I'm giving the home brew archer nav antenna a try. It calls for a small strip of Bakelite,also known as phenolic. Where do folks get this from? I can find sheets on eBay but it's way more than I need and cost ends up around $25. Not that much but takes a big chunk of the cost savings from rolling my own.
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Where can I find Bakelite
- Thread starter unitink72
- Start date
Carl Froehlich
Well Known Member
A scrap piece of fiberglass works fine as well. If not thick enough, stack a couple together. You can adjust the gamma match by making this dialecgric thicher (less capacitance) or thinner (more capacitance). Same for the price of aluminum coupling the antenna to the feed line. More aluminum (more capacitance), etc.
The best way to tune this antenna is to use an antenna analyzer like this one:https://www.amazon.com/SWR-Antenna-...21992933&sr=8-2&keywords=mfj+antenna+analyzer
First adjust the antenna over all length for the center of nav band (about 113 MHz). Longer is lower frequency. Leave it a little long for this first adjustment. Now adjust the gamma match to achieve the lowest SWR. Then go back and trim the antenna to resonate at 113mhz.
I also suggest you modify the dimensions so that the antenna extends as far out from the rib as it can go into the wingtip. The over all length from wing rib to antenna tip will remain about the same. Mounting the antenna on a 0.032? angle attached to the wing rib instead on glassing it into the wingtip makes like a lot easier as well.
Carl
The best way to tune this antenna is to use an antenna analyzer like this one:https://www.amazon.com/SWR-Antenna-...21992933&sr=8-2&keywords=mfj+antenna+analyzer
First adjust the antenna over all length for the center of nav band (about 113 MHz). Longer is lower frequency. Leave it a little long for this first adjustment. Now adjust the gamma match to achieve the lowest SWR. Then go back and trim the antenna to resonate at 113mhz.
I also suggest you modify the dimensions so that the antenna extends as far out from the rib as it can go into the wingtip. The over all length from wing rib to antenna tip will remain about the same. Mounting the antenna on a 0.032? angle attached to the wing rib instead on glassing it into the wingtip makes like a lot easier as well.
Carl
JonJay
Well Known Member
How are they using it? Bakelite was popular as it could be molded into shapes. If all you need is some flat stock, almost any insulating material would probably work. You might consider tempered Masonite which you can get at any big box store. Not as brittle and easier to work with. Not sure if they sell smaller than a sheet though. That is as close to Bakelite as you can probably get in density.
Charles in SC
Well Known Member
Try Radio Shack for a small piece of phenelic if you have one near you or most any electronic supply house. A piece of circuit board will probably do the same thing. I doubt if you will fing any genuine Bakelite that is not in an antique shop.
az_gila
Well Known Member
RS gone
All of our local Radio Shacks went belly up. Isn't that true across the whole country?
All of our local Radio Shacks went belly up. Isn't that true across the whole country?
Plummit
Well Known Member
You might try JK Electronics in Westminster, CA. They probably have it.
http://jkelectronics.com/home.html
~Marc
http://jkelectronics.com/home.html
~Marc
Some of the local EAA guys that are HAMS (like me) may have one you can borrow.
All of our local Radio Shacks went belly up. Isn't that true across the whole country?
I thought so too till I met a guy last year that owns several.
https://www.radioshack.com/
Virtually any electronic hobby store will sell you this stuff, it's used to make printed circuit boards. Or, use fiberglass or whatever. BUT, as Carl said above, unless you are able to exactly duplicate (material, thickness, area, of) the capacitor, you will need some test equipment to tune the antenna to resonance and the capacitor to proper phase match.
I like Carl's idea of mounting it to an aluminum angle attached to the rib, although I captured mine under the wingtip nut plate rivets, and left enough slack in the coax to allow removal and laying the tip on top of the wing.
I suspect most reports of poor performance come from people who did not do proper tuning. (Not counting the grossly incorrect installations!)
I like Carl's idea of mounting it to an aluminum angle attached to the rib, although I captured mine under the wingtip nut plate rivets, and left enough slack in the coax to allow removal and laying the tip on top of the wing.
I suspect most reports of poor performance come from people who did not do proper tuning. (Not counting the grossly incorrect installations!)
Not withstanding the excellent discussions above, Aircraft Spruce does offers phenolic sheet in various thicknesses.....
az_gila
Well Known Member
Maybe in CA, but it only lists 3 in AZ (way out in the boonies even) and they come under "authorized dealer" label not an actual store. I think they are regular A-V stores with a RS parts drawer cabinet in the back.
Floppy
If you mount it via a piece of angle on the outboard rib, how do you support the long (opposite) end of the antenna?
What about running the nav/strobe power wires along the leading edge. If the antenna is mounted to the rib, do you still run those wires along that angled leg? I could see that getting complicated. A well thought out connector might help.
If you mount it via a piece of angle on the outboard rib, how do you support the long (opposite) end of the antenna?
What about running the nav/strobe power wires along the leading edge. If the antenna is mounted to the rib, do you still run those wires along that angled leg? I could see that getting complicated. A well thought out connector might help.
Carl Froehlich
Well Known Member
The outboard side of the antenna just rests against the inside, outboard edge of the wingtip.
Running strobe and nav light wires on the angle edge of the antenna is not only unnecessary, it is not desired. Mount the antenna a few inches aft of the Nav/strobe wires and gain some separation. With the antenna mounted on the outboard rib, no additional connector is required.
The photo shows a nav antenna installed on an RV-14 in the process of being tuned (overall length is way too long). The black tape is use just to hold it up for tuning. The wingtip slides over the antenna.
Carl
Carl
Aircraft Spruce p/n 03-52400
This.
I used a piece of Aircraft Spruce p/n 03-52400 phenolic for my most-excellent-wingtip-mounted copy of the Bob Archer Nav antenna. One square foot (minimum order) will provide you a lifetime supply of the material.
That said, I'll give you a piece large enough for your needs if you send me an S.A.S.E.
This.
I used a piece of Aircraft Spruce p/n 03-52400 phenolic for my most-excellent-wingtip-mounted copy of the Bob Archer Nav antenna. One square foot (minimum order) will provide you a lifetime supply of the material.
That said, I'll give you a piece large enough for your needs if you send me an S.A.S.E.
