DK3 AKA Screwdriver Antenna Build.

[Jeff Covert]

I have been wanting to build one of these compact HF antennas for some time. I have several different plans and one is setup for use in an apartment. I am attaching one of the plans so you can see how it look. this antenna was intended as a mobile for you car or truck. It can be used anywhere and has almost the same ERP as a long Dipole. 

I have to buy a spool of wire to make the coil and will have a ton left over. Also setting up the lath for several coil forms would make more sense than to just do it once.

[Jerry Davis]

This looks like a Hi-Q antenna.

Although you will be able to "get out" on all the freqencies, the problem with all of these type of antennas are the "bandwidth". You have to constantly retune. Most Transcievers have an Auto Tune feature, where you just push a button.

Nothing wrong with that, if you know that you have to do that. If you live in an HOA like I do, then a small antenna is one that you HAVE to go with anyway. Why my HOA even wrote me up for one side of my jeep tires was on the rocks instead of the driveway! Let alone anything like a big antenna with lots of bandwidth!

Jerry

On Sun, Sep 14, 2014 at 1:17 PM, Jeff Covert <cove...@gmail.com> wrote:

I have been wanting to build one of these compact HF antennas for some time. I have several different plans and one is setup for use in an apartment. I am attaching one of the plans so you can see how it look. this antenna was intended as a mobile for you car or truck. It can be used anywhere and has almost the same ERP as a long Dipole. 

I have to buy a spool of wire to make the coil and will have a ton left over. Also setting up the lath for several coil forms would make more sense than to just do it once.

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[Jeff Covert]

the Q on this antenna is 200. so you turn on the screwdriver as you change frq. it will give you full band coverage on all ham bands from 3.5 to 30 MHz. my radio has an auto tuner and a function that will run the screwdriver motor and keep everything tuned as I go...

[Jerry Davis]

take a look at this: http://www.k0bg.com/myths.html

it says it better than I ever could.

[Jeff Covert]

Warning:  I'm highly functional Assburgers, so if I sound offensive, I'm not. I'm just trying to get you to help me understand what it is you are trying to say...

OK???

I'm trying to figure out where you are coming from with your attack on the DK3 antenna. 

Any first year engineering student knows that any resonator that is less then 1/4 wave is going to have less than optimal output. So unless you can tell me how to mount My G5RV on my car, we need to have a compromise on this antenna problem. 

The article you listed ends with "you need to read the ARRL handbook several times before you can truly understand what I'm saying". I have read every ARRL handbook printed since 1985 as well as there antenna handbooks. They say that the best mobile antenna compromise (for HF) is a base loaded antenna, and the best of them is the screwdriver.  they even have instructions on how to build one.

The article drones on for all the myths of mobile antennas but never gives the reader a heads up on what is the best compromise out there. In my 30 years of communications we had a saying, "if you give criticism without a solution, you are just whining".

This forum is for us to share what we know to help others. I am looking forward to your solutions to the mobile and apartment communications problem we trying to solve here. You appear to have a lot of knowledge and I hope you will share it and help us out.

Thanks...

P.S. I will be using capacitance hats for the lower bands on the apartment model. something the article mentions but fails to add as a good thing to do.

[Jeff Covert]

Here is the write-up on the Apartment version...

[Jerry Davis]

Jeff,

Slow down ...

I am not attacking you or the antenna. There are real good reasons that they sell those, or in your case, make them.

I can think of two very good reasons to have/make one of those. 1) you want to get HF on your vehicle, or 2) You live in a GD HOA that won't allow a good antenna to be installed.

It is very hard to get real good efficiency here in AZ anyway. The soil here is not very conducive to a good ground plane anyway. So one has to live with what one is given.

I just wanted to point out that these kinds of antennas, will not be very efficient. 

Go for it, and I wish you well. In fact, I would like to see what you come up with, and I know 150 other hams who would like to see what you come up with. Once, you have it up and running, could you come to our ham club and do a talk on it, as my guest? We meet every Mon at 10am Oct-Apr (it is somewhat made up of snowbirds)

Jerry

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[Jerry Davis]

well there's a 3rd reason I can think of. Field Day, up in the mountains.

I have some Hustlers on a home-made outbacker type of tripod.

On a good night, I have, with 100W output (on the radio, much much less out of the antenna), reached Oklahoma/Texas pretty well. Getting to Alabama or the Carolina's once in a while. California, Washington, Oregon, come in pretty well. I have tried WI, MI, but never been able to get there.

So unless conditions are exactly right, I know I will never do much. I know guys with G5RV type of dipoles, that get out much better than I do, but unless you have the "yard" for it, they aren't very practical. I have heard of guys stringing a wire around the top of their house, and getting some results.