1.5 MHz range, subtract it from 7 MHz, and get 5 to 5.5 MHz For 80, you would take the 4 to 3.5 MHz range, subtract it from 9 MHz, and get 5 to 5.5 MHz For 40, you would take the 7.5 to 7 MHz range, subtract it from 12.5 MHz, and get 5 to 5.5 MHz For 30, you would take the 10.5 to 10.0 MHz range, subtract it from 15.5 MHz, and get 5 to 5.5 MHz For 20, you would take the 14 to 14.5 MHz range, subtract 9 MHz from it, and get 5 to 5.5 MHz (Note that the 9 MHz xtal works on two bands) For 17, you would take the 18 to 18.5 MHz range, subtract 13 MHz from it, and get 5 to 5.5 MHz For 15, you would take the 21 to 21.5 MHz range, subtract 16 MHz from it, and get 5 to 5.5 MHz For 12, you would take the 24.5 to 25 MHz range, subtract 19.5 MHz from it, and get 5 to 5.5 MHz So you cover 8 ranges below 25 MHz with 7 xtals Ten meters is left as an exercise for the reader. For the higher frequencies, harmonics of the can be used. For example, an 8 MHz xtal could be used for 15 meters by doubling. Here's another one: Tunable range is 3.5 to 4.1 MHz For 160, you would take the 2 to 1.4 MHz range, subtract it from 5.5 MHz, and get 3.5 to 4.1 MHz For 80, the conversion section is bypassed and you use the basic tuning range For 40, you would take the 7.5 to 6.9 MHz range, subtract it from 11 MHz, and get 3.5 to 4.1 MHz (Note that the second harmonic of the 5.5 MHz xtal used for 160 is 11 MHz) For 30, you would take the 10.6 to 10.0 MHz range, subtract it from 14.1 MHz, and get 3.5 to 4.1 MHz For 20, you would take the 14 to 14.6 MHz range, subtract 10.5 MHz from it, and get 3.5 to 4.1 MHz For 17, you would take the 17.6 to 18.2 MHz range, subtract 14.1 MHz from it, and get 3.5 to 4.1 MHz (Note that the same xtal that gives you 30 meters also works on 17 meters) For 15, you would take the 21 to 21.6 MHz range, subtract 17.5 MHz from it, and get 3.5 to 4.1 MHz For 12, you would take the 24.5 to 25.1 MHz range, subtract 21 MHz from it, and get 3.5 to 4.1 MHz (Note that the second harmonic of the 10.5 MHz xtal used for 20 is 21 MHz) So you cover cover 8 ranges below 25.1 MHz with 6 xtals. If you use harmonics of certain xtals, those 8 ranges can be covered with just 4 xtals. Ten meters is left as an exercise for the reader. There are lots of other schemes. 73 de Jim, N2EY |
#24
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Heterodyne conversion crystals
The real reason for the popularity of synthesizers is cost. When you
need a new rock for every band they get costly, but a synthesizer doesn't. This wasn't practical until chips that could do most of the work became cheap. The main reason for eliminating the commercial operator licenses was cost too. Here's what happened: There was a time, not so long ago, when there were a large number of tasks that could only be performed (legally, anyway) by a person with an FCC Commercial Operator license. No others need apply, regardless of experience, education or background. Either you were a Radio Operator of a certain class, or you weren't. Those licenses meant that a person with a high-school education and some smarts could have a good middle-class income if they had the license. Not that all the jobs were easy, or that you didn't need a certain amount of knowledge to do them, but that the Commercial license became the equivalent of a union card, and the jobs were, in a way, protected by FCC regulations. In other words, the Commercial licenses protected a craft known as Radio Operators, with a set of skills and knowledge specific to them, and jobs only they could do. The masters of industry didn't like that, so they prevailed on the FCC to reduce the requirements and eliminate most of the licenses and the requirements for tasks to be done only by Radio Operators. The jobs went with them. This is also why the maritime services went to satellite-based comms rather than HF and MF radio and Morse Code - it eliminated the need for ships to carry licensed Radio Operators. Oddly enough, FCC still issues Commercial RadioTelegraph licenses, both First and Second Class, though I don't know where in the USA you can get the required experience for a First Class. 73 de Jim, N2EY |
#25
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Heterodyne conversion crystals
On Sep 6, 7:38�pm, raypsi wrote:
They want everyone dumbed down so they can be controlled, that's why they did away with code, nobody will ever know it ever existed in 5 years time. They didn't do away with Morse Code. They did away with the test for it. It was done a little at a time over the past 30 years. My personal theory on why it was eliminated is this: Since the early 1980s, the FCC has been required to do more and more stuff with less and less resources. So they have constantly sought out ways to reduce their workload, particularly for radio services that don't bring in $$, like ham radio. That's why they turned over the job of amateur license testing to the QPC and VECs back in 1983 or so. Instead of paid FCC employees making up and conducting amateur license tests, unpaid volunteers do almost all the work. It's also why they doubled the license term to 10 years about that same time - reduces the number of renewals by half. Reducing the number of license classes reduces the number of tests and the number of upgrade applications to process. In the old days when there were six license classes, a ham who went from Novice or Tech to Extra could upgrade as many as four times. Now there are only two steps. Eliminating the Morse Code test means one less license test. Less work. But even though the last remnants of the Morse Code test were removed back in February 2007, there are still plenty of hams using it on the air. This past Field Day, for example, the group I went with had one Morse Code station and three voice stations, all similarly equipped. There were three Morse Code operators and far more voice ops, yet the Morse Code station made more QSOs than all the voice stations combined. This wasn't a surprise, either. 73 de Jim, N2EY |
#26
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Heterodyne conversion crystals
On Sep 6, 9:03*pm, wrote:
They didn't do away with Morse Code. They did away with the test for it. It was done a little at a time over the past 30 years. hey jim: Sorry I wasn't talking Morse code, . Real Morse code nobody knows. That is lost already gone kaput history. Vail invented the code you so aptly call Morse, So it's not real Morse code it's Vail code. What is really lost: everybody still calls it Morse code. I think I could make some money fire up the ole solar powered kiln and start growing quartz. I break out that old ARRL handbook that tells you exactly how to cut the crystals for the desired frequencies and sell them for 50 cent apiece. I'd make so much money in volume sales. 73 OM n8zu |
#27
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Heterodyne conversion crystals
On Sep 6, 8:31*pm, wrote:
On Sep 2, 4:12 pm, Gary@ removenospamandputkf9cm.com wrote: I am looking for some Heterodyne conversion crystals for a receiver I am making. The frequencies a 5 MHz, 7 MHz, 10.5 MHz, 13.5 MHz, 17.5 MHz and 21.5 MHz. The variable mixing frequency will be from 3 to 3.5 MHz. I would prefer all the same type holder. . 73 de Jim, N2EY What you ain't got no IF? All those fine numbers and no IF You know what the image frequency is with no IF? I think he can get's 12 and 15 meters. 21.5+3.39=24.89 the bottom of the 12 meter band. 21.5+3.49=24.99 the top of the 12 meter band 17.5+3.5=21.0 the bottom of 15 meters for an extra squeeze the tuning range to 3.95 and 17.5+3,95 =21.45 the top of the 15 meter band. Back in the day the reason for Heterodyne was simple to get a lower frequency at which you could amplify the signal more readily getting you more SN ratio and selectivity. 73 OM n8zu |
#28
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Heterodyne conversion crystals
On Sun, 7 Sep 2008, raypsi wrote:
On Sep 6, 9:03*pm, wrote: They didn't do away with Morse Code. They did away with the test for it. It was done a little at a time over the past 30 years. hey jim: Sorry I wasn't talking Morse code, . Real Morse code nobody knows. That is lost already gone kaput history. Vail invented the code you so aptly call Morse, So it's not real Morse code it's Vail code. What is really lost: everybody still calls it Morse code. I think I could make some money fire up the ole solar powered kiln and start growing quartz. I break out that old ARRL handbook that tells you exactly how to cut the crystals for the desired frequencies and sell them for 50 cent apiece. I'd make so much money in volume sales. Nobody has ground their crystals from scratch since about the 1930's, if even then. I've been licensed since 1972 and in all the time since then I've never seen anything about it, not in magazines and books going back to the late 1940's and not in more recent material. I do recall the 1964 article in QST about a buy in SOuth America who made his own tubes. Go back far enough, and hams just needed crystals within the band. They had relatively little need for exact frequencies. I suspect even if the Handbook did give such details at one time, little bits may be lost since when something is current, "everyone knows" things that may not be obvious to someone who comes later. Now, they need them on exact frequencies, and they want them in nice small packages, none of those FT-243 ones that were held together with pressure. Even if you can so easily grind a piece of quartz to frequency, packaging them will be problematic, since a sealed metal case is going to be a lot more trouble than an FT-243 package. Michael VE2BVW |
#29
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Heterodyne conversion crystals
"Michael Black" wrote in message ample.org... On Sun, 7 Sep 2008, raypsi wrote: On Go back far enough, and hams just needed crystals within the band. They had relatively little need for exact frequencies. And Novice regulations required the use of Xtal control, a ready market... I suspect even if the Handbook did give such details at one time, little bits may be lost since when something is current, "everyone knows" things that may not be obvious to someone who comes later. Tools, techiques, sources for raw or processed materials. WWII end provided what seemed to be an endless supply of radio related parts and equipment. Tons of FT-243 xtals, ready to use or to regrind, etc. I remember when one could find surplus 455kc xtals to make SSB filters; they are unobtanium now. Pete, k1zjh Michael VE2BVW |
#30
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Heterodyne conversion crystals
On Sep 7, 2:43�pm, Michael Black wrote:
Nobody has ground their crystals from scratch since about the 1930's, if even then. �I've been licensed since 1972 and in all the time since then I've never seen anything about it, not in magazines and books going back to the late 1940's and not in more recent material. There were articles in QST in the 1920s about cutting and grinding your own crystals from the raw quartz, making holders, etc. A lot of work and specialized equipment. The market was such that the specialists quickly took over in the early 1930s. After WW2 the enormous amount of surplus dominated the amateur market for decades. Many of the "new" FT-243 crystals we bought were actually surplus holders with new crystal inside. �I do recall the 1964 article in QST about a buy in SOuth America who made his own tubes. There's a guy in France doing it today. Has a movie on his website. But again, lots of work and specialized equipment. Go back far enough, and hams just needed crystals within the band. They had relatively little need for exact frequencies. Well, yes and no. Some xtal frequencies were more prized than others, because the harmonics fell in higher bands. I suspect even if the Handbook did give such details at one time, little bits may be lost since when something is current, "everyone knows" things that may not be obvious to someone who comes later. That's true of many things. Reading older radio books and magazines can require knowledge of a lot of the jargon and methods of the day. Now, they need them on exact frequencies, and they want them in nice small packages, none of those FT-243 ones that were held together with pressure. The big difference is plated electrodes vs. pressure electrodes. FT-243s are capable of quite good accuracy; .005% was common, which works out to 200 Hz at 4 MHz. Pre-WW2 xtals were big and rugged, but used a lot of quartz. Radio- grade natural quartz came almost exclusively from Brazil, and the difficulty of supply caused US xtal makers to develop xtal designs that used less quartz. The FT-243 was ultra-miniature in its time! 73 de Jim, N2EY |
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