---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 03/17/12: 8 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:49 AM - Source for Bakelite - 1/32" thick (Alfio) 2. 05:41 AM - Re: Source for Bakelite - 1/32" thick (Ed Anderson) 3. 05:43 AM - Re: Source for Bakelite - 1/32" thick (Robert Borger) 4. 06:32 AM - Re: Source for Bakelite - 1/32" thick (Vern Little) 5. 07:19 AM - Re: Poor Wiring Practice for VHF Noise? (stearman456) 6. 08:50 AM - Re: Source for Bakelite - 1/32" thick (Robert L. Nuckolls, III) 7. 04:43 PM - Re: Source for Bakelite - 1/32" thick (Robert L. Nuckolls, III) 8. 09:10 PM - Re: Source for Bakelite - 1/32" thick (Don) ________________________________ Message 1 _____________________________________ Time: 04:49:37 AM PST US Subject: AeroElectric-List: Source for Bakelite - 1/32" thick From: "Alfio" I am building a Wingtip VOR Antenna, and am in need of 1/32" thick bakelite (3.25" x .8"). Any body have a source (mail order as reside in Canada) for this bakelite? Thanks. Alfio Read this topic online here: http://forums.matronics.com/viewtopic.php?p=368760#368760 ________________________________ Message 2 _____________________________________ Time: 05:41:58 AM PST US From: "Ed Anderson" Subject: Re: AeroElectric-List: Source for Bakelite - 1/32" thick Here is some material that may serve as a stand-in for bakelite - appears to be used as an arc insulator among other things. http://www.mcmaster.com/#garolite/=gp981g Ed -------------------------------------------------- From: "Alfio" Sent: Saturday, March 17, 2012 7:48 AM Subject: AeroElectric-List: Source for Bakelite - 1/32" thick > > I am building a Wingtip VOR Antenna, and am in need of 1/32" thick > bakelite (3.25" x .8"). Any body have a source (mail order as reside in > Canada) for this bakelite? Thanks. > > Alfio > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=368760#368760 > > > ________________________________ Message 3 _____________________________________ Time: 05:43:35 AM PST US Subject: Re: AeroElectric-List: Source for Bakelite - 1/32" thick From: Robert Borger Alfio, Why bakelite? There are lots of much better (stronger, more durable, more easily worked) plastics available today. I don't know about bakelite in particular, but McMaster-Carr has a large selection of plastics of various types and sizes. http://www.Mcmaster.com/ > Raw Materials > Plastics There is probably something suitable for your purpose. Blue skies & tailwinds, Bob Borger Europa XS Tri, Rotax 914, Airmaster C/S Prop. Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP 3705 Lynchburg Dr. Corinth, TX 76208-5331 Cel: 817-992-1117 rlborger@mac.com On Mar 17, 2012, at 6:48 AM, Alfio wrote: I am building a Wingtip VOR Antenna, and am in need of 1/32" thick bakelite (3.25" x .8"). Any body have a source (mail order as reside in Canada) for this bakelite? Thanks. Alfio ________________________________ Message 4 _____________________________________ Time: 06:32:25 AM PST US From: "Vern Little" Subject: Re: AeroElectric-List: Source for Bakelite - 1/32" thick When all else fails, Aircraft Spruce. They only offer down to 1/16" material, however. Search for Phenolic. Beware: This stuff is toxic so be careful when machining it. Also know as Micarta in some places. V -----Original Message----- From: Alfio Sent: Saturday, March 17, 2012 4:48 AM Subject: AeroElectric-List: Source for Bakelite - 1/32" thick I am building a Wingtip VOR Antenna, and am in need of 1/32" thick bakelite (3.25" x .8"). Any body have a source (mail order as reside in Canada) for this bakelite? Thanks. Alfio Read this topic online here: http://forums.matronics.com/viewtopic.php?p=368760#368760 ----- No virus found in this message. Checked by AVG - www.avg.com ________________________________ Message 5 _____________________________________ Time: 07:19:00 AM PST US Subject: AeroElectric-List: Re: Poor Wiring Practice for VHF Noise? From: "stearman456" nuckolls.bob(at)aeroelect wrote: > > When every systems guy has to fight for and then > jealously guard space on the airplane allotted to > his efforts, it would be a disaster of some discovery > were made where separation of certain wires from certain > other wires was necessary or useful. > Of course! I never stopped to look at it from that angle. That makes perfect sense. Thanks very much for the help. Dan Read this topic online here: http://forums.matronics.com/viewtopic.php?p=368766#368766 ________________________________ Message 6 _____________________________________ Time: 08:50:11 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Source for Bakelite - 1/32" thick At 06:48 AM 3/17/2012, you wrote: I am building a Wingtip VOR Antenna, and am in need of 1/32" thick bakelite (3.25" x .8"). Any body have a source (mail order as reside in Canada) for this bakelite? Thanks. Alfio Bakelite is is the world's first synthetic plastic. It was the material of choice for millions of molded shapes in the crafting of consumer products back about 1933. http://en.wikipedia.org/wiki/Bakelite The stuff is still made but it's position in the marketplace is more for historical authenticity or decorative purposes as opposed to new product design. The stuff is brittle and in 1/32" thickness would be VERY fragile. In fact, I sort of doubt that Bob's design uses real Bakelite. I think he may have used the term to describe the piece of plastic more as a historical recognition of its function than for it's material. Bob is of my generation . . . many terms applied to ideas common to our experience took on names that were more generic than specific. I.e., all copy machines are 'xerox' machines, all tissues are 'kleenex' etc. The purist craftsman would recognize that this insulator serves TWO purposes. First, it's a structural material that maintains the position (.31" gap) between the two lower pieces of aluminum. It's second function is to serve as the dielectric in the capacitor formed between the lower left and upper aluminum strips. The exact value of that capacitor is a function of separation, surface area and the dielectric constant of the insulating material in the gap. This capacitor was no doubt 'tuned' on the bench. Substitution of some plastic other than the material used in the original design will change the value of that capacitor. Emacs! This particular technique for attaching a feedline to the antenna is called a 'gamma match'. It is characterized by a gamma rod that taps up from ground onto the radiating element of the antenna. If the rod tapped onto the radiator at the base, the impedance presented to the feedline is zero ohms; if connected at the tip, it is thousands of ohms. Somewhere between the base and the tip, we find 50 ohms. Problem is, the gamma rod is not itself a confined transmission line . . . it has an inductive reactance that degrades the transfer of power between the antenna and feedline. We can put a capacitor in series with that inductance to resonant it at the frequency of interest thus creating a series-resonant circuit. This has the net effect of putting a 'dead short' between the end of the feedline and the tap on the antenna in spite of the fact that they are separated from each other by some distance. Back in my much younger days, adjustment of a gamma match involved moving the tap in search of the impedance Nirvana followed by a re-tuning a variable capacitor . . . Emacs! to wash out the new value of inductive reactance in the gamma rod. In fact, the last antenna I built with this technology used a capacitor very much like this one. In the case before us, Bob Archer has deduced the right place to tap the antenna for 50 ohms. He also crafted the DIMENSIONS and MATERIALS for a capacitor that most nearly cancels out the reactance of the gamma-rod. In the capacitor above, the dielectric (insulator) is air. In Bob's design, the dielectric is 'Bakelite' . . . or something he called by name. The short answers come with two options: (1) use any durable dielectric material of the same thickness to craft a similar device knowing that the 'match' will not be optimized. I suspect that the resulting antenna will not suffer so badly that degradation of performance will be observable by a pilot in the cockpit. Epoxy/Fiberglas (like etched circuit boards) would be good. (2) craft a new capacitor design that is adjustable. You could use a small variable capacitor like this . . . Emacs! With an adjustable capacitor, the new match can be optimized with the application of suitable test equipment. Even better, I might craft a new, optimized but fixed capacitor as a double sided etched circuit board and even add an SMA right angle connetor to the assembly to make a more elegant termination of the coax. To make a reasonable approximation of Bob's original design, look for any plastic material of the right thickness. 1/32 is not going to be easy, thicker material will be much easier but demand large changes to other dimensions. Bob . . . ________________________________ Message 7 _____________________________________ Time: 04:43:30 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Source for Bakelite - 1/32" thick At 07:40 AM 3/17/2012, you wrote: > > >Here is some material that may serve as a stand-in for bakelite - >appears to be used as an arc insulator among other things. > >http://www.mcmaster.com/#garolite/=gp981g Looks like this comes in lots of flavors none of which are named 'Bakelite' and include some of the legacy g-type insulations that were once popular for etch circuit boards. These were in fact epoxy glass formulations. There are a bunch of plastic materials that could be substituted for the Bakelite. I was just walking down the isles at Lowes and found a number of plastic products or containers for product that were fabricated from 1/32" (or thereabouts) material. Some of the bottles for stuff like liquid dishwasher detergents looked like they could supply a piece of pretty durable plastic of that thickiness. I thought about this on the way home from Wichita and concluded that one handy solution would be to craft the capacitor/insulator assembly from a piece of single sided copper clad. The copper would replace the top aluminum plate. It would also provide nice 'solder pads' for direct connection of the coaxial feedline. The two nylon screws would be replaced by bonding the under side of the ECB material to the matching stub. I've got some plans for some experiments on the Medicine Lodge OBAM aircraft antenna range (my back yard) to see if I can measure any performance difference between a VOR antenna with versus one without a BALUN. I can also craft the Archer style VOR antenna and do the experiment to deduce the proper change in dimensions to us 1/16" FR-4 ECB material in place of the Bakelite. I've got probably 100 square feet of the ECB material and a shear. I could provide .8" wide strips of the stuff along with modified dimensions optimized to the change of dielectric constant for the insulating materials. Does anyone have a B-A wing tip antenna kit that they've not yet installed? It would be handy to borrow it for the experiment . . . to be returned in as-new condition. Bob . . . Bob . . . ________________________________ Message 8 _____________________________________ Time: 09:10:42 PM PST US From: "Don" Subject: RE: AeroElectric-List: Source for Bakelite - 1/32" thick Bob, I have one that has the wrong cap on it. I talked to Bob Archer and he told me thet the cap belongs on one of his dipole ant rather than on the monopole that it is installed on. He sent me a replacement cap that I have not installed yet. I can ship the entire thing to you for the experiment. You will also notice that the "Bakelite is different on each cap" Send me an address via the email address that shows with my name. -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Saturday, March 17, 2012 4:42 PM Subject: Re: AeroElectric-List: Source for Bakelite - 1/32" thick At 07:40 AM 3/17/2012, you wrote: > > >Here is some material that may serve as a stand-in for bakelite - >appears to be used as an arc insulator among other things. > >http://www.mcmaster.com/#garolite/=gp981g Looks like this comes in lots of flavors none of which are named 'Bakelite' and include some of the legacy g-type insulations that were once popular for etch circuit boards. These were in fact epoxy glass formulations. There are a bunch of plastic materials that could be substituted for the Bakelite. I was just walking down the isles at Lowes and found a number of plastic products or containers for product that were fabricated from 1/32" (or thereabouts) material. Some of the bottles for stuff like liquid dishwasher detergents looked like they could supply a piece of pretty durable plastic of that thickiness. I thought about this on the way home from Wichita and concluded that one handy solution would be to craft the capacitor/insulator assembly from a piece of single sided copper clad. The copper would replace the top aluminum plate. It would also provide nice 'solder pads' for direct connection of the coaxial feedline. The two nylon screws would be replaced by bonding the under side of the ECB material to the matching stub. I've got some plans for some experiments on the Medicine Lodge OBAM aircraft antenna range (my back yard) to see if I can measure any performance difference between a VOR antenna with versus one without a BALUN. I can also craft the Archer style VOR antenna and do the experiment to deduce the proper change in dimensions to us 1/16" FR-4 ECB material in place of the Bakelite. I've got probably 100 square feet of the ECB material and a shear. I could provide .8" wide strips of the stuff along with modified dimensions optimized to the change of dielectric constant for the insulating materials. Does anyone have a B-A wing tip antenna kit that they've not yet installed? It would be handy to borrow it for the experiment . . . to be returned in as-new condition. Bob . . . 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