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Clean Roller Inductor
I have been using a MFJ-989C tuner for about (5) years without any problems.
Just recently I have noticed that on the higher band, 24 MHz that the SWR occasionally would jump from an adjusted 1:1 SWR to infinity. A slight adjustment of the roller inductance appeared to solve the problem although I haven't ruled out a balum or antenna problem. I plan on investigating that this weekend, however, before I open the cabinet and look for problems I would ask the group for recommendations on cleaning the roller assembly and inductor to ensure good conductivity after I am done. I still have some old cleaning solutions from the old TV tuner days, some electrical cleaner (Appears heavy duty stuff) but maybe there is some other solutions someone might recommend. Your thoughts and recommendations are appreciated Ron - W4LDE |
Ron, Sounds like a dirty contact. Your cleaner should work. So will soap and water, or 'Windex'. Just be sure to 'blow' the dust out of it and dry it out. 'Doc PS - In extreme cases, take it to the car wash (no wax). |
On Wed, 22 Oct 2003 12:43:20 GMT, "Ronald Walters"
wrote: I would ask the group for recommendations on cleaning the roller assembly and inductor to ensure good conductivity after I am done. Hi Ron, One contact cleaner that I used that was better than most was Cramolin. This is a monomolecular layer solution that you would use very sparingly. However, as your tuner did not arrive brand-new (or brand-used) with it, your problem may be more mundane. The simplest way to defeat corrosion is with pressure. The spring tension of the roller may have slackened up over the years. 73's Richard Clark, KB7QHC |
"Ronald Walters" wrote in message om...
I have been using a MFJ-989C tuner for about (5) years without any problems. Just recently I have noticed that on the higher band, 24 MHz that the SWR occasionally would jump from an adjusted 1:1 SWR to infinity. A slight adjustment of the roller inductance appeared to solve the problem although I haven't ruled out a balum or antenna problem. I plan on investigating that this weekend, however, before I open the cabinet and look for problems I would ask the group for recommendations on cleaning the roller assembly and inductor to ensure good conductivity after I am done. I still have some old cleaning solutions from the old TV tuner days, some electrical cleaner (Appears heavy duty stuff) but maybe there is some other solutions someone might recommend. Your thoughts and recommendations are appreciated Ron - W4LDE I use Muriatic acid for this and when working on coax e.t.c Inexpensive to purchase at hardware or lumber yards ( $4 a gallon) I dilute it with an equal amount of water. This is also ideal to clean copper prior to soldering Cheers Art First came across this many years ago when I was in the Carribean on one of many many business trips. A local gave me a large sea shell with a beutiful pattern on it but it was encrusted with all sorts of sea matter. Immersing it a short while as per above and all the crud was removed leaving a very shiny and elaborate surface. Ten years on the side board and still looks good and shiny. Passed on the tip to a vendor on the beach in San Juan so hopefully his business improved. |
Richard Clark wrote in message . ..
On Wed, 22 Oct 2003 12:43:20 GMT, "Ronald Walters" wrote: I would ask the group for recommendations on cleaning the roller assembly and inductor to ensure good conductivity after I am done. Hi Ron, One contact cleaner that I used that was better than most was Cramolin. This is a monomolecular layer solution that you would use very sparingly. However, as your tuner did not arrive brand-new (or brand-used) with it, your problem may be more mundane. The simplest way to defeat corrosion is with pressure. Garbage For continued use you must have a wipe or what is termed a scrubbing action. Period. Even with silver or gold the lack of scrubbing action will permit intermitent contact unless the power is high enough to blow away the oxides. Art The spring tension of the roller may have slackened up over the years. 73's Richard Clark, KB7QHC |
On Wed, 22 Oct 2003 12:43:20 GMT, "Ronald Walters"
wrote: I have been using a MFJ-989C tuner for about (5) years without any problems. Just recently I have noticed that on the higher band, 24 MHz that the SWR occasionally would jump from an adjusted 1:1 SWR to infinity. According to the downloadable manual, page 3, the roller inductor has a self-resonance killer that is switched in and out of the circuit automatically, and you may feel a slight bump when it happens. That may be causing your swr jump. The manual says not to be alarmed. My roller inductor has some black, moist stuff on it. I just assumed it was lubricant and haven't tried to remove it. My tuner, about 10 years old, seems to tune my dipole just fine on multiple bands. Bob k5qwg A slight adjustment of the roller inductance appeared to solve the problem although I haven't ruled out a balum or antenna problem. I plan on investigating that this weekend, however, before I open the cabinet and look for problems I would ask the group for recommendations on cleaning the roller assembly and inductor to ensure good conductivity after I am done. I still have some old cleaning solutions from the old TV tuner days, some electrical cleaner (Appears heavy duty stuff) but maybe there is some other solutions someone might recommend. Your thoughts and recommendations are appreciated Ron - W4LDE |
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It's an "abuse of language" shared by many, including manufacturers of
switches and relays of all kinds. A google search on "contact 'wiping action'" brought around 3000 hits. The few I glanced at dealt with just that topic, using those words. The only contact-related document I have readily at hand is a 3M catalog of "Electronic Interconnection Systems". Just about every connector has a specification for "wipe area" or "wiping area". Roy Lewallen, W7EL Richard Clark wrote: Hi Art, You are out of your turf. Pressure is the way all contacts work to break the insulating barrier formed by oxides. Your typical abuse of language here with "wipe" is another example that demonstrates pressure. The indiscriminate use of chemicals to treat a mechanical problem is one that I have demonstrated as being wholly unnecessary: none of your new gear, nor any old gear just acquired that works fine came with this chemical bath treatment. Long before anyone here was born, precision contacts were tapered plugs that fit into tapered sockets. The sockets were bifurcated (split in two halves) such that the plug created the closure between them with a simple insert and twist to break the layer of oxide. Note, there is no "wipe" as the twist translates the torque into pressure (wiping has nowhere to deposit what is "wiped" away in the tapered socket). No one needed sandpaper or a bottle of acid to erode the surface and corrode other parts through the solvent's vapor (a very insidious imposition). There is a very good reason why electronics manufacturers avoid acid core solder (unless they use a water wash down following board construction and faithfully use rosin core solder for touch up work - with extreme care not to mix the two solders). For contacts that have little pressure, the voltage presented across them can penetrate the barrier; however, there are applications where those voltages are not sufficient, and when the contact pressure is not enough either, you get into these problems. Mechanical TV tuners back in the early days suffered this problem and a special grease surfactant was used to insulate the contact face from corrosion while the pressure was sufficient to displace it for electrical contact. 73's Richard Clark, KB7QHC |
On Thu, 23 Oct 2003 10:40:36 -0700, Roy Lewallen
wrote: It's an "abuse of language" shared by many, including manufacturers of switches and relays of all kinds. A google search on "contact 'wiping action'" brought around 3000 hits. The few I glanced at dealt with just that topic, using those words. The only contact-related document I have readily at hand is a 3M catalog of "Electronic Interconnection Systems". Just about every connector has a specification for "wipe area" or "wiping area". Roy Lewallen, W7EL Hi Roy, And does that render the issue of pressure as "garbage" or negate any comment offered by myself? Does it elevate the injudicious application of chemicals? Does it replace common sense? Many of the mythical lurkers might be lead down the primrose path of dunking their 'tronics into a vat of Coca Cola simply because of its Phosphoric Acid content. Is a google search the barometer of accuracy for rec.radio.amateur.chemistry when supported by 3000 hits? If so, "tits" would eclipse the charts. ;-) 73's Richard Clark, KB7QHC |
It's an "abuse of language" shared by many, including manufacturers of
switches and relays of all kinds. ============================== Yet you still insist on using manufacturers' sales blurbs and specifications as engineering educational standards. |
I just like to give the readers an option. For transmission line terms,
they can choose between HP/Agilent's usages and definitions, or yours. For terminology regarding contacts, they have their choice between 3M's and Richard's. And for engineering educational standards, readers can choose among Ronold King, Terman, and Kraus, or Reg Edwards. I'm sure each will make the choice that he/she feels most confident with. Roy Lewallen, W7EL Reg Edwards wrote: It's an "abuse of language" shared by many, including manufacturers of switches and relays of all kinds. ============================== Yet you still insist on using manufacturers' sales blurbs and specifications as engineering educational standards. |
Thanks for that piece of reseach Roy. My career was in the engineering
side of Pilot devices at G.E. and thus the subject of contacts was very much my turf. Anybody can obtain an unused pilot device, pushbutton or what ever and they can measure the resistance as being in the 100s of ohms area across the N.C. contacts because of oxide build up even tho under pressure. If one was using one of the hand held instruments in a lot of cases it will show as being open since the battery voltage was less than 28 volts D.C As far as books are concerned major users such as the auto inductry required a certain number of operations without failure where in the past operators would just push the button again until it finally makes. This subject came up a few years back when computors came into the field and the natural reaction was to use gold plated contacts but these could not meet required criteria because gold plating is porous. G.E were benefitted with large contracts for contact blocks e.t.c. using reed switches and the like when the automotives decreed voltages of less than 28 volts D.C. where other contractors failed to meet required criteria of the customer. I could go on of course but there really isn't any need to. The initial statement that pressure solves things is just not true even tho in the past when television repairmen had the opportunity of pressing a button several times to make it operate. In todays world buyers demand evidence of quality without the option of one or two second tries I am surprised that "wipe" was the most common term that you saw in your brief search where as scrubbing action is more descriptive . Wipe alone describes distance of button operation after the initial contact is made which by rolling scraping action creates a side movement to push the oxides aside. If wipe alone is required without including a scrubbing action then wipe really only specifies available contact wear. But on the other hand we can admit that tho English is the common language there are differences. For your info at San Diego there is a college for American English no less I certainly do not advocate the use of acids to clean contacts in the normal sense but used it as an illustration of how it could remove oxide created by copper leaching thru the silver plating which inevitably causes momentary failures especially with older equipment. The same problem is avoided with reostats where they have a sliding/scraping motion to ensure accuracy of measurement. I have said enough since I am 'out of my turf' whereas on my own turf the grass is growing and it needs to be cut Regards Art crRoy Lewallen wrote in message ... I just like to give the readers an option. For transmission line terms, they can choose between HP/Agilent's usages and definitions, or yours. For terminology regarding contacts, they have their choice between 3M's and Richard's. And for engineering educational standards, readers can choose among Ronold King, Terman, and Kraus, or Reg Edwards. I'm sure each will make the choice that he/she feels most confident with. Roy Lewallen, W7EL Reg Edwards wrote: It's an "abuse of language" shared by many, including manufacturers of switches and relays of all kinds. ============================== Yet you still insist on using manufacturers' sales blurbs and specifications as engineering educational standards. |
"Ronald Walters" wrote in message om...
I have been using a MFJ-989C tuner for about (5) years without any problems. Just recently I have noticed that on the higher band, 24 MHz that the SWR occasionally would jump from an adjusted 1:1 SWR to infinity. A slight adjustment of the roller inductance appeared to solve the problem although I haven't ruled out a balum or antenna problem. I plan on investigating that this weekend, however, before I open the cabinet and look for problems I would ask the group for recommendations on cleaning the roller assembly and inductor to ensure good conductivity after I am done. I still have some old cleaning solutions from the old TV tuner days, some electrical cleaner (Appears heavy duty stuff) but maybe there is some other solutions someone might recommend. Your thoughts and recommendations are appreciated Ron - W4LDE Theories on wiping, etc non withstanding, the usual cause of roller problems on that tuner, " I have one" is due to gradual weakening of the pressure of the roller on the coil due to the weak micky mouse design of the coil. You can tighten it up by adjustng the little things on the end, that are locked with a hex key. But be very careful when you are doing this. It's easy to overtighten, and then it will bind easier. A dirty coil could be the problem, but I bet it's that coil starting to slightly loosen up from 5 years of turning back and forth. It then starts to "skip" at places, due to the lack of normal pressure against the coil. I've had to adjust mine a couple of times. If you coil feels overly easy to turn, compared to when new, that may well be the problem. MK |
Hi,
Deoxit by Caig Labs replaces the Cramolin product. http://www.caig.com The D5 is a 5 % concentration and normally cleans up most dirty contacts and surfaces. Very little is needed. 73 luke Richard wrote... One contact cleaner that I used that was better than most was Cramolin. This is a monomolecular layer solution that you would use very sparingly. However, as your tuner did not arrive brand-new (or brand-used) with it, your problem may be more mundane. The simplest way to defeat corrosion is with pressure. The spring tension of the roller may have slackened up over the years. 73's Richard Clark, KB7QHC |
On Fri, 24 Oct 2003 15:54:31 GMT, luke
wrote: Hi, Deoxit by Caig Labs replaces the Cramolin product. http://www.caig.com The D5 is a 5 % concentration and normally cleans up most dirty contacts and surfaces. Very little is needed. 73 luke Hi Luke, Thanks for your update. The suggestion of using Hydrochloric Acid for contact cleaning is one of the most outrageous suggestions I've seen come down the pike. I read of one poster who had obtained a gallon to accomplish a task, who then asked "what do I do with the 99.99% left over?" After I had just participated in the Washington Toxic Coalition's fund raiser the night before, the posting of indiscriminate advice that toxic chemicals are the best choice over and beyond what is a simple fix with Mark's allen wrench was another nail in the environmental coffin for our children. I fielded a contact problem for a local here and offered an even simpler suggestion: use clean water. Complete immersion followed by air drying at an elevated temperature works far better than a vat of chemicals. For those plagued with static problems, visit: www.aclstaticide.com/ which is one of the best and safest anti-static products on the market. You can use it as a spray or a wash, and do your floors or carpets with it without the fear of toxicity. 73's Richard Clark, KB7QHC |
Richard Clark wrote:
For those plagued with static problems, visit: www.aclstaticide.com/ which is one of the best and safest anti-static products on the market. Is that the stuff to use on dirty pots? -- 73, Cecil, W5DXP |
On Fri, 24 Oct 2003 12:56:54 -0500, Cecil Moore
wrote: Richard Clark wrote: For those plagued with static problems, visit: www.aclstaticide.com/ which is one of the best and safest anti-static products on the market. Is that the stuff to use on dirty pots? Hi Cecil, No. It used to be Freon, a very heavy liquid solvent used as a wash for dirty pots. As I offered, I use water. If the problem is not amenable to that, replace the pot. If you gain relief from some other product, you might be lucky that it will have solved it; or if repetition is necessary, then you have become "hooked" on that chemical solution (which again suggests a contact pressure problem). One might want to investigate the logic of "wiping" in the context of bad pots. ;-) [hint: HCL will not work.] 73's Richard Clark, KB7QHC |
Hi,
The Caig Labs products are also very effective on switches and pots. Deoxit D5 works great on the older radio dirty or scratchy pots, makes them work as new. Again, only very little of the stuff is needed to do the job. http://www.caig.com 73 luke Cecil wrote: Richard Clark wrote: For those plagued with static problems, visit: www.aclstaticide.com/ which is one of the best and safest anti-static products on the market. Is that the stuff to use on dirty pots? -- 73, Cecil, W5DXP |
Richard Clark wrote: On Wed, 22 Oct 2003 12:43:20 GMT, "Ronald Walters" wrote: I would ask the group for recommendations on cleaning the roller assembly and inductor to ensure good conductivity after I am done. Hi Ron, One contact cleaner that I used that was better than most was Cramolin. This is a monomolecular layer solution that you would use very sparingly. However, as your tuner did not arrive brand-new (or brand-used) with it, your problem may be more mundane. The simplest way to defeat corrosion is with pressure. The spring tension of the roller may have slackened up over the years. 73's Richard Clark, KB7QHC How about silver polish - is that any good for this? Someone told me it is - but I don't know. |
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One test for a counterfeit (U.S.) bill is to rub it on a piece of paper.
The ink on a genuine bill never dries, so you'll always get a slight smear. Somehow that doesn't seem like a good thing to leave behind on a relay contact you're trying to clean. Roy Lewallen, W7EL Richard Clark wrote: . . . You could also use a typing eraser to clean the mating surface. This is an old board cleaning tip that was NASA approved back when there were typewriters to need typing erasers. These erasers had the right amount of abrasive without having too much. The same goes for a dollar bill having just enough abrasive (useful for cleaning fouled relay contacts). But none of this really takes care of the problem. It simply puts you into the lock-step of a chemical dependency. . . . |
Richard Clark wrote:
This all returns to the same lack of need when tightening up the contact spring would do the trick just as Mark described. The "good" chemicals that have been suggested are not cheap, and the "bad" chemicals (Hydrochloric Acid no less) are extremely cheap to get, but a pain to get rid of. Not that I'd ever use Hydrochloric acid, but aren't we talking about a simple acid/basic reaction to turn it into something benign? I used to use an acidic Cibachrome photo developing solution which we used some magnesium hydroxide to neutralize. - Mike KB3EIA - |
On Mon, 27 Oct 2003 20:39:04 GMT, Mike Coslo
wrote: Richard Clark wrote: This all returns to the same lack of need when tightening up the contact spring would do the trick just as Mark described. The "good" chemicals that have been suggested are not cheap, and the "bad" chemicals (Hydrochloric Acid no less) are extremely cheap to get, but a pain to get rid of. Not that I'd ever use Hydrochloric acid, but aren't we talking about a simple acid/basic reaction to turn it into something benign? I used to use an acidic Cibachrome photo developing solution which we used some magnesium hydroxide to neutralize. - Mike KB3EIA - Hi Mike, Yes, I've done darkroom work too and I have worked professionally with acids in chemistry analysis (Titration and back-titrations). The difference there is that I could always measure my reaction products with indicators or probes or test strips. None of that has been offered as part of the regimen for fixing what an allen wrench can do quite well with none of the risk of uncontrolled exposure. If you have to buffer and wash the coil, you may as well skip the acid anyway and do it right. 73's Richard Clark, KB7QHC |
Richard, When you are wrong then why not admit it instead of digging a
hole for yourself Yes, you can clean a contact by drawing a clean piece of paper thru it but never anything as abrasive as a file or sandpaper as the deposit left is offtimes worse than the original contact contaminate. Look back at Roy's comment with respect to wipe. It is probably for a circuyit board insertion and where wipe is the one and the same as a scrubbing dimension, It says nothing about pressure. You also referred to bifircated contacts in one of your wrigglings, a bifocated contact can help in a life or reliability test only because the odds of closure are enhanced because you have a backup contact. Unfortunaley if the wipe or scrubbing action is not sufficient for closure it will not help.....two bad apples does not trump one single good apple. The fact is that you will do anything to knock me and are now reducing yourself to 'on the fly' thoughts, thus Reg said "garbage to another post contact by yourself as I also did with your pressure statement. Straighten yourself up. You are a very knoweledgable person even though you do not have a technical degree but your studies in Literature and Shakespere should not hold you to the of the voice of Punchinello when you decide to dig a hole for somebody else. Why not put hate thoughts aside and get back to sharing your considerable knoweledge in the electrical field Regards Art Richard Clark wrote in message . .. On Mon, 27 Oct 2003 03:58:10 GMT, wrote: How about silver polish - is that any good for this? Someone told me it is - but I don't know. Hi OM, If silver polish worked, then you could as easily boil it in water in an aluminum pan - does the same thing. You could also use a typing eraser to clean the mating surface. This is an old board cleaning tip that was NASA approved back when there were typewriters to need typing erasers. These erasers had the right amount of abrasive without having too much. The same goes for a dollar bill having just enough abrasive (useful for cleaning fouled relay contacts). But none of this really takes care of the problem. It simply puts you into the lock-step of a chemical dependency. This all returns to the same lack of need when tightening up the contact spring would do the trick just as Mark described. The "good" chemicals that have been suggested are not cheap, and the "bad" chemicals (Hydrochloric Acid no less) are extremely cheap to get, but a pain to get rid of. 73's Richard Clark, KB7QHC |
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