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#1
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On Mon, 7 Mar 2005 13:23:17 UTC, "W8KZW" wrote:
The LMO is supposed to tune 500 KC - from X.0 to X.5. Mine physically stops at X.055 ... in other words, the counterclockwise "end of travel thunk" comes too early, and won't let me tune the bottom 55 kc of the band. The clockwise "end of travel thunk" comes where it should. These "thunks" both sound and feel the same .... as you would expect them to: solid and defined, neither end like the feel / sound of a coil getting caught up inside a tube. The tuning is smooth and unobstructed across the full range. coil in a tube? The LMO has a shaft with rings on it. The rings have stops that prevent you from making too many turns. It gives you five turns of the shaft. Each stop engages the next ring and is, in turn, engaged by the previous. I can't quite visualize how that simple mechanism could be defective. Within the LMO, there is a typical worm driven capacitor. No obvious way that can be defective either. The question is, how many turns does the big plastic disk make? Should be a little over 5. If your problem is mechanical, then it's strictly a matter of counting the turns. This is a capacitor tuned oscillator, not a PTO. de ah6gi/4 |
#2
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ckh wrote:
On Mon, 7 Mar 2005 13:23:17 UTC, "W8KZW" wrote: The LMO is supposed to tune 500 KC - from X.0 to X.5. Mine physically stops at X.055 ... in other words, the counterclockwise "end of travel thunk" comes too early, and won't let me tune the bottom 55 kc of the band. The clockwise "end of travel thunk" comes where it should. These "thunks" both sound and feel the same .... as you would expect them to: solid and defined, neither end like the feel / sound of a coil getting caught up inside a tube. The tuning is smooth and unobstructed across the full range. coil in a tube? He is thinking of a PTO where a slug could get jammed inside the coil form. The LMO has a shaft with rings on it. The rings have stops that prevent you from making too many turns. It gives you five turns of the shaft. Each stop engages the next ring and is, in turn, engaged by the previous. I can't quite visualize how that simple mechanism could be defective. Visualize what happens when two or more of the range limiting disks get frozen together by gummed up grease. Within the LMO, there is a typical worm driven capacitor. No obvious way that can be defective either. Although it is harder, if part of the worm gear has a block of hardened grease in its tooth, it will jamb the mechanism before the capacitor can turn its full range. Usually there is enough mechanical advantage in the worm gear assy that you could over come the block but 30 year old grease can become quite hard. The question is, how many turns does the big plastic disk make? Should be a little over 5. If your problem is mechanical, then it's strictly a matter of counting the turns. His wording was difficult, but I got the impression that the markings on the dial are exactly correct with the received frequency. So that would mean that there is something mechanical wrong. I would bet on the range limiting disks being frozen solid with grease or rust. -Chuck Harris |
#3
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On Tue, 8 Mar 2005 13:22:03 UTC, Chuck Harris
wrote: He is thinking of a PTO where a slug could get jammed inside the coil form. The LMO has a shaft with rings on it. The rings have stops that prevent you from making too many turns. It gives you five turns of the shaft. Each stop engages the next ring and is, in turn, engaged by the previous. I can't quite visualize how that simple mechanism could be defective. Visualize what happens when two or more of the range limiting disks get frozen together by gummed up grease. I just spun an LMO from lock to lock, 521 kHz on the dial. How do you get from that to his 432? I have an LMO in my parts bin. Lemme see.... Ah-HAH! There are 6 tabs, not 5. Each ring is about 86 kHz. 521 434 347 260 173 86 The width of the tab must be about 14 kHz... seems too wide but maybe. de ah6gi/4 Within the LMO, there is a typical worm driven capacitor. No obvious way that can be defective either. Although it is harder, if part of the worm gear has a block of hardened grease in its tooth, it will jamb the mechanism before the capacitor can turn its full range. Usually there is enough mechanical advantage in the worm gear assy that you could over come the block but 30 year old grease can become quite hard. The question is, how many turns does the big plastic disk make? Should be a little over 5. If your problem is mechanical, then it's strictly a matter of counting the turns. His wording was difficult, but I got the impression that the markings on the dial are exactly correct with the received frequency. So that would mean that there is something mechanical wrong. I would bet on the range limiting disks being frozen solid with grease or rust. -Chuck Harris -- |
#4
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ckh wrote: On Tue, 8 Mar 2005 13:22:03 UTC, Chuck Harris wrote: The LMO has a shaft with rings on it. The rings have stops that prevent you from making too many turns. It gives you five turns of the shaft. Each stop engages the next ring and is, in turn, engaged by the previous. I can't quite visualize how that simple mechanism could be defective. Visualize what happens when two or more of the range limiting disks get frozen together by gummed up grease. I just spun an LMO from lock to lock, 521 kHz on the dial. How do you get from that to his 432? I have an LMO in my parts bin. Lemme see.... Ah-HAH! There are 6 tabs, not 5. Each ring is about 86 kHz. 521 434 347 260 173 86 The width of the tab must be about 14 kHz... seems too wide but maybe. If two of the rings are locked together, they will move as a unit and reduce the travel by one turn. Your test shows that the LMO moves about 432-434 kHz in four turns. I bet the problem is purely mechanical. Frozen ring or some such. 73 de Jim, N2EY |
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