[Drakelist] So if crystals change frequency ...
...what about crystal filters? We're all using crystal filters in our rigs that are as old as the crystals that we're talking about replacing. Do the crystals in the filters also drift over time, shifting the passband (or distorting it, if the crystals in it don't all drift at the same rate)? Is the drift just too small to worry about in the case of a filter? Thanks for any insights. Art Delibert KB3FJO ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] So if crystals change frequency ...
hi Art, Yes, that's a problem also. The early Drake soupcan filters in the TR-3 early TR-4's were/are notable for going bad. They weren't made by Drake, but by an outside provider, which changed as time progressed, just like the filters. Lter filters don't seem to be as much of a problem. Dunno abt other brands. 73, Al, W8UT www.boatanchors.org www.hammarlund.info There is nothing -- absolutely nothing -- half so much worth doing as simply messing about in boats Ratty, to Mole On 9/18/2011 8:01 AM, Arthur Delibert wrote: ...what about crystal filters? We're all using crystal filters in our rigs that are as old as the crystals that we're talking about replacing. Do the crystals in the filters also drift over time, shifting the passband (or distorting it, if the crystals in it don't all drift at the same rate)? Is the drift just too small to worry about in the case of a filter? Thanks for any insights. Art Delibert KB3FJO ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] So if crystals change frequency ...
Art - Yes they do. How important it is depends on several factors. Certainly the quality of the original manufacturing process has a large effect. First, MOST crystal filters are below 10 MHz until just recently. Many, like the Drake twins, are at 5.6 MHz, and since aging is generally a percentage factor, the lower the crystal frequency, the fewer 'Hz' shift will occur. I don't know if this is true, but logic tells me that six or eight crystals all made by the same manufacturer, on essentially the same frequency, will 'probably age at about the same rate and roughly the same number of Hz. So I would expect (hope?) that the filter bandwidth would just shift slightly higher in frequency over time. Obviously, the bandwidth of the filter also determines how much shift can be tolerated. All that aside, the early 'soupcan' filters used in the TR-3/4 seem to have a pretty high 'failure' rate, not from aging of the crystals, but from drastic changes in one or more crystals causing large chunks of dropout. The LSB filter in the T-4X/B/C is the only one of the later hermetically sealed filters that I have heard about failing. There don't seem to be THAT many, but seems like it always the LSB. I wonder the the LSB filter line just had a bad day? :-) The 'good' ones MAY just be slowly drifting, hopefully all at the same rate, and just shifting the Carrier Oscillator frequency will take care of it! I'm certainly not an expert on crystals, and hopefully we have someone here who is and can debunk all my theories and give us the 'right' answers!! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Arthur Delibert wrote: ...what about crystal filters? We're all using crystal filters in our rigs that are as old as the crystals that we're talking about replacing. Do the crystals in the filters also drift over time, shifting the passband (or distorting it, if the crystals in it don't all drift at the same rate)? Is the drift just too small to worry about in the case of a filter? ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Frequency crystals
I saw some crystals made by Hunt. Anyone heard of them? ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] So if crystals change frequency ...
- Original Message - From: Arthur Delibert radio7...@msn.com To: drakelist@zerobeat.net Sent: Sunday, September 18, 2011 5:01 AM Subject: [Drakelist] So if crystals change frequency ... ...what about crystal filters? We're all using crystal filters in our rigs that are as old as the crystals that we're talking about replacing. Do the crystals in the filters also drift over time, shifting the passband (or distorting it, if the crystals in it don't all drift at the same rate)? Is the drift just too small to worry about in the case of a filter? Thanks for any insights. Art Delibert KB3FJO I was able to find out quite a bit about crystals by doing Google searches for both quartz crystals and crystal filters. I did not find a comprehensive explanation of why crystals change frequency but it does seem that its a matter of the crystal lattice structure changing due to: impurities, mechanical shock, dirt, perhaps oxidation, and other things. Modern crystals are adjusted by frequency by chemical etching rather than mechanical grinding which yields a more uniform surface which is less prone to changes in the structure of the surface. They are also fine-adjusted by control of the plating which forms the electrodes. For many years the most stable crystals used evacuated containers. Even with all these changes crystals still change with age. Filters are quite critical of the exact characteristics of the crystals that make them up. Slight changes in either series or parallel resonance or the spacing of the two affect all the filter properties; bandwidth, shape and flatness of the pass band, spurious responses outside of the passband. The more complex the filter (the more poles) the more sensitive it is to changes in value. According to one article, both ceramic and mechanical filters are more stable than quartz crystal filters but neither type of resonator has the extremely high Q of quartz. In fact, any of these filters could be made using L's and C's if one could obtain a sufficiently high Q. It is the enormous Q available from quartz and other essentially mechanical resonators which makes these filters possible. But, its also the high Q that makes these devices so sensitive to small changes in values. Probably the best sourc of theoretical information on quartz crystals remains W.G.Cady's old book but its highly technical and mathematical. There is a ton of literature on complex filter design, mostly also highly mathematical. While the Bell System used astonishingly complex filters for carrier telephone service in the 1950's calculating them without modern computers must have been extremely difficult and manufacturing them a tour-de-force. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Changing Crystal frequency...Penning
HI, Not sure if I can post to this list, I have tried for years... This talk of changing crystal frequencies is great. Do you guys know about penning?? Google it. I learned about it on the Softrock40 group. You can take a cheap ( $1.00) computer crystal and change its frequency down by HUNDREDS of KHz! You just open it up (I use a Dremel with a cutoff wheel) and write on the crystal with a Sharpie Permenant marker. Just go little mark by little mark (and wait for it to dry) and you can make a custom crystal for any frequency you want (well, depending... look at all the crystals available that are just a little higher in frequency).. 73, Gary WB6OGD___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] So if crystals change frequency ...
They had pencil, paper, slide rules, and brains. The modern computer may be faster, but not necessarily smarter. I still carry a Decilon around with me.Just to convince myself that 64-bit floating point doesn't guarantee a better or simpler (or necessarily faster) answer :-) Grant/NQ5T While the Bell System used astonishingly complex filters for carrier telephone service in the 1950's calculating them without modern computers must have been extremely difficult ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Frequency crystals
Drake used some Hunt crystals. The company was started in the early 30's in Carlisle, PA, by a couple of hams, of course. The demand for crystals in WW II was so great that literally hundreds of crystal manufacturing companies were formed. The process was extremely labor intensive, LOTS of hand processing. Most of those companies are long gone, International Crystal Manufacturing is still around (run by a ham, of course, and makes the best rocks available today. The crystal controlled oscillator was 'discovered' in the early 1920's. By the mid 20's hams were using crystal control, but only the most adventurous. They were cutting their own blanks from raw quartz and lapping it to frequency and then fashioning a mount of some sort. I think the FCC 'insisted' on crystal control for ham transmitters by 1935 or so. Probably some errors, the memory ain't what it used to be! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Neil M Califano wrote: I saw some crystals made by Hunt. Anyone heard of them? ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Crystals and audio
Can a frequency crystal affect the audio quality? ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] So if crystals change frequency ...
I'd add also to the bibliography the book published , by Virgil E. Bottom, Introduction to Quartz Crystal Design He has quite a list of literature on this subject, but I've only owned the one book. Several involve crystal aging effects that are being discussed. www.ieee-uffc.org/main/history/Bottom/appendix.doc I seem to remember he was a professor in Texas somewhere. John K5MO At 04:18 PM 9/18/2011, Richard Knoppow wrote: - Original Message - From: Arthur Delibert radio7...@msn.com To: drakelist@zerobeat.net Sent: Sunday, September 18, 2011 5:01 AM Subject: [Drakelist] So if crystals change frequency ... ...what about crystal filters? We're all using crystal filters in our rigs that are as old as the crystals that we're talking about replacing. Do the crystals in the filters also drift over time, shifting the passband (or distorting it, if the crystals in it don't all drift at the same rate)? Is the drift just too small to worry about in the case of a filter? Thanks for any insights. Art Delibert KB3FJO I was able to find out quite a bit about crystals by doing Google searches for both quartz crystals and crystal filters. I did not find a comprehensive explanation of why crystals change frequency but it does seem that its a matter of the crystal lattice structure changing due to: impurities, mechanical shock, dirt, perhaps oxidation, and other things. Modern crystals are adjusted by frequency by chemical etching rather than mechanical grinding which yields a more uniform surface which is less prone to changes in the structure of the surface. They are also fine-adjusted by control of the plating which forms the electrodes. For many years the most stable crystals used evacuated containers. Even with all these changes crystals still change with age. Filters are quite critical of the exact characteristics of the crystals that make them up. Slight changes in either series or parallel resonance or the spacing of the two affect all the filter properties; bandwidth, shape and flatness of the pass band, spurious responses outside of the passband. The more complex the filter (the more poles) the more sensitive it is to changes in value. According to one article, both ceramic and mechanical filters are more stable than quartz crystal filters but neither type of resonator has the extremely high Q of quartz. In fact, any of these filters could be made using L's and C's if one could obtain a sufficiently high Q. It is the enormous Q available from quartz and other essentially mechanical resonators which makes these filters possible. But, its also the high Q that makes these devices so sensitive to small changes in values. Probably the best sourc of theoretical information on quartz crystals remains W.G.Cady's old book but its highly technical and mathematical. There is a ton of literature on complex filter design, mostly also highly mathematical. While the Bell System used astonishingly complex filters for carrier telephone service in the 1950's calculating them without modern computers must have been extremely difficult and manufacturing them a tour-de-force. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Frequency crystals
I think I have a TR-3 or two that has that brand of crystals in the pre-mix section. They looked stock to me. Mark N5KAE - Original Message From: Neil M Califano cchange...@yahoo.com To: Drakelist@zerobeat.net Sent: Sun, September 18, 2011 2:59:56 PM Subject: [Drakelist] Frequency crystals I saw some crystals made by Hunt. Anyone heard of them? ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Crystals and audio
- Original Message - From: Neil M Califano cchange...@yahoo.com To: Drakelist@zerobeat.net Sent: Sunday, September 18, 2011 1:47 PM Subject: [Drakelist] Crystals and audio Can a frequency crystal affect the audio quality? Depends on where it is. If the crystal that generates a local carrier for either generation or detection of SSB changes it will shift the sidbands with relation to the filter passband which can definitely change the audio. If the crystal simply generates the transmitting carrier frequency it probably does not. Of crystals which are part of a filter will cause some change, maybe small or maybe large, depending on how much they change. A lot of the problems we are faced with when dealing with equipment like Drake or Collins is that they were designed using parts with perhaps a ten year liftime and are now anywhere from thirty to sixty years old. We often expect this stuff to work just like it did when it came out of the box new. Pretty often it does but I think that's a bit of a miracle. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] New or used crystals
Are there any advantages to buying new crystals besides they might last longer? ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
