View Full Version : HomeBrew ScrewDriver 160-10 mtr plans wanted
04-04-2009, 10:17 AM
Has anyone built a 160-10 meter ScrewDriver antenna who would be willing to share their plans/experiences with it?
Thanks in advance for any help/assistance/tips..
04-04-2009, 04:51 PM
I'd be interested also .
04-05-2009, 12:38 AM
04-05-2009, 02:19 PM
I down loaded , will look at later , thanks .
04-19-2009, 08:54 PM
Thanks for the link. I have also found both of D.K. Johnson, W6AAQ, books on CD from WR6WR.com(World Radio) and ordered them - they have the same info and more and the 2nd book has some updates. I am attempting to call/contact him now to see if there are more updates since that book, as last update was around 2000.
I have since been to the World Radio site and it has expired as of 04/05//09 and doesnt say whether it will be renewed - CQ aquired World Radio evidently last fall and is putting out a web only issue, but there is nothing about the cds(I got WorldRadio 1999 and 2000 - the 2000 disk has the 2 W6AAQ books; "40 + 5 years of HF Mobileering", and "Everything You Forgot to Ask About HF Mobileering"). Not sure where or if you can get them now.
I am hoping to get in touch with W6AAQ and see if he has any updated info and tips for building this. I also would like to get in touch with anyone in my area(Salt Lake and/or Utah counties Utah and join heads and share some materials - most of the pipe/tubing for sale at the local Home Depot or Lowes, has to be bought in greater lengths than needed for one antenna.
Thanks again and 73,
04-28-2009, 03:49 AM
Has anyone built a 160-10 meter ScrewDriver antenna who would be willing to share their plans/experiences with it?
Thanks in advance for any help/assistance/tips..
Here's one for 40m to 10m. Not for the faint hearted though!
05-19-2009, 04:34 PM
I just finished building the DK3 and am pleased with it, and it wasn't a real brain-buster to do.
I found everything except for the finger stock and buss wire for the coil locally ... the $12 screwdriver at Harbor Freight, the PVC, threaded rod, nuts, and washers, at Lowes, and the THIN WALL wall PVC for the weather cover at an irrigation supply (Lowes doesn't have it).
If your screwdriver is less than 12-volt (mine was 4.5 volts), you will need a series resistor to drop the voltage to the motor or you'll smoke it.
For the main mast I found a piece of 2" aluminum pipe at a metal recycling center, but in the absence of that you can order a 6-foot length from Texas Towers for $3.30/foot plus about $8 to ship, enough for two antennas.
Depending on your aluminum mast, the PVC pipe that is used for a coil form may have to be sanded a little to get it to fit inside the aluminum mast. If you can't find someone to cut the groove for the coil wire on a lathe', you'll have to get resourceful and wind the wire simutaneously with monofilament fishing line of the same size to maintain spacing. However, in the absence of grooves, the 15 inch section for the coil will have to have it's diameter reduced somehow so that the coil diameter is no larger than the PVC coil form diameter, so you'll have to get creative to figure out how to do it. (I cut my diameter down with a jig I made for my router and bought the monofiliment, but got lucky and found someone with a lathe before having to do it that way.)
I bought the 16 gauge tinned buss wire at Wireman. To wind the 150 turn, 10 TPI coil you will need about 75 feet, but I recommend you spend another few bucks and buy 100 feet.
Finding finger stock was a pain in the neck, but I was finally able to locate a manufacturer that agreed to send me a free 15 inch sample strip, enough for two antennas, for a shipping and handling charge of $15 which I readily accepted. They put a conductive adhesive strip on it that allowed me to secure it to the aluminum tube. I wrapped about two turns of electrical tape around it to make sure it stayed put.
After completing it I built a little 1-inch long, 9-turn shunt matching coil and got mine to give me a <= 1.5:1 swr from 3.5 to 30 mhz using a 102" Radio Shack CB whip cut down to 72"
The above comments are just some things that came to mind, but if you have any specific questions or want any suggestions or maybe photos, I'll try to help. My home email is "rabarber at comcast dot net".
05-19-2009, 06:43 PM
I am building the one that is sdescibed in the ARRL Antenna Book. Essentially the same design I guess. I went to the scrap yard and found a 3' piece of 2" copper. I used 1 1/2" PVC for the coil.
After several fruitless attempts at threading the PVC, I found an adjustable pipe die at work. I adjusted the jaws to a little bit wider than the 1 1/2" size and threaded the PVC through by hand. Three passes later, I had it threaded completely.
For the coil, I went to Lowes and bought a 250' roll of 17 ga. electric fence wire and wound that onto the PVC.
For the finger stock, I am leaning towards something using a 2" copper pipe coupling and soldering some fingers made out some thin (0.030" maybe) copper sheet metal and possibly wrapping a spring around the fingers to keep them place.
Total so far has been around $30.00 so far. I am looking around for a screwdriver with dead batteries to use.
05-19-2009, 07:07 PM
Sounds like you're on the way.
Since you started with copper pipe instead of aluminum for the mast you have more options for the finger stock. I was looking for copper initially but everyone wanted an arm and a leg for it, and 10 feet minimum @$12 a foot nixed that route.
I'm thinking about building another one. I took a Ryobi cordless 12 volt drill apart the the planetary gearmotor inside is perfect, but it's a few thousands too large to fit inside the 2" aluminum so I'm thinking about getting the next larger tubing size from Texas Towers which should accept the motor and will telescope over the 2".
I'd like to see ARRL's version of it, but don't have any of the antenna books and don't know which book of the several that are offered it would be in. What's the title of the book you are using?
By the way, you might want to check out Wal-Mart, the other day I found a cordless screwdriver for about $8. I wanna say it was a Black and Decker, but don't remember for sure, but it was fair sized cordless tool display.
05-19-2009, 07:21 PM
The article I am referncing is from the 2007 Antenna Book. It is the chapter about Mobile and Maritime Antennas.
Not really a hard set of plans to follow, just a basic description of what you'd need to build one.
05-19-2009, 09:24 PM
Check out ON4CFC web site. He has made 2 kinds of screw type antennas, with one being motorized.
He also has some other neat stuff there as well.
05-19-2009, 09:33 PM
Nice website. I wish I were able to machine some of the stuff he has. Really beautiful stuff.
05-20-2009, 12:01 AM
That kind of machine work is outta my realm.
Here is a shot of my attempt at posting a photo:
Aha ... that worked.
05-20-2009, 12:43 AM
Good job! Looks good. Got any pics of the feed point?
05-20-2009, 01:08 AM
OK, here is the feed point. There are two wingnuts that you can see. The antenna has a stud at the bottom with a wingnut which secures the PVC motor holder into the mast or tube, and also serves as the RF feed point.
The lower wingnut has a ring crimp lug and short piece of wire with a hook on the end. I set the antenna into the tube and the stud slides down into the slotted portion. I hook the bottom wingnut stud to the top wingnut stud with the hook jumper, and tighten both wingnuts. This holds it in place (at least so far it has).
the lower wingnut goes to the center connector of the SO-239 connector. The very bottom stud goes to the shield of the SO-239, and has the ground braid that connects to the frame of the car.
The shunt coil which wasn't installed when the photo was taken connects between the bottom and center studs, which is between ground and RF hot.
The red and black leads are the power to the screwdriver motor which goes through a dropping resistor just inside the hatch and on to the radio mount between the seats that has a DPDT spring loaded center off switch to control the motor.
The worm clamps and a portion of white steel mount are visible and are a mount with a quick disconnect for my Hamsticks and Webster Bandspanner antennas. The coax serves both mounts and gets moved to whichever antenna is in use. I have a 90 degree adapter on the coax now so it looks a little neater.
This is what the whole mess looks like from the rear:
05-20-2009, 10:29 AM
Again, very nice and clean looking installation.
05-20-2009, 05:44 PM
Nice, love the craftmanship, and the install looks good on the van......cool little VW bug in the background too, looks like a '69 maybe '70?
05-20-2009, 06:29 PM
You're correct, that's a '69 Bug. It and my motorcycle are my daily drivers and the van is the XYL's.
Thanks for the compliments. If/when I remove the other mount and worm clamps that should clean it up a little more.
It took a little bit of head scratching to come up with a mount that would clear the hatch, be visible in the left mirror for a tuning aid, and not stick out on the side to minimize the risk of snagging it on something (like a kneecap). The steel part of the mount is two pieces of 3/8" x 2" mild steel bar and two pieces of 1-1/2" square tubing. It attaches to the left side of the trailer hitch frame with a piece of 1-1/2" angle iron and two nuts and bolts, so it can be removed in a couple of minutes if need be.
This isn't antenna related, but below is a picture of the mount for the radio in case anybody needs a van mounting suggestion. It is a piece of plywood with another piece of plywood that hinges, and there is a hinged leg underneath that props it up. When the radio isn't installed, the leg folds underneath and the platform hinges down flat so you can walk between the seats per request from the wife. You can see the spring loaded toggle switch that moves the antenna coil up and down. The power for the antenna switch and the radio is fed by a 10 gauge cable and power poles. The cable runs under the center console, through a rubber grommet in the firewall directly to the battery through a pair of 30 amp fuses at the battery. I plan on adding a 5 or 10 amp fuse for the antenna power instead of relying on the big fuses.
Before anybody points out "loose cannon" safety issues I will be addressing that shortly. Right now the front of the plywood base is secured by wedging under the console. Later I am going to anchor the rear with some sort of a bracket that goes across the base and under the two seat rails, and then add some type of metal bracket to lock the hinged platform in the open position. Right now I have a locking nylon strap which is visible in the photo, but not in place, which buckles around the radio. I usually just hang the mic on the toggle switch. There is a 3/4" x 1/2" wood strip underneath the rear of the radio that the rubber feet rest against to keep the radio from sliding back. With the armrest folded down my right arm is in an ideal and comfortable position for the tuning knob, and the panel is easy to see at a glance.
05-20-2009, 09:38 PM
super slick, I like the mounting up front in between the seats, gives me a few ideas for our '04 honda odyssey mini-van. And I'm really digging the antenna mount on the rear corner, out of the way enough to clear the shins, and yet sturdy too being mounted to the hitch. I really like it, nice job. Aircooled VW's are my passion, been rebuilding the old microbuses for most of my life, started with the beetles, and eventually into the microbus scene, so very cool on having a daily driving VW.
05-22-2009, 11:00 AM
Roger on the aircooled Bugs. I got my first one, a '67, in 1968, and have had one pretty much continuously since then, about fourteen I think, so I guess you could say I'm fond of them myself.
No plans to put a mobile in this one ... Hi
06-04-2009, 09:55 PM
Here are some pics of mone that I have built so far. I now need to start working out how to mount it to the truck.
The "screwdriver" or how it started out life.
The screwdriver after I modified it. The nutdriver has a 1/4-20 nut epoxied into it. There is a 12-24 screw that runs through the base of the screwdriver to attach it to the copper pipe.
The base of the coil. I heated the nut up and pressed it into the cap. After it cooled down, I filled the other side up with epoxy to help hold in place.
06-04-2009, 10:04 PM
The screwdriver and coil attached.
The top of the coil.
Some pics of the "fingerstock". It is made out of a 2" copper coupling.
The top of the antenna.
The completed antenna.
The copper pipe is 2" diameter. The PVC is 1-1/2". As I posted earlier, I threaded the PVC pipe. The wire is 17 gauge electric fence wire. I expoxied it every 10 or so turns to stay in place. The first time I woulnd the coil, I didn't epoxy the wire in place and it came loose.
The "fingerstock" is attached to the pipe with three 6-32 screws. The four 8-32 screws towards the base of the antenna screw into the pipe and bite into the the PVC collar on the screwdriver. I did that to help center the screwdriver in the copper pipe and take out the "wobble" of the antenna.
Now to work on the mount for the truck.
06-05-2009, 10:56 AM
That looks decent and I like your approach for the finger stock. I'm already trying to think of something you can use as a weather cover. Thin wall PVC irrigation pipe comes to mind. I guess the best way to describe it would be like a schedule 10 or schedule 20 (thin wall).
If it ever becomes necessary to replace the threaded nutplate in the motor end of the coil you can pick up a threaded brass insert from Tru-value and with the proper sized hole, it will thread into the plastic fitting without epoxy. It is tapped with machine threads that will match the allthread. These inserts are used in woodworking projects and here is a link to one:
On the whip end, you can go to Lowes and get a brass fitting that has a male pipe (npt) thread on one end, and is tapped with finer threads to accept a 3/8" pipe, but it can be rethreaded easily to accept the standard 3/8 x 24 antenna whip threads. It looks similar to this:
If you go to Tru-Value, or anyone with a good assortment of nuts and bolts, etc, you can get a 3/8" x 24 threaded stud (and a couple of 3/8 x 24 nuts). The stud will screw into the rethreaded fitting and give you a standard stud to try different whips. If you don't have or want to buy a 3/8 x 24 tap, you can use jam-nuts to get a wrench on the stud, and force it into the fitting. The threads are close enough so that even though you "cross thread" it by forcing it in, it pretty much rethreads it so it can be removed and replaced afterward if necessary. While you're at Tru-Value, pick up a couple of 3/8 x 24 threaded collars. They look like this, except have 24 tpi instead of the 20 tpi as shown. (20 tpi is the threaded rod pitch).
All of this 3/8" by 24 stuff is the standard size for most whips such as the Radio Shack 102" whip, and is handy to have around for "adapting".
06-05-2009, 02:14 PM
Yeah, I have been looking around at irrigation pipe and DWV pipe for a weather cover.
I like the idea of the threaded brass insert. I was originally going to use something similar but was more like a pop rivet. You'd use a tool very similar to a pop rivet tool to set the nut into the hole. The only reason I didn't use it was that I couldn't find any 1/4-20 inserts.
I have a 2" receiver hitch on my truck and I'd like to use it for mounting the antenna so I could easily remove it. But yet I'd still like it to come over to the drivers side so I could see it in the mirror.
06-05-2009, 03:09 PM
The 1/4 x 20 is a really common brass insert and is available in a "quantity of one" at Tru-Value and I think also at Home Depot in the hardware sections that have the stuff in compartmented drawers.
Is your receiver hitch factory or aftermarket?
Mine was a U-Haul flavor and installed by them as part of the deal when I bought the van. It has two vertical frame rails about 3 feet or so apart which is ideal for bolting a short piece of 1/4" thick, 2-inch steel angle to and then building from there. I'll see if I can take a couple of photos of the attachment to the hitch frame, maybe yours could be done in a similar fashion.
06-05-2009, 03:12 PM
It's an aftermarket hitch.
I'll have to check out and see how far it tucks in under the truck. I am wanting to avoid making an arm that has a lot of bends in it just to clear the bedside.
06-05-2009, 04:52 PM
Here is a pdf drawing of one that fits my van which isn't exactly like my U-Haul hitch, but is close enough for illustration:
The two brackets that bolt to the frame are a perfect location to mount a piece of angle using two bolts and nuts, with the horizontal side of the angle being at the bottom like a backwards "L" which in my case was flush with the bottome of the bumper. I used this to mount a 2" wide 3/4" thick piece of barstock (with two more bolts and nuts) that peeks out from the bumper.
Once you get that far, you have a lot of possibilities since you are now working with a flat horizontal surface.
Of course like you say, if yours is tucked further the body it might require some headscratching. You might have to add an extension plate to drop the angle down a little further to be even with the bottom of the bumper.
06-05-2009, 05:26 PM
I just came across two more really spiffy antenna motors. I took apart a 12-volt Ryobi cordless drill and it has a very nice planetary drive gearmotor. I was able to strip all the unecessary stuff off including the adjustable clutch function and ended up with just the motor and gearbox. I disabled the clutch by removing the 6 pairs of ball bearings and installing two allen set screws in two of the holes. This secures the star gear and locks the clutch.
The drill chuck was threaded on with ... you guessed it ... a fine thread 3/8" x 24 tpi shaft just like a standard whip, so I was able to use one of the threaded couplers I was talking about earlier, and secure it using a jam nut. Then I could drill a hole through the end of it and the threaded rod so that a cotter pin could secure the rod to the motor shaft, but be able to flex like a u-joint.
I'll try to post a picture of it this weekend when I'm home.
Just for grins, I took another cordless drill apart, a Firestorm 19-volt I think, and it was the same setup as the Ryobi, including the shaft, except that it is a two-speed, so I modified it also and locked it into "high" gear. It runs just fine on "12-volts" (car battery).
I'll try to get a photo of this gear motor also.
I now have two planetary gearmotors begging for antenna versions two and three.
06-05-2009, 07:20 PM
I originally scrounged a 19V cordless drill for the drive part of the antenna. I stripped it all down and locked out the clutch in a similar fashion. I was feeling really good about it until I went to install it inside of the pipe and it was about a 1/4" too wide.
I thought about fabricating something out of PVC to house the motor and connect to the bottom of the copper pipe but I couldn't come up with anything to suit me.
06-05-2009, 08:33 PM
(I went back and edited my two or three previous posts ... I was using 1/4" x 24 where I shoulda used 3/8" x 24)
That's where I was at on these two motors, but not quite 1/4". Mine was more like thousandths of an inch larger than the coil form and main tube ID.
However, I found that the ID of the largest of the Texas Towers aluminum tubing will accept the motor. (Actually, either motor).
Trouble with that is that the coil form would be a sloppy fit in the tube, but the next size smaller Texas Towers tube (which is the same size as the one I now use on my working antenna), which telescopes inside the largest, would accept the coil form with no slop.
What I want to try is to take 6-1/2" of smaller tube and pin it to the bottom 6-1/2" of the PVC coil form so that it slides inside the larger main mast tube. This way the DK3 coil form now has an aluminum "bearing surface". (The DK3 PVC coil form is divided into three sections: 6-1/2" bottom, 15" of winding, and 1/2" of top)
Trouble with this arrangement is that now the larger mast tube won't fit into the PVC that I currently use for the mount and feed in the photos, so like you, it's back to the drawing board for a mount, but I can't pass up this gear motor.
06-06-2009, 11:37 AM
I agree, I am going to keep my drill motor as well. I was piddling around with it and when the gear box is in low gear, that thing has some torque. More than enough to turn a screwdriver antenna.
06-06-2009, 08:51 PM
Yup, you're right about the torque, it would take quite a bind to stop it. At least when the coil reaches the upper or lower limit, the coil just rotates without hurting anything.
Here's a pic of the Ryobi gearmotor with the threaded rod, coupler, and nut that I added. The 1/4" rod fits loosely inside the 3/8 coupler and I put a cotter pin through the holes and it acts sort of like a universal joint in case of any slight misalignment or shaft wobble.
You can see the piece of PVC pipe with the hole in it that has been pressed onto the gear case and it is the same diameter as the coil form. As you can tell, the gear case is a few thousandths larger in diameter than the PVC, so that kept it from being a drop in replacement motor for the Harbor Freight cheapie, so I gotta go to the next larger Texas Tower aluminum tube.
Here it is assembled (without the cotter pin). The nut is used as a jam nut to keep the coupler from backing off the shaft.
The other motor with the black tape is the Firestorm 19-volt, 2-speed. For now, the electrical tape keeps the two locator tabs in place. They use a bayonet arrangement for assembly and if they rotate and misalign by about 10 degrees, the gear case will separate. The tape also holds the shift lever in high gear. The Ryobi doesn't have all that mess.