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Have you seen this oscillator?
Hi, I'm trying to track down the name for a certain type of oscillator which I dimly recall seeing in an old book called Radio & Line Transmission that I bought and lost over 3 decades ago. In simple terms, it has a crystal in the base/emitter circuit and a C/L tank for the resonant frequency of the crystal in the collector circuit. In this way it can't flip into an overtone since it only has gain at the crystal's fundamental. Anyone know the name for it? Thanks, p. -- The BBC: Licensed at public expense to spread lies. |
"Paul Burridge" wrote in message ... Hi, I'm trying to track down the name for a certain type of oscillator which I dimly recall seeing in an old book called Radio & Line Transmission that I bought and lost over 3 decades ago. In simple terms, it has a crystal in the base/emitter circuit and a C/L tank for the resonant frequency of the crystal in the collector circuit. In this way it can't flip into an overtone since it only has gain at the crystal's fundamental. Anyone know the name for it? Why don't you think the crystal goes low impedance at it's odd harmonics? If you'll design the circuit properly, it will give no trouble with overtone operation. Don't remember ever having any problems selecting one to operate on the fundamental, usually, it's selecting between 5th and 7th overtone or 7th and 9th that gets a little sticky. W4ZCB |
"Paul Burridge" wrote in message ... Hi, I'm trying to track down the name for a certain type of oscillator which I dimly recall seeing in an old book called Radio & Line Transmission that I bought and lost over 3 decades ago. In simple terms, it has a crystal in the base/emitter circuit and a C/L tank for the resonant frequency of the crystal in the collector circuit. In this way it can't flip into an overtone since it only has gain at the crystal's fundamental. Anyone know the name for it? Why don't you think the crystal goes low impedance at it's odd harmonics? If you'll design the circuit properly, it will give no trouble with overtone operation. Don't remember ever having any problems selecting one to operate on the fundamental, usually, it's selecting between 5th and 7th overtone or 7th and 9th that gets a little sticky. W4ZCB |
In article lXI_b.395225$na.763604@attbi_s04, Harold E. Johnson
writes "Paul Burridge" wrote in message .. . Hi, I'm trying to track down the name for a certain type of oscillator which I dimly recall seeing in an old book called Radio & Line Transmission that I bought and lost over 3 decades ago. In simple terms, it has a crystal in the base/emitter circuit and a C/L tank for the resonant frequency of the crystal in the collector circuit. In this way it can't flip into an overtone since it only has gain at the crystal's fundamental. Anyone know the name for it? Why don't you think the crystal goes low impedance at it's odd harmonics? If you'll design the circuit properly, it will give no trouble with overtone operation. Don't remember ever having any problems selecting one to operate on the fundamental, usually, it's selecting between 5th and 7th overtone or 7th and 9th that gets a little sticky. W4ZCB A universal series resonant circuit "Butler?" meets most of your criteria. I dont like these names myself. Collector to +ve supply via tank LC with the C = 2 C in series the base decoupled to ground with a potential divider to set base bias and a low value (220R?) in the emitter to ground. The crystal goes from the junction of the 2 tapped capacitors and the emitter. The 2 Cs are arranged to lower the o/p impedance from the collector tank i.e. the C nearest the collector would be 100pF and the C to the +ve supply 330pF. With the LC arranged to resonate at the crystal frequency. The beauty of the circuit is that the crystal can be replaced by a 50R resistor and the circuit L and C tweaked to oscillate at the crystal freq. Can be used to select overtone or fundamental. -- ddwyer |
In article lXI_b.395225$na.763604@attbi_s04, Harold E. Johnson
writes "Paul Burridge" wrote in message .. . Hi, I'm trying to track down the name for a certain type of oscillator which I dimly recall seeing in an old book called Radio & Line Transmission that I bought and lost over 3 decades ago. In simple terms, it has a crystal in the base/emitter circuit and a C/L tank for the resonant frequency of the crystal in the collector circuit. In this way it can't flip into an overtone since it only has gain at the crystal's fundamental. Anyone know the name for it? Why don't you think the crystal goes low impedance at it's odd harmonics? If you'll design the circuit properly, it will give no trouble with overtone operation. Don't remember ever having any problems selecting one to operate on the fundamental, usually, it's selecting between 5th and 7th overtone or 7th and 9th that gets a little sticky. W4ZCB A universal series resonant circuit "Butler?" meets most of your criteria. I dont like these names myself. Collector to +ve supply via tank LC with the C = 2 C in series the base decoupled to ground with a potential divider to set base bias and a low value (220R?) in the emitter to ground. The crystal goes from the junction of the 2 tapped capacitors and the emitter. The 2 Cs are arranged to lower the o/p impedance from the collector tank i.e. the C nearest the collector would be 100pF and the C to the +ve supply 330pF. With the LC arranged to resonate at the crystal frequency. The beauty of the circuit is that the crystal can be replaced by a 50R resistor and the circuit L and C tweaked to oscillate at the crystal freq. Can be used to select overtone or fundamental. -- ddwyer |
You're probably thinking of the oscillator that Marv Frerking
called a "grounded-base oscillator". I have seen it called other names as well. Basically, what you do is first build an LC (ie no xtal) Colpitts oscillator and tune it to the crystal frequency you want to eventually use. Then insert a resistor of a few dozen ohms in series with the emitter. Now, readjust the feedback capacitors on the oscillator to get it to oscillate OK with the resistor. Finally, replace the resistor with a series resonant crystal. It will be forced to oscillate at the frequency of the original LC oscillator, since there is no gain anywhere else. Thus you can design for either the fundamental or a specific harmonic and like you say it can't flip to a different overtone. For more details, read one of Frerking's books. Rick N6RK "Paul Burridge" wrote in message ... Hi, I'm trying to track down the name for a certain type of oscillator which I dimly recall seeing in an old book called Radio & Line Transmission that I bought and lost over 3 decades ago. In simple terms, it has a crystal in the base/emitter circuit and a C/L tank for the resonant frequency of the crystal in the collector circuit. In this way it can't flip into an overtone since it only has gain at the crystal's fundamental. Anyone know the name for it? Thanks, p. -- The BBC: Licensed at public expense to spread lies. |
You're probably thinking of the oscillator that Marv Frerking
called a "grounded-base oscillator". I have seen it called other names as well. Basically, what you do is first build an LC (ie no xtal) Colpitts oscillator and tune it to the crystal frequency you want to eventually use. Then insert a resistor of a few dozen ohms in series with the emitter. Now, readjust the feedback capacitors on the oscillator to get it to oscillate OK with the resistor. Finally, replace the resistor with a series resonant crystal. It will be forced to oscillate at the frequency of the original LC oscillator, since there is no gain anywhere else. Thus you can design for either the fundamental or a specific harmonic and like you say it can't flip to a different overtone. For more details, read one of Frerking's books. Rick N6RK "Paul Burridge" wrote in message ... Hi, I'm trying to track down the name for a certain type of oscillator which I dimly recall seeing in an old book called Radio & Line Transmission that I bought and lost over 3 decades ago. In simple terms, it has a crystal in the base/emitter circuit and a C/L tank for the resonant frequency of the crystal in the collector circuit. In this way it can't flip into an overtone since it only has gain at the crystal's fundamental. Anyone know the name for it? Thanks, p. -- The BBC: Licensed at public expense to spread lies. |
You're probably thinking of the oscillator that Marv Frerking called a "grounded-base oscillator". Alternatively, take a look at the Butler design by John Stephensen in November/December 1999 QEX. He explains clearly why folks ever had problems with Butlers and better yet, how to cure them. I've used this circuit (without the Varactor tuning) on 9th overtone oscillators using hound dog crystals. W4ZCB |
You're probably thinking of the oscillator that Marv Frerking called a "grounded-base oscillator". Alternatively, take a look at the Butler design by John Stephensen in November/December 1999 QEX. He explains clearly why folks ever had problems with Butlers and better yet, how to cure them. I've used this circuit (without the Varactor tuning) on 9th overtone oscillators using hound dog crystals. W4ZCB |
On Tue, 24 Feb 2004 16:02:23 GMT, the renowned "Harold E. Johnson"
wrote: You're probably thinking of the oscillator that Marv Frerking called a "grounded-base oscillator". Alternatively, take a look at the Butler design by John Stephensen in November/December 1999 QEX. He explains clearly why folks ever had problems with Butlers and better yet, how to cure them. I've used this circuit (without the Varactor tuning) on 9th overtone oscillators using hound dog crystals. W4ZCB What's a "hound dog crystal"? How to deal with butlers: http://etext.library.adelaide.edu.au...chapter41.html Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com |
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