[Drakelist] Drake crystals accuracy
Do aging Drake crystals lose accuracy? ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Drake crystals accuracy
Yes, ALL crystals drift with age. Strangely enough, it's called 'aging'!! :-) The rate at which they age varies with the cut of the quartz, frequency, the manufacturer's quality control, storage temperature, operating current, etc., etc., etc. The original frequency spec is +/- 0.003%. 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: Do aging Drake crystals lose accuracy? ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Changing crystal frequency
Someone I know used to write on crystals with a pencil claiming the frequency could be changed. Is this true or an urban legend, because graphite is crystalline? ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Changing crystal frequency
- Original Message - From: Neil M Califano cchange...@yahoo.com To: Drakelist@zerobeat.net Sent: Friday, September 16, 2011 5:05 PM Subject: [Drakelist] Changing crystal frequency Someone I know used to write on crystals with a pencil claiming the frequency could be changed. Is this true or an urban legend, because graphite is crystalline? Its true but not because pencil is graphite. A crystal is a mechanical oscillator! The frequency is determined by the mass and thickeness of the crystal along with the cut. Crystals are cut from large crystals which are grown. the angle at which the crystal is sliced in relation to its axis determines the mode of oscillation and many other properties including temperature coefficient. The nature of piezeo electric materials is that they generate a voltage when deformed and will deform if subjected to a voltage difference across the appropriate face of the crystal. Anything on the surface will influence the resonant frequency including the any dirt. Old time crystals were simply blocks of crystal cut to the right angle and placed loosely between two electrodes. They could be varied in frequency a little by the pressure of the electrodes and some crystal holders were made with an adjustment to get a short range of frequencies. Crystals can also be varied by abrasive treatment or adding something to the surface to increase the mass. A pencil mark does this. In the days when crystals were quite expensive there were a lot of articals in ham magazines about how to make your own. After WW-2, when lots of crystals became available surplus, there were numerous articles on how to convert military crystals to ham frequencies and kits with the necessary abrasives were sold. Modern crystals are usually grown and are made with cuts not known sixty years ago. For instance, its possible to make a crystal with zero temperature coefficient over a very wide range. I have not done a web search for piezio electric crystals but I am sure there must be a decent tutorial on them. There was some controversey about just who originated the use of crystals for control of oscillators but the two most likely were A. M. Nicholson and W.G.Cady, the latter of Bell Labs. I think Cady got the patent but Nicholson was probably actually first. Cady's application give much more detail on how to make an actual oscillator, that is probably why he was recognized as the inventor. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Drake crystals accuracy
On Fri, 16 Sep 2011 18:31:39 -0400, Garey Barrell wrote: Yes, ALL crystals drift with age. Strangely enough, it's called 'aging'!! :-) Interstingly enough, the 40 Meter crystals (at least in the C-Line era) seem to age less gracefully than most. 73 -Jim -- Ham Radio NU0C Lincoln, Nebraska, U.S.S.A. TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time! Give a man a URL, and he will learn for an hour; teach him to Google, and he will learn for a lifetime. HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/ http://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Changing crystal frequency
- Original Message - From: Richard Knoppow 1oldle...@ix.netcom.com To: Neil M Califano cchange...@yahoo.com; Drakelist@zerobeat.net Sent: Friday, September 16, 2011 7:32 PM Subject: Re: [Drakelist] Changing crystal frequency Did this myself in 1960, and it works. The added mass will lower the frequency a little, more scribble lowered the frequency more. There is an OP out in Eureka that grinds old FT243 crystals to bring the lower frequency ones up to the desired ham band frequency. The products he sells work FB for boatanchors like my old Globe Scout. That rig has a high crystal current so the fake metalcan crystal in an FT243 case won't cut the mustard. Choip de choip de ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Drake crystals accuracy
- Original Message - From: Jim Shorney jshor...@inebraska.com To: Drakelist@zerobeat.net Sent: Friday, September 16, 2011 6:41 PM Subject: Re: [Drakelist] Drake crystals accuracy On Fri, 16 Sep 2011 18:31:39 -0400, Garey Barrell wrote: Yes, ALL crystals drift with age. Strangely enough, it's called 'aging'!! :-) Interstingly enough, the 40 Meter crystals (at least in the C-Line era) seem to age less gracefully than most. 73 -Jim There may have been a difference in the quality of manufacture, perhaps some impurities got in somehow. One great improvement in crystals was the use of welded rather than soldered cases. Crystals from soldered cases can suffer from impurities from the soldering process and from an imperfect seal. Modern crystals (and I don't know when this started) use welded seams. They look a little different than the soldered kind. Its too bad someone from International Crystal doesn't follow this list because I am sure they know all the historical details as well as exactly why crystals drift with time. BTW, the drift of the highly precise crystals used in frequency standards, like the General Radio standards, were adjusted with the idea that they would drift toward the desired frequency. The drift was expected to be very slow and the circuit allowed adjustment, but the idea was that after a long ageing period the drift would stop or at least become very slow. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Changing crystal frequency
The older (FT-243 style) crystals could be opened with just three small screws. The rectangular piece of quartz could be removed and cleaned, -OR-, you could make marks on it with a pencil to LOWER the frequency a very small amount. Essentially you were just adding a little mass to the vibrating quartz, slowing it down slightly. Had nothing to do with the composition of the pencil, just added mass. The risk was if you added too much mass, the crystal would get sluggish and even quit oscillating. Then it was time to open it up again and clean off all the pencil marks. 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: Someone I know used to write on crystals with a pencil claiming the frequency could be changed. Is this true or an urban legend, because graphite is crystalline? ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Drake crystals accuracy
Jim - I don't know about that on the C-Line. The 40M crystal in the 2-B is definitely more 'failure prone' that the others, but I think that is because of the oscillator circuit Drake used. The 40M crystal is the 'last' (highest) fundamental crystal used, the next one up is run in overtone mode. Perhaps the 40M crystal is confused about which mode it's supposed to be in?!?! A new 6EA8 seems to 'fix' a large number of these crystals. 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 Jim Shorney wrote: On Fri, 16 Sep 2011 18:31:39 -0400, Garey Barrell wrote: Yes, ALL crystals drift with age. Strangely enough, it's called 'aging'!! :-) Interstingly enough, the 40 Meter crystals (at least in the C-Line era) seem to age less gracefully than most. 73 -Jim ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Drake crystals accuracy
On Fri, 16 Sep 2011 22:07:04 -0400, Garey Barrell wrote: Perhaps the 40M crystal is confused about which mode it's supposed to be in?!?! A new 6EA8 seems to 'fix' a large number of these crystals. Does it fix them when they are 40 KHz off? 73 -Jim -- Ham Radio NU0C Lincoln, Nebraska, U.S.S.A. TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time! Give a man a URL, and he will learn for an hour; teach him to Google, and he will learn for a lifetime. HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/ http://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Drake crystals accuracy
There are crystal made cheaply and then some made with more labor and usually are more expensive. Better ones are slowly ground to frequency. Cheaper ones are ground close to frequency and then doped to bring them on frequency. This process is faster then the prior one. However, the doped crystals will drift with age a lot more then those which have not been doped to get them on frequency. Lee Bahr w0vt ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Changing crystal frequency
Rubbing solder on instead of graphite works a little better as the lead has more mass then graphite. Thus, the oscillations are slightly less and the lead can lower the frequency slightly more then graphite. Lee Bahr, w0vt -Original Message- From: Neil M Califano Sent: Friday, September 16, 2011 7:05 PM To: Drakelist@zerobeat.net Subject: [Drakelist] Changing crystal frequency Someone I know used to write on crystals with a pencil claiming the frequency could be changed. Is this true or an urban legend, because graphite is crystalline? ___ 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
