Minding My Beeswax... RF style
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If I understand correctly, the coating on the RF coils and such is Natural Beeswax- Is this correct? While my RF coils are ok(show good continuity where good continuity should occur) some of the coating has gone missing, both through normal wear and during the rebuilding process, and I wish to recoat those areas. I just wanted to confirm it is indeed natural beesawax.
Scott[/list]
Old Cars, Old Radios, Old Pipes and Young Women... What more is there?
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Well, failing to receive a reply, I went ahead with the experiment. Having gently cleaned the original coating with a soft toothbrush, I heated a small amount of unscented natural beeswax(courtesy of the candle section of a local "Michaels" craft store) in a cleaned and de-labelled small "Bush's Baked Beans" can. The can was placed into water in a pot, and set on the stove, with the stove heating the water, water heating the can, and the wax melting quite nicely.
The can, being about 2" diameter, by 3" deep, was large enough to do a nice job. I carefully bent all the leads to the same direction, and gingerly lowered the coils into the melted wax, and then right back out. I repeated once, immediately, then let them drain for a couple moments. Then it was off to cool, and all looks very good. Nicely sealed.
Now to go finish putting together the antenna broadcast & range coils, and start on the RF ones next... Finally the oscillator set... This thing will be completely like new when done..
Scott
Old Cars, Old Radios, Old Pipes and Young Women... What more is there?
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Scott - sorry, been busy this evening and could not reply until now.
Were it me, I would not reseal the coils in wax. I would carefully melt off all remaining wax with a hair dryer and then spray them with lacquer.
Yes, Philco used wax originally. But this is one of those instances where we have learned from their mistakes. Wax is great for retaining moisture in those old coils. OTOH, lacquer will do a much better job of sealing out moisture; once you have baked the moisture out with a hair dryer or, in severe cases, literal baking in an oven at a fairly low temperature; typically 200-225 degrees F for a half hour or so.
As you have already used wax, all I can tell you is "lotsa luck, pal."
One man's opinion...that's all...
--
Ron Ramirez
Ferdinand IN
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I don't believe Philco used pure bees-wax. I think it will melt way too easily in the hot environment of a radio chassis.
The wax originally used had a higher melting-point too many sulfur compounds (as it turns out) which over time and with moisture absorption, created weak suphuric acid which corroded the copper ("The Greenies") and opened up coils 60-70 years later.
Spray lacquer is much better, as Ron advises.
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Pure beeswax has a melting point around 140deg.F if I remember the information I read yesterday in the package... I don't know how hot the chassis gets- but your comment sounds reasonable, Chuck. So I guess that means I get to tear down the antenna section again, and strip and laquer the coils... I'm having fun...   Suggestions on laquer? Or any clear spray on will do?
Thanks for the replies!
Scott
Old Cars, Old Radios, Old Pipes and Young Women... What more is there?
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I've always liked beeswax; HP and Boonton Radio did also.
For 40 years the Boonton Radio Q Meter Inductors were all dipped in a pot of pharmaceutical grade beeswax- anyone in the industry has seen USP beeswax. It was my department- I dipped them at times too.
I've always used it on my coils whenever rewinding or repairing and never had any problem with it. It has the advantage of allowing repair while the modern sealers are set for life- there's no going back. Another advantage is using a microscopic bit on the end of a screwdriver to hold a screw for those difficult to get at places.
Pete AI2V
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What is the melting point on the pharmaceutical grade beeswax? And how does it differ from natural beeswax for this purpose?
Scott
Old Cars, Old Radios, Old Pipes and Young Women... What more is there?
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I don't know the melting point of the USP beewax. It was bought by the 1 pound brick and pieces melted as needed in a pot. I suspect that it is only a sterile and filtered version.
As a radio hobbyist it has taken 40 years to use up one brick. None of my coils ever melted or moved. Keep in mind that the fine wire that is waxed will fuse (at the bend points) before it gets warm enough to melt. If you are worried about the wax melting by tube heat, relax. Heat generating rectifiers and audio output tubes are usually located distant from RF/IF coils.
Pete AI2V
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Thanks Pete!
Scott
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Everything you wanted to know about the melting point of Bees Wax http://www.spwax.com/spbeeswa.htm The high point of the melting point would be about 150'F and the low point would be about 140'F. I would think in most situations unless one had the coils right next to a tube there would be no way that it would get up to 140F to melt the wax.
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They've got a site for EVERYTHING! lol
Thanks for the info-
Scott
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The ambient temperature underneath a typical 5 or 6-tube chassis can rise over 100 degrees in that enclosed, poorly ventilated space - conducted heat from the tubes and large power resistors, and the power transformer.
The beeswax may not melt, but over time it will soften and creep and slough off the coil. I've seen many coil forms with all the impregnating wax globbed up at one end (lowest point) of the form from this.
Just my observations.
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As an alternate way of sealing coils, in the past I've used clear fingernail polish with fairly good results. Anyone else use this?
Bill
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I think clear nail polish is just "thick" clear lacquer anyway. I've used it too. Also to dab over a repair on a single coil lug re-connect.
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