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Looking for 12V tube Rx design
Looking for a nice superhet Rx design for 75M/40M, using 12V fil. & plate tubes. Not needing anything fancy, schematic and any addional info appreciated, if anyone can point me to this. Thanks. Ed K7AAT |
Ed wrote:
Looking for a nice superhet Rx design for 75M/40M, using 12V fil. & plate tubes. Not needing anything fancy, schematic and any addional info appreciated, if anyone can point me to this. Thanks. Ed K7AAT Try some of the links found he http://www.duntemann.com/12vtubes/12vtubesindex.htm -Bill |
Looking for a nice superhet Rx design for 75M/40M, using 12V fil. & plate tubes. Not needing anything fancy, schematic and any addional info appreciated, if anyone can point me to this. Thanks. Ed K7AAT Try some of the links found he http://www.duntemann.com/12vtubes/12vtubesindex.htm -Bill Thanks, Bill. I can't find any good info on an HF superhet circuit, but there's lots of good info on that site, anyway. Appreciate it. Ed |
The site does have reference to a superhet.
Colin K7FM |
"COLIN LAMB" wrote in news:Eqque.8243$jX6.7991
@newsread2.news.pas.earthlink.net: The site does have reference to a superhet. Colin K7FM Yes, I saw the Japanese site.... had an FM/AM broadcast radio circuit. I suppose I could work with their circuits, but I was looking for a design that was already closer to my needs (CW detection). Another reference to "superhet" circuit was a dead link, for me. It looks like my best chance to find what I'm looking for is to try to find those back issues of QST which were referenced. Ed |
Ed wrote:
Looking for a nice superhet Rx design for 75M/40M, using 12V fil. & plate tubes. Not needing anything fancy, schematic and any addional info appreciated, if anyone can point me to this. Thanks. My suggestion is that you get out the Sam's Photofacts book on car radios and look at some of the vibrator-free tube car radio designs. It should not be too hard to change the loopstick and/or tuning cap for 75M and 40M. The problem you'll have is that the IF is wide as hell, but that's part of the fun. Be sure to add a BFO! --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
Scott Dorsey wrote:
Ed wrote: Looking for a nice superhet Rx design for 75M/40M, using 12V fil. & plate tubes. Not needing anything fancy, schematic and any addional info appreciated, if anyone can point me to this. Thanks. My suggestion is that you get out the Sam's Photofacts book on car radios and look at some of the vibrator-free tube car radio designs. It should not be too hard to change the loopstick and/or tuning cap for 75M and 40M. The problem you'll have is that the IF is wide as hell, but that's part of the fun. Be sure to add a BFO! --scott 12V plate tubes are rather rare, perform poorly compared to most anything else. They are very low power, low gain, and low frequency. Typical amplification factor is 10 or less. With the exception of the R392, which used 28V tubes, and some automobile radios from the late '50s to early '60s, I don't recall that they were used for much of anything... which is why they are rare. There were a whole pile of different types made, pentagrid converters, sharp and remote cutoff pentodes, triodes with diodes, pentodes with diodes, twin triodes, .... the most amusing thing was the "power" tubes that had maximum output ratings of 20mw! The typical automobile radio used the following tube lineup: RF: 12AF6 - Sharp cutoff pentode Mixer: 12AD6 - Pentagrid converter IF: 12AF6 - Sharp cutoff pentode Det/AGC/1st audio: 12AE6 or 12AJ6 - medium mu triode/ twin diode Audio amp: DS-501 Delco Germanium PNP transistor. In a car radio, the RF/Mix/LO was tuned by a very fancy rig that moved the slugs in the coils. The IF was 256KHz, with a 4KHz bandwidth...Real Hi-Fi! Somewhere in my archives I have a Sams Photofact for the 12V tube radio that is in my '60 'vette. By 1960, all transistor car radios were already on the scene in Corvettes and Cadillacs. In the R392, the 28V tubes in the RF section are generally bad, and kill the sensitivity of the radio above 14MHz. Is there a particular reason that you want to use this style of tube? Today it is trivial to make a simple switching power supply that can provide a couple of hundred volts at 98% efficiency, why not make one of them, and use some real tubes? -Chuck |
Chuck Harris wrote:
Today it is trivial to make a simple switching power supply that can provide a couple of hundred volts at 98% efficiency, why not make one of them, and use some real tubes? The problem I've encountered with switching supplies is that they're so blasted noisy because of the fast risetimes in the high-current parts of the supplies and because they're usually not very well shielded and/ or decoupled. -- Ah, yes, _The Dying Earth_: a wonderful title, greatly spoiled by the book. -- Nix, in a newsgroup inhabited by a better class of people |
"Mike Andrews" ) writes: Chuck Harris wrote: Today it is trivial to make a simple switching power supply that can provide a couple of hundred volts at 98% efficiency, why not make one of them, and use some real tubes? The problem I've encountered with switching supplies is that they're so blasted noisy because of the fast risetimes in the high-current parts of the supplies and because they're usually not very well shielded and/ or decoupled. But given the topic, I'm always surprised that people don't treat switching supplies like those cars of old. Look in the old ARRL mobile manual (and a later edition just might have a receiver using those 12v tubes), and there was always material about filtering the alternator noise. Make it go through feedthrough capacitors, put in tuned circuits in series with the 12V (to null out the whine), and good shielding. These are the things that apply to switching supplies, though too often they are so treated as black boxes that nobody considers such things. As for 12v tubes, you most certainly saw converter using them. SOmeone was asking about 12v Nuvistors a while back, and the next to last edition of the ARRL VHF Manual, late sixties or so, has a converter using one. Michael |
Michael Black wrote:
As for 12v tubes, you most certainly saw converter using them. SOmeone was asking about 12v Nuvistors a while back, and the next to last edition of the ARRL VHF Manual, late sixties or so, has a converter using one. We are not talking about normal radio tubes that have 12V heaters, we are talking about special tubes that have 12V heaters, and a 30V maximum plate voltage rating. These special tubes were designed to use normal car battery voltages as their plate voltages. -Chuck |
Mike Andrews wrote:
Chuck Harris wrote: Today it is trivial to make a simple switching power supply that can provide a couple of hundred volts at 98% efficiency, why not make one of them, and use some real tubes? The problem I've encountered with switching supplies is that they're so blasted noisy because of the fast risetimes in the high-current parts of the supplies and because they're usually not very well shielded and/ or decoupled. If you make it yourself, you can apply proper shielding and decoupling techniques. It is done all the time in commercial radios. For a small receiver like is being discussed here, the supply can be made in a couple of cubic inches... Something that can be easily made in a soldered shut can with feedthru's on all of the leads. -Chuck |
On Thu, 23 Jun 2005 10:58:02 -0400, Chuck Harris
wrote: 12V plate tubes are rather rare, perform poorly compared to most anything else. They are very low power, low gain, and low frequency. Philips produced a number of low-voltage tubes,such as the DAH50, A221 and A441, in the '20s and '30s that people built successful radios with. A few people have experimented in recent years with using normal tubes at low voltages, try googling for "space-charge tubes". -- Cheers, Stan Barr stanb .at. dial .dot. pipex .dot. com (Remove any digits from the addresses when mailing me.) The future was never like this! |
SNIPPED Is there a particular reason that you want to use this style of tube? Today it is trivial to make a simple switching power supply that can provide a couple of hundred volts at 98% efficiency, why not make one of them, and use some real tubes? -Chuck OK, good info in your reply, Chuck. My reply to your question (above) will probably elicit a whole lot of comments. I hope they're not too negative! HI HI I am recently retired, and am about to have some extra time on my hands for some construction projects. With the re-surfacing of an old news item about terrorists or certain nations who may attempt to launch a nuclear EMP strike on this country, I was thinking about an old project I had once wished to start many years ago; That is an EMP proof ham rig for 75/40 .... probably CW only, for simplicity sake. So I'm thinking of building a fairly simple tube rig, preferably superhet Rx, with tubes that will run totally on a 12V supply. Assuming that we never have such a terrible thing happen to us, a rig like this would still be fun to use. Following the building of a Rx, I'll probably build a simple one tube TX to match. Ed |
Ed wrote:
I am recently retired, and am about to have some extra time on my hands for some construction projects. With the re-surfacing of an old news item about terrorists or certain nations who may attempt to launch a nuclear EMP strike on this country, I was thinking about an old project I had once wished to start many years ago; That is an EMP proof ham rig for 75/40 .... probably CW only, for simplicity sake. So I'm thinking of building a fairly simple tube rig, preferably superhet Rx, with tubes that will run totally on a 12V supply. Assuming that we never have such a terrible thing happen to us, a rig like this would still be fun to use. Following the building of a Rx, I'll probably build a simple one tube TX to match. The QST Mobile Manual has a great project transceiver. The transmitter is rockbound and based on a 1J6G tube, but it really gets out well. The receiver I never built, but it didn't look like a bad design. This thing WILL require a substantial B+... I think it needs a 67.V battery. But you can put a few 9V radio batteries in series if you really want. Or you can build a vibrator supply. I think the Mobile Manual has an article on vibrator designs as well. The space-charge tubes are lousy... they worked well enough for cheap car radios, but they never worked all that well. You can do a lot better with a conventional tube design. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
Ed wrote:
SNIPPED Is there a particular reason that you want to use this style of tube? Today it is trivial to make a simple switching power supply that can provide a couple of hundred volts at 98% efficiency, why not make one of them, and use some real tubes? -Chuck OK, good info in your reply, Chuck. My reply to your question (above) will probably elicit a whole lot of comments. I hope they're not too negative! HI HI I am recently retired, and am about to have some extra time on my hands for some construction projects. With the re-surfacing of an old news item about terrorists or certain nations who may attempt to launch a nuclear EMP strike on this country, I was thinking about an old project I had once wished to start many years ago; That is an EMP proof ham rig for 75/40 .... probably CW only, for simplicity sake. So I'm thinking of building a fairly simple tube rig, preferably superhet Rx, with tubes that will run totally on a 12V supply. Assuming that we never have such a terrible thing happen to us, a rig like this would still be fun to use. Following the building of a Rx, I'll probably build a simple one tube TX to match. Hi Ed, I would put the probability of experiencing EMP in our life times at somewhere around zero, but that isn't a good reason not to proceed down the path you are intending to travel. The IC manufacturers suffered a wakeup call back in the 70s when things were pretty hot with the cold war. It became a commonly held belief that virtually all of the electronic devices in the country would fail when faced with a nuclear attack. So, a hustle was begun to harden all of the IC's against EMP. It turned out to be pretty easy to do. All they did was redesign the pads, which are specialized circuits that connect to the outside world, so that they could safely absorb the EMP. It had a beneficial effect on static electricity survival too! So, if you do a good job of keeping the EMP from coupling in through large antennas, power connections, etc. The IC's pads should be able to do the rest. Power FET's are similarily protected, so they should be a good bet in an environment where EMP is a possibility. If you are planning to make a transmitter too, you are going to find that the 12V tubes aren't much help. There are a couple that are called "Power amplifier" tubes. Despite their encouraging name, they were not designed to provide more than about 20 milliwatts. Their purpose was to go between the detector/preamplifier tube, and the DS501 power transistor that was used to drive the speaker. As to designing with the 12V tubes, that shouldn't be a big problem, they behave very similarily to normal tubes. The big issues are high plate resistances, low gains, and low power levels. There is a group of antique military radio collectors that want to play with their radios, but don't want to recap, or permanently modificy the radios in any way. They have done extensive experimentation with running military receivers with plate voltages down around 28V. Their reasoning is that even the worst electrolytic will still perform OK at 1/10th of its normal operating voltage. The radios play...weakly.. but they play. -Chuck |
On 23 Jun 2005 18:07:27 GMT, Stan Barr wrote:
On Thu, 23 Jun 2005 10:58:02 -0400, Chuck Harris wrote: 12V plate tubes are rather rare, perform poorly compared to most anything else. They are very low power, low gain, and low frequency. Philips produced a number of low-voltage tubes,such as the DAH50, A221 and A441, in the '20s and '30s that people built successful radios with. A few people have experimented in recent years with using normal tubes at low voltages, try googling for "space-charge tubes". See: http://www.duntemann.com/12vtubes/12vtubesindex.htm -- Cheers, Stan Barr stanb .at. dial .dot. pipex .dot. com (Remove any digits from the addresses when mailing me.) The future was never like this! |
The IC manufacturers suffered a wakeup call back in the 70s when things were pretty hot with the cold war. It became a commonly held belief that virtually all of the electronic devices in the country would fail when faced with a nuclear attack. So, a hustle was begun to harden all of the IC's against EMP. It turned out to be pretty easy to do. All they did was redesign the pads, which are specialized circuits that connect to the outside world, so that they could safely absorb the EMP. It had a beneficial effect on static electricity survival too! So, if you do a good job of keeping the EMP from coupling in through large antennas, power connections, etc. The IC's pads should be able to do the rest. Power FET's are similarily protected, so they should be a good bet in an environment where EMP is a possibility. During the 70s I did notice a lot of IC & FET failures in various communications devices that were attributed to static electricty. I was under the impression that the manufacturers had improved their designs for that reason? On the other hand, doesn't really matter, I suppose, since the end results help for both cases. I'll probably continue my research on this project and start it this Fall, if for no other reason than the fun of it. From what responses I'm hearing to my original question, I'd be better off using conventional tubes over the low voltage designs. I did want something that would function off a 12V battery, though. We'll see.... My thanks to all. Ed K7AAT |
Has this link been posted yet? http://www.duntemann.com/12vtubes/12vtubesindex.htm -- Steven D. Swift, , http://www.novatech-instr.com NOVATECH INSTRUMENTS, INC. P.O. Box 55997 206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA |
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Behold, Steven Swift scribed on tube chassis:
Has this link been posted yet? http://www.duntemann.com/12vtubes/12vtubesindex.htm Cool, thanks! I've been using 12V 300V SMPS. -- Gregg "t3h g33k" http://geek.scorpiorising.ca *Ratings are for transistors, tubes have guidelines* |
Back in the late 1950's, hybrid auto radios with 12 volt plate tubes for all
except the audio output stages were built by Automatic Radio for Ford and Chrysler. The first production was in 1958. A Motorola power transistor was used in the audio output stage. A search through Sams Fotofacts for 1958 and later should give you some schematics to start with. A trip to an auto junkyard might give you a radio. |
Kilcummin wrote:
Back in the late 1950's, hybrid auto radios with 12 volt plate tubes for all except the audio output stages were built by Automatic Radio for Ford and Chrysler. The first production was in 1958. A Motorola power transistor was used in the audio output stage. A search through Sams Fotofacts for 1958 and later should give you some schematics to start with. A trip to an auto junkyard might give you a radio. If you're going to go JunkYardin' for a radio - might as well get a goodun' - late 50's early 60's era Cad. The WonderBar mechanism is a treat (and works VERY well) - and all of the tubes (including the relay driver tube) are 12V tubes (audio out is a single transistor). best regards... -- randy guttery A Tender Tale - a page dedicated to those Ships and Crews so vital to the United States Silent Service: http://tendertale.com |
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