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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Grid Dip Meter
Looking for recommendations for a Grid Dip Meter built or a kit.
--- news://freenews.netfront.net/ - complaints: --- |
#2
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Grid Dip Meter
On Sun, 29 Nov 2015 15:35:20 -0800, OldGuy
wrote: Looking for recommendations for a Grid Dip Meter built or a kit. It's now called a GDO (grid dip oscillator). Here's a page of various manufacturers and models: http://www.n4xy.com/gdos.html I have three Heathkit HD-1250 GDO's. Not the best. You can get what might be a clone of a Heathkit HD-1250 from MFJ: http://www.mfjenterprises.com/Product.php?productid=MFJ-201 Also, check out the sold listings on eBay for approximate pricing: http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=grid%20dip%20meter& LH_Complete=1&LH_Sold=1&rt=nc&_trksid=p2045573.m16 84 Sorry, no recommendations as all my stuff is ancient. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#3
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Grid Dip Meter
On Sun, 29 Nov 2015 16:16:27 -0800, Jeff Liebermann wrote:
Sorry, no recommendations as all my stuff is ancient. So's a lot of my stuff. But there's nothing wrong with old gear IMO it's the quality of it and whether it's in calibration that counts. The only issues with GDOs IME are that they're not too bad for the lower frequency RF stuff, but hopeless for anything higher. |
#4
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Grid Dip Meter
On 30.11.15 0:35, OldGuy wrote:
Looking for recommendations for a Grid Dip Meter built or a kit. --- news://freenews.netfront.net/ - complaints: --- In google (images) about 10 solutions. |
#5
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Grid Dip Meter
On Sun, 29 Nov 2015 16:16:27 -0800, Jeff Liebermann
wrote: This looks very interesting: http://www.qrpproject.de/UK/dipit.htm No clue how to purchase one and it's only 1 to 42 MHz. May 2003 QST article on building a "modern" GDO: http://www.qsl.net/k8mcr/downloads/Modern_GDO.pdf Feb 2013 Circuit Cellar article on building a GDO: http://circuitcellar.com/wp-content/uploads/2013/01/CC25_ProjCard_Pres_Ball-CC271.pdf Goes to 1GHz by changing both the oscillator and the coil with frequency range. See "Plug in Oscillators" section: http://elm-chan.org/works/ddm/report_e.html July 2014 QST. Using an MFJ-259/269 as a GDO: http://www.ka6wke.net/finished-projects/grid-dip-meter-coils MFJ sells these as MFJ-66C: http://www.mfjenterprises.com/Product.php?productid=MFJ-66C Mo http://w5dor.com/W5DOR-GridDip.html -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#6
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Grid Dip Meter
On Mon, 30 Nov 2015, Cursitor Doom wrote:
On Sun, 29 Nov 2015 16:16:27 -0800, Jeff Liebermann wrote: Sorry, no recommendations as all my stuff is ancient. So's a lot of my stuff. But there's nothing wrong with old gear IMO it's the quality of it and whether it's in calibration that counts. The only issues with GDOs IME are that they're not too bad for the lower frequency RF stuff, but hopeless for anything higher. Huh? VHF and UHF is where they really worked well, because at lower frequencies, a lot of the coils were shielded. There were GDOs that worked well at VHF and UHF. Michael |
#7
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Grid Dip Meter
On Sun, 29 Nov 2015, OldGuy wrote:
Looking for recommendations for a Grid Dip Meter built or a kit. You can build simple or you can build complicated. With semiconductors, the cost of extra transistors and the space they take up doesn't amount to much, but you can end up with a better device, and one that can be used for more things. The biggest problem seems to be false dips, coming from an rf choke feeding the oscillator that resonates in the wrong place, or just the layout of the circuit. I suppose it's made worse if the oscillator doesn't oscillate very well as you move up in frequency. Calibration was always kind of vague, but nowadays with so many having frequency counters, one can build something that has a buffer to feed a frequency counter, so you can either have vague calibration on the dial, or none at all. It's probably also worth adding a buffer and output jack so you can use it as a rudimentary signal generator. SOme circuits are better than others. Something that uses a two terminal coil is simpler (Heathkit used phono plugs in at least one of their GDOs) but I suppose you get more control with more contacts. If nothing else, you can pre-adjust the level of the oscillator from band to band. Of course a circuit that uses only two terminals can then be useful in other ways, put a crystal where the coil goes and you can test that crystal, connect a shielded coil where the coil goes and with the variable capacitor at minimum, you get the general frequency of that shielded coil if you listen for it in a receiver, or have the frequency counter hooked up. Since coupling to shielded coils can be a problem, this works out well. Like regen receivers, for a long time a GDO was a minimal circuit, yet nowadays you can complicate it. Why not have a nice 3terminal voltage regulator? Why not use an exotic oscillator circuit that uses more than one transistor? For a long time, most GDOs were about the same, the difference being that anytime someone wrote about their GDO, they'd built it just like someone else's, except changed the coils a bit or used a tube socket instead of a phono jack for the coils, or vice versa. Even the Measurements Corporation or the Millen GDO were fairly simple circuits, though I gather Millen put a lot of effort into a nice flat output. It was the move to solid state that shook things up, technically those were no longer GDOs but everyone knew what was meant. So Heathkit used a tunnel diode in an early sixties one, not sure if it gave any advantage. In some circuits there wasn't anything that really dipped, so they'd measure the signal strenght of the oscillator and see where it dipped. Bipolar transistors often didn't work so well, at least not if someone was basically transcribing a tube GDO to a bipolar oscillator. Later FETs and mosfets came along, more like tube GDOs. IN the seventies, Heathkit and some others used mosfets, and more peripheral devices, still fairly simple. The December 1971 issue of QST (I'm pretty sure it was that issue) had an article by someone from Millen talking about their effort to come out with a solid state GDO. I think they set out to use the same variable capacitor and coil set used by their tube one, but I remember one thing was they had to use ferrite beads and RF chokes in series to get rid of false dips. GDOs can still be found at hamfests on the used market. I think someone is still making new ones, but I'm not sure who. There was period when people were taking tube GDOs and solid stating them, the magazines had articles about that. Michael |
#8
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Grid Dip Meter
On 11/29/2015 6:03 PM, Michael Black wrote:
On Mon, 30 Nov 2015, Cursitor Doom wrote: On Sun, 29 Nov 2015 16:16:27 -0800, Jeff Liebermann wrote: Sorry, no recommendations as all my stuff is ancient. So's a lot of my stuff. But there's nothing wrong with old gear IMO it's the quality of it and whether it's in calibration that counts. The only issues with GDOs IME are that they're not too bad for the lower frequency RF stuff, but hopeless for anything higher. Huh? VHF and UHF is where they really worked well, because at lower frequencies, a lot of the coils were shielded. There were GDOs that worked well at VHF and UHF. Michael Best one I ever used was the tube version of the Millen. I switched to the solid state version and regretted it. Much less sensitive and more fiddly than the tube version. Tunnel dipper was the worst for sensitivity. If ham swapmeets are any indicator, most GDO's available second hand are missing some or all of the coils. |
#9
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Grid Dip Meter
On 11/29/2015 06:35 PM, OldGuy wrote:
Looking for recommendations for a Grid Dip Meter built or a kit. --- news://freenews.netfront.net/ - complaints: --- Find an old Measurements (Boonton) 59 'Megacycle Meter' on eBay. I used to have a Heath 12something that I used for years. On Joerg's recommendation, I got a Measurements 59, and soon afterwards the Heath went in the trash. The 59 has accurate frequency calibration. Mine is still within 2% over the full range, by actual measurement, and it hasn't been trimmed in a loooong time. It also gives a nice deep dip even with quite weak coupling--much weaker than the Heath, especially on low-Q resonances. I've used it to measure the coupling coefficient of toroidal transformers, for instance. (An ISDN unit had a CC of 0.99986.) Besides, it has such a nice retro look and feel. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net |
#10
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Grid Dip Meter
"OldGuy" wrote in message ... Looking for recommendations for a Grid Dip Meter built or a kit. --- news://freenews.netfront.net/ - complaints: --- Just downloaded an archive of Radio Constructor from Americanradiohistory.com - in the course of browsing through them, I found a valve design that uses untapped coils. It would probably adapt well to a JFET. Can't remember which issue, but it was before mid 50s. |
#11
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Grid Dip Meter
"mike" wrote in message ... On 11/29/2015 6:03 PM, Michael Black wrote: On Mon, 30 Nov 2015, Cursitor Doom wrote: On Sun, 29 Nov 2015 16:16:27 -0800, Jeff Liebermann wrote: Sorry, no recommendations as all my stuff is ancient. So's a lot of my stuff. But there's nothing wrong with old gear IMO it's the quality of it and whether it's in calibration that counts. The only issues with GDOs IME are that they're not too bad for the lower frequency RF stuff, but hopeless for anything higher. Huh? VHF and UHF is where they really worked well, because at lower frequencies, a lot of the coils were shielded. There were GDOs that worked well at VHF and UHF. Michael Best one I ever used was the tube version of the Millen. I switched to the solid state version and regretted it. Much less sensitive and more fiddly than the tube version. Tunnel dipper was the worst for sensitivity. A while back I acquired a small Tektronix component envelope containing very tiny "top hat" style diodes that there's a faint possibility they could be TDs. Copying the Heathkit TD dipper had crossed my mind - now I probably won't. |
#12
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Grid Dip Meter
On Mon, 30 Nov 2015, Ian Field wrote:
"mike" wrote in message ... On 11/29/2015 6:03 PM, Michael Black wrote: On Mon, 30 Nov 2015, Cursitor Doom wrote: On Sun, 29 Nov 2015 16:16:27 -0800, Jeff Liebermann wrote: Sorry, no recommendations as all my stuff is ancient. So's a lot of my stuff. But there's nothing wrong with old gear IMO it's the quality of it and whether it's in calibration that counts. The only issues with GDOs IME are that they're not too bad for the lower frequency RF stuff, but hopeless for anything higher. Huh? VHF and UHF is where they really worked well, because at lower frequencies, a lot of the coils were shielded. There were GDOs that worked well at VHF and UHF. Michael Best one I ever used was the tube version of the Millen. I switched to the solid state version and regretted it. Much less sensitive and more fiddly than the tube version. Tunnel dipper was the worst for sensitivity. A while back I acquired a small Tektronix component envelope containing very tiny "top hat" style diodes that there's a faint possibility they could be TDs. Copying the Heathkit TD dipper had crossed my mind - now I probably won't. It seemed like the Tunnel Diode got a lot of press in the sixties in the hobby magazines, but much of it wsa novelty. I can't remember anything where some other device couldn't be used. I suppose when the Heathkit GDO came out, the Tunnel Diode might have had better bandwidth, though I don't remember that GDO has having great VHF and UHF coverage. But while neat things were shown, that tunnel diode FM broadcast receiver was more unique becuase of the low IF and pulse counting detector than that it used a tunnel diode as a mixer/oscillator down to that low IF. There were uses for tunnel diodes that hobbyists generally didn't see, and those at least took advantage of the device at the time, but the time passed pretty fast before other things didn't do most of what a tunnel diode could do. So I think the Heathkit tunnel diode dipper was mostly for novelty sake. Michael |
#13
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Grid Dip Meter
On Mon, 30 Nov 2015 19:05:02 -0500, Michael Black
wrote: It seemed like the Tunnel Diode got a lot of press in the sixties in the hobby magazines, but much of it wsa novelty. For good reason. Tunnel diodes flew in most of the early satellites up to about 1990 because it was the only reliable microwave device available at the time. I can't remember anything where some other device couldn't be used. I suppose when the Heathkit GDO came out, the Tunnel Diode might have had better bandwidth, though I don't remember that GDO has having great VHF and UHF coverage. But while neat things were shown, that tunnel diode FM broadcast receiver was more unique becuase of the low IF and pulse counting detector than that it used a tunnel diode as a mixer/oscillator down to that low IF. I believe you're referring to the HW-10 GDO: http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_H-HM/HM-10a/ http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_H-HM/HM-10a/HM-10A.gif No pulse counting detector but rather a simple half wave RF rectifier followed by 3 stages of DC amplification. As I vaguely recall, I had difficulties getting a clean dip because the tunnel diode was probably oscillating on multiple frequencies at the same time. I may have an HW-10 GDO somewhere in my junk pile. I dropped it from about 60ft up during an antenna raising party. It landed in some bushes and did not appear to be damaged, but failed to function afterwards. I also have a few new TEK tunnel diodes. There were uses for tunnel diodes that hobbyists generally didn't see, and those at least took advantage of the device at the time, but the time passed pretty fast before other things didn't do most of what a tunnel diode could do. Tektronix also used tunnel diodes in their oscilloscope trigger circuitry: http://w140.com/tekwiki/wiki/Tunnel_diodes I use one testing scope rise time: https://richardsears.wordpress.com/2013/04/27/tunnel-diode-pulser/ GE Tunnel Diode Manual (1961): http://w140.com/Ge1961TunnelDiodeManual.pdf Today, Aeroflex/Cobham/Metelics currently sell tunnel diode detectors and use them in their instruments: http://ams.aeroflex.com/metelics/micro-metelics-prods-TD-MTD.cfm http://ams.aeroflex.com/metelics/micro-metelics-prods-TD-MBD.cfm Sorry, but tunnel diodes are not quite dead and obsolete. So I think the Heathkit tunnel diode dipper was mostly for novelty sake. Nope. During the 1960's, the big draw for Heathkit was that kits were much cheaper than labor intensive assembled products. Heathkit had to do something to keep the price down on their products. Cheap was the order of the day and tunnel diodes were CHEEEEEEP. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#14
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Grid Dip Meter
On 11/30/2015 08:05 PM, Jeff Liebermann wrote:
On Mon, 30 Nov 2015 19:05:02 -0500, Michael Black wrote: It seemed like the Tunnel Diode got a lot of press in the sixties in the hobby magazines, but much of it wsa novelty. For good reason. Tunnel diodes flew in most of the early satellites up to about 1990 because it was the only reliable microwave device available at the time. I can't remember anything where some other device couldn't be used. I suppose when the Heathkit GDO came out, the Tunnel Diode might have had better bandwidth, though I don't remember that GDO has having great VHF and UHF coverage. But while neat things were shown, that tunnel diode FM broadcast receiver was more unique becuase of the low IF and pulse counting detector than that it used a tunnel diode as a mixer/oscillator down to that low IF. I believe you're referring to the HW-10 GDO: http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_H-HM/HM-10a/ http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_H-HM/HM-10a/HM-10A.gif No pulse counting detector but rather a simple half wave RF rectifier followed by 3 stages of DC amplification. As I vaguely recall, I had difficulties getting a clean dip because the tunnel diode was probably oscillating on multiple frequencies at the same time. I may have an HW-10 GDO somewhere in my junk pile. I dropped it from about 60ft up during an antenna raising party. It landed in some bushes and did not appear to be damaged, but failed to function afterwards. I also have a few new TEK tunnel diodes. There were uses for tunnel diodes that hobbyists generally didn't see, and those at least took advantage of the device at the time, but the time passed pretty fast before other things didn't do most of what a tunnel diode could do. Tektronix also used tunnel diodes in their oscilloscope trigger circuitry: http://w140.com/tekwiki/wiki/Tunnel_diodes I use one testing scope rise time: https://richardsears.wordpress.com/2013/04/27/tunnel-diode-pulser/ GE Tunnel Diode Manual (1961): http://w140.com/Ge1961TunnelDiodeManual.pdf Today, Aeroflex/Cobham/Metelics currently sell tunnel diode detectors and use them in their instruments: http://ams.aeroflex.com/metelics/micro-metelics-prods-TD-MTD.cfm http://ams.aeroflex.com/metelics/micro-metelics-prods-TD-MBD.cfm Sorry, but tunnel diodes are not quite dead and obsolete. So I think the Heathkit tunnel diode dipper was mostly for novelty sake. Nope. During the 1960's, the big draw for Heathkit was that kits were much cheaper than labor intensive assembled products. Heathkit had to do something to keep the price down on their products. Cheap was the order of the day and tunnel diodes were CHEEEEEEP. I've never used one, but I suspect that part of the reason that tunnel diode dippers are inferior is that you can't run a high-Z tank without tapping the TD way way down, so that you need an impractically large split variable capacitor. Nuvistors are really good for that, over a pretty wide frequency range. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net |
#15
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Grid Dip Meter
"Michael Black" wrote in message xample.org... On Mon, 30 Nov 2015, Ian Field wrote: "mike" wrote in message ... On 11/29/2015 6:03 PM, Michael Black wrote: On Mon, 30 Nov 2015, Cursitor Doom wrote: On Sun, 29 Nov 2015 16:16:27 -0800, Jeff Liebermann wrote: Sorry, no recommendations as all my stuff is ancient. So's a lot of my stuff. But there's nothing wrong with old gear IMO it's the quality of it and whether it's in calibration that counts. The only issues with GDOs IME are that they're not too bad for the lower frequency RF stuff, but hopeless for anything higher. Huh? VHF and UHF is where they really worked well, because at lower frequencies, a lot of the coils were shielded. There were GDOs that worked well at VHF and UHF. Michael Best one I ever used was the tube version of the Millen. I switched to the solid state version and regretted it. Much less sensitive and more fiddly than the tube version. Tunnel dipper was the worst for sensitivity. A while back I acquired a small Tektronix component envelope containing very tiny "top hat" style diodes that there's a faint possibility they could be TDs. Copying the Heathkit TD dipper had crossed my mind - now I probably won't. It seemed like the Tunnel Diode got a lot of press in the sixties in the hobby magazines, but much of it wsa novelty. I can't remember anything where some other device couldn't be used. Back then there was a fanatical craze for FM bug transmitters - with a tunnel diode, the circuitry was always smaller than the battery. |
#16
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Grid Dip Meter
"Phil Hobbs" wrote in message ... On 11/30/2015 08:05 PM, Jeff Liebermann wrote: On Mon, 30 Nov 2015 19:05:02 -0500, Michael Black wrote: It seemed like the Tunnel Diode got a lot of press in the sixties in the hobby magazines, but much of it wsa novelty. For good reason. Tunnel diodes flew in most of the early satellites up to about 1990 because it was the only reliable microwave device available at the time. I can't remember anything where some other device couldn't be used. I suppose when the Heathkit GDO came out, the Tunnel Diode might have had better bandwidth, though I don't remember that GDO has having great VHF and UHF coverage. But while neat things were shown, that tunnel diode FM broadcast receiver was more unique becuase of the low IF and pulse counting detector than that it used a tunnel diode as a mixer/oscillator down to that low IF. I believe you're referring to the HW-10 GDO: http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_H-HM/HM-10a/ http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_H-HM/HM-10a/HM-10A.gif No pulse counting detector but rather a simple half wave RF rectifier followed by 3 stages of DC amplification. As I vaguely recall, I had difficulties getting a clean dip because the tunnel diode was probably oscillating on multiple frequencies at the same time. I may have an HW-10 GDO somewhere in my junk pile. I dropped it from about 60ft up during an antenna raising party. It landed in some bushes and did not appear to be damaged, but failed to function afterwards. I also have a few new TEK tunnel diodes. There were uses for tunnel diodes that hobbyists generally didn't see, and those at least took advantage of the device at the time, but the time passed pretty fast before other things didn't do most of what a tunnel diode could do. Tektronix also used tunnel diodes in their oscilloscope trigger circuitry: http://w140.com/tekwiki/wiki/Tunnel_diodes I use one testing scope rise time: https://richardsears.wordpress.com/2013/04/27/tunnel-diode-pulser/ GE Tunnel Diode Manual (1961): http://w140.com/Ge1961TunnelDiodeManual.pdf Today, Aeroflex/Cobham/Metelics currently sell tunnel diode detectors and use them in their instruments: http://ams.aeroflex.com/metelics/micro-metelics-prods-TD-MTD.cfm http://ams.aeroflex.com/metelics/micro-metelics-prods-TD-MBD.cfm Sorry, but tunnel diodes are not quite dead and obsolete. So I think the Heathkit tunnel diode dipper was mostly for novelty sake. Nope. During the 1960's, the big draw for Heathkit was that kits were much cheaper than labor intensive assembled products. Heathkit had to do something to keep the price down on their products. Cheap was the order of the day and tunnel diodes were CHEEEEEEP. I've never used one, but I suspect that part of the reason that tunnel diode dippers are inferior is that you can't run a high-Z tank without tapping the TD way way down, so that you need an impractically large split variable capacitor. Nuvistors are really good for that, over a pretty wide frequency range. There's a low voltage 8056 Nuvistor in my bits box waiting for a *VERY* elusive round-tuit. |
#17
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Grid Dip Meter
On Tue, 1 Dec 2015, Ian Field wrote:
"Phil Hobbs" wrote in message ... On 11/30/2015 08:05 PM, Jeff Liebermann wrote: On Mon, 30 Nov 2015 19:05:02 -0500, Michael Black wrote: It seemed like the Tunnel Diode got a lot of press in the sixties in the hobby magazines, but much of it wsa novelty. For good reason. Tunnel diodes flew in most of the early satellites up to about 1990 because it was the only reliable microwave device available at the time. I can't remember anything where some other device couldn't be used. I suppose when the Heathkit GDO came out, the Tunnel Diode might have had better bandwidth, though I don't remember that GDO has having great VHF and UHF coverage. But while neat things were shown, that tunnel diode FM broadcast receiver was more unique becuase of the low IF and pulse counting detector than that it used a tunnel diode as a mixer/oscillator down to that low IF. I believe you're referring to the HW-10 GDO: http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_H-HM/HM-10a/ http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_H-HM/HM-10a/HM-10A.gif No pulse counting detector but rather a simple half wave RF rectifier followed by 3 stages of DC amplification. As I vaguely recall, I had difficulties getting a clean dip because the tunnel diode was probably oscillating on multiple frequencies at the same time. I may have an HW-10 GDO somewhere in my junk pile. I dropped it from about 60ft up during an antenna raising party. It landed in some bushes and did not appear to be damaged, but failed to function afterwards. I also have a few new TEK tunnel diodes. There were uses for tunnel diodes that hobbyists generally didn't see, and those at least took advantage of the device at the time, but the time passed pretty fast before other things didn't do most of what a tunnel diode could do. Tektronix also used tunnel diodes in their oscilloscope trigger circuitry: http://w140.com/tekwiki/wiki/Tunnel_diodes I use one testing scope rise time: https://richardsears.wordpress.com/2013/04/27/tunnel-diode-pulser/ GE Tunnel Diode Manual (1961): http://w140.com/Ge1961TunnelDiodeManual.pdf Today, Aeroflex/Cobham/Metelics currently sell tunnel diode detectors and use them in their instruments: http://ams.aeroflex.com/metelics/micro-metelics-prods-TD-MTD.cfm http://ams.aeroflex.com/metelics/micro-metelics-prods-TD-MBD.cfm Sorry, but tunnel diodes are not quite dead and obsolete. So I think the Heathkit tunnel diode dipper was mostly for novelty sake. Nope. During the 1960's, the big draw for Heathkit was that kits were much cheaper than labor intensive assembled products. Heathkit had to do something to keep the price down on their products. Cheap was the order of the day and tunnel diodes were CHEEEEEEP. I've never used one, but I suspect that part of the reason that tunnel diode dippers are inferior is that you can't run a high-Z tank without tapping the TD way way down, so that you need an impractically large split variable capacitor. Nuvistors are really good for that, over a pretty wide frequency range. There's a low voltage 8056 Nuvistor in my bits box waiting for a *VERY* elusive round-tuit. I'd forgotten about those. The only time I remember seeing them mentioned (and this was after the fact) was one or two converters that used them, no need to have a high voltage power supply. Nuvistors came in just on the cusp of transistors taking off. So other than tv set front ends, they didn't see a lot of use, people going after transistors instead. I remember one review for a nuvistor converter (I think it was for 144MHz), where someone compared it to their existing converter and said "the noise figure is better, which probably means my old converter needs returning). The Nuvistor did give good noise figure without the fussing needed with previous devices. Or the cost, the previous converter in the article was either a 416 or 417. Michael |
#18
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Grid Dip Meter
In article ,
Ian Field wrote: Best one I ever used was the tube version of the Millen. I switched to the solid state version and regretted it. Much less sensitive and more fiddly than the tube version. Tunnel dipper was the worst for sensitivity. A while back I acquired a small Tektronix component envelope containing very tiny "top hat" style diodes that there's a faint possibility they could be TDs. Copying the Heathkit TD dipper had crossed my mind - now I probably won't. By all accounts I've ever read, the Heathkit TD dipper isn't a good performer. I've played around with one briefly and it had a very difficult time sensing a resonance even with a large high-Q air-core inductor and an air-variable cap. It was actually worse than the "grid dip meter" accessory for an MFJ-259/269 antenna analyzer, and that's saying something... something profoundly bad :-( I compared the MFJ to a more recent Heathkit solid-state dipper (an HD-1250 if I recall correctly), to a B&W, and to a Measurements 59. Sensitivity was in that order... the Heathkit was better than the MFJ, the B&W next, and the Measurement 59 was the stand-out winner. I've never had a chance to test a Millen; from what I've heard they'd probably come in between the B&W and the 59. There are a couple of projects out on the net which show how to make a GD meter using a (composite) lambda diode. These are negative-resistance devices which behave a bit like a tunnel diode. These can be made from two JFETs (one N-channel, one P-channel) or an N-JFET and a bipolar transistor. http://users.tpg.com.au/ldbutler/NegResDipMeter.htm Lambda diodes typically require more voltage and use more power than a tunnel diode - the negative-resistance part of their curve covers several volts. Strong oscillators... the dip-meter design requires a band-specific resistor to tame the strength of the oscillator so that the dip can be seen. |
#19
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Grid Dip Meter
"Michael Black" wrote in message xample.org... On Tue, 1 Dec 2015, Ian Field wrote: "Phil Hobbs" wrote in message ... On 11/30/2015 08:05 PM, Jeff Liebermann wrote: On Mon, 30 Nov 2015 19:05:02 -0500, Michael Black wrote: It seemed like the Tunnel Diode got a lot of press in the sixties in the hobby magazines, but much of it wsa novelty. For good reason. Tunnel diodes flew in most of the early satellites up to about 1990 because it was the only reliable microwave device available at the time. I can't remember anything where some other device couldn't be used. I suppose when the Heathkit GDO came out, the Tunnel Diode might have had better bandwidth, though I don't remember that GDO has having great VHF and UHF coverage. But while neat things were shown, that tunnel diode FM broadcast receiver was more unique becuase of the low IF and pulse counting detector than that it used a tunnel diode as a mixer/oscillator down to that low IF. I believe you're referring to the HW-10 GDO: http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_H-HM/HM-10a/ http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_H-HM/HM-10a/HM-10A.gif No pulse counting detector but rather a simple half wave RF rectifier followed by 3 stages of DC amplification. As I vaguely recall, I had difficulties getting a clean dip because the tunnel diode was probably oscillating on multiple frequencies at the same time. I may have an HW-10 GDO somewhere in my junk pile. I dropped it from about 60ft up during an antenna raising party. It landed in some bushes and did not appear to be damaged, but failed to function afterwards. I also have a few new TEK tunnel diodes. There were uses for tunnel diodes that hobbyists generally didn't see, and those at least took advantage of the device at the time, but the time passed pretty fast before other things didn't do most of what a tunnel diode could do. Tektronix also used tunnel diodes in their oscilloscope trigger circuitry: http://w140.com/tekwiki/wiki/Tunnel_diodes I use one testing scope rise time: https://richardsears.wordpress.com/2013/04/27/tunnel-diode-pulser/ GE Tunnel Diode Manual (1961): http://w140.com/Ge1961TunnelDiodeManual.pdf Today, Aeroflex/Cobham/Metelics currently sell tunnel diode detectors and use them in their instruments: http://ams.aeroflex.com/metelics/micro-metelics-prods-TD-MTD.cfm http://ams.aeroflex.com/metelics/micro-metelics-prods-TD-MBD.cfm Sorry, but tunnel diodes are not quite dead and obsolete. So I think the Heathkit tunnel diode dipper was mostly for novelty sake. Nope. During the 1960's, the big draw for Heathkit was that kits were much cheaper than labor intensive assembled products. Heathkit had to do something to keep the price down on their products. Cheap was the order of the day and tunnel diodes were CHEEEEEEP. I've never used one, but I suspect that part of the reason that tunnel diode dippers are inferior is that you can't run a high-Z tank without tapping the TD way way down, so that you need an impractically large split variable capacitor. Nuvistors are really good for that, over a pretty wide frequency range. There's a low voltage 8056 Nuvistor in my bits box waiting for a *VERY* elusive round-tuit. I'd forgotten about those. The only time I remember seeing them mentioned (and this was after the fact) was one or two converters that used them, no need to have a high voltage power supply. Nuvistors came in just on the cusp of transistors taking off. So other than tv set front ends, they didn't see a lot of use, people going after transistors instead. Mine came from an old Sealy TV that someone left in the bin room at the flats. It didn't suit the UK standard so I just pulled the back off to look for interesting bits. Apparently there was a time that most remote garage door openers had a Nuvistor of some description. |
#20
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Grid Dip Meter
On 12/01/2015 01:41 PM, Ian Field wrote:
"Michael Black" wrote in message xample.org... On Mon, 30 Nov 2015, Ian Field wrote: "mike" wrote in message ... On 11/29/2015 6:03 PM, Michael Black wrote: On Mon, 30 Nov 2015, Cursitor Doom wrote: On Sun, 29 Nov 2015 16:16:27 -0800, Jeff Liebermann wrote: Sorry, no recommendations as all my stuff is ancient. So's a lot of my stuff. But there's nothing wrong with old gear IMO it's the quality of it and whether it's in calibration that counts. The only issues with GDOs IME are that they're not too bad for the lower frequency RF stuff, but hopeless for anything higher. Huh? VHF and UHF is where they really worked well, because at lower frequencies, a lot of the coils were shielded. There were GDOs that worked well at VHF and UHF. Michael Best one I ever used was the tube version of the Millen. I switched to the solid state version and regretted it. Much less sensitive and more fiddly than the tube version. Tunnel dipper was the worst for sensitivity. A while back I acquired a small Tektronix component envelope containing very tiny "top hat" style diodes that there's a faint possibility they could be TDs. Copying the Heathkit TD dipper had crossed my mind - now I probably won't. It seemed like the Tunnel Diode got a lot of press in the sixties in the hobby magazines, but much of it wsa novelty. I can't remember anything where some other device couldn't be used. Back then there was a fanatical craze for FM bug transmitters - with a tunnel diode, the circuitry was always smaller than the battery. The problem was that TDs had such a lot of capacitance that it was only the ones with the huge peak currents (200 mA!) that were really fast. I have a bunch of 2 mA TDs with 200 pF of capacitance. Fast? Not so much. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net |
#21
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Grid Dip Meter
On Tue, 1 Dec 2015, Ian Field wrote:
"Michael Black" wrote in message xample.org... On Tue, 1 Dec 2015, Ian Field wrote: "Phil Hobbs" wrote in message ... On 11/30/2015 08:05 PM, Jeff Liebermann wrote: On Mon, 30 Nov 2015 19:05:02 -0500, Michael Black wrote: It seemed like the Tunnel Diode got a lot of press in the sixties in the hobby magazines, but much of it wsa novelty. For good reason. Tunnel diodes flew in most of the early satellites up to about 1990 because it was the only reliable microwave device available at the time. I can't remember anything where some other device couldn't be used. I suppose when the Heathkit GDO came out, the Tunnel Diode might have had better bandwidth, though I don't remember that GDO has having great VHF and UHF coverage. But while neat things were shown, that tunnel diode FM broadcast receiver was more unique becuase of the low IF and pulse counting detector than that it used a tunnel diode as a mixer/oscillator down to that low IF. I believe you're referring to the HW-10 GDO: http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_H-HM/HM-10a/ http://tubularelectronics.com/Heath_Manual_Collection/Heath_Manuals_H-HM/HM-10a/HM-10A.gif No pulse counting detector but rather a simple half wave RF rectifier followed by 3 stages of DC amplification. As I vaguely recall, I had difficulties getting a clean dip because the tunnel diode was probably oscillating on multiple frequencies at the same time. I may have an HW-10 GDO somewhere in my junk pile. I dropped it from about 60ft up during an antenna raising party. It landed in some bushes and did not appear to be damaged, but failed to function afterwards. I also have a few new TEK tunnel diodes. There were uses for tunnel diodes that hobbyists generally didn't see, and those at least took advantage of the device at the time, but the time passed pretty fast before other things didn't do most of what a tunnel diode could do. Tektronix also used tunnel diodes in their oscilloscope trigger circuitry: http://w140.com/tekwiki/wiki/Tunnel_diodes I use one testing scope rise time: https://richardsears.wordpress.com/2013/04/27/tunnel-diode-pulser/ GE Tunnel Diode Manual (1961): http://w140.com/Ge1961TunnelDiodeManual.pdf Today, Aeroflex/Cobham/Metelics currently sell tunnel diode detectors and use them in their instruments: http://ams.aeroflex.com/metelics/micro-metelics-prods-TD-MTD.cfm http://ams.aeroflex.com/metelics/micro-metelics-prods-TD-MBD.cfm Sorry, but tunnel diodes are not quite dead and obsolete. So I think the Heathkit tunnel diode dipper was mostly for novelty sake. Nope. During the 1960's, the big draw for Heathkit was that kits were much cheaper than labor intensive assembled products. Heathkit had to do something to keep the price down on their products. Cheap was the order of the day and tunnel diodes were CHEEEEEEP. I've never used one, but I suspect that part of the reason that tunnel diode dippers are inferior is that you can't run a high-Z tank without tapping the TD way way down, so that you need an impractically large split variable capacitor. Nuvistors are really good for that, over a pretty wide frequency range. There's a low voltage 8056 Nuvistor in my bits box waiting for a *VERY* elusive round-tuit. I'd forgotten about those. The only time I remember seeing them mentioned (and this was after the fact) was one or two converters that used them, no need to have a high voltage power supply. Nuvistors came in just on the cusp of transistors taking off. So other than tv set front ends, they didn't see a lot of use, people going after transistors instead. Mine came from an old Sealy TV that someone left in the bin room at the flats. It didn't suit the UK standard so I just pulled the back off to look for interesting bits. Apparently there was a time that most remote garage door openers had a Nuvistor of some description. I've never heard of that, but it's possible. There were those subminiature tubes (the leads were generally laid out in parallel with each other, and the leads were relatively low gauge wire) seen in hearing aids and some portable radios. I think those came early enough that they had a longer span, but they too were whiped out by transistors. Michael |
#22
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Grid Dip Meter
On Tuesday, December 1, 2015 at 5:23:03 PM UTC-8, Michael Black wrote:
On Tue, 1 Dec 2015, Ian Field wrote: Apparently there was a time that most remote garage door openers had a Nuvistor of some description. I've never heard of that, but it's possible. There were those subminiature tubes (the leads were generally laid out in parallel with each other, and the leads were relatively low gauge wire) seen in hearing aids and some portable radios. I've heard those called 'pencil tubes'; the ones in hybrid walkie-talkies (for the transmitter) didn't get replaced with semiconductors until mid-to-late seventies. Nuvistors were ceramic-metal base, metal envelope tubes, very rugged, and much less microphonic than other vacuum tubes. There was a long period when they were the best fast-slewing amplifiers around, and for HV handling (like electrostatic deflection in CRTs) very hard to replace with silicon. |
#23
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Grid Dip Meter
On Wed, 2 Dec 2015, whit3rd wrote:
On Tuesday, December 1, 2015 at 5:23:03 PM UTC-8, Michael Black wrote: On Tue, 1 Dec 2015, Ian Field wrote: Apparently there was a time that most remote garage door openers had a Nuvistor of some description. I've never heard of that, but it's possible. There were those subminiature tubes (the leads were generally laid out in parallel with each other, and the leads were relatively low gauge wire) seen in hearing aids and some portable radios. I've heard those called 'pencil tubes'; the ones in hybrid walkie-talkies (for the transmitter) didn't get replaced with semiconductors until mid-to-late seventies. I dont' think anything much new got released after a certain point. But those tubes did offer the chance to make equipment smaller, and certainly in the early days of transistors, the tubes had better high frequency response. I had one of those hybrid lunch box walkie talkies, never used it, and if I recall properly the transmitter was all tube, the receiver had a diode mixer (no rf stage ahead of it) and a tube oscillator and multiplier chain, with the transistors in the IF strip and audio. But by the end of the sixties, you could get Motorola handie talkies like the HT-200, which were all solid state. Hearing aids must have made the transition to transistors by then, and you could get portable radios that used transistors. Nuvistors were ceramic-metal base, metal envelope tubes, very rugged, and much less microphonic than other vacuum tubes. There was a long period when they were the best fast-slewing amplifiers around, and for HV handling (like electrostatic deflection in CRTs) very hard to replace with silicon. But at the time, top end test equipment wasn't as well known to the hobbyist. It was only later that I learned the Tek 454? (the mostly solid state one, not the one from 1959 with the plugins) used nuvistors. Michael |
#24
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Grid Dip Meter
"Michael Black" wrote in message news:alpine.LNX.2.02.1512021325170.11559@darkstar. example.org... On Wed, 2 Dec 2015, whit3rd wrote: On Tuesday, December 1, 2015 at 5:23:03 PM UTC-8, Michael Black wrote: On Tue, 1 Dec 2015, Ian Field wrote: Apparently there was a time that most remote garage door openers had a Nuvistor of some description. I've never heard of that, but it's possible. There were those subminiature tubes (the leads were generally laid out in parallel with each other, and the leads were relatively low gauge wire) seen in hearing aids and some portable radios. I've heard those called 'pencil tubes'; the ones in hybrid walkie-talkies (for the transmitter) didn't get replaced with semiconductors until mid-to-late seventies. I dont' think anything much new got released after a certain point. But those tubes did offer the chance to make equipment smaller, and certainly in the early days of transistors, the tubes had better high frequency response. They didn't have any transistors in WW2 - but they needed a crude doppler radar for proximity shells that could be fired out of an anti-aircraft gun. AFAIK: they used what were basically ruggedised hearing aid valves potted in wax to stop them bouncing about. |
#25
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