SCREWDRIVER ANTENNA BASICS

A Screwdriver is a motorized antenna that extends and retracts, shorting a coil, which adjusts the length of the antenna as it is tuned.
In order to effectively tune the antenna, you need to understand where each of the bands are, and be able to get into the area of the band, and then tune the antenna.
Until you get used to this, you should park your vehicle and tune your antenna.. I don't want to pass you on a two lane while you are trying to figure it out.... Ha...

Once you find out where the bands are, this becomes very easy, and very quick. This is my first screwdriver, so this is my only reference.


FIGURING OUT WHERE THE BANDS ARE:
Make a chart on a piece of paper. Put the frequencies for the bands on the chart.
Lower the antenna all of the way down. Make a mark on the antenna with a sharpie.
Raise the antenna all of the way up. Make another mark.
Select the lower edge of a band on your radio. (IE.. 3.80 for Technician on 75Meters)
Set your Radio on AM, and lower your power to 5 watts.
The SWR on AM will register fully without Audio, so it is better than trying to tune on SSB.
Key up your radio, and hit the switch on your Antenna. Watch the SWR meter, and note when the SWR drops to the desired level.
NOTE: Some of the bands may be located on more than one spot on the antenna, so, once you find a spot, measure from one of the marks you made at the top or bottom of the antenna, and continue to see if you find another.

Do this for every band, and then look at your sheet. Then, you can decide what your favorite bands are, and if you find two of your bands close together, use those two resonant areas closer together.
If you are the type that just wants to run through the bands, and see who is online, just pick it in a reasonable order.
You will find that some of the bands are right on top of each other.

Decide where you will work each band, then get your sharpie and get ready.
Pick your first band, swithch to low power AM, key up, and hit the switch.
When you are motorning up or down, you will most likely pass the resonant area before you release the switch.
I have the Alpine Antenna Screwdriver and the Two Speed Controller that is an option for it that Wes builds.
It has two speeds: Normal and Slow. This feature is very nice for tuning the antenna.

NOTE: Just Remember.. When you tune the antenna, I think it is best if you bump up to the frequency, rather than down.
When you raise the antenna, you can hear the antenna go under load, and then start rising. It is better to bump it up and get it under torque in my opinion, rather than lower it and stop.
I think the frequency would be much more stable when all of the parts are under a torque considering vibration, etc.. It just makes sense.
So, when you pass the resonant area, go just below it, and tune to the exact spot on the way up, rather than down.
Mark the Band location with your sharpie once you have found the bands and decided where you want to work them,

Once you make all of your marks,, Make a Chart and put it on a 3x5 card and put it in the truck with you. It won't take you long to get used to it.
When you want to change bands, move directly to the area, and then, tune the antenna. You will go from minutes to seconds to tune the antenna.
Mount your controls where you can operate them easily, and keep your eyes on the road.

As you can see in the pictures, the Bands are marked. Notice the three marks at the top of the antenna. It is the 80/75 Meter Band. There is quite a bit of space between 3.6 and down on the antenna 3.8 and 4.0. Other bands do not take up so much space on the antenna.

Take a Look at the Chart that relates to this Alpine Screwdriver antenna here:
Let me explain a few things first about the chart. I only listed on resonant area on the band. I failed to keep my notes, but as I remember, there were only thtee bands that had only one resonant spot ont the antenna. I believe they were 75/80, 40, and 10meters, but might have included 20. When I find my notes, I'll update this, but you'll see what I mean when you start learning your setup.
The Alpine Antenna travels approximately 14-1/2 inches. The fist band on the antenna, on the way down is 3.6(the extra Voice Portion of the 80M Band). It is 2-1/2" down from the top of the antenna.
That should tell you what the chart is all about.
Notice that 3.6 starts at 2-1/2" and 3.9 starts at 3", so obviously 3.7 and 3.8 are between that 1/2" inch of travel.
Also notice that 17Meters is in the same area as the 3.6Mhz area of the 80Meter band. Also about the 17Meter band, look at 14" down from the top. A second resonant area for the 17Meter band. I like this band, so I marked it in two places. I can check it quickly when I am on 80 meters, or check it when I move between 15meter and 20meters.
Same as 10Meters is in the same area as 3.9Mhz and the 80Meter band.
So, you can see how this works on the Bands/Antenna setup.

What is the other Chart?
I print this on a piece of paper, and then trim it with a pair of scissors and fold it over and tape it. I drop it in the accessory pocket of the truck close to the radio. What is the second chart?
I just moved from General to Extra, and my Girlfriend is working on her General. I have not gotten used to the new added frequencies yet, so I made a quick little chart.
For 75 Meters, the Voice portion of the Extra Priveledges are from 3.6-3.8Mhz. The General is the 3.8-4.0. So, Extra-Genera-End of band is how I have it.
The 60 Meter frequencies just changed. I just heard about it, but have not found it yet, so at least one of these frequencies is incorrect. I suspect the last number 5.403.5 should be the deleted channel with one added in its place.
The County hunters and Truckers frequencies are notes for me.
The Rampgroup is a group of local Hams here in Western North Carolina. A great bunch of guys. They Ragchew on 75meters twice per day, and more on most days, and that same group plus many others wear out the local repeater.. Ha.. Like I said.. A great bunch of guys. You can always yell at someone and get them.. They are a real hoot..
This year, we got invited to the New Years Eve "OPOSSUM DROP".. New York drops a Ball, they drop Possums around here. Ha.. Sounds like a ball of fun..

Those were the questions that I had, and the things that I experimented with to learn it.
I hope you were where I was when I was figuring this out. This should make it a snap for you.
The bands are not just like you think they would be.. Just take a look at the chart and you'll agree.
If you have any questions, or want to make a comment, please do.. Look me up on QRZ.com.


Anyway.. That is the knowledge I was missing when I bough the screwdriver. I searched and could not find any document like this, so I decided to write one. If one person finds this and reads it and it helps them, it was surely worth the time it took to write it. If that is you,, drop me a line..

Mark Thomas (KJ4SLY).