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Grid Dip Meters
Does anybody here have any honest-to-goodness experience with Grid Dip
Meters? I have an old Heath HD-1250, which is a solid state equivalent, and I have never been convinced that it works well. Seems like the dips are vague, unless coupling to the circuit is awfully tight. Anyway, looking for opinions, or preferably facts, as to which grid dip meters are the good ones and why. Thanks in advance. |
I have an old Heath HD-1250, which is a solid state equivalent, and I have
never been convinced that it works well. Seems like the dips are vague, unless coupling to the circuit is awfully tight. BF- How tight is tight? I think my newer GDO is the HD-1250, but I haven't touched it in several years. I also have the old GD-1B. As I recall, they do have to be coupled fairly tightly. Once you find the dip, you should be able to back away some and get a more "accurate" dip. Tight coupling seems to pull the oscillator's frequency somewhat. It is also possible to use them in an absorption mode, where energy from an energized circuit will deflect the meter when it is tuned to the frequency. Have you tried that mode? 73, Fred, K4DII |
I have an old Heath HD-1250, which is a solid state equivalent, and I have
never been convinced that it works well. Seems like the dips are vague, unless coupling to the circuit is awfully tight. BF- How tight is tight? I think my newer GDO is the HD-1250, but I haven't touched it in several years. I also have the old GD-1B. As I recall, they do have to be coupled fairly tightly. Once you find the dip, you should be able to back away some and get a more "accurate" dip. Tight coupling seems to pull the oscillator's frequency somewhat. It is also possible to use them in an absorption mode, where energy from an energized circuit will deflect the meter when it is tuned to the frequency. Have you tried that mode? 73, Fred, K4DII |
I have an old Heath HD-1250, which is a solid state equivalent, and I have
never been convinced that it works well. Seems like the dips are vague, unless coupling to the circuit is awfully tight. BF- How tight is tight? I think my newer GDO is the HD-1250, but I haven't touched it in several years. I also have the old GD-1B. As I recall, they do have to be coupled fairly tightly. Once you find the dip, you should be able to back away some and get a more "accurate" dip. Tight coupling seems to pull the oscillator's frequency somewhat. It is also possible to use them in an absorption mode, where energy from an energized circuit will deflect the meter when it is tuned to the frequency. Have you tried that mode? 73, Fred, K4DII |
I have an old Heath HD-1250, which is a solid state equivalent, and I have
never been convinced that it works well. Seems like the dips are vague, unless coupling to the circuit is awfully tight. I have one of those (eBay purchase as of a couple of years ago) and I agree with your assessment. The oscillator is fairly weak, I think, and you need very tight coupling to get a significant dip... and of course the tight coupling tends to perturb the circuit being measured. The dip-meter attachment for the MJF antenna analyzer isn't much better. I've heard that the James Millen dipmeter is somewhat better, but not great. If you can manage to get your hands on a Measurements Inc. ("Boonton") tube-powered grid dip meter, I think you'll find that it's another bushel of peas entirely. It's big, a bit clumsy (the oscillator head alone is almost half the size of the HD-1250, plus a desktop power supply and meter), and it may need to have its tubes replaced, but WOW does it ever dip! I used a test coil and cap combination to test it - with the HD-1250 the dipper coil had to be held inside the test coil to couple well enough, while with the Boonton I got a very usable dip with the dipper coil 3-4" away on axis! B&W also made a grid dip meter, with an acorn-tube oscillator (similar to the one used in the Boonton) which might be worth a look. Keep your eyes peeled for one of these old firebottle-powered GDMs at local hamfests! -- 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! |
I have an old Heath HD-1250, which is a solid state equivalent, and I have
never been convinced that it works well. Seems like the dips are vague, unless coupling to the circuit is awfully tight. I have one of those (eBay purchase as of a couple of years ago) and I agree with your assessment. The oscillator is fairly weak, I think, and you need very tight coupling to get a significant dip... and of course the tight coupling tends to perturb the circuit being measured. The dip-meter attachment for the MJF antenna analyzer isn't much better. I've heard that the James Millen dipmeter is somewhat better, but not great. If you can manage to get your hands on a Measurements Inc. ("Boonton") tube-powered grid dip meter, I think you'll find that it's another bushel of peas entirely. It's big, a bit clumsy (the oscillator head alone is almost half the size of the HD-1250, plus a desktop power supply and meter), and it may need to have its tubes replaced, but WOW does it ever dip! I used a test coil and cap combination to test it - with the HD-1250 the dipper coil had to be held inside the test coil to couple well enough, while with the Boonton I got a very usable dip with the dipper coil 3-4" away on axis! B&W also made a grid dip meter, with an acorn-tube oscillator (similar to the one used in the Boonton) which might be worth a look. Keep your eyes peeled for one of these old firebottle-powered GDMs at local hamfests! -- 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! |
I have an old Heath HD-1250, which is a solid state equivalent, and I have
never been convinced that it works well. Seems like the dips are vague, unless coupling to the circuit is awfully tight. I have one of those (eBay purchase as of a couple of years ago) and I agree with your assessment. The oscillator is fairly weak, I think, and you need very tight coupling to get a significant dip... and of course the tight coupling tends to perturb the circuit being measured. The dip-meter attachment for the MJF antenna analyzer isn't much better. I've heard that the James Millen dipmeter is somewhat better, but not great. If you can manage to get your hands on a Measurements Inc. ("Boonton") tube-powered grid dip meter, I think you'll find that it's another bushel of peas entirely. It's big, a bit clumsy (the oscillator head alone is almost half the size of the HD-1250, plus a desktop power supply and meter), and it may need to have its tubes replaced, but WOW does it ever dip! I used a test coil and cap combination to test it - with the HD-1250 the dipper coil had to be held inside the test coil to couple well enough, while with the Boonton I got a very usable dip with the dipper coil 3-4" away on axis! B&W also made a grid dip meter, with an acorn-tube oscillator (similar to the one used in the Boonton) which might be worth a look. Keep your eyes peeled for one of these old firebottle-powered GDMs at local hamfests! -- 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! |
There was a very useful article in a recent issue of QST about
dip meters. Anyone with a GDO should read it! The depth and width of the 'dip' is a function of the Q of the circuit. Some GDO's are not very sensitive, and that may be the case with yours. If you have an oscillator coil out of an old AM radio, put a good quality cap (mica) across it and see how your GDO works with it. You should be able to get a good dip with your GDO coil about 0.5" away.. Steve W6SSP BFoelsch wrote in message ... Does anybody here have any honest-to-goodness experience with Grid Dip Meters? I have an old Heath HD-1250, which is a solid state equivalent, and I have never been convinced that it works well. Seems like the dips are vague, unless coupling to the circuit is awfully tight. Anyway, looking for opinions, or preferably facts, as to which grid dip meters are the good ones and why. Thanks in advance. |
There was a very useful article in a recent issue of QST about
dip meters. Anyone with a GDO should read it! The depth and width of the 'dip' is a function of the Q of the circuit. Some GDO's are not very sensitive, and that may be the case with yours. If you have an oscillator coil out of an old AM radio, put a good quality cap (mica) across it and see how your GDO works with it. You should be able to get a good dip with your GDO coil about 0.5" away.. Steve W6SSP BFoelsch wrote in message ... Does anybody here have any honest-to-goodness experience with Grid Dip Meters? I have an old Heath HD-1250, which is a solid state equivalent, and I have never been convinced that it works well. Seems like the dips are vague, unless coupling to the circuit is awfully tight. Anyway, looking for opinions, or preferably facts, as to which grid dip meters are the good ones and why. Thanks in advance. |
There was a very useful article in a recent issue of QST about
dip meters. Anyone with a GDO should read it! The depth and width of the 'dip' is a function of the Q of the circuit. Some GDO's are not very sensitive, and that may be the case with yours. If you have an oscillator coil out of an old AM radio, put a good quality cap (mica) across it and see how your GDO works with it. You should be able to get a good dip with your GDO coil about 0.5" away.. Steve W6SSP BFoelsch wrote in message ... Does anybody here have any honest-to-goodness experience with Grid Dip Meters? I have an old Heath HD-1250, which is a solid state equivalent, and I have never been convinced that it works well. Seems like the dips are vague, unless coupling to the circuit is awfully tight. Anyway, looking for opinions, or preferably facts, as to which grid dip meters are the good ones and why. Thanks in advance. |
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