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gibert cell in glass?
Hi,
Has anyone ever implemented a gilbert cell mixer using valves instead of FETs? I'm considering this instead of using the increasingly rare and costly heptode mixer. Thanks, The Eternal Squire (yes, I have a call, I just like my privacy) |
"The Eternal Squire" wrote in message
om... Hi, Has anyone ever implemented a gilbert cell mixer using valves instead of FETs? I'm considering this instead of using the increasingly rare and costly heptode mixer. There was some sort of dual tetrode (6164?) that used to be used in high performance mixers for valve radios. Leon |
"The Eternal Squire" wrote in message
om... Hi, Has anyone ever implemented a gilbert cell mixer using valves instead of FETs? I'm considering this instead of using the increasingly rare and costly heptode mixer. There was some sort of dual tetrode (6164?) that used to be used in high performance mixers for valve radios. Leon |
6U8 or 6X8 are a dime a dozen and great mixers. Also 6BL8, 6EA8 are good
up to 220MHz. 6J6 goes to 600MHz. I have tried to develop "glass Gilberts", but tubes are too linear. -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
6U8 or 6X8 are a dime a dozen and great mixers. Also 6BL8, 6EA8 are good
up to 220MHz. 6J6 goes to 600MHz. I have tried to develop "glass Gilberts", but tubes are too linear. -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
the greatest valve mixer ever was based on 7360. a dual beam tetrode
specifically meant for being a high dynamic range mixer. you can also try making a commutation mixer with four triodes. - farhan |
the greatest valve mixer ever was based on 7360. a dual beam tetrode
specifically meant for being a high dynamic range mixer. you can also try making a commutation mixer with four triodes. - farhan |
Behold, Ashhar Farhan signalled from keyed 4-1000A filament:
the greatest valve mixer ever was based on 7360. snip How true!! -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
Behold, Ashhar Farhan signalled from keyed 4-1000A filament:
the greatest valve mixer ever was based on 7360. snip How true!! -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
In article ,
(The Eternal Squire) writes: Has anyone ever implemented a gilbert cell mixer using valves instead of FETs? I'm considering this instead of using the increasingly rare and costly heptode mixer. To do this, one needs a minimum of three triodes, the top pair being (essentially) a differential amplifier, the bottom being a configured constant-current source replacing a moderately- high common cathode resistor for the differential pair. That's a LOT of circuit work where a single dual triode could (and has) work just as well. Connect it as a differential pair and put the signal in one side, the LO in the other. Any valve that runs its control grid into the positive region is going to be operating in a non-linear region and will therefore "mix" well enough to do some heterodyning. The name "Gilbert cell" got there in later integrated circuit times to describe a particular arrangement of BJT junctions to do mixing or AGC actions. Valve circuitry had other names and worked for decades as mixers quite will without fancy names. :-) |
Avery Fineman ) writes:
In article , (The Eternal Squire) writes: Has anyone ever implemented a gilbert cell mixer using valves instead of FETs? I'm considering this instead of using the increasingly rare and costly heptode mixer. To do this, one needs a minimum of three triodes, the top pair being (essentially) a differential amplifier, the bottom being a configured constant-current source replacing a moderately- high common cathode resistor for the differential pair. That's a LOT of circuit work where a single dual triode could (and has) work just as well. Connect it as a differential pair and put the signal in one side, the LO in the other. Any valve that runs its control grid into the positive region is going to be operating in a non-linear region and will therefore "mix" well enough to do some heterodyning. The name "Gilbert cell" got there in later integrated circuit times to describe a particular arrangement of BJT junctions to do mixing or AGC actions. Valve circuitry had other names and worked for decades as mixers quite will without fancy names. :-) But the "Gilbert Cell" mixer also got by for a good long time without the fancy name. Nobody used the term in the early seventies when the MC1496 came along. It was just a double balanced mixer. It was the late eighties when I started hearing the term, in reference to the NE602, though suddenly decades of the same circuit was suddenly a Gilbert Cell. I know I mentioned this at one time in one of the newsgroups, and there was an explanation, but I can't remember what it was. Michael VE2BVW |
Avery Fineman ) writes:
In article , (The Eternal Squire) writes: Has anyone ever implemented a gilbert cell mixer using valves instead of FETs? I'm considering this instead of using the increasingly rare and costly heptode mixer. To do this, one needs a minimum of three triodes, the top pair being (essentially) a differential amplifier, the bottom being a configured constant-current source replacing a moderately- high common cathode resistor for the differential pair. That's a LOT of circuit work where a single dual triode could (and has) work just as well. Connect it as a differential pair and put the signal in one side, the LO in the other. Any valve that runs its control grid into the positive region is going to be operating in a non-linear region and will therefore "mix" well enough to do some heterodyning. The name "Gilbert cell" got there in later integrated circuit times to describe a particular arrangement of BJT junctions to do mixing or AGC actions. Valve circuitry had other names and worked for decades as mixers quite will without fancy names. :-) But the "Gilbert Cell" mixer also got by for a good long time without the fancy name. Nobody used the term in the early seventies when the MC1496 came along. It was just a double balanced mixer. It was the late eighties when I started hearing the term, in reference to the NE602, though suddenly decades of the same circuit was suddenly a Gilbert Cell. I know I mentioned this at one time in one of the newsgroups, and there was an explanation, but I can't remember what it was. Michael VE2BVW |
Gregg wrote:
Behold, Ashhar Farhan signalled from keyed 4-1000A filament: the greatest valve mixer ever was based on 7360. snip How true!! There were also some tv tubes used in chroma demodulators that were sorta 7360 ish. The 6AR8 for one, I know there were a few others. BTW you had to use mu-metal shields on these for best results. |
Gregg wrote:
Behold, Ashhar Farhan signalled from keyed 4-1000A filament: the greatest valve mixer ever was based on 7360. snip How true!! There were also some tv tubes used in chroma demodulators that were sorta 7360 ish. The 6AR8 for one, I know there were a few others. BTW you had to use mu-metal shields on these for best results. |
Ken Scharf wrote:
Gregg wrote: Behold, Ashhar Farhan signalled from keyed 4-1000A filament: the greatest valve mixer ever was based on 7360. snip How true!! There were also some tv tubes used in chroma demodulators that were sorta 7360 ish. The 6AR8 for one, I know there were a few others. BTW you had to use mu-metal shields on these for best results. And if you're going to design anything new, the 7360 is on sale for only $27 a pop (down from $49!) while the 6AR8 is about $5. Four diodes and a couple of ferrite cores, on the other hand... -- Tim Wescott Wescott Design Services http://www.wescottdesign.com |
Ken Scharf wrote:
Gregg wrote: Behold, Ashhar Farhan signalled from keyed 4-1000A filament: the greatest valve mixer ever was based on 7360. snip How true!! There were also some tv tubes used in chroma demodulators that were sorta 7360 ish. The 6AR8 for one, I know there were a few others. BTW you had to use mu-metal shields on these for best results. And if you're going to design anything new, the 7360 is on sale for only $27 a pop (down from $49!) while the 6AR8 is about $5. Four diodes and a couple of ferrite cores, on the other hand... -- Tim Wescott Wescott Design Services http://www.wescottdesign.com |
Behold, Ken Scharf signalled from keyed 4-1000A filament:
Gregg wrote: Behold, Ashhar Farhan signalled from keyed 4-1000A filament: the greatest valve mixer ever was based on 7360. snip How true!! There were also some tv tubes used in chroma demodulators that were sorta 7360 ish. The 6AR8 for one, I know there were a few others. BTW you had to use mu-metal shields on these for best results. Hi Ken, I have experimented with those - their noisy as stink above 4MHz :-( -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
Behold, Ken Scharf signalled from keyed 4-1000A filament:
Gregg wrote: Behold, Ashhar Farhan signalled from keyed 4-1000A filament: the greatest valve mixer ever was based on 7360. snip How true!! There were also some tv tubes used in chroma demodulators that were sorta 7360 ish. The 6AR8 for one, I know there were a few others. BTW you had to use mu-metal shields on these for best results. Hi Ken, I have experimented with those - their noisy as stink above 4MHz :-( -- Gregg *It's probably useful, even if it can't be SPICE'd* http://geek.scorpiorising.ca |
Some time ago, Barrie Gilbert, for whom the "Gilbert cell" is named,
gave a talk at a local ham club. He began by showing a copy of the patent for the "Gilbert cell", and emphatically pointed out that his name isn't on it. As he explained, he didn't invent the circuit nor did he have anything to do with its invention. At the time it was patented, he was an application engineer, and he wrote a lengthy article in one of the trade magazines about the circuit and its applications (and giving proper credit to the inventor). Shortly after that, through no action of his own, someone dubbed it the "Gilbert cell". The name stuck, and Barrie has spent the time since trying to straighten out the record -- without success. As far as I know, he gives the explanation every time he presents a talk. Ironically, I don't remember the name of the actual inventor of this very useful circuit -- it's in my notes from that talk, buried somewhere. Barrie is an engineer at Analog Devices, and the chief designer of many of their advanced analog products. He's an exceptionally talented engineer, a real gentleman, and a humble and honest person. But NOT the inventor of the "Gilbert cell" -- as he's the first one to point out. Roy Lewallen, W7EL Michael Black wrote: But the "Gilbert Cell" mixer also got by for a good long time without the fancy name. Nobody used the term in the early seventies when the MC1496 came along. It was just a double balanced mixer. It was the late eighties when I started hearing the term, in reference to the NE602, though suddenly decades of the same circuit was suddenly a Gilbert Cell. I know I mentioned this at one time in one of the newsgroups, and there was an explanation, but I can't remember what it was. Michael VE2BVW |
Some time ago, Barrie Gilbert, for whom the "Gilbert cell" is named,
gave a talk at a local ham club. He began by showing a copy of the patent for the "Gilbert cell", and emphatically pointed out that his name isn't on it. As he explained, he didn't invent the circuit nor did he have anything to do with its invention. At the time it was patented, he was an application engineer, and he wrote a lengthy article in one of the trade magazines about the circuit and its applications (and giving proper credit to the inventor). Shortly after that, through no action of his own, someone dubbed it the "Gilbert cell". The name stuck, and Barrie has spent the time since trying to straighten out the record -- without success. As far as I know, he gives the explanation every time he presents a talk. Ironically, I don't remember the name of the actual inventor of this very useful circuit -- it's in my notes from that talk, buried somewhere. Barrie is an engineer at Analog Devices, and the chief designer of many of their advanced analog products. He's an exceptionally talented engineer, a real gentleman, and a humble and honest person. But NOT the inventor of the "Gilbert cell" -- as he's the first one to point out. Roy Lewallen, W7EL Michael Black wrote: But the "Gilbert Cell" mixer also got by for a good long time without the fancy name. Nobody used the term in the early seventies when the MC1496 came along. It was just a double balanced mixer. It was the late eighties when I started hearing the term, in reference to the NE602, though suddenly decades of the same circuit was suddenly a Gilbert Cell. I know I mentioned this at one time in one of the newsgroups, and there was an explanation, but I can't remember what it was. Michael VE2BVW |
So if the Gilbert cell is simply a differential pair on top of a
constant current source, and you are advocating only the differential pair, then I suppose you are advocating the equivalent of a Gilbert cell with no current source. Someone had mentioned that I should be using a silicon diode mixer, but that's not the point... I want my designs to be all battery tubes (plate 25-60 volt), so that the gear can be portable and also withstand electromagnetic pulse. The 7360 and 6AR8 require too much plate voltage. Now from what I understand, the passive double balanced mixer has the best port isolation, which makes it superior to the Gilbert cell for avoiding spurs. On the other hand, the Gilbert cell has conversion gain but is more vulnerable to spurs. So I wonder if the better answer is to build a DBM in glass, or the differential pair? The Eternal Squire (Avery Fineman) wrote in message ... In article , (The Eternal Squire) writes: Has anyone ever implemented a gilbert cell mixer using valves instead of FETs? I'm considering this instead of using the increasingly rare and costly heptode mixer. To do this, one needs a minimum of three triodes, the top pair being (essentially) a differential amplifier, the bottom being a configured constant-current source replacing a moderately- high common cathode resistor for the differential pair. That's a LOT of circuit work where a single dual triode could (and has) work just as well. Connect it as a differential pair and put the signal in one side, the LO in the other. Any valve that runs its control grid into the positive region is going to be operating in a non-linear region and will therefore "mix" well enough to do some heterodyning. The name "Gilbert cell" got there in later integrated circuit times to describe a particular arrangement of BJT junctions to do mixing or AGC actions. Valve circuitry had other names and worked for decades as mixers quite will without fancy names. :-) |
So if the Gilbert cell is simply a differential pair on top of a
constant current source, and you are advocating only the differential pair, then I suppose you are advocating the equivalent of a Gilbert cell with no current source. Someone had mentioned that I should be using a silicon diode mixer, but that's not the point... I want my designs to be all battery tubes (plate 25-60 volt), so that the gear can be portable and also withstand electromagnetic pulse. The 7360 and 6AR8 require too much plate voltage. Now from what I understand, the passive double balanced mixer has the best port isolation, which makes it superior to the Gilbert cell for avoiding spurs. On the other hand, the Gilbert cell has conversion gain but is more vulnerable to spurs. So I wonder if the better answer is to build a DBM in glass, or the differential pair? The Eternal Squire (Avery Fineman) wrote in message ... In article , (The Eternal Squire) writes: Has anyone ever implemented a gilbert cell mixer using valves instead of FETs? I'm considering this instead of using the increasingly rare and costly heptode mixer. To do this, one needs a minimum of three triodes, the top pair being (essentially) a differential amplifier, the bottom being a configured constant-current source replacing a moderately- high common cathode resistor for the differential pair. That's a LOT of circuit work where a single dual triode could (and has) work just as well. Connect it as a differential pair and put the signal in one side, the LO in the other. Any valve that runs its control grid into the positive region is going to be operating in a non-linear region and will therefore "mix" well enough to do some heterodyning. The name "Gilbert cell" got there in later integrated circuit times to describe a particular arrangement of BJT junctions to do mixing or AGC actions. Valve circuitry had other names and worked for decades as mixers quite will without fancy names. :-) |
Roy Lewallen ) writes:
Some time ago, Barrie Gilbert, for whom the "Gilbert cell" is named, gave a talk at a local ham club. He began by showing a copy of the patent for the "Gilbert cell", and emphatically pointed out that his name isn't on it. As he explained, he didn't invent the circuit nor did he have anything to do with its invention. At the time it was patented, he was an application engineer, and he wrote a lengthy article in one of the trade magazines about the circuit and its applications (and giving proper credit to the inventor). Shortly after that, through no action of his own, someone dubbed it the "Gilbert cell". The name stuck, and Barrie has spent the time since trying to straighten out the record -- without success. As far as I know, he gives the explanation every time he presents a talk. Ironically, I don't remember the name of the actual inventor of this very useful circuit -- it's in my notes from that talk, buried somewhere. Barrie is an engineer at Analog Devices, and the chief designer of many of their advanced analog products. He's an exceptionally talented engineer, a real gentleman, and a humble and honest person. But NOT the inventor of the "Gilbert cell" -- as he's the first one to point out. Roy Lewallen, W7EL That sounds almost exactly the way I read it before, so you may have been the one who responded the last time. Michael VE2BVW Michael Black wrote: But the "Gilbert Cell" mixer also got by for a good long time without the fancy name. Nobody used the term in the early seventies when the MC1496 came along. It was just a double balanced mixer. It was the late eighties when I started hearing the term, in reference to the NE602, though suddenly decades of the same circuit was suddenly a Gilbert Cell. I know I mentioned this at one time in one of the newsgroups, and there was an explanation, but I can't remember what it was. Michael VE2BVW |
Roy Lewallen ) writes:
Some time ago, Barrie Gilbert, for whom the "Gilbert cell" is named, gave a talk at a local ham club. He began by showing a copy of the patent for the "Gilbert cell", and emphatically pointed out that his name isn't on it. As he explained, he didn't invent the circuit nor did he have anything to do with its invention. At the time it was patented, he was an application engineer, and he wrote a lengthy article in one of the trade magazines about the circuit and its applications (and giving proper credit to the inventor). Shortly after that, through no action of his own, someone dubbed it the "Gilbert cell". The name stuck, and Barrie has spent the time since trying to straighten out the record -- without success. As far as I know, he gives the explanation every time he presents a talk. Ironically, I don't remember the name of the actual inventor of this very useful circuit -- it's in my notes from that talk, buried somewhere. Barrie is an engineer at Analog Devices, and the chief designer of many of their advanced analog products. He's an exceptionally talented engineer, a real gentleman, and a humble and honest person. But NOT the inventor of the "Gilbert cell" -- as he's the first one to point out. Roy Lewallen, W7EL That sounds almost exactly the way I read it before, so you may have been the one who responded the last time. Michael VE2BVW Michael Black wrote: But the "Gilbert Cell" mixer also got by for a good long time without the fancy name. Nobody used the term in the early seventies when the MC1496 came along. It was just a double balanced mixer. It was the late eighties when I started hearing the term, in reference to the NE602, though suddenly decades of the same circuit was suddenly a Gilbert Cell. I know I mentioned this at one time in one of the newsgroups, and there was an explanation, but I can't remember what it was. Michael VE2BVW |
In article ,
(The Eternal Squire) writes: So if the Gilbert cell is simply a differential pair on top of a constant current source, and you are advocating only the differential pair, then I suppose you are advocating the equivalent of a Gilbert cell with no current source. I wan't "advocating" anything, just stating generalities. Mixers MUST be non-linear in order to do the mixing. Someone had mentioned that I should be using a silicon diode mixer, but that's not the point... I want my designs to be all battery tubes (plate 25-60 volt), so that the gear can be portable and also withstand electromagnetic pulse. Okay, then use the 1R5 pentagrid and be done with it. That worked fine for Motorola and Hallicrafters in the old days. Lacking that humongous EMP simulator, I don't know how you are going to check the EMP-withstanding qualities you want. :-) The 7360 and 6AR8 require too much plate voltage. I never mentioned those. Now from what I understand, the passive double balanced mixer has the best port isolation, which makes it superior to the Gilbert cell for avoiding spurs. On the other hand, the Gilbert cell has conversion gain but is more vulnerable to spurs. So I wonder if the better answer is to build a DBM in glass, or the differential pair? 1. You've never outlined the necessity of the double-balance in a mixer. The non-balanced type has worked fine in the original WW2 "handie-talkie" and on into the BC-1000 VHF manpack transceiver and lots of battery-operated consumer radios. Unbalanced mixers were used in the Korean War era PRC-8 series using subminiature battery tubes. For both the Tx and Rx sections. Also the PRC-6 handy-talky, also VHF. 2. A balanced mixer of any kind is not necessarily a relief from spurious responses. The choice of frequencies to mix will do that...for any mixer type. Note: The intermodulation products are a different situation and depend on the characteristics of the mixer. 3. I'm not convinced that "battery tubes" wil "withstand an EMP." It's become an urban myth that "all solid-state electronics is destroyed by EMP but tubes/valves miraculously survive." Not absolutely true...but I can't quibble with urban myths so I've just met the MIL STDs with attention to detail on the probable EMP effects which then passed the EMP simulator. 4. Designing a circuit using battery powered, directly-heated filaments as a differential pair is going to be difficult...unless you have a separate "A" battery supply for that differential pair. Since the cathodes ARE the filaments, not separate as in indirectly-heated tubes, those cathode-filaments are going to be elevated or, if run near common, will require a "B-" supply for the long-tailed pair's large "cathode" resistor. 5. Battery packs are almost in the unobtanium category except for the single, lower voltage variety. You could use DC-DC converters but those are now all solid-state and that doesn't meet the "EMP requirement." Electro-mechanical vibrators could generate the higher B+ (or B-) but those are terribly inefficient, short-lived, and get bulky with transformers that must be at low AC frequencies. Primary batteries such as the carbon-zinc variety don't last long, maybe several years if kept very cold to slow down the internal chemistry...all those being made 30 to 40 years ago are now NG. 6. You CAN use techniques for suppressing ESD (electrostatic discharge) to protect from EMP effects, then go ahead and work with solid-state devices with some assurance of surviveability. But, you MUST know the EMP characteristics and do a thorough design task analysis on every part. Anyone using battery-filament tubes should do the same thing although I haven't any idea if anyone has done that. |
In article ,
(The Eternal Squire) writes: So if the Gilbert cell is simply a differential pair on top of a constant current source, and you are advocating only the differential pair, then I suppose you are advocating the equivalent of a Gilbert cell with no current source. I wan't "advocating" anything, just stating generalities. Mixers MUST be non-linear in order to do the mixing. Someone had mentioned that I should be using a silicon diode mixer, but that's not the point... I want my designs to be all battery tubes (plate 25-60 volt), so that the gear can be portable and also withstand electromagnetic pulse. Okay, then use the 1R5 pentagrid and be done with it. That worked fine for Motorola and Hallicrafters in the old days. Lacking that humongous EMP simulator, I don't know how you are going to check the EMP-withstanding qualities you want. :-) The 7360 and 6AR8 require too much plate voltage. I never mentioned those. Now from what I understand, the passive double balanced mixer has the best port isolation, which makes it superior to the Gilbert cell for avoiding spurs. On the other hand, the Gilbert cell has conversion gain but is more vulnerable to spurs. So I wonder if the better answer is to build a DBM in glass, or the differential pair? 1. You've never outlined the necessity of the double-balance in a mixer. The non-balanced type has worked fine in the original WW2 "handie-talkie" and on into the BC-1000 VHF manpack transceiver and lots of battery-operated consumer radios. Unbalanced mixers were used in the Korean War era PRC-8 series using subminiature battery tubes. For both the Tx and Rx sections. Also the PRC-6 handy-talky, also VHF. 2. A balanced mixer of any kind is not necessarily a relief from spurious responses. The choice of frequencies to mix will do that...for any mixer type. Note: The intermodulation products are a different situation and depend on the characteristics of the mixer. 3. I'm not convinced that "battery tubes" wil "withstand an EMP." It's become an urban myth that "all solid-state electronics is destroyed by EMP but tubes/valves miraculously survive." Not absolutely true...but I can't quibble with urban myths so I've just met the MIL STDs with attention to detail on the probable EMP effects which then passed the EMP simulator. 4. Designing a circuit using battery powered, directly-heated filaments as a differential pair is going to be difficult...unless you have a separate "A" battery supply for that differential pair. Since the cathodes ARE the filaments, not separate as in indirectly-heated tubes, those cathode-filaments are going to be elevated or, if run near common, will require a "B-" supply for the long-tailed pair's large "cathode" resistor. 5. Battery packs are almost in the unobtanium category except for the single, lower voltage variety. You could use DC-DC converters but those are now all solid-state and that doesn't meet the "EMP requirement." Electro-mechanical vibrators could generate the higher B+ (or B-) but those are terribly inefficient, short-lived, and get bulky with transformers that must be at low AC frequencies. Primary batteries such as the carbon-zinc variety don't last long, maybe several years if kept very cold to slow down the internal chemistry...all those being made 30 to 40 years ago are now NG. 6. You CAN use techniques for suppressing ESD (electrostatic discharge) to protect from EMP effects, then go ahead and work with solid-state devices with some assurance of surviveability. But, you MUST know the EMP characteristics and do a thorough design task analysis on every part. Anyone using battery-filament tubes should do the same thing although I haven't any idea if anyone has done that. |
In article ,
Roy Lewallen wrote: Some time ago, Barrie Gilbert, for whom the "Gilbert cell" is named, gave a talk at a local ham club. He began by showing a copy of the patent for the "Gilbert cell", and emphatically pointed out that his name isn't on it. As he explained, he didn't invent the circuit nor did he have anything to do with its invention. At the time it was patented, he was an application engineer, and he wrote a lengthy article in one of the trade magazines about the circuit and its applications (and giving proper credit to the inventor). Shortly after that, through no action of his own, someone dubbed it the "Gilbert cell". The name stuck, and Barrie has spent the time since trying to straighten out the record -- without success. As far as I know, he gives the explanation every time he presents a talk. #chuckle# Harry Stubbs (who wrote quite a few SF novels using his middle name - Hal Clement) has had a similar problem. In his 1950s (I think) novel "Needle", he mistakenly thought that an organism which was taking part in a symbiotic relationship was a "symbiote", and he spelled it that way - the correct Greek word is "symbiont". The incorrect word was picked up by the SF community, spread, and has gained common use. He formally retracted the incorrect word when he published the sequel "Through the Eye of a Needle", but his comments make it clear he doesn't think there's a chance in hell that his neologism will be replaced in popular use by the correct term. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
In article ,
Roy Lewallen wrote: Some time ago, Barrie Gilbert, for whom the "Gilbert cell" is named, gave a talk at a local ham club. He began by showing a copy of the patent for the "Gilbert cell", and emphatically pointed out that his name isn't on it. As he explained, he didn't invent the circuit nor did he have anything to do with its invention. At the time it was patented, he was an application engineer, and he wrote a lengthy article in one of the trade magazines about the circuit and its applications (and giving proper credit to the inventor). Shortly after that, through no action of his own, someone dubbed it the "Gilbert cell". The name stuck, and Barrie has spent the time since trying to straighten out the record -- without success. As far as I know, he gives the explanation every time he presents a talk. #chuckle# Harry Stubbs (who wrote quite a few SF novels using his middle name - Hal Clement) has had a similar problem. In his 1950s (I think) novel "Needle", he mistakenly thought that an organism which was taking part in a symbiotic relationship was a "symbiote", and he spelled it that way - the correct Greek word is "symbiont". The incorrect word was picked up by the SF community, spread, and has gained common use. He formally retracted the incorrect word when he published the sequel "Through the Eye of a Needle", but his comments make it clear he doesn't think there's a chance in hell that his neologism will be replaced in popular use by the correct term. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
Hi,
I hope you'll pardon me for putting my reply to your post as of 6/8/2004 10:37 PM here, because my cable newsgroup connection is not letting me send messages out, its going to look a little out of order. Okay, then use the 1R5 pentagrid and be done with it. That worked fine for Motorola and Hallicrafters in the old days. That's a definite possibility. I won't mind using a pentagrid converter if there is really nothing better for glass. My question is simply to ask whether "21rst century" topologies for silicon such as DBM, Gilbert cell, or commutating mixer might help make hotter equipment than the original designers of the tubes intended. However, if all topologies including pentagrid basically deliver the same performance, than you are right: I should stick with simple and be done with it. Lacking that humongous EMP simulator, I don't know how you are going to check the EMP-withstanding qualities you want. Let's assume that someone living in a city, suburb, or large town is going to be quite dead if they live in the same range as something that could kill a tube (unless of course it was a "coldbringer" EMP warhead). Let's posit that vacuum tubes are still more surviveable than semiconductors, all else being equal. 1. You've never outlined the necessity of the double-balance in a mixer. The non-balanced type has worked fine in the original WW2 "handie-talkie" and on into the BC-1000 VHF manpack transceiver and lots of battery-operated consumer radios. Unbalanced mixers were used in the Korean War era PRC-8 series using subminiature battery tubes. For both the Tx and Rx sections. Also the PRC-6 handy-talky, also VHF. 2. A balanced mixer of any kind is not necessarily a relief from spurious responses. The choice of frequencies to mix will do that...for any mixer type. Note: The intermodulation products are a different situation and depend on the characteristics of the mixer. okay... 4. Designing a circuit using battery powered, directly-heated filaments as a differential pair is going to be difficult...unless you have a separate "A" battery supply for that differential pair. Since the cathodes ARE the filaments, not separate as in indirectly-heated tubes, those cathode-filaments are going to be elevated or, if run near common, will require a "B-" supply for the long-tailed pair's large "cathode" resistor. But a 1.5 volt "AA" alkaline battery is cheap enough if I need a seperate filament. 5. Battery packs are almost in the unobtanium category except for the single, lower voltage variety. You could use DC-DC converters but those are now all solid-state and that doesn't meet the "EMP requirement." Electro-mechanical vibrators could generate the higher B+ (or B-) but those are terribly inefficient, short-lived, and get bulky with transformers that must be at low AC frequencies. Primary batteries such as the carbon-zinc variety don't last long, maybe several years if kept very cold to slow down the internal chemistry...all those being made 30 to 40 years ago are now NG. B+ will likely be 4-6 9V alkaline batteries in series... cheap in bulk at Target. 6. You CAN use techniques for suppressing ESD (electrostatic discharge) to protect from EMP effects, then go ahead and work with solid-state devices with some assurance of surviveability. But, you MUST know the EMP characteristics and do a thorough design task analysis on every part. Anyone using battery-filament tubes should do the same thing although I haven't any idea if anyone has done that. Anything to which I can apply common sense or overkill to? I can't possibly hope for this to be Cold War equipment, I'm only just looking for some kind of edge. The Eternal Squire |
Hi,
I hope you'll pardon me for putting my reply to your post as of 6/8/2004 10:37 PM here, because my cable newsgroup connection is not letting me send messages out, its going to look a little out of order. Okay, then use the 1R5 pentagrid and be done with it. That worked fine for Motorola and Hallicrafters in the old days. That's a definite possibility. I won't mind using a pentagrid converter if there is really nothing better for glass. My question is simply to ask whether "21rst century" topologies for silicon such as DBM, Gilbert cell, or commutating mixer might help make hotter equipment than the original designers of the tubes intended. However, if all topologies including pentagrid basically deliver the same performance, than you are right: I should stick with simple and be done with it. Lacking that humongous EMP simulator, I don't know how you are going to check the EMP-withstanding qualities you want. Let's assume that someone living in a city, suburb, or large town is going to be quite dead if they live in the same range as something that could kill a tube (unless of course it was a "coldbringer" EMP warhead). Let's posit that vacuum tubes are still more surviveable than semiconductors, all else being equal. 1. You've never outlined the necessity of the double-balance in a mixer. The non-balanced type has worked fine in the original WW2 "handie-talkie" and on into the BC-1000 VHF manpack transceiver and lots of battery-operated consumer radios. Unbalanced mixers were used in the Korean War era PRC-8 series using subminiature battery tubes. For both the Tx and Rx sections. Also the PRC-6 handy-talky, also VHF. 2. A balanced mixer of any kind is not necessarily a relief from spurious responses. The choice of frequencies to mix will do that...for any mixer type. Note: The intermodulation products are a different situation and depend on the characteristics of the mixer. okay... 4. Designing a circuit using battery powered, directly-heated filaments as a differential pair is going to be difficult...unless you have a separate "A" battery supply for that differential pair. Since the cathodes ARE the filaments, not separate as in indirectly-heated tubes, those cathode-filaments are going to be elevated or, if run near common, will require a "B-" supply for the long-tailed pair's large "cathode" resistor. But a 1.5 volt "AA" alkaline battery is cheap enough if I need a seperate filament. 5. Battery packs are almost in the unobtanium category except for the single, lower voltage variety. You could use DC-DC converters but those are now all solid-state and that doesn't meet the "EMP requirement." Electro-mechanical vibrators could generate the higher B+ (or B-) but those are terribly inefficient, short-lived, and get bulky with transformers that must be at low AC frequencies. Primary batteries such as the carbon-zinc variety don't last long, maybe several years if kept very cold to slow down the internal chemistry...all those being made 30 to 40 years ago are now NG. B+ will likely be 4-6 9V alkaline batteries in series... cheap in bulk at Target. 6. You CAN use techniques for suppressing ESD (electrostatic discharge) to protect from EMP effects, then go ahead and work with solid-state devices with some assurance of surviveability. But, you MUST know the EMP characteristics and do a thorough design task analysis on every part. Anyone using battery-filament tubes should do the same thing although I haven't any idea if anyone has done that. Anything to which I can apply common sense or overkill to? I can't possibly hope for this to be Cold War equipment, I'm only just looking for some kind of edge. The Eternal Squire |
Avery Fineman wrote:
In article , (The Eternal Squire) writes: -- snip -- 4. Designing a circuit using battery powered, directly-heated filaments as a differential pair is going to be difficult...unless you have a separate "A" battery supply for that differential pair. Since the cathodes ARE the filaments, not separate as in indirectly-heated tubes, those cathode-filaments are going to be elevated or, if run near common, will require a "B-" supply for the long-tailed pair's large "cathode" resistor. -- snip -- I agree with everything else, but at RF you can just make a bifilar-wound filament choke -- you'll be at DC ground but you can inject whatever signal you want. Since everything is so high impedance and you want low power you can make it the final inductor in a matching network, for that matter. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com |
Avery Fineman wrote:
In article , (The Eternal Squire) writes: -- snip -- 4. Designing a circuit using battery powered, directly-heated filaments as a differential pair is going to be difficult...unless you have a separate "A" battery supply for that differential pair. Since the cathodes ARE the filaments, not separate as in indirectly-heated tubes, those cathode-filaments are going to be elevated or, if run near common, will require a "B-" supply for the long-tailed pair's large "cathode" resistor. -- snip -- I agree with everything else, but at RF you can just make a bifilar-wound filament choke -- you'll be at DC ground but you can inject whatever signal you want. Since everything is so high impedance and you want low power you can make it the final inductor in a matching network, for that matter. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com |
In article ,
(The Eternal Squire) writes: I hope you'll pardon me for putting my reply to your post as of 6/8/2004 10:37 PM here, because my cable newsgroup connection is not letting me send messages out, its going to look a little out of order. No problem here... Okay, then use the 1R5 pentagrid and be done with it. That worked fine for Motorola and Hallicrafters in the old days. That's a definite possibility. I won't mind using a pentagrid converter if there is really nothing better for glass. Those and pentodes (such as 1T4) work fine as mixers on up to 10m in consumer radio receivers such as the Zenith Transoceanic series...but they are starting to get rare, as are 7-pin miniature tube sockets using ceramic or mica- filled plastic dielectric! My question is simply to ask whether "21rst century" topologies for silicon such as DBM, Gilbert cell, or commutating mixer might help make hotter equipment than the original designers of the tubes intended. One has to consider the type of active device as to configurations. A "Gilbert cell" or double-balanced mixer-multiplier arrangement is only practical in a single-chip semiconductor package. One can also make a good operational amplifier out of two dual triodes as George A. Philbrick Inc. once did under the "GAP-R" model series. [Bob Pease likes to mention those in Electronic Design since he once worked there] The sizes of the two, even if the GAP-R was efficiently packaged, just doesn't compare to a typical 741 op- amp can. As to "hotter," let's put it this way: ANY radio can be made with enough amplification to have the front-end noise come roaring out the speaker like Yosemite Falls at the collecting basin. The type of device or the device configuration doesn't matter...but the bandwidth and the first device's inherent noise generation does matter. There is some information on indirectly-heated tubes' inherent noise generation in some older textbooks but I didn't look at a sampling to see if directly-heated filament types are included. I once had a nice Hallicrafters "all-band" receiver using battery tubes, bought in a PX about early 1955. After military days that became a trial device for modifications and other ideas. With some changes in the Ls and Cs in the front end, it could do a 2 uV sensitivity at 6 KHz BW with a 10 db Sig:Sig+Noise ratio. Not terrific, of course, compared to modern solid-state receivers, but adequate for SWL with its built-in telescoping whip antenna. 1T4 RF amp, 1R5 mixer, single conversion originally. However, if all topologies including pentagrid basically deliver the same performance, than you are right: I should stick with simple and be done with it. Actually, the Dan Tayloe design for a DC receiver front-end has got to be the simplest. It can handle keyed CW and SSB right off and the CMOS switch used as the "mixer" should be able to handle large overloads of RF or broadband pulses, etc. What you now have to contend with is low-noise audio amplification following the mixer and (if used) the polyphase filter in between. Lacking that humongous EMP simulator, I don't know how you are going to check the EMP-withstanding qualities you want. Let's assume that someone living in a city, suburb, or large town is going to be quite dead if they live in the same range as something that could kill a tube (unless of course it was a "coldbringer" EMP warhead). Let's posit that vacuum tubes are still more surviveable than semiconductors, all else being equal. Posit what you will. If the community is killed off, there won't be anyone to operate anything that survives the initial blast. Moot. 1. You've never outlined the necessity of the double-balance in a mixer. The non-balanced type has worked fine in the original WW2 "handie-talkie" and on into the BC-1000 VHF manpack transceiver and lots of battery-operated consumer radios. Unbalanced mixers were used in the Korean War era PRC-8 series using subminiature battery tubes. For both the Tx and Rx sections. Also the PRC-6 handy-talky, also VHF. 2. A balanced mixer of any kind is not necessarily a relief from spurious responses. The choice of frequencies to mix will do that...for any mixer type. Note: The intermodulation products are a different situation and depend on the characteristics of the mixer. okay... There does exist information, rather detailed TMs on that old stuff, from rare sites like August Johnson's fine collection of PDFs of boat anchors (free download and he says he will come out with CDs to order - small charge - for surface mail later). For slightly newer stuff, like the PRC-25 and -77 VHF portable transceivers and the current HF transceiver, PRC-104, the www.logsa.mil site has some for distribution (a devil of a time trying to find their CD listings but some files are downloadable by anyone). Those newer radios are solid-state in the receiver front-ends. 4. Designing a circuit using battery powered, directly-heated filaments as a differential pair is going to be difficult...unless you have a separate "A" battery supply for that differential pair. Since the cathodes ARE the filaments, not separate as in indirectly-heated tubes, those cathode-filaments are going to be elevated or, if run near common, will require a "B-" supply for the long-tailed pair's large "cathode" resistor. But a 1.5 volt "AA" alkaline battery is cheap enough if I need a seperate filament. That brings up DC power control. Two many different batteries means multi-pole power switches plus adequate bypassing of elevated A+ supply lines. 5. Battery packs are almost in the unobtanium category except for the single, lower voltage variety. You could use DC-DC converters but those are now all solid-state and that doesn't meet the "EMP requirement." Electro-mechanical vibrators could generate the higher B+ (or B-) but those are terribly inefficient, short-lived, and get bulky with transformers that must be at low AC frequencies. Primary batteries such as the carbon-zinc variety don't last long, maybe several years if kept very cold to slow down the internal chemistry...all those being made 30 to 40 years ago are now NG. B+ will likely be 4-6 9V alkaline batteries in series... cheap in bulk at Target. Okay, but add up the prices on those 9 Volters...allowing for the income adjustment and COLA for monies, that sort of series arrangement is today roughly twice the cost of the (adjusted) price back in 1960. Primary batteries have taken a large price raising (because they can) since portable consumer devices began appearing three decades ago. 6. You CAN use techniques for suppressing ESD (electrostatic discharge) to protect from EMP effects, then go ahead and work with solid-state devices with some assurance of surviveability. But, you MUST know the EMP characteristics and do a thorough design task analysis on every part. Anyone using battery-filament tubes should do the same thing although I haven't any idea if anyone has done that. Anything to which I can apply common sense or overkill to? I can't possibly hope for this to be Cold War equipment, I'm only just looking for some kind of edge. Okay, then drop the "EMP withstanding" personal specification. Common sense says: Individual stage shielding and bypassing anything that isn't an RF/AC signal; have the power switch also short the antenna input; put in back-to-back switching diodes on all RF/AC stage-stage lines that aren't handling more than a 0.5 volt if you must have some kind of EMP withstanding capability. "EMP" is ElectroMagnetic and is a very broadband impulse. It isn't juju or magic, just very high level Ultra Wideband stuff. It doesn't reach in to find out if a circuit has tubes or transistors, selectively blowing out only the solid-state things. Approach the total design with this super UWB environment, looking at EVERYTHING that might pick up the super UWB of an EMP. If you want real survivability, then get a sturdy metal box with an excellent conductive seal all around and store the radio in there. Add a sign telling others what is there since local humans can be fried by an EMP through their own internal wiring. Or, just have fun making whatever you want to make, hoping the powers-in-charge never decide to use an EMP beastie. |
In article ,
(The Eternal Squire) writes: I hope you'll pardon me for putting my reply to your post as of 6/8/2004 10:37 PM here, because my cable newsgroup connection is not letting me send messages out, its going to look a little out of order. No problem here... Okay, then use the 1R5 pentagrid and be done with it. That worked fine for Motorola and Hallicrafters in the old days. That's a definite possibility. I won't mind using a pentagrid converter if there is really nothing better for glass. Those and pentodes (such as 1T4) work fine as mixers on up to 10m in consumer radio receivers such as the Zenith Transoceanic series...but they are starting to get rare, as are 7-pin miniature tube sockets using ceramic or mica- filled plastic dielectric! My question is simply to ask whether "21rst century" topologies for silicon such as DBM, Gilbert cell, or commutating mixer might help make hotter equipment than the original designers of the tubes intended. One has to consider the type of active device as to configurations. A "Gilbert cell" or double-balanced mixer-multiplier arrangement is only practical in a single-chip semiconductor package. One can also make a good operational amplifier out of two dual triodes as George A. Philbrick Inc. once did under the "GAP-R" model series. [Bob Pease likes to mention those in Electronic Design since he once worked there] The sizes of the two, even if the GAP-R was efficiently packaged, just doesn't compare to a typical 741 op- amp can. As to "hotter," let's put it this way: ANY radio can be made with enough amplification to have the front-end noise come roaring out the speaker like Yosemite Falls at the collecting basin. The type of device or the device configuration doesn't matter...but the bandwidth and the first device's inherent noise generation does matter. There is some information on indirectly-heated tubes' inherent noise generation in some older textbooks but I didn't look at a sampling to see if directly-heated filament types are included. I once had a nice Hallicrafters "all-band" receiver using battery tubes, bought in a PX about early 1955. After military days that became a trial device for modifications and other ideas. With some changes in the Ls and Cs in the front end, it could do a 2 uV sensitivity at 6 KHz BW with a 10 db Sig:Sig+Noise ratio. Not terrific, of course, compared to modern solid-state receivers, but adequate for SWL with its built-in telescoping whip antenna. 1T4 RF amp, 1R5 mixer, single conversion originally. However, if all topologies including pentagrid basically deliver the same performance, than you are right: I should stick with simple and be done with it. Actually, the Dan Tayloe design for a DC receiver front-end has got to be the simplest. It can handle keyed CW and SSB right off and the CMOS switch used as the "mixer" should be able to handle large overloads of RF or broadband pulses, etc. What you now have to contend with is low-noise audio amplification following the mixer and (if used) the polyphase filter in between. Lacking that humongous EMP simulator, I don't know how you are going to check the EMP-withstanding qualities you want. Let's assume that someone living in a city, suburb, or large town is going to be quite dead if they live in the same range as something that could kill a tube (unless of course it was a "coldbringer" EMP warhead). Let's posit that vacuum tubes are still more surviveable than semiconductors, all else being equal. Posit what you will. If the community is killed off, there won't be anyone to operate anything that survives the initial blast. Moot. 1. You've never outlined the necessity of the double-balance in a mixer. The non-balanced type has worked fine in the original WW2 "handie-talkie" and on into the BC-1000 VHF manpack transceiver and lots of battery-operated consumer radios. Unbalanced mixers were used in the Korean War era PRC-8 series using subminiature battery tubes. For both the Tx and Rx sections. Also the PRC-6 handy-talky, also VHF. 2. A balanced mixer of any kind is not necessarily a relief from spurious responses. The choice of frequencies to mix will do that...for any mixer type. Note: The intermodulation products are a different situation and depend on the characteristics of the mixer. okay... There does exist information, rather detailed TMs on that old stuff, from rare sites like August Johnson's fine collection of PDFs of boat anchors (free download and he says he will come out with CDs to order - small charge - for surface mail later). For slightly newer stuff, like the PRC-25 and -77 VHF portable transceivers and the current HF transceiver, PRC-104, the www.logsa.mil site has some for distribution (a devil of a time trying to find their CD listings but some files are downloadable by anyone). Those newer radios are solid-state in the receiver front-ends. 4. Designing a circuit using battery powered, directly-heated filaments as a differential pair is going to be difficult...unless you have a separate "A" battery supply for that differential pair. Since the cathodes ARE the filaments, not separate as in indirectly-heated tubes, those cathode-filaments are going to be elevated or, if run near common, will require a "B-" supply for the long-tailed pair's large "cathode" resistor. But a 1.5 volt "AA" alkaline battery is cheap enough if I need a seperate filament. That brings up DC power control. Two many different batteries means multi-pole power switches plus adequate bypassing of elevated A+ supply lines. 5. Battery packs are almost in the unobtanium category except for the single, lower voltage variety. You could use DC-DC converters but those are now all solid-state and that doesn't meet the "EMP requirement." Electro-mechanical vibrators could generate the higher B+ (or B-) but those are terribly inefficient, short-lived, and get bulky with transformers that must be at low AC frequencies. Primary batteries such as the carbon-zinc variety don't last long, maybe several years if kept very cold to slow down the internal chemistry...all those being made 30 to 40 years ago are now NG. B+ will likely be 4-6 9V alkaline batteries in series... cheap in bulk at Target. Okay, but add up the prices on those 9 Volters...allowing for the income adjustment and COLA for monies, that sort of series arrangement is today roughly twice the cost of the (adjusted) price back in 1960. Primary batteries have taken a large price raising (because they can) since portable consumer devices began appearing three decades ago. 6. You CAN use techniques for suppressing ESD (electrostatic discharge) to protect from EMP effects, then go ahead and work with solid-state devices with some assurance of surviveability. But, you MUST know the EMP characteristics and do a thorough design task analysis on every part. Anyone using battery-filament tubes should do the same thing although I haven't any idea if anyone has done that. Anything to which I can apply common sense or overkill to? I can't possibly hope for this to be Cold War equipment, I'm only just looking for some kind of edge. Okay, then drop the "EMP withstanding" personal specification. Common sense says: Individual stage shielding and bypassing anything that isn't an RF/AC signal; have the power switch also short the antenna input; put in back-to-back switching diodes on all RF/AC stage-stage lines that aren't handling more than a 0.5 volt if you must have some kind of EMP withstanding capability. "EMP" is ElectroMagnetic and is a very broadband impulse. It isn't juju or magic, just very high level Ultra Wideband stuff. It doesn't reach in to find out if a circuit has tubes or transistors, selectively blowing out only the solid-state things. Approach the total design with this super UWB environment, looking at EVERYTHING that might pick up the super UWB of an EMP. If you want real survivability, then get a sturdy metal box with an excellent conductive seal all around and store the radio in there. Add a sign telling others what is there since local humans can be fried by an EMP through their own internal wiring. Or, just have fun making whatever you want to make, hoping the powers-in-charge never decide to use an EMP beastie. |
in case of a nuke attack (far more likely than an EMP), the valves'
shell will shatter. you are better off storing your regular transceiver inside a thick copper box with an 'rf tight' lid. instead of EMP-proofing the transceiver from inside, EMP-proof it from the outside. your best bet would be to use a 7MHz CW transceiver with 5 watts output. This will give you consistent communicability with reasonable power to get through. More power will drain your battries (or your legs, if u are pedalling a generator) faster. Avoid FETs and MOSFETs in your design, stick to bipolars. also avoid ICs, use discrete transistors, store a few spares in a bag inside the transceiver. have soldering iron handy too, u might have to repair quite a few things. you will also need an antenna tuner and a long wire. this is a pretty grim discussion. in 1999, my country(india) and pakistan were on the brink of war. my city was considered a high value target. i have lived these thoughts far too close to comfort. there are no nuclear shelters in india save a few for the president and the prime minister etc. thinking back about those days, i find it ironic that i thought that i would personally survive an nuclear attack and have enough sense left to get on with establishing a wireless station. - farhan |
in case of a nuke attack (far more likely than an EMP), the valves'
shell will shatter. you are better off storing your regular transceiver inside a thick copper box with an 'rf tight' lid. instead of EMP-proofing the transceiver from inside, EMP-proof it from the outside. your best bet would be to use a 7MHz CW transceiver with 5 watts output. This will give you consistent communicability with reasonable power to get through. More power will drain your battries (or your legs, if u are pedalling a generator) faster. Avoid FETs and MOSFETs in your design, stick to bipolars. also avoid ICs, use discrete transistors, store a few spares in a bag inside the transceiver. have soldering iron handy too, u might have to repair quite a few things. you will also need an antenna tuner and a long wire. this is a pretty grim discussion. in 1999, my country(india) and pakistan were on the brink of war. my city was considered a high value target. i have lived these thoughts far too close to comfort. there are no nuclear shelters in india save a few for the president and the prime minister etc. thinking back about those days, i find it ironic that i thought that i would personally survive an nuclear attack and have enough sense left to get on with establishing a wireless station. - farhan |
Those and pentodes (such as 1T4) work fine as mixers on
up to 10m in consumer radio receivers such as the Zenith Transoceanic series...but they are starting to get rare, as are 7-pin miniature tube sockets using ceramic or mica- filled plastic dielectric! Yes indeed, the 1L5 and 1T5 are getting extremely costly. I had been doing other surfing between our exchanges. I found a duo-triode battery tube, one of those could make a long-tailed pair mixer. I also found a duo-diode plus pentode, and a diode plus pentode. Two of the former tubes could make a 4-diode mixer plus signal/buffer amps on each side. Two of the latter tubes could make a 2-diode mixer pls plus signal/buffer amps on each side. Okay, then drop the "EMP withstanding" personal specification. Common sense says: Individual stage shielding and bypassing anything that isn't an RF/AC signal; have the power switch also short the antenna input; put in back-to-back switching diodes on all RF/AC stage-stage lines that aren't handling more than a 0.5 volt if you must have some kind of EMP withstanding capability. "EMP" is ElectroMagnetic and is a very broadband impulse. It isn't juju or magic, just very high level Ultra Wideband stuff. It doesn't reach in to find out if a circuit has tubes or transistors, selectively blowing out only the solid-state things. Approach the total design with this super UWB environment, looking at EVERYTHING that might pick up the super UWB of an EMP. If you want real survivability, then get a sturdy metal box with an excellent conductive seal all around and store the radio in there. Add a sign telling others what is there since local humans can be fried by an EMP through their own internal wiring. All very good suggestions, thank you. So if EMP is simply a noise spike from DC to daylight, is it that I should employ traps on all input and output leads to shunt everything outside the band of interest to ground? And the metal box makes sense. Or, just have fun making whatever you want to make, hoping the powers-in-charge never decide to use an EMP beastie. Um yeah, like I said, this design is for my daughter and her cousins for thier 10th-12th birthdays, with another for myself, so I have at least 7 more years to get this working. So how's this for a possible lineup for the receiver? Preselector: grounded grid amplifier with variable tanks on each side. VFO: triode oscillator with low voltage neon bulb as regulator and variable tank. All three tanks use a single section each of a 3 section variable capacitor. Converter: duo-triode differential amplifier as mixer. IF filter: Crystal lattice filter, 8 Mhz IF, 3-6 khz bandwidth Detector: single-tube regenerative detector fixed to 8 Mhz with +- 6 Khz tuning through a small variable capacitor added to the capacitor in the 8 Mhz fixed tank. Also has a manual regeneration control. Audio amp: standard OTL implemented with battery tubes. Output to 1 Watt speaker. In theory, the IF filter with the 3-6 Khz bandwidth provides me with a window open either to SSB or CW. The fixed detector would allow me to receive either SSB or CW depending on the setting of the regeneration control. The detector would be 'tweakable' +- 6 Khz to provide some degree of passband tuning against the IF window. Now the transmitter: I have a novel idea for the CW transmitter to reduce the size of the final amplifier tube and the heat dissipation. Implement the final as a high frequency pentode or beam tetrode wired in triode mode, running as class E. I could possibly take that type of battery tube meant for 200 mw IF amplification, and run it at 5 watts class E without much great harm to the tube. Anything I am missing with this lineup? The Eternal Squire |
Those and pentodes (such as 1T4) work fine as mixers on
up to 10m in consumer radio receivers such as the Zenith Transoceanic series...but they are starting to get rare, as are 7-pin miniature tube sockets using ceramic or mica- filled plastic dielectric! Yes indeed, the 1L5 and 1T5 are getting extremely costly. I had been doing other surfing between our exchanges. I found a duo-triode battery tube, one of those could make a long-tailed pair mixer. I also found a duo-diode plus pentode, and a diode plus pentode. Two of the former tubes could make a 4-diode mixer plus signal/buffer amps on each side. Two of the latter tubes could make a 2-diode mixer pls plus signal/buffer amps on each side. Okay, then drop the "EMP withstanding" personal specification. Common sense says: Individual stage shielding and bypassing anything that isn't an RF/AC signal; have the power switch also short the antenna input; put in back-to-back switching diodes on all RF/AC stage-stage lines that aren't handling more than a 0.5 volt if you must have some kind of EMP withstanding capability. "EMP" is ElectroMagnetic and is a very broadband impulse. It isn't juju or magic, just very high level Ultra Wideband stuff. It doesn't reach in to find out if a circuit has tubes or transistors, selectively blowing out only the solid-state things. Approach the total design with this super UWB environment, looking at EVERYTHING that might pick up the super UWB of an EMP. If you want real survivability, then get a sturdy metal box with an excellent conductive seal all around and store the radio in there. Add a sign telling others what is there since local humans can be fried by an EMP through their own internal wiring. All very good suggestions, thank you. So if EMP is simply a noise spike from DC to daylight, is it that I should employ traps on all input and output leads to shunt everything outside the band of interest to ground? And the metal box makes sense. Or, just have fun making whatever you want to make, hoping the powers-in-charge never decide to use an EMP beastie. Um yeah, like I said, this design is for my daughter and her cousins for thier 10th-12th birthdays, with another for myself, so I have at least 7 more years to get this working. So how's this for a possible lineup for the receiver? Preselector: grounded grid amplifier with variable tanks on each side. VFO: triode oscillator with low voltage neon bulb as regulator and variable tank. All three tanks use a single section each of a 3 section variable capacitor. Converter: duo-triode differential amplifier as mixer. IF filter: Crystal lattice filter, 8 Mhz IF, 3-6 khz bandwidth Detector: single-tube regenerative detector fixed to 8 Mhz with +- 6 Khz tuning through a small variable capacitor added to the capacitor in the 8 Mhz fixed tank. Also has a manual regeneration control. Audio amp: standard OTL implemented with battery tubes. Output to 1 Watt speaker. In theory, the IF filter with the 3-6 Khz bandwidth provides me with a window open either to SSB or CW. The fixed detector would allow me to receive either SSB or CW depending on the setting of the regeneration control. The detector would be 'tweakable' +- 6 Khz to provide some degree of passband tuning against the IF window. Now the transmitter: I have a novel idea for the CW transmitter to reduce the size of the final amplifier tube and the heat dissipation. Implement the final as a high frequency pentode or beam tetrode wired in triode mode, running as class E. I could possibly take that type of battery tube meant for 200 mw IF amplification, and run it at 5 watts class E without much great harm to the tube. Anything I am missing with this lineup? The Eternal Squire |
Farhan,
I saw your post re nukes on my personal account new server but can't post out, and I don't see your post on Google yet. I hope you don't mind my answering your second message here. I understand what you mean about the India/Pakistan conflict. I really don't know what to say. Yes, it is a grim business. But I'm thinking about the kind of world my daughter will inherit, and I want her to be equipped for it. I think that an attack meant to wipe out a country will simply not happen, thank gawd, because the balance of terror still exists today and that balance works just fine. Thats why India and Pakistan came to thier senses, and that's why the US and USSR shadow-boxed each other without doing anything serious. The only likely scenarios I see are two-fold: 1) Terrorist sneaks in by motor boat or rogue sub to the seashore, walks into a major city with a 50 kilotonne warhead in a backpack and ignites it kamikaze style. The city is wiped, the suburbs are fried, and the farm and ranch country gets hit with the EMP. It's the people in the farm and ranch country that would be in the best shape to use my design and coordinate with FEMA about how to handle the survivors and the damage. 2) In response to our conventional defense of Taiwan when China inevitably loses patience and invades, China fires a single large coldbringer warhead in the ionosphere above the center of the continental US. The purpose of a coldbringer is not to ruin a city, although it still might very well do so. It is to generate a large EMP across the country to ruin a country's ability to communicate or compute, thereby ruining thier economy and ability to mobilize anything larger than a single army or marine division for some period of years. It is most likely the unwritten policy within members of UN Security Council that a massive retalitation will never be made in response to the detonation of a single warhead. China would likely say: "oops, so sorry, it was an accident, some general had an itchy trigger finger. We'll execute him and make reparations.". Plausible deniability. In the meantime, our country is powerless to defend Taiwan because while our teeth might be there, our supply lines still originate in the US. China then conquers Taiwan with ease. In a scenario like this, the entire country will be physically unharmed but will be in chaos, needing operators with equipment not damaged by EMP. I'd like my daughter to be able to help out if she can. That's all I have to say for tonight. The Eternal Squire |
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